U.S. Department of 

Transportation

Federal Railroad 

Administration

High-Speed Ground Transportation

Noise and Vibration Impact Assessment

Office of Railroad Policy and Development

Washington, DC 20590

DOT/FRA/ORD-12/15 Final Report

September 2012
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1. AGENCY USE ONLY (Leave blank) 2. REPORT DATE

September 2012

3. REPORT TYPE AND DATES COVERED

Guidance Manual

4. TITLE AND SUBTITLE

High-Speed Ground Transportation Noise and Vibration Impact Assessment

5. FUNDING NUMBERS

6. AUTHOR(S)

Carl E. Hanson, P.E., Jason C. Ross, P.E., and David A. Towers, P.E.

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)

Harris Miller Miller & Hanson, Inc.

77 South Bedford Street

Burlington, MA 01803

8. PERFORMING ORGANIZATION 

REPORT NUMBER

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)

U.S. Department of Transportation 

Federal Railroad Administration

Office of Railroad Policy and Development

Washington, DC 20590

10. SPONSORING/MONITORING

AGENCY REPORT NUMBER

DOT/FRA/ORD-12/15

11. SUPPLEMENTARY NOTES

COTR: Cameron Stuart; COTM: Devin Rouse

12a. DISTRIBUTION/AVAILABILITY STATEMENT

This document is available to the public through the FRA Web site at http://www.fra.dot.gov.

12b. DISTRIBUTION CODE

13. ABSTRACT (Maximum 200 words)

This report is the second edition of a guidance manual originally issued in 2005, which presents procedures for predicting and 

assessing noise and vibration impacts of high-speed ground transportation projects. Projects involving high-speed trains using 

traditional steel-wheel on steel-rail technology as well as magnetically levitated (maglev) systems are included. Procedures for 

assessing noise and vibration impacts are provided for different stages of project development, from early planning through 

preliminary engineering and final design. For both noise and vibration, three levels of analysis are described including a 

preliminary impact screening, a general assessment and a detailed analysis.

This updated guidance contains models for predicting high-speed train noise and vibration as well as criteria for assessing the 

magnitude of potential impacts. A range of mitigation measures are described for dealing with adverse noise and vibration 

impacts. There is a discussion of noise and vibration during the construction stage and also a discussion of how the technical 

information should be presented in the Federal Railroad Administration’s environmental documents. This guidance will be of 

interest not only to technical specialists who conduct the analyses but also to project sponsors, Federal agency reviewers, and 

members of the general public who may be affected by the projects.

14. SUBJECT TERMS

High-speed train noise and vibration analysis, noise and vibration impact criteria, noise and 

vibration mitigation measures, environmental impact assessment, National Environmental Policy 

Act compliance.

15. NUMBER OF PAGES

248

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METRIC/ENGLISH CONVERSION FACTORS

ENGLISH TO METRIC METRIC TO ENGLISH

LENGTH (APPROXIMATE) LENGTH (APPROXIMATE)

1 inch (in) = 2.5 centimeters (cm) 1 millimeter (mm) = 0.04 inch (in)

1 foot (ft) = 30 centimeters (cm) 1 centimeter (cm) = 0.4 inch (in)

1 yard (yd) = 0.9 meter (m) 1 meter (m) = 3.3 feet (ft)

1 mile (mi) = 1.6 kilometers (km) 1 meter (m) = 1.1 yards (yd)

1 kilometer (km) = 0.6 mile (mi)

AREA (APPROXIMATE) AREA (APPROXIMATE)

1 square inch (sq in, in2) = 6.5 square centimeters (cm2) 1 square centimeter (cm2) = 0.16 square inch (sq in, in2)

1 square foot (sq ft, ft2) = 0.09 square meter (m2) 1 square meter (m2) = 1.2 square yards (sq yd, yd2)

1 square yard (sq yd, yd2) = 0.8 square meter (m2) 1 square kilometer (km2) = 0.4 square mile (sq mi, mi2)

1 square mile (sq mi, mi2) = 2.6 square kilometers (km2) 10,000 square meters (m2) = 1 hectare (ha) = 2.5 acres

1 acre = 0.4 hectare (he) = 4,000 square meters (m2)

MASS - WEIGHT (APPROXIMATE) MASS - WEIGHT (APPROXIMATE)

1 ounce (oz) = 28 grams (gm) 1 gram (gm) = 0.036 ounce (oz)

1 pound (lb) = 0.45 kilogram (kg) 1 kilogram (kg) = 2.2 pounds (lb)

1 short ton = 2,000 pounds 

(lb)

= 0.9 tonne (t) 1 tonne (t) =

=

1,000 kilograms (kg)

1.1 short tons

VOLUME (APPROXIMATE) VOLUME (APPROXIMATE)

1 teaspoon (tsp) = 5 milliliters (ml) 1 milliliter (ml) = 0.03 fluid ounce (fl oz)

1 tablespoon (tbsp) = 15 milliliters (ml) 1 liter (l) = 2.1 pints (pt)

1 fluid ounce (fl oz) = 30 milliliters (ml) 1 liter (l) = 1.06 quarts (qt)

1 cup (c) = 0.24 liter (l) 1 liter (l) = 0.26 gallon (gal)

1 pint (pt) = 0.47 liter (l)

1 quart (qt) = 0.96 liter (l)

1 gallon (gal) = 3.8 liters (l)

1 cubic foot (cu ft, ft3) = 0.03 cubic meter (m3) 1 cubic meter (m3) = 36 cubic feet (cu ft, ft3)

1 cubic yard (cu yd, yd3) = 0.76 cubic meter (m3) 1 cubic meter (m3) = 1.3 cubic yards (cu yd, yd3)

TEMPERATURE (EXACT) TEMPERATURE (EXACT)

[(x-32)(5/9)] °F = y °C [(9/5) y + 32] °C = x °F

QUICK INCH - CENTIMETER LENGTH CONVERSION

0 1 2 3 4 5

Inches

Centimeters 0 1 2 3 4 5 6 7 8 9 10 11 12 13

QUICK FAHRENHEIT - CELSIUS TEMPERATURE CONVERSIO

 -40° -22° -4° 14° 32° 50° 68° 86° 104° 122° 140° 158° 176° 194° 212°

 

°F

 °C -40° -30° -20° -10° 0° 10° 20° 30° 40° 50° 60° 70° 80° 90° 100°

For more exact and or other conversion factors, see NIST Miscellaneous Publication 286, Units of Weights and 

Measures. Price $2.50 SD Catalog No. C13 10286 Updated 6/17/98
Contents 1-1

Contents

CHAPTER 1. INTRODUCTION............................................................................................................1-1

1.1 PURPOSE .......................................................................................................................................1-1

1.2 ORGANIZATION OF THE MANUAL ...............................................................................................1-2

1.3 UPDATES TO THE MANUAL .........................................................................................................1-2

1.4 REVISION HISTORY.......................................................................................................................1-4

CHAPTER 2. BASICS OF HIGH-SPEED TRAIN NOISE....................................................................2-1

2.1 NOISE DESCRIPTORS...................................................................................................................2-2

2.1.1 Standard Noise Descriptors.............................................................................................................2-3

2.1.2 The Lmax-SEL Relationship ..............................................................................................................2-5

2.1.3 The Passby Level-SEL Relationship ...............................................................................................2-5

2.1.4 Onset Rate.......................................................................................................................................2-6

2.2 SOURCES OF HIGH SPEED TRAIN NOISE..................................................................................2-8

2.2.1 Regime I: Propulsion Sources .........................................................................................................2-9

2.2.2 Regime II: Mechanical/Structural Sources ....................................................................................2-11

2.2.3 Regime III: Aerodynamic Sources .................................................................................................2-11

2.3 SOUND PROPAGATION PATH....................................................................................................2-12

2.3.1 Divergence.....................................................................................................................................2-12

2.3.2 Atmospheric Absorption.................................................................................................................2-14

2.3.3 Ground Effects...............................................................................................................................2-14

2.3.4 Shielding ........................................................................................................................................2-15

CHAPTER 3. NOISE IMPACT CRITERIA ...........................................................................................3-1

3.1 NOISE IMPACT CRITERIA FOR HIGH SPEED RAIL PROJECTS................................................3-1

3.1.1 Basis of Noise Impact Criteria .........................................................................................................3-2

3.1.2 Definitions of Levels of Impact.........................................................................................................3-5

3.2 APPLICATION OF NOISE IMPACT CRITERIA..............................................................................3-7

3.2.1 Noise-Sensitive Land Uses .............................................................................................................3-7

3.2.2 Considerations in Applying the Noise Impact Criteria .....................................................................3-8

3.2.3 Mitigation Policy Considerations......................................................................................................3-9

3.2.4 Determining the Need for Noise Mitigation....................................................................................3-10

CHAPTER 4. INITIAL NOISE EVALUATION......................................................................................4-1

4.1 NOISE SCREENING PROCEDURE...............................................................................................4-2

4.2 GENERAL NOISE ASSESSMENT..................................................................................................4-4

4.2.1 Noise Source Levels for General Assessment................................................................................4-6

4.2.2 Project Operating Conditions...........................................................................................................4-8

4.2.3 Propagation Characteristics ............................................................................................................4-9

4.2.4 Study Area Characteristics ............................................................................................................4-11

4.2.5 Noise Impact Estimation................................................................................................................4-15

4.2.6 Noise Impact Inventory..................................................................................................................4-17

4.2.7 Noise Mitigation Requirements......................................................................................................4-18

CHAPTER 5. DETAILED NOISE ANALYSIS......................................................................................5-1

5.1 EXISTING CONDITIONS ................................................................................................................5-3

5.1.1 Step 1: Noise Sensitive Receivers .................................................................................................5-3

5.1.2 Step 2: Existing Noise Exposure ....................................................................................................5-5

5.2 PROJECTIONS OF HIGH-SPEED RAIL NOISE ............................................................................5-8

5.2.1 Step 3: Source Reference Levels...................................................................................................5-8

5.2.2 Step 4: Project Operating Conditions ...........................................................................................5-11

5.2.3 Step 5: Propagation of Noise to Receivers...................................................................................5-12

5.2.4 Step 6: Cumulative Noise Exposure.............................................................................................5-17
Contents 1-2

5.2.5 Step 7: Maximum Noise Level for Train Passbys.........................................................................5-22

5.3 STEP 8: NOISE IMPACT ASSESSMENT....................................................................................5-24

5.3.1 Assessment Procedure..................................................................................................................5-24

5.4 STEP 9: MITIGATION OF NOISE IMPACT ..................................................................................5-25

5.4.1 Source Treatments ........................................................................................................................5-27

5.4.2 Path Treatments ............................................................................................................................5-29

5.4.3 Receiver Treatments .....................................................................................................................5-31

5.5 EXAMPLE OF GIS IMPLEMENTATION .......................................................................................5-31

CHAPTER 6. GROUND-BORNE VIBRATION CONCEPTS.............................................................6-34

6.1 DESCRIPTORS OF GROUND BORNE VIBRATION AND NOISE ..............................................6-35

6.1.1 Vibratory Motion.............................................................................................................................6-35

6.1.2 Amplitude Descriptors....................................................................................................................6-36

6.1.3 Ground-Borne Noise......................................................................................................................6-37

6.2 HUMAN PERCEPTION OF GROUND-BORNE VIBRATION AND NOISE ..................................6-37

6.2.1 Typical Levels of Ground-Borne Vibration and Noise ...................................................................6-38

6.2.2 Quantifying Human Response to Ground-Borne Vibration and Noise ..........................................6-39

6.3 FACTORS THAT INFLUENCE GROUND-BORNE VIBRATION AND NOISE.............................6-40

6.4 GROUND-BORNE VIBRATION FROM HIGH-SPEED TRAINS...................................................6-43

CHAPTER 7. VIBRATION IMPACT CRITERIA...................................................................................7-1

7.1 VIBRATION IMPACT CRITERIA FOR GENERAL ASSESSMENT ................................................7-3

7.1.1 Sensitive-Use Categories ................................................................................................................7-3

7.1.2 Existing Vibration Conditions...........................................................................................................7-4

7.1.3 Application to Freight Trains............................................................................................................7-5

7.2 VIBRATION IMPACT CRITERIA FOR DETAILED ANALYSIS.......................................................7-6

7.2.1 Ground-Borne Vibration...................................................................................................................7-6

7.2.2 Ground-Borne Noise........................................................................................................................7-8

CHAPTER 8. PRELIMINARY VIBRATION ASSESSMENT................................................................8-1

8.1 VIBRATION SCREENING PROCEDURE.......................................................................................8-2

8.2 GENERALIZED VIBRATION ASSESSMENT PROCEDURE.........................................................8-3

8.2.1 Base Curve ......................................................................................................................................8-3

8.2.2 Adjustment Factors..........................................................................................................................8-5

8.3 INVENTORY OF VIBRATION IMPACT.........................................................................................8-11

CHAPTER 9. DETAILED VIBRATION ASSESSMENT ......................................................................9-1

9.1 ASSESSMENT OF VIBRATION IMPACT.......................................................................................9-3

9.2 CHARACTERIZING EXISTING VIBRATION CONDITIONS...........................................................9-4

9.3 VIBRATION PREDICTION PROCEDURE......................................................................................9-6

9.3.1 Background......................................................................................................................................9-6

9.3.2 Overview of Prediction Procedure using Measured Transfer Mobility ............................................9-7

9.3.3 Measuring Transfer Mobility and Force Density (Vibration Propagation Testing)...........................9-9

9.3.4 Vibration and Structure-Borne Noise in Buildings .........................................................................9-16

9.4 VIBRATION MITIGATION .............................................................................................................9-18

CHAPTER 10. NOISE AND VIBRATION DURING CONSTRUCTION...............................................10-1

10.1 CONSTRUCTION NOISE ASSESSMENT....................................................................................10-2

10.1.1Noise from Typical Construction Equipment and Operations........................................................10-3

10.1.2Construction Noise Criteria............................................................................................................10-6

10.1.3Quantitative Noise Assessment Methods......................................................................................10-6

10.1.4Mitigation of Construction Noise....................................................................................................10-9

10.2 CONSTRUCTION VIBRATION ASSESSMENT .........................................................................10-11

10.2.1Vibration Source Levels from Construction Equipment...............................................................10-11

10.2.2Construction Vibration Criteria.....................................................................................................10-12

10.2.3Quantitative Construction Vibration Assessment Methods .........................................................10-13
Contents 1-3

10.2.4Construction Vibration Mitigation.................................................................................................10-14

CHAPTER 11. DOCUMENTATION OF NOISE AND VIBRATION ASSESSMENT ...........................11-1

11.1 THE TECHNICAL REPORT ON NOISE AND VIBRATION ..........................................................11-1

11.1.1Organization of Technical Report ..................................................................................................11-2

11.2 THE ENVIRONMENTAL DOCUMENT..........................................................................................11-3

11.2.1Organization of Noise and Vibration Sections...............................................................................11-4

APPENDIX A BACKGROUND – NOISE CONCEPTS........................................................................ A-1

A.1 NOISE METRICS ............................................................................................................................A-1

A.1.1 A-weighted Level: The Basic Noise Unit .........................................................................................A-1

A.1.2 Maximum Level (Lmax) During a Single Noise Event .......................................................................A-2

A.1.3 SEL: The Cumulative Exposure from a Single Noise Event...........................................................A-3

A.1.4 Hourly Equivalent Sound Level [Leq(h)] ...........................................................................................A-3

A.1.5 Day-Night Sound Level (Ldn): The Cumulative 24-Hour Exposure from All Events .......................A-6

A.1.6 Passby Level ...................................................................................................................................A-9

A.1.7 Other Descriptors.............................................................................................................................A-9

A.2 RECEIVER RESPONSE TO TRANSPORTATION NOISE...........................................................A-10

A.3 NOISE IMPACT CRITERIA DEVELOPMENT...............................................................................A-12

A.3.1 Relevant Literature ........................................................................................................................A-12

A.3.2 Basis for Noise Impact Criteria Curves..........................................................................................A-14

A.3.3 Equations for Noise Impact Criteria Curves ..................................................................................A-15

A.4 STARTLE EFFECTS FROM RAPID ONSET RATES...................................................................A-16

A.4.1 High-Speed Rail Noise Signatures ................................................................................................A-17

A.4.2 Research on Startle Effects...........................................................................................................A-17

A.4.3 Startle Effects Applied to High-Speed Rail Impact Assessment ...................................................A-18

A.5 EFFECTS ON LIVESTOCK AND WILDLIFE ................................................................................A-19

A.5.1 Summary .......................................................................................................................................A-19

A.5.2 Noise Descriptor ............................................................................................................................A-20

A.5.3 Thresholds for Disturbance ...........................................................................................................A-20

A.5.4 Habituation.....................................................................................................................................A-21

APPENDIX B DETERMINING EXISTING NOISE............................................................................... B-1

APPENDIX C CONVERTING BETWEEN Lmax OR PASSBY LEVEL AND SEL................................ C-1

C.1 COMPUTING Lmax FOR A SINGLE TRAIN PASSBY..................................................................... C-1

C.2 COMPUTING REFERENCE SEL'S FROM LMAX FOR GENERAL ASSESSMENT METHOD ...... C-2

C.3 ESTIMATING SEL FROM PASSBY LEVEL................................................................................... C-4

APPENDIX D HIGH-SPEED TRAIN NOISE AND VIBRATION MEASUREMENTS.......................... D-1

D.1 HIGH-SPEED TRAIN NOISE MEASUREMENTS.......................................................................... D-1

D.2 EFFECTIVENESS OF NOISE SOURCE MITIGATION ................................................................. D-5

D.3 HIGH-SPEED TRAIN VIBRATION MEASUREMENTS ................................................................. D-8

APPENDIX E SOURCE REFERENCE LEVELS FOR CONVENTIONAL TRAINS (FREIGHT AND 

PASSENGER) ........................................................................................................................................E-1

APPENDIX F GLOSSARY OF TERMS ...............................................................................................F-1

APPENDIX G BACKGROUND INFORMATION FOR FRA NOISE SCREENING TABLE ................ G-1

Figures

Figure 2-1 The Source-Path-Receiver Framework....................................................................................2-2

Figure 2-2 Typical A-Weighted Maximum Sound Levels...........................................................................2-3

Figure 2-3 Typical High-Speed Train Passby ............................................................................................2-5
Contents 1-4

Figure 2-4 Typical Longer-Duration High-Speed Train Event....................................................................2-6

Figure 2-5 Measured High-Speed Rail Onset Rates .................................................................................2-7

Figure 2-6 Generalized Sound Level Dependence on Speed ...................................................................2-9

Figure 2-7 Noise Sources on a Steel-Wheeled High-Speed Train System .............................................2-10

Figure 2-8 Noise Sources on a Maglev System.......................................................................................2-10

Figure 2-9 Attenuation Because of Distance (Divergence)......................................................................2-13

Figure 2-10 Attenuation Because of Soft (Sound-Absorptive) Ground....................................................2-15

Figure 2-11 Noise Barrier Geometry........................................................................................................2-16

Figure 3-1 Noise Impact Criteria for High-Speed Rail Projects .................................................................3-3

Figure 3-2 Increase in Cumulative Noise Levels Allowed by Criteria (Land-Use Cat. 1 & 2)....................3-7

Figure 4-1 Generalized SEL vs. Speed for a High-Speed Train Passby...................................................4-8

Figure 4-2 Distance from Tracks within which Surprise Can Occur for HST...........................................4-16

Figure 4-3 Typical Corridor Segment for Example 4-1, Alignment Alternative 2 .....................................4-20

Figure 4-4 Noise Exposure vs. Distance for Example 4-1 .......................................................................4-22

Figure 5-1 Guide to Selecting Receivers of Interest ..................................................................................5-3

Figure 5-2 Recommended Microphone Locations for Existing Noise Measurements...............................5-7

Figure 5-3 Computation of Ground Factor G for Ground Attenuation......................................................5-14

Figure 5-4 Barrier Geometry Models of Terrain for Computation of Shielding ........................................5-16

Figure 5-5 Determining Noise Impact Using GIS.....................................................................................5-33

Figure 6-1 Propagation of Ground-Borne Vibrations into Buildings.........................................................6-35

Figure 6-2 Different Methods of Describing a Vibration Signal................................................................6-36

Figure 6-3 Typical Levels of Ground-Borne Vibration..............................................................................6-38

Figure 6-4 Occupant Response to Urban Transit-Induced Residential Vibration....................................6-39

Figure 7-1 Criteria for Detailed Vibration Analysis.....................................................................................7-7

Figure 8-1 Generalized Ground-Borne Vibration Curve ............................................................................8-4

Figure 9-1 Impact Method for Measuring Transfer Mobility .....................................................................9-10

Figure 9-2 Schematic of Two Approaches for Transfer Mobility Measurements.....................................9-12

Figure 9-3 Equipment Required for Field Testing and Laboratory Analysis ............................................9-13

Figure 9-4 Analysis of Transfer Mobility...................................................................................................9-14

Figure 9-5 Force Densities for High-Speed Trains ..................................................................................9-17

Figure 9-6 Characteristics Force Spectra for the TR08 on Each Type of Guideway...............................9-18

Figure 9-7 Approximate Foundation Response for Various Types of Buildings ......................................9-18

Figure A-1 Example A-Weighted Sound Level Time Histories ..................................................................A-5

Figure A-2 Typical Hourly Leqs ...................................................................................................................A-6

Figure A-3 Typical Ldns...............................................................................................................................A-8

Figure A-4 Community Reaction to New Noise, Relative to Existing Noise in a Residential Urban 

Environment..................................................................................................................................A-11

Figure A-5 Community Annoyance Because of Noise.............................................................................A-12

Figure A-6 Time History of A-weighted Sound Level of Maglev at 25 m .................................................A-17

Figure A-7 Zones of Potential Startle Effect.............................................................................................A-19
Contents 1-5

Figure D-1 Measured and Modeled SEL’s vs. Speed from Electric Locomotive-Hauled Trains .............. D-3

Figure D-2 Measured and Modeled SELs vs. Speed from EMU Trains ................................................... D-4

Figure D-3 Measured and Modeled SELs vs. Speed from Fossil Fuel Locomotive-Hauled Trains ......... D-4

Figure D-4 Measured and Modeled SELs vs. Speed from Maglev Trains ............................................... D-5

Figure D-5 Measured and Modeled SELs vs. Speed from EMU Trains Including Shinkansen 700T 

and Fastech 360Z ........................................................................................................................... D-7

Figure D-6 SELs vs. Speed from Shinkansen EMU Trains With and Without Noise Source Mitigation 

Measures......................................................................................................................................... D-8

Figure D-7 Overall Vibration Velocity Level for Different High-Speed Trains ........................................... D-9

Figure D-8 Best-Fit Curves of Vibration Velocity Level vs. Distance...................................................... D-10

Figure D-9 Vibration Velocity vs. Distance Calculated from Smoothed One-Third Octave Bands......... D-11

Figure D-10 Comparison of One-Third Octave Band Spectra................................................................ D-12

Figure D-11 Line-Source Transfer Mobility at the Test Sites.................................................................. D-13

Figure D-12 Force Density Functions Derived from Measurements....................................................... D-14

Figure D-13 Projected Vibration Velocity, Transfer Mobility from Site in France.................................... D-15

Figure D-14 Projected Vibration Velocity, Transfer Mobility from Site in Sweden.................................. D-16

Figure D-15 Projected Vibration Velocity, X2000 Force Density ............................................................ D-17

Tables

Table 1-1 Revision History of Updated Manual (2012)..............................................................................1-4

Table 3-1 Noise Levels Defining Impact for High-Speed Train Projects ...................................................3-4

Table 3-2 Land-Use Categories and Metrics for High-Speed Train Noise Impact Criteria........................3-5

Table 3-3 Interim Criteria for High-Speed Train Noise Effects on Animals ...............................................3-5

Table 3-4 Noise Impact Thresholds: Effect on Cumulative Noise Exposure ............................................3-6

Table 4-1 Screening Distances for Noise Assessments............................................................................4-3

Table 4-2 Assumptions for Screening Distances* .....................................................................................4-4

Table 4-3 Reference Parameters at 50 ft from Track/Guideway ...............................................................4-7

Table 4-4 Shielding Corrections for Track Geometry ..............................................................................4-10

Table 4-5 Computation of Noise Exposure at 50 ft for General Assessment..........................................4-11

Table 4-6 Estimating Existing Noise Exposure for General Assessment ................................................4-14

Table 4-7 Sample Noise Impact Inventory Table.....................................................................................4-18

Table 5-1 Noise-Sensitive Land Uses........................................................................................................5-4

Table 5-2 Noise Source Reference Levels for High-Speed Trains (SELs at 50 ft)..................................5-11

Table 5-3 Computation of Shielding: Barriers and Terrain .....................................................................5-15

Table 5-4 Computation of Leq and Ldn ...................................................................................................5-18

Table 5-5 Computation of Excess Shielding: Rows of Buildings and Dense Tree Zones ......................5-19

Table 5-6 High-Speed Train Noise Mitigation Measures .........................................................................5-27

Table 6-1 Human Response to Different Levels of Ground-Borne Noise and Vibration .........................6-42

Table 6-2 Factors that influence Levels of Ground-Borne Vibration and Noise ......................................6-42

Table 7-1 Ground-Borne Vibration (GBV) and Ground-Borne Noise (GBN) Impact Criteria for 

General Assessment..........................................................................................................................7-2
Contents 1-6

Table 7-2 Ground-Borne Vibration and Noise Impact Criteria for Special Buildings .................................7-4

Table 7-3 Interpretation of Vibration Criteria for Detailed Analysis............................................................7-8

Table 8-1 Screening Distances for Vibration Assessments.......................................................................8-2

Table 8-2 Adjustment Factors for Generalized Predictions of Ground-Borne Vibration and Noise...........8-6

Table 10-1 Construction Equipment Noise Emission Levels ...................................................................10-5

Table 10-2 General Assessment Criteria for Construction Noise............................................................10-6

Table 10-3 Detailed Assessment Criteria for Construction Noise............................................................10-6

Table 10-4 Computing Total Noise Exposure..........................................................................................10-8

Table 10-5 Vibration Source Levels for Construction Equipment (from measured data.,,) ....................10-12

Table 10-6 Construction Vibration Damage Criteria ..............................................................................10-13

Table A-1 Summary of Noise Levels Associated with Effects on Animals and Birds ..............................A-21

Table C-1 Computation of Lmax for a High-Speed Train Passby using General Assessment or 

Detailed Analysis Method ................................................................................................................. C-2

Table C-2 Computation of SEL for a High-Speed Train Passby from Lmax for General Assessment....... C-4

Table E-1 Noise Source Reference Levels for Conventional Freight Trains (SEL at 50 ft).......................E-2
Chapter 1: Introduction 1-1

CHAPTER 1. INTRODUCTION

1.1 PURPOSE

High-Speed Ground Transportation Noise and Vibration Impact Assessment provides guidance and 

procedures for the assessment of potential noise and vibration impacts resulting from proposed highspeed ground transportation (HSGT) projects, including high-speed trains using traditional steel-wheel on 

steel-rail technologies including and magnetically levitated (maglev) systems.

1

 This manual is intended

for projects with train speeds of 90–250 mph. The document reflects the results of research conducted for 

the Federal Railroad Administration (FRA) and is presented as part of FRA’s efforts to promote the 

consideration of HSGT as a transportation option in those intercity corridors where it has the potential to 

be a cost-effective and environmentally sound component of the intermodal transportation system. The 

Federal Transit Administration’s (FTA) Transit Noise and Vibration Impact Assessment2 manual provides 

guidance for projects with conventional train speeds below 90 mph. The National Environmental Policy 

Act (NEPA) and related statutes, regulations, and orders mandate consideration of potential impacts on 

the human and natural environment as part of the decisionmaking process when Federal agencies evaluate 

proposals to fund or otherwise approve major actions. Most States have similar environmental review 

requirements. This manual provides guidance on conducting noise and vibration impact assessments for 

NEPA studies. Following the guidelines in this manual does not necessarily ensure that a proposed 

project would meet all regulatory requirements in regard to noise and vibration impacts.

Experience during previous environmental impact reviews of high-speed rail projects has shown that 

possible increases in noise and vibration are frequently among the potential impacts of most concern to 

 

1 For brevity, this manual uses the terms “high-speed ground transportation” and “high-speed train” interchangeably, 

both referring to guided high-speed intercity transportation. 2 U.S. Department of Transportation (U.S. DOT), FTA. Transit Noise and Vibration Impact Assessment, Report No. 

FTA-VA-90-1003-06, May 2006.
Chapter 1: Introduction 1-2

residents in the vicinity of a proposed project. As the interest in HSGT grows and environmental reviews

of HSGT projects are initiated across the country, it becomes clear to FRA that there is a need to provide 

a standardized set of procedures for the evaluation of noise and vibration impacts. There is also a need to 

provide guidance to promoters and designers of HSGT projects on ways in which the design of those 

projects can incorporate measures that address these concerns. In addition, there is a need for providing a 

means through which public agency reviewers of projects can determine where and to what extent the 

public benefits of HSGT justify investment in noise and vibration impact mitigation. This manual 

attempts to fulfill these needs.

1.2 ORGANIZATION OF THE MANUAL

The guidance is divided into two parts, noise and vibration. Each part has a parallel organization, which 

addresses the following topics:

Topic Noise Vibration

Basic Concepts Chapter 2 Chapter 6

Criteria Chapter 3 Chapter 7

Initial Evaluation Chapter 4 Chapter 8

Detailed Analysis Chapter 5 Chapter 9

Construction Noise/Vibration Chapter 10.1 Chapter 10.2

Documentation Chapter 11 Chapter 11

Appendices

A. Background for Noise Concepts

B. Existing Noise Determination

C. Noise Source Reference Level Determination 

D. Trainset Noise and Vibration Measurement Results

E. Freight and Passenger Train Noise Levels

F. Glossary of Terms

G. Background Information for FRA Noise Screening Table

1.3 UPDATES TO THE MANUAL

The revisions reflect the most current knowledge on noise and vibration emissions from high-speed trains, 

noise source mitigation, and clarifications to policy-related topics such as guidance on determining the 

need for mitigation of moderate noise impacts. The following outlines all of the significant updates to 

this manual:

• Updated information on typical noise descriptors, such as Passby Level, and its relationship to 

Sound Exposure Level (SEL) has been included. The fundamental description and illustration of 

SEL as an “energy” metric has been removed.

• The fundamental overview of the noise modeling methodology in Chapter 2 has been removed to 

eliminate redundancy because this information is provided in Chapter 4 for the Initial Noise 

Evaluation and Chapter 5 for the Detailed Noise Analysis.
Chapter 1: Introduction 1-3

• Although the noise impact criteria have not changed, the guidance for startle from high-speed 

trains has been clarified to recommend identifying sensitive receptors that are within a certain 

threshold of rapid onset rate (as opposed to applying a quantitative adjustment to SEL values).

• Guidance on defining the need for noise mitigation has been included in Chapter 3. The decision 

to include mitigation assessments may depend on factors such as the number of noise-sensitive 

sites affected, the relative increase in noise levels, the sensitivity at affected land uses, the

effectiveness of mitigation measures, community views, costs versus benefits, design limitations,

whether sensitive use is solely indoors, and safety. For example, where land-use activity is solely 

indoors, an interior Ldn criterion of 45 decibels A-weighted (dBA) from project sources is 

recommended to determine whether building sound insulation improvements should be 

considered for mitigation. It is suggested, however, that each project sponsor develop a noise 

mitigation policy to delineate a consistent approach to mitigating Moderate and Severe impacts 

early in the planning process. It is also suggested that project sponsors develop an approach to 

determining whether to assess potential impact and to consider mitigation for undeveloped lands 

where noise or vibration-sensitive uses are planned.

• Noise model input variables have been updated to reflect currently available data on high-speed 

trainsets in the United States, Europe, and Asia. Information on projecting noise levels from 

high-speed electric multiple-unit trains has been added. Directions are included for how to use 

the FTA guidance manual for modeling high-speed diesel-electric locomotive trains and diesel 

multiple-unit trains. General guidance on methods to collect reference noise emission data of 

high-speed trains has been added. Noise measurement data supporting the models, including data 

collected for the initial model development and more recent measurement results for high-speed 

train systems in the United States, Europe, and Asia, is presented in Appendix D.

• The methods to compute sound propagation from high-speed trains have not been revised, 

although information on when and how to include atmospheric absorption in sound propagation 

calculations over long distances has been added.

• Current noise source mitigation measures and information on their potential overall effectiveness

have been included.

• The discussion has been updated regarding the use of geographical information system (GIS) 

tools and acoustic modeling tools for assessing potential noise and vibration impact.

• The ground-borne vibration criteria have been updated to be consistent with FTA criteria,

including categories for frequent, occasional, and infrequent vibration events and the use of 

detailed one-third octave band vibration criteria for human annoyance and vibration-sensitive 

equipment. The relationship between ground-borne vibration and ground-borne noise has been 

revised, based on recent studies. Ground-borne vibration limits to minimize potential structural 

damage for different building construction types also have been added.

• Guidance on when to conduct a quantitative versus a qualitative construction noise and vibration 

impact assessment has been provided and methods to conduct both general and detailed 

construction noise impact assessments have been included. In addition, noise source emission 

levels for typical construction equipment used in rail projects have been updated and the principal 

components of a typical construction noise and vibration mitigation plan have been provided.
Chapter 1: Introduction 1-4

1.4 REVISION HISTORY

The following table provides detailed information on the significant updates to this version of the manual:

Table 1-1 Revision History of Updated Manual (2012)

Chapter Section Revision

1 1.3 Section 1.3 has been added to summarize the updates to the manual.

2

2.1.1

The definition of SEL noise descriptor has been expanded to describe the time 

over which this descriptor is evaluated.

A definition for Passby Level noise descriptor has been added.

2.1.2 Former section on other noise descriptors has been deleted. Information on 

these descriptors is provided in Appendix A.

2.1.3 New to this section is the relationship between Passby Level and SEL.

Description and illustration of SEL as an “energy” metric have been deleted.

2.1.4 A paragraph has been added to this section with an example to better describe 

the concept of rapid onset rate.

Figure 2-7 This figure has been updated to indicate motor/gear noise on electric multiple 

unit (EMU) trains.

2.3.2 This new section has been added to address sound attenuation along the 

propagation path by atmospheric absorption.

2.3.3 Section has been renamed “Ground Effects”

2.4

This former section (“Mathematical Model of High-Speed Train Noise”) has 

been deleted. The noise modeling methods are covered in Chapters 4 and 5,

and the sources of supporting data for the noise models are presented in 

Appendix D. 

3

3.1.1

Table 3-1 has been revised to define noise impact ranges with a precision of 

within one-tenth of a decibel to correspond more precisely to the impact criteria 

equations in Appendix A.3.3.

In Table 3-2, the descriptions for land-use categories 1 and 3 have been revised,

and the footnote recommending the use of onset-rate adjusted sound levels has 

been deleted.

3.2.1 A paragraph has been added to provide guidance for the consideration of 

undeveloped land in the noise assessment.

3.2.2 The second paragraph has been revised with regard to the locations where the 

noise criteria should be applied.

3.2.4

This new section has been added to provide guidance on determining the need 

for noise mitigation for factors such as the number of noise-sensitive sites 

affected, the relative increase in noise levels, the sensitivity at affected land 

uses, the effectiveness of mitigation measures, community views, costs vs.

benefits, design limitations, whether sensitive use is solely indoors, and safety.

4

4.2.1

Descriptions the train technologies represented by each modeling category are 

provided. The electric-powered category include electric locomotive-hauled 

trains and EMU trains. The fossil fuel category includes gas-turbine 

locomotive hauled trains. The FTA guidance manual is recommended for 

modeling high-speed (up to 150 mph) diesel-electric locomotive hauled trains 

and diesel multiple unit trains.

Table 4-3 This table has been updated for the electric steel-wheeled reference SEL in 

Regime I and the applicable speeds in which the models should be used.

Table 4-5 This table has been updated to provide accurate reference lengths for modeling 

trains in Regime I.

4.2.5 Information on the threshold for rapid onset rate as an additional annoyance has 

been moved to this section on Noise Impact Assessment.
Chapter 1: Introduction 1-5

Table 1-1 Revision History of Updated Manual (2012)

Chapter Section Revision

4.2.7 The need to consider the safety of mitigation measures during the engineering 

design phase has been added.

5

Table 5-1 Table has been updated to address sensitivity of parks with passive recreation.

5.1.1 Current web-based geographical information system tools are presented as 

additional methods of identifying sensitive land use.

5.2 A repeated list of Steps 3 to 7 has been removed from the section.

5.2.1

This section has been updated to include more detailed information about the 

representative trains within each modeling category and the type of system on 

which the trains are operating (i.e., ballast and tie track and wheel and rail 

roughness conditions). The modeling categories have been redefined to include 

high-speed and very high-speed electric locomotive hauled trains, high-speed 

and very high-speed EMU trains, high-speed gas turbine locomotive-hauled 

trains, and maglev trains.

A paragraph was added for further guidance on conducting reference noise 

measurements.

Table 5-2

This noise source reference levels have been updated based on currently 

available noise emission data for high-speed trains around the world. The highspeed electric locomotive reference levels have been updated to be consistent 

with the very high-speed reference levels (not including aerodynamic 

subsources). The reference speed for the propulsion subsource on electric 

locomotive hauled trains has been deleted because there is no speed 

dependence for this subsource. The high-speed and very high-speed EMU train 

categories are consistent (not including aerodynamic subsources). The 

effective propulsion source height for EMU trains has been updated to 2 feet 

(ft) above the rail. The propulsion subsource reference SEL and reference 

length for EMU trains have been updated to reflect the distribution of noise 

over the entire length of the train. There are no changes to the high-speed gasturbine category reference levels. The train nose subsource reference length for 

maglev trains has been deleted because this subsource does not depend on total 

length of the train, and the subsource height has been updated to 0 ft above the 

rail. The turbulent boundary layer subsource reference length has been updated 

to reflect the total length of the train.

Example 5-2 This example has been updated to reflect changes to the source reference levels 

of high-speed electric locomotive hauled trains.

Table 5-6

This table has been updated to indicate that the noise models are based on 

ballast and tie track and that using slab track would increase to the modeled 

noise levels.

5.4.1

Information on the overall effectiveness of mitigation for trains that incorporate 

several noise source mitigation measures is included. More detail on the noise 

emissions of these trains is provided in Appendix D.

Typical costs for noise barrier materials, not including installation, design, or 

construction inspection, have been updated.

Further guidance on sound insulation improvements is included. Sound 

insulation improvements should be considered if interior noise levels would be 

45 Ldn or greater from project noise sources prior to mitigation. 

5.5

A typical procedure for using GIS technology for assessing potential impact, 

analyzing mitigation, preparing figures, and using as a public outreach tool is 

presented.

6 6.2.1

The recommended adjustment for converting ground-borne vibration to 

ground-borne noise in buildings has been changed from 0 to -5 decibels (dB),

based on recent research findings.
Chapter 1: Introduction 1-6

Table 1-1 Revision History of Updated Manual (2012)

Chapter Section Revision

7

Table 7-1 The general assessment criteria have been updated to include limits for 

frequent, occasional, and infrequent events, consistent with FTA criteria.

7.1.1 The text in this section has been modified for improved clarity on the types of 

vibration-sensitive receivers.

7.1.2

The text in this section has been modified for improved clarity on the 

consideration of existing vibration in existing railroad corridors and shared-use 

corridors.

7.2

This new section has been added to provide ground-borne vibration criteria for 

the Detailed Analysis, consistent with FTA criteria. A description of assessing 

potential ground-borne noise impact is provided.

8

Table 8-1 This table has been updated to include vibration screening distance for sources 

in the occasional number of events category.

8.2.2

In the paragraph discussing vibration radiated as ground-borne noise, the 

recommended adjustment for converting vibration to ground-borne noise has 

been changed from 0 to -5 dB, based on recent research findings.

9

9.3.3 The use of FM recorders for achieving low-frequency response when 

measuring vibration has been removed.

9.3.4 The recommended adjustment for radiated noise has been changed from 0 to 

-5 dB, based on recent research findings.

9.4

A description of tire-derived aggregate (TDA) has been added to the list of 

potential vibration control measures, although the feasibility and effectiveness 

of such mitigation has not been addressed.

10

10.1 This section has been expanded to provide guidance for both qualitative and 

quantitative construction noise assessments.

10.1.1

Some of the equipment source noise levels in Table 10-1 have been updated,

based on recent Federal Highway Administration (FHWA) investigations.

A footnote was removed from Table 10-3 that permitted higher construction 

noise criteria for residential land use, based on the existing noise levels in noisy 

urban areas.

10.1.2

This section on construction noise assessment methods has been revised to 

provide quantitative methods for both a general assessment and a detailed 

assessment.

10.1.3 Guidance has been added recommending the development of a noise mitigation 

plan for major construction projects.

10.2 Guidance has been provided for cases where quantitative construction vibration 

assessments are appropriate.

10.2.1 In Table 10-5, new vibration source levels have been added for vibratory rollers 

and hoe rams.

10.2.2 This section has been added to provide construction vibration damage criteria.

10.2.4 Guidance has been added for the development of a construction vibration 

mitigation plan.

11 11.2

This section has been significantly expanded to provide more detailed guidance 

on the content of the environmental document, particularly with regard to 

mitigation.

Appendix A

A.1.6 This section has been added to define the Passby Level.

A.4.2 The text in this section has been modified for improved clarity on the approach 

to considering potential startle from high-speed trains.

A.4.3 The text in this section has been modified for improved clarity on the approach 

to considering potential startle from high-speed trains.

Appendix B No revisions have been made to this appendix.

Appendix C C.3 This section has been added to provide a procedure for estimating the SEL 

from the Passby Level.
Chapter 1: Introduction 1-7

Table 1-1 Revision History of Updated Manual (2012)

Chapter Section Revision

Appendix D

D.1

This section has been added to include high-speed train noise data and general 

and detailed modeling results for all train technologies. Data from former 

Section 2.4 of the manual as well as more recent data is included.

D.2

This new section has been added to show the typical overall effectiveness of 

mitigation for high-speed trains that incorporate several noise source mitigation 

measures.

Appendix E

This section has been updated to include a reference to the FRA Chicago 

Region Environmental and Transportation Efficiency (CREATE) model for 

conventional-speed freight and diesel-electric passenger trains.

Appendix F No revisions have been made to this appendix.

Appendix G The figures in this appendix have been enhanced.

Chapter 2: Basics of High-Speed Train Noise 2-1

CHAPTER 2. BASICS OF HIGH-SPEED TRAIN NOISE

Noise from high-speed train systems is similar to noise from other rail systems except for a few unique 

features resulting from the higher speeds of travel. The rail systems defined as “high-speed” are primarily 

steel wheeled, both electrically powered and fossil fueled, capable of maximum speeds of 125 mph and 

greater. Noise characteristics of these trains vary considerably as speed increases. Consequently, this 

manual subdivides these systems into three categories:

• “high-speed,” with a maximum speed of 150 mph,

• “very high-speed,” with a maximum speed of 250 mph, and

• “maglev,” magnetically levitated and powered systems representing the upper range of speed 

performance up to 300 mph.3

Because ancillary sources are not unique to high-speed train systems, noise from electrical substations, 

maintenance facilities, yards, and stations are not addressed in this manual. These noise sources are 

substantially the same for any type of rail system and do not have characteristics specific to high-speed 

train systems. The methods described in the corresponding transit noise manual from FTA are 

applicable.4

 

This chapter discusses the basic concepts of high-speed ground transportation noise to provide 

background for the assessment procedures presented in Chapters 4 and 5. Noise from a ground 

transportation system is often expressed for a Source-Path-Receiver framework. This framework is 

 

3

Noise from maglev in this manual is based principally on research and test track data from the German 

TransRapid System.

4

U.S. DOT, FTA. Transit Noise and Vibration Impact Assessment, Final Report, FTA-VA-90-1003-06, 

May 2006.
Chapter 2: Basics of High-Speed Train Noise 2-2

sketched in Figure 2-1 and is central to all environmental noise studies. Each project source generates 

close-by noise levels, which depend on the type of source and its operating characteristics. Then, along 

the propagation path between all sources and receivers, noise levels are reduced (attenuated) by distance, 

intervening obstacles, and other factors. Finally, at each receiver, noise combines from all sources and 

may interfere with receiver activities.

Figure 2-1 The Source-Path-Receiver Framework

This chapter emphasizes the sources of noise from high-speed trains and, to a lesser extent, the path

component, which includes aspects such as sound attenuation with increasing distance from the source, 

excess attenuation as a result of atmospheric absorption and ground effects, and acoustic shielding by 

terrain, sound barriers, or intervening buildings. Noise sensitivity at the receiver is addressed in Chapter 3 

on noise impact criteria.

In brief, this chapter contains:

• a summary of the noise descriptors used in this manual for high-speed train noise (Section 2.1);

• an overview of noise sources, including a list of major sources specific to high-speed train 

systems and discussion of noise-generation mechanisms (Section 2.2); and

• an overview of noise paths, with a discussion of the various attenuating mechanisms on the path 

between source and receiver (Section 2.3).

2.1 NOISE DESCRIPTORS

The universal descriptor used for environmental noise is the A-weighted sound level. It describes the 

level of noise measured at a receiver at any moment in time and is read directly from noise-monitoring 

equipment, with the weighting switch set on “A.” Typical A-weighted maximum sound levels for highspeed ground transportation and other sources are shown in Figure 2-2. The high-speed ground 

transportation sources are described further in Section 2.2.
Chapter 2: Basics of High-Speed Train Noise 2-3

Figure 2-2 Typical A-Weighted Maximum Sound Levels

As shown in Figure 2-2, typical A-weighted sound levels range from the 40s to the 90s, where 40 is very 

quiet and 90 is very loud. The scale in the figure is labeled “dBA” to denote the way A-weighted sound 

levels are typically written. The letters “dB” stand for “decibels” and refer to the general strength of the 

noise. The letter “A” indicates that the sound has been filtered to reduce the strength of very low and 

very high frequency sounds, much as the human ear does. Without this A-weighting, noise monitoring 

equipment would respond to events people cannot hear, such as high-frequency dog whistles and lowfrequency seismic disturbances. On the average, each A-weighted sound level increase of 10 dB

corresponds to an approximate doubling of subjective loudness. Definitions of acoustical terms are given 

in Appendix F. Additional information about noise and its measurement can be obtained from textbooks 

and handbooks on acoustics.

2.1.1 Standard Noise Descriptors

The following single-number descriptors, all based on the A-weighted sound level as the fundamental 

unit, are commonly used for environmental noise measurements, computations, and assessment:

The Maximum Level (Lmax) during a single noise event. There are two standard ways of 

obtaining the Lmax, one using the “fast” response setting on the sound level meter, or Lmax,f

(obtained by using a 0.125-second (s) averaging time), and the other using the “slow” setting, or 

Lmax,slow (obtained by using a 1-second averaging time). Lmax,fast can occur arbitrarily and is 

usually caused by a single component on a moving train, often a defective component such as a 

flat spot on a wheel. As a result, inspectors from FRA use Lmax,fast to identify excessively noisy 
Chapter 2: Basics of High-Speed Train Noise 2-4

locomotives and rail cars during enforcement of Railroad Noise Emission Compliance 

Regulations.5

 Lmax,slow, with its greater averaging time, tends to de-emphasize the effects of 

nonrepresentative impacts and impulses and is generally better correlated with the SEL, defined 

below, which is the basis of impact assessment. Thus, Lmax,slow is typically used for modeling 

train noise mathematically. In general, however, the Lmax descriptor in either form is not 

recommended for noise impact assessment. Because it is used in vehicle–noise specifications and 

commonly measured for individual vehicles, equations are included in Appendix C to convert 

between Lmax,slow and the cumulative descriptors described below. 

The Sound Exposure Level (SEL) describes a receiver’s cumulative noise exposure from a 

single noise event. It is represented by the total A-weighted sound energy during the event, 

normalized to a 1-second interval. For a vehicle passby, the time interval over which the SEL is 

evaluated includes all the acoustic energy related to the event, extending over the points in time 

when the sound level is at least 10 dB below the highest sound level during the passby. SEL is 

the primary descriptor of high-speed rail vehicle noise emissions and an intermediate value in the 

calculation of both Leq (h) and Ldn (defined below).

The Passby Level (LpAeq, Tp) represents an average of the noise energy that the train generates 

from all cars during the time of a passby of the entire train, where the time of the passby is the 

length of the train divided by its speed. The European Union limits for high-speed train noise are 

based on this noise metric.

The Hourly Equivalent Sound Level [Leq(h)] describes a receiver’s cumulative noise exposure 

from all events over a 1-hour period. The underlying metric for calculating Leq(h) from single 

noise events during a 1-hour period is SEL. Leq(h) is used in this manual to assess noise for 

nonresidential land uses. For assessment, Leq is computed for the loudest operating hour during 

the hours of noise-sensitive activity.

The Day-Night Sound Level (Ldn or DNL) describes a receiver’s cumulative noise exposure 

from all events over a 24-hour period. The basic unit used in calculating Ldn is the Leq(h) for each 

1-hour period. It may be thought of as a noise exposure, totaled after increasing all nighttime ALevels (between 10 p.m. and 7 a.m.) by 10 dB. Every noise event during the 24-hour period 

increases this exposure, louder events more than quieter events, and events that are of longer 

duration more than briefer events. In this manual, Ldn is used to assess noise for residential land 

uses. Typical community Ldns range from approximately 50–70 dBA, where 50 represents a quiet 

noise environment and 70 is a noisy one. 

Detailed definitions and mathematical representations for all of the above noise descriptors, as well as for 

other descriptors used in various parts of the world, are presented in Appendix A.

 

5

U.S. DOT, FRA. Railroad Noise Emission Compliance Regulations, Final Rule, 48 Federal Register

56756-56761, December 23, 1983 (23 Code of Federal Regulations 210).
Chapter 2: Basics of High-Speed Train Noise 2-5

2.1.2 The Lmax-SEL Relationship

To help the reader gain a preliminary understanding of high-speed ground transportation noise descriptors 

and the interrelationships among descriptors, the following discussion illustrates how SEL, the 

fundamental descriptor used in calculating noise exposure from single events, relates to Lmax. Both 

descriptors characterize a single noise event; however, they do not always correlate with each other. 

Detailed methods for converting between Lmax and SEL are included in Appendix C.

The Lmax for a typical high-speed train passby is identified in Figure 2-3, where time is plotted 

horizontally and A-weighted sound level is plotted vertically. The event shown represents a measured 

time signature of a TGV passby at 180 mph at 82 ft (25 meters (m)).

The noise exposure that occurred during the high-speed train passby is shaded in Figure 2-3. This 

exposure represents the total amount of sound energy that is detected by the receiver's ears (or the 

measurement microphone) during the passby. A noise event of longer duration, a Eurostar train passby at 

90 mph, is shown in Figure 2-4. For this event, the noise exposure is large because of duration. Since the 

Eurostar train is nearly two times as long as the standard TGV trains, both the added length and slower 

speed contribute to the increased duration of the Eurostar event. Compared with the event in Figure 2-3, 

the Lmax is 4 dBA lower, but the measured SELs are the same.

2.1.3 The Passby Level–SEL Relationship

Although the Passby Level is not used in this manual for calculating noise exposure, it can be used to 

approximate the SEL by normalizing the sound energy represented by this metric to a 1-second interval. 

However, because the Passby Level is evaluated only over the time period of the event, the SEL is 

typically approximately 1 dB greater than this normalized value because of the additional sound energy 

received during the time intervals just before and after the passby that is included the SEL.

Figure 2-3 Typical High-Speed Train Passby
Chapter 2: Basics of High-Speed Train Noise 2-6

Figure 2-4 Typical Longer-Duration High-Speed Train Event

2.1.4 Onset Rate

An important characteristic of the noise from high-speed rail systems is the onset rate of the sound 

signature. Onset rate is the average rate of change of increasing sound pressure level in decibels per 

second during a single noise event. The rapid approach of a high-speed train is accompanied by a sudden 

increase in noise for a receiver near the tracks. Researchers report that sounds of approaching vehicles 

carry a sense of convergence and cause greater annoyance than receding sounds.6

 Moreover, sounds with 

fast onset rates are more annoying than sounds with less rapid variation or steady noise with the same 

maximum noise level.7

 Research by the U.S. Air Force on the effect of onset rate on aircraft noise 

annoyance shows that people are increasingly annoyed by sudden sounds with onset rates greater than 

approximately 15 dB/s, as described more fully in Appendix A.8,9

 Onset rates of greater than 15 dB/s 

occur for receivers within 60 ft of a 150-mile per hour train, and occur at greater distances for trains at 

 

6

G. Rosinger, D. W. Nixon, and H. E. von Gierke. Quantification of the noisiness of ‘approaching’ and 

‘receding’ sounds. Journal of the Acoustical Society of America, 48, 843-853 (October 1970).

7

K. Plotkin, L. C. Sutherland, and J. A. Molino. Environmental Noise Assessment for Military Aircraft 

Training Routes: Volume 2: Recommended Noise Metric. Wyle Laboratories Report WR 86-21 prepared for 

Wright-Patterson Air Force Base AAMRL/BBE, April 1987.

8

K. J. Plotkin, K. W. Bradley, J. A. Molino, K. G. Helbing, and D. A. Fisher. The Effect of Onset Rate on 

Aircraft Noise Annoyance, Vol. 1: Laboratory Experiments, U.S. Air Force Systems Command, Report No. AL-TR1992-0093, May 1992.

9

E. Stusnick, K. A. Bradley, J. A. Molino, and G. deMiranda, The Effect of Onset Rate on Aircraft Noise 

Annoyance, Vol. 2: Rented Home Experiment, U.S. Air Force Materiel Command, Report No. AL/OE-TR-1993-

0170, October 1992.
Chapter 2: Basics of High-Speed Train Noise 2-7

higher speeds. Measured onset rates for a steel wheel train (ICE) and a maglev train (TR 07) are shown 

plotted for the ratio of speed to distance in Figure 2-5. The plot shows that onset rate:

• increases as speed increases for a given distance, and

• decreases as distance increases for a given speed.

Figure 2-5 Measured High-Speed Rail Onset Rates

For example, if a person is located at a distance of 50 ft from the track and a train passes at a speed of 100 

mph the Speed/Distance Factor is 2, and Figure 2-5 indicates an onset rate of approximately 10 dB/s, 

whereas for a train speed of 150 mph the Speed/Distance Factor is 3, resulting in a much higher onset rate 

of approximately 20 dB/s. However, if the person moves back to a position 75 ft from the track, the 

Speed/Distance Factor for a 150-mile per hour train is 2, and the onset rate drops back to approximately

10 dB/s. Thus, there is greater potential for increased annoyance with higher train speeds and at locations 

close to the track.

Although the measured onset rates in Figure 2-5 do not exceed approximately 25 dB/s at normal 

measurement distances, actual onset rates can rise to greater values close to the tracks. When onset rates 

exceed approximately 30 dB/s, people tend to be startled, or surprised, by the sudden onset of the sound. 

Startle as an added factor in annoyance is discussed in Appendix A-4. The onset rate of 30 dB/s is used 

as the basis for establishing distances within which startle is likely to occur and serves as added 

information in the impact assessment methods presented in Chapters 4 and 5.
Chapter 2: Basics of High-Speed Train Noise 2-8

2.2 SOURCES OF HIGH-SPEED TRAIN NOISE

Noise source information used to develop the high-speed ground transportation noise model in this 

manual are taken from the trainset noise measurement data included in Appendix D. This section 

presents a general discussion of the sources of noise from high-speed trains.

The total wayside noise generated by a high-speed train passby consists of several individual noisegenerating mechanisms, each with its own characteristics of source location, strength, frequency content, 

directivity, and speed dependence. These noise sources can be generalized into three major regimes:

10

Regime I. propulsion or machinery noise

Regime II. mechanical noise resulting from wheel-rail interactions and/or guideway vibrations

Regime III. aerodynamic noise resulting from airflow moving past the train, including the pantograph

For a conventional train with a maximum speed of up to approximately 125 mph, propulsion and 

mechanical noise are sufficient to describe the total wayside noise. The aerodynamic noise component 

begins to be an important factor when the train speed exceeds approximately 160 mph.

The significance of these different regimes is that, for a given train, there are three distinct speed ranges in 

which one sound source contributes most to the total noise level. The dependence of the A-weighted 

sound level on vehicle speed (S) for a typical high-speed train is illustrated in Figure 2-6. A qualitative 

indication of the maximum sound level during a passby is plotted vertically in this figure. The three 

speed regimes are labeled “I,” “II,” and “III,” each corresponding to the most significant sound source in 

the regime, or propulsion, mechanical, and aerodynamic noise, respectively. The speed at which the 

major sound source changes from one to another is called an acoustical transition speed (vt). The 

transition from propulsion noise to mechanical noise occurs at the lower acoustical transition speed (vt1), 

and the transition from mechanical to aerodynamic noise occurs at the upper acoustical transition speed 

(vt2). 

 

10B. Barsikow and B. Müller. Wayside Noise Generated by the German High-Speed Transport Systems, 

ICE and Transrapid, 72nd Annual Meeting of the Transportation Research Board, Washington, DC, 1993.
Chapter 2: Basics of High-Speed Train Noise 2-9

Figure 2-6 Generalized Sound Level Dependence on Speed

The various noise sources for a steel-wheeled high-speed tracked system and maglev system are 

illustrated in Figures 2-7 and 2-8, respectively. These sources differ in where they originate on the train 

and in what frequency range they dominate.

2.2.1 Regime I: Propulsion Sources

Steel-Wheeled Trains. At low speeds, Regime I, propulsion mechanisms, or machinery and auxiliary 

equipment that provide power to the train are the predominant sound sources. Most high-speed trains are 

electrically powered; the propulsion noise sources are, depending on the technology, associated with 

electric traction motors or electromagnets, control units, and associated cooling fans (see Figure 2-7). 

These noise sources are at the power units for conventional trains and are distributed over the length of 

the train for electric multiple unit (EMU) trains. Fans can be a major source of noise; on conventional 

steel-wheeled trains, the fans are usually located near the top of the power units, approximately 10 ft 

above the rails, where on EMU trains the fans are located near the bottom of the cars. Fan noise tends to 

dominate the noise spectrum in the frequency bands near 1,000 Hz. External cooling fan noise tends to be 

constant with respect to train speed, which makes fans the dominant noise when a train is stopped in a 

station.
Chapter 2: Basics of High-Speed Train Noise 2-10

Figure 2-7 Noise Sources on a Steel-Wheeled High-Speed Train System

Figure 2-8 Noise Sources on a Maglev System

Maglev Trains. Noise from the propulsion magnets in a maglev system is a result of induced vibration 

from magnetic forces. One source of vibration is oscillating magnetostriction, which also causes the 

characteristic hum sometimes heard from electrical transformers and which is likely to be tonal in 

character (see Figure 2-8). Sound at the magnetic pole-passing frequency is another effect of magnetic 

traction; the interaction of the moving vehicle and the stationary magnetic poles at a uniform spacing 

causes a tonal sound that varies uniformly with velocity. These forces are located at the magnet gaps 

between the vehicle and the guideway. Propulsion noise in general has a relatively weak speed 

dependence, typically following a relationship of 10 times the logarithm of speed.
Chapter 2: Basics of High-Speed Train Noise 2-11

2.2.2 Regime II: Mechanical/Structural Sources

Steel-Wheeled Trains. The effects of wheel-rail interaction of high-speed trains, guideway structural 

vibrations, and vehicle-body vibrations fall into the category of mechanical noise sources. These sources 

tend to dominate the total noise level at intermediate speeds (Regime II) and cover the widest of the threespeed regimes. For steel-wheeled trains, wheel-rail interaction is the source of the rolling noise radiated 

by steel wheels and rails caused by small roughness elements in the running surfaces. This noise source 

is close to the track bed with an effective height of approximately 2 ft above the rails. The spectrum for 

rolling noise peaks in the 2- to 4-kilohertz frequency range, and it increases more rapidly with speed than 

does propulsion noise, typically following the relationship of 30 times the logarithm of train speed. 

Wheel-rail noise typically dominates the A-weighted sound level at speeds up to approximately 160 mph. 

Maglev Trains. Maglev technology is not free from mechanical/structural noise sources despite the lack 

of physical contact with the guideway. The maglev analogies to wheel-rail noise from a steel-wheeled 

train are noise from wheels rolling on guideway support surfaces at low speeds for electrodynamic 

systems (EDS), which require forward motion up to a certain speed before lift can occur, and noise from 

magnetic pole-passing. Sound also is radiated by guideway vibrations and vehicle body vibrations. Both 

of these sources tend to radiate sounds at relatively low acoustical frequencies; fundamental resonance 

frequencies of guideway support beams are generally below 10 Hz, with radiation from box beam panels 

up to approximately 80 Hz. Vehicle body vibrations depend on the details of body panel construction; 

they can result in substantial sound radiation throughout the audible range. For maglev systems, the 

combination of all mechanical sources results in an increase of noise approximately proportional to 

40 times the logarithm of speed. 

2.2.3 Regime III: Aerodynamic Sources

Propulsion and rolling noise are generally sufficient to describe the total noise up to speeds of 

approximately 160 mph for steel-wheeled trains. Above this speed, however, aerodynamic noise sources 

tend to dominate the radiated noise levels. These sources begin to generate significant noise at speeds of 

approximately 180 mph, depending on the magnitude of the mechanical/structural noise. For maglev, this 

transition occurs at a lower speed because of low levels of mechanical noise.

Steel-Wheeled Trains. Aerodynamic noise is generated from high-velocity airflow over the train. For a 

conventional steel-wheeled train, the components of aerodynamic noise are generated by unsteady flow 

separations at the front and rear of the train and on structural elements of the train (mainly in the regions 

encompassing the trucks, the pantograph, intercoach gaps, and discontinuities along the surface) and a 

turbulent boundary layer generated over the entire surface of the train. 

Maglev Trains. For a maglev vehicle, aerodynamic noise sources include the flow separation on the 

front and rear ends, vortex shedding from the antennae, flow interactions in the gap between the vehicle 

and guideway, the wake generated at the trailing end, and the turbulent boundary layer. 

Aerodynamic sources generally radiate sound in the frequency bands below 500 Hz, generally described 

as a rumbling sound. Aerodynamic noise level increases with train speed much more rapidly than does 

propulsion or rolling noise, with typical governing relationships of 60–70 times the logarithm of speed.
Chapter 2: Basics of High-Speed Train Noise 2-12

2.3 SOUND PROPAGATION PATH

This section contains a qualitative overview of noise-path characteristics from source to receiver, 

including attenuation along these paths. Sound paths from source to receiver are predominantly air-borne. 

Along these paths, sound reduces with distance as a result of (1) divergence, (2) atmospheric 

absorption, (3) ground effects, and (4) shielding. The general equation for the prediction of the Aweighted sound level at various distances from the track can be expressed as follows:

LA = LA(ref) + Cd + Ca + Cg + Cb

where: LA(ref) = a known A-weighted sound level at some reference distance ref from the source

Cd = adjustment factor for attenuation because of divergence

Ca = adjustment factor for excess attenuation because of atmospheric absorption

Cg = adjustment factor for excess attenuation from ground effects

Cb = adjustment factor for excess attenuation because of obstacles such as barriers, 

berms, and buildings.

In nearly all cases, the adjustment factors are negative numbers due to the nature of the reference 

conditions. Each of these adjustment factors are discussed in Sections 2.3.1–2.3.4 in terms of their 

mechanisms of sound attenuation. Specific equations for computing noise-level attenuations along 

source-receiver paths are presented in Chapters 4 and 5. Sometimes a portion of the source-to-receiver 

path is not through the air but rather through the ground or through structural components of the 

receiver’s building. Ground-borne and structure-borne noise propagation are discussed in Chapter 6.

2.3.1 Divergence

Sound levels naturally attenuate with distance. Such attenuation, technically called “divergence,”

depends on source configuration and source-emission characteristics. Divergence is shown graphically 

for point sources and line sources separately in terms of how they attenuate with distance in Figure 2-9. 

The divergence adjustment factor, Cd, for the receiver is plotted vertically relative to the sound level 50 ft 

from the source. As shown, the sound level attenuates with increasing distance because of the geometric 

spreading of sound energy. 

For sources grouped closely together (called point sources), attenuation with distance is large: 6 dB per 

doubling of distance. Most individual noise sources on a moving high-speed rail vehicle radiate sound as 

point sources. When many point sources are arrayed in a line, all radiating sound at the same time so any 

one source is not distinguishable, the arrangement is called a line source. For line sources, divergence 

with distance is less: 3 dB per doubling of distance for Leq and Ldn, and 3–6 dB per doubling of distance 

for Lmax. A train passing along a track or guideway can be considered a line source. In Figure 2-9, the 

line source curve separates into three separate lines for Lmax, with the point of departure depending on the 

length of the line source. For example, close to a short train, it behaves like a line source; far away, it 

behaves as a point source. The curves shown in Figure 2-9 are for illustrative purposes only, and the 

exact equations for these curves given Chapter 5 should be used for quantitative analyses.
Chapter 2: Basics of High-Speed Train Noise 2-13

Figure 2-9 Attenuation Because of Distance (Divergence)

Some sound sources, such as warning bells, radiate sound energy nearly uniformly in all directions. 

These are called nondirectional, or monopole, sources. For train noise, however, the rolling noise from 

wheel-rail interactions, as well as some types of aerodynamic noise, is complicated because the sources 

do not radiate sound equally well in all directions. This unequal radiation is known as source directivity, 

which is a measure of the variation in a source’s radiation with direction. Studies have shown that wheelrail noise can be modeled by representing the source as a line source (or continuous row of point sources) 

with dipole directivity.11 A dipole radiation pattern has also been observed in the turbulent boundary 

 

11E. J. Rathe. Railway noise propagation. Journal of Sound and Vibration, 51, 371-388 (1977).
Chapter 2: Basics of High-Speed Train Noise 2-14

layer near the sides of a train.12 Typically, a dipole source radiates a directivity pattern such that the 

sound pressure is proportional to the cosine of the angle between the source orientation and the receiver. 

Consequently, wheel-rail noise is propagated more efficiently to either side of a moving train than in 

front, above, or behind it.

2.3.2 Atmospheric Absorption

In addition to geometric spreading, sound energy is attenuated by molecular absorption by the air. 

Although this effect is often neglected for urban rail transit projects where noise impacts are typically 

limited to distances of one-quarter mile or less, atmospheric absorption can become more significant for 

high-speed rail projects, particularly where noise projections are required for receptors located at greater 

distances in open areas with low ambient sound levels. In such cases, it is appropriate to include 

attenuation for atmospheric absorption to avoid overpredicting noise levels and impacts from high-speed 

train operations. Sound absorption in the air is a function of temperature, humidity, and atmospheric 

pressure as well as the frequency content of the sound. For the purpose of predicting sound attenuation as 

a result of atmospheric absorption (Ca), the methods contained in the American National Standards 

Institute Standard S1.26-1995 or the International Standards Organization (ISO) Standard 9613-2 can be 

applied. For purposes of rough estimation, atmospheric absorption can be taken to be 1 dBA per 1,000 ft 

for “standard day” conditions (temperature of 59 °F and relative humidity of 70 percent), assuming that 

the A-weighted sound level for trains is most influenced by noise in the 500- to 1,000-hertz frequency 

range.

2.3.3 Ground Effects

In addition to attenuating because of geometric spreading and atmospheric absorption of the sound 

energy, sound levels are further attenuated when sound paths lie close to absorptive or “soft” ground, such 

as freshly plowed or vegetation-covered areas. This additional attenuation, which can be 5 dB or more 

within a few hundred feet, is illustrated graphically in Figure 2-10. In this figure, the adjustment factor, 

Cg, is plotted vertically as a function of distance. At very large distances, wind and temperature gradients 

can alter the ground attenuation shown here; such variable atmospheric effects generally influence noise 

levels well beyond the range of typical railway noise impact and are not included in this manual. 

 

12W. F. King. “On the boundary layer contribution to wayside noise generated by high-speed tracked 

vehicles,” Inter-Noise ’94 Proceedings, pp. 175-180 (1994).
Chapter 2: Basics of High-Speed Train Noise 2-15

Equations for the curves in Figure 2-10 are presented in Chapter 5.

Figure 2-10 Attenuation Because of Soft (Sound-Absorptive) Ground

2.3.4 Shielding

Sound paths are sometimes interrupted by noise barriers, by terrain, by rows of buildings, or by 

vegetation. Noise barriers, usually the most effective means of mitigating noise in sensitive areas, are the 

most important of these path interruptions. A noise barrier reduces sound levels at a receiver by breaking 

the direct path between source and receiver with a solid wall; vegetation, in contrast, hides the source but 

does not reduce sound levels significantly. Sound energy reaches the receiver only by bending 

(diffracting) over the top of the barrier, as shown in Figure 2-11. This diffraction reduces the sound level 

at the receiver.
Chapter 2: Basics of High-Speed Train Noise 2-16

Figure 2-11 Noise Barrier Geometry

Noise barriers for transportation systems typically attenuate noise at the receiver by 5–15 dBA (which 

corresponds to an adjustment factor Cb range of -5 to -15 dBA), depending on receiver and source height, 

barrier height, length, and distance from both source and receiver. The attenuation of noise by a barrier 

also is frequency dependent (i.e., all other factors being the same, the higher the frequency of the noise, 

the greater the barrier attenuation). As discussed in Section 2.2, the peak frequencies and source heights 

of high-speed ground transportation noise vary according to the dominant noise source in a particular 

speed regime. In general, aerodynamic noise has lower peak frequencies than that of wheel-rail noise, 

which means that a barrier is less effective at attenuating aerodynamic noise. In addition, aerodynamic 

noise sources tend to be located higher up on the train than wheel-rail noise sources. As a result, a noise 

barrier high enough to shield aerodynamic noise will be relatively expensive compared with a barrier for 

controlling wheel-rail noise, because it must extend 15 ft or more above the top of rail. For operating 

speeds up to approximately 160 mph, a barrier high enough to shield wheel-rail and other lower carbody 

sound sources would normally provide sufficient sound attenuation. 

Barriers on structure, very close to the source, provide less attenuation than predicted using standard 

barrier attenuation formulae, because of reverberation (multiple reflections) between the barrier and the 

body of the train. This reverberation can be offset by increased barrier height, which is easy to obtain for 

such close barriers and/or the use of acoustically absorptive material on the source side of the barrier. 

These concepts are illustrated in Figure 2-11. Acoustical absorption is included as a mitigation option in 

Chapter 5. Equations for barrier attenuation, as well as equations for other sound-path interruptions, also 

are presented in Chapter 5.
Chapter 3: Noise Impact Criteria 3-1

CHAPTER 3. NOISE IMPACT CRITERIA

The criteria used in evaluating noise impacts from high-speed ground transportation are based on 

maintaining a noise environment considered acceptable for land uses where noise may have an effect. 

These criteria take into account the unusual noise characteristics of high-speed rail operations, including 

the effects of startle on humans, livestock, and wildlife to the extent that these effects are known. 

The noise impact criteria for high-speed ground transportation facilities are presented in Section 3.1. 

These criteria are adapted from criteria developed by FTA for rail noise sources operating on fixed 

guideways or at fixed facilities.

13 The criterion for the onset of Moderate Impact varies according to the 

existing noise level and the predicted project noise level, and it is determined by the minimum measurable 

change in community reaction. The corresponding criterion for Severe Impact also varies according to 

the existing noise level as well as the project noise level, but it is determined by the change in community 

reaction between an acceptable and an unacceptable noise environment. Guidelines for the application of 

the criteria are included in Section 3.2, and background material on the development of the criteria is 

included in Appendix A.

3.1 NOISE IMPACT CRITERIA FOR HIGH-SPEED RAIL PROJECTS

The noise impact criteria for high-speed ground transportation projects are shown in graphs and tables in 

this section. The equations used to define these criteria are included in Appendix A. The criteria apply to 

high-speed train operations as well as to fixed facilities such as storage and maintenance yards, passenger 

stations and terminals, parking facilities, and substations.

 

13 U.S. DOT, FTA. Transit Noise and Vibration Impact Assessment, Final Report, FTA-VA-90-1003-06, May 2006.
Chapter 3: Noise Impact Criteria 3-2

3.1.1 Basis of Noise Impact Criteria

The noise impact criteria for human annoyance, presented in Figure 3-1 and Table 3-1, are based on 

comparison of the existing outdoor noise levels and the future outdoor noise levels from a proposed highspeed train project. They incorporate both absolute criteria, which consider activity interference caused 

by the high-speed train project alone, and relative criteria, which consider annoyance because of the 

change in the noise environment caused by the project. These criteria were developed to apply to a wide 

variety of surface transportation modes, to recognize the heightened community annoyance caused by 

late-night or early-morning operations, and to respond to the varying sensitivities of communities to 

projects under different background noise conditions. Background information on the development of the 

noise impact criteria is included in Appendix A.

The noise criteria and descriptors for human annoyance depend on land use, as defined in Table 3-2. 

Further guidance on the definition of land use, the selection of the appropriate noise metric, and the 

application of these criteria are given in Section 3.2, with more detailed guidelines provided in Chapters 4 

and 5.

Noise effects on livestock and wildlife also have been considered. There are no established criteria 

relating high-speed train noise and animal behavior. However, some characteristics of high-speed train 

noise are similar to low overflights of aircraft, and researchers generally agree that high noise levels from 

aircraft overflights can have a disturbing effect on both domestic livestock and wildlife. Some animals get 

used to noise exposure while some do not. Documented effects range from simply taking notice and 

changing body position to taking flight in panic. Whether these responses represent a threat to survival of 

animals remains unclear, although panic flight may result in injuries to animals in rough terrain or in 

predation of unprotected eggs of birds. A limited amount of quantitative noise data relating actual levels 

to effects provides enough information to develop a screening procedure to identify areas where noise 

from high-speed train operations could affect domestic and wild animals. The basis for the screening is 

shown in Table 3-3. A summary of recent literature related to noise effects on livestock and wildlife is 

included in Appendix A. 
Chapter 3: Noise Impact Criteria 3-3

Figure 3-1 Noise Impact Criteria for High-Speed Rail Projects
Chapter 3: Noise Impact Criteria 3-4

Table 3-1 Noise Levels Defining Impact for High-Speed Train Projects

Existing 

Noise 

Exposure*

Leq(h) or Ldn

(dBA)

Project Noise Impact Exposure,* Leq(h) or Ldn (dBA)

Category 1 or 2 Sites Category 3 Sites

No Impact Moderate 

Impact

Severe 

Impact No Impact Moderate Impact

Severe 

Impact

<43 < Ambient+10

Ambient +

10 to 15 >Ambient+15 <Ambient+15

Ambient +

15 to 20 >Ambient+20

43 <51.6 51.6–57.6 >57.6 <56.6 56.6–62.6 >62.6

44 <51.8 51.8–58.6 >58.6 <56.8 56.8–63.6 >63.6

45 <52.0 52.0–58.6 >58.6 <57.0 57.0–63.6 >63.6

46 <52.2 52.2–58.7 >58.7 <57.2 57.2–63.7 >63.7

47 <52.5 52.5–58.9 >58.9 <57.5 57.5–63.9 >63.9

48 <52.7 52.7–59.1 >59.1 <57.7 57.7–64.1 >64.1

49 <53.0 53.0–59.3 >59.3 <58.0 58.0–64.3 >64.3

50 <53.4 53.4–59.5 >59.5 <58.4 58.4–64.5 >64.5

51 <53.7 53.7–59.7 >59.7 <58.7 58.7–64.7 >64.7

52 <54.1 54.1–60.0 >60.0 <59.1 59.1–65.0 >65.0

53 <54.4 54.4–60.4 >60.4 <59.4 59.4–65.4 >65.4

54 <54.9 54.9–60.7 >60.7 <59.9 59.9–65.7 >65.7

55 <55.3 55.3–61.1 >61.1 <60.3 60.3–66.1 >66.1

56 <55.7 55.7–61.5 >61.5 <60.7 60.7–66.5 >66.5

57 <56.2 56.2–61.9 >61.9 <61.2 61.2–66.9 >66.9

58 <56.7 56.7–62.3 >62.3 <61.7 61.7–67.3 >67.3

59 <57.2 57.2–62.8 >62.8 <62.2 62.2–67.8 >67.8

60 <57.8 57.8–63.3 >63.3 <62.8 62.8–68.3 >68.3

61 <58.4 58.4–63.8 >63.8 <63.4 63.4–68.8 >68.8

62 <58.9 58.9–64.4 >64.4 <63.9 63.9–69.4 >69.4

63 <59.6 59.6–64.9 >64.9 <64.6 64.6–69.9 >69.9

64 <60.2 60.2–65.5 >65.5 <65.2 65.2–70.5 >70.5

65 <60.8 60.8–66.1 >66.1 <65.8 65.8–71.1 >71.1

66 <61.5 61.5–66.7 >66.7 <66.5 66.5–71.7 >71.7

67 <62.2 62.2–67.4 >67.4 <67.2 67.2–72.4 >72.4

68 <62.9 62.9–68.0 >68.0 <67.9 67.9–73.0 >73.0

69 <63.6 63.6–68.7 >68.7 <68.6 68.6–73.7 >73.7

70 <64.4 64.4–69.4 >69.4 <69.4 69.4–74.4 >74.4

71 <65.0 65.0–70.1 >70.1 <70.0 70.0–75.1 >75.1

72 <65.0 65.0–70.8 >70.8 <70.0 70.0–75.8 >75.8

73 <65.0 65.0–71.6 >71.6 <70.0 70.0–76.6 >76.6

74 <65.0 65.0–72.3 >72.3 <70.0 70.0–77.3 >77.3

75 <65.0 65.0–73.1 >73.1 <70.0 70.0–78.1 >78.1

76 <65.0 65.0–73.9 >73.9 <70.0 70.0–78.9 >78.9

77 <65.0 65.0–74.7 >74.7 <70.0 70.0–79.7 >79.7

>77 <65.0 65.0–75.0 >75.0 <70.0 70.0–80.0 >80.0 * Ldn is used for land use where nighttime sensitivity is a factor; Leq during the hour of maximum transit noise exposure is 

used for land use involving only daytime activities.
Chapter 3: Noise Impact Criteria 3-5

Table 3-2 Land-Use Categories and Metrics for High-Speed Train Noise Impact Criteria

Land-Use

Category

Noise Metric

(dBA) Description of Land-Use Category

1 Outdoor Leq(h)*

Tracts of land where quiet is an essential element in their intended purpose. 

This category includes lands set aside for serenity and quiet, and such land 

uses as outdoor amphitheaters and concert pavilions, as well as national 

historic landmarks with significant outdoor use. Also included are 

recording studios and concert halls.

2 Outdoor Ldn

Residences and buildings where people normally sleep. This category 

includes homes, hospitals, and hotels where a nighttime sensitivity to noise 

is assumed to be of utmost importance.

3 Outdoor Leq(h)*

Institutional land uses with primarily daytime and evening use. This 

category includes schools, libraries, theaters, and churches, where it is 

important to avoid interference with such activities as speech, meditation, 

and concentration on reading material. Places for meditation or study 

associated with cemeteries, monuments, and museums can also be 

considered to be in this category. Certain historical sites, parks, 

campgrounds, and recreational facilities are also included. *

 Leq for the noisiest hour of transit-related activity during hours of noise sensitivity.

Table 3-3 Interim Criteria for High-Speed Train Noise Effects on Animals

Animal Category Class Noise Metric Noise Level (dBA)

Domestic

Mammals (Livestock) SEL 100

Birds (Poultry) SEL 100

Wild

Mammals SEL 100

Birds SEL 100

3.1.2 Definitions of Levels of Impact

The noise impact criteria are defined by two curves relating project noise levels to existing noise. Below 

the lower curve in Figure 3-1, a proposed project is considered to have no noise impact because, on the 

average, the introduction of the project will result in an insignificant increase in the number of people 

highly annoyed by the new noise. The curve defining the onset of Moderate Impact stops increasing at 

65 dB for Category 1 and 2 land use, a standard limit for an acceptable living environment as defined by a 

number of Federal agencies. Project noise above the upper curve is considered to cause Severe Impact 

because a significant percentage of people would be highly annoyed by the new noise. This curve flattens 

out at 75 dB for Category 1 and 2 land use, a level associated with an unacceptable living environment. 

As indicated by the right-hand scale on Figure 3-1, the project noise criteria are 5 dB higher for Category 

3 land uses because these types of land use are considered to be slightly less sensitive to noise than the 

types of land use in Categories 1 and 2.

The proposed project is judged to have Moderate Impact between these two curves. The change in the 

cumulative noise level is noticeable to most people, but it may not be sufficient to cause strong, adverse 

reactions from the community. In this transitional area, other project-specific factors must be considered 
Chapter 3: Noise Impact Criteria 3-6

to determine the magnitude of the impact and the need for mitigation, such as the predicted level of 

increase over existing noise levels and the types and numbers of noise-sensitive land uses affected.

Although the curves in Figure 3-1 are defined in terms of the project noise exposure and the existing noise 

exposure, it is important to emphasize that the increase in the cumulative noise—when the project noise is 

added to existing noise—is the basis for the criteria. The complex shapes of the curves are based on the 

considerations of cumulative noise increase described in Appendix A. To illustrate this point, Figure 3-2 

shows the noise impact criteria for Category 1 and 2 land use in terms of the allowable increase in the 

cumulative noise exposure. The horizontal axis is the existing noise exposure, and the vertical axis is the 

increase in cumulative noise level as a result of the high-speed train project. The measure of noise 

exposure is Ldn for residential areas and Leq for land uses that do not have nighttime noise sensitivity. 

Because Ldn and Leq are measures of total acoustic energy, any new noise source in a community will 

cause an increase, even if the new source level is less than the existing level. Figure 3-2 shows that the 

criterion for Moderate Impact allows a noise exposure increase of 10 dBA if the existing noise exposure 

is 42 dBA or less but only a 1-decibal A increase when the existing noise exposure is 70 dBA.

As the existing level of ambient noise increases, the allowable level of project noise increases, but the 

total allowable increase in community noise exposure is reduced. This reduction accounts for an

unexpected result—project noise exposure levels that are less than the existing noise exposure can still 

cause impact. The examples in Table 3-4 more clearly illustrate the levels of project noise and existing 

levels of exposure that result in crossing the threshold of impact. In this table, the total noise exposure is 

calculated by combining the existing and project noise exposure as follows:

Ltotal = 10*log[10(Lexisting/10) + 10(Lproject/10)]

Table 3-4 Noise Impact Thresholds: Effect on Cumulative Noise Exposure

Ldn or Leq in dBA (rounded to nearest whole decibel)

Existing Noise 

Exposure

Project Noise 

Exposure

Combined Total Noise 

Exposure

Noise Exposure 

Increase

45 52 53 8

50 53 55 5

55 55 58 3

60 58 62 2

65 61 66 1

70 65 71 1

75 65 75 0
Chapter 3: Noise Impact Criteria 3-7

Figure 3-2 Increase in Cumulative Noise Levels Allowed by Criteria (Land-Use Cat. 1 & 2)

Any increase in noise exposure equal to or greater than what is shown in Table 3-4 will cause impact. 

This table indicates that as the existing noise exposure increases from 45 to 75 dBA, the allowed project 

noise exposure impact threshold increases from 52 to 65 dBA. However, the impact threshold for 

increase in the cumulative noise level decreases from 8 to 0 dBA (rounded to the nearest whole decibel). 

The justification for this decrease is that people already exposed to high levels of noise will notice and be 

annoyed by even a small increase in the amount of noise in their community. In contrast, if the existing

noise levels are quite low, a greater change in the community noise will be required for the equivalent 

level of annoyance. It should be noted that these annoyance levels are based on general community 

reactions to noise at varying levels that have been documented in scientific literature and do not account 

for specific community attitudinal factors that may exist.

3.2 APPLICATION OF NOISE IMPACT CRITERIA

This section provides practical guidance on interpretation of the land-use categories and application of the 

impact criteria.

3.2.1 Noise-Sensitive Land Uses

As indicated in Section 3.1.1, the noise impact criteria and descriptors for human annoyance depend on 

land use, designated Category 1, Category 2, or Category 3. Category 1 includes tracts of land where 

quiet is an essential element in their intended purpose, such as outdoor concert pavilions or national 

historic landmarks where outdoor interpretation (e.g., guided tours, etc.) routinely takes place. Category 2 

includes residences and buildings where people sleep, whereas Category 3 includes institutional land uses 

with daytime and evening use, such as schools, places of worship, and libraries.
Chapter 3: Noise Impact Criteria 3-8

The criteria do not apply to most commercial or industrial uses because, in general, the activities within

these buildings are compatible with higher noise levels. They do apply, however, to business uses that 

depend on quiet as an important part of operations, such as concert halls and recording studios.

Historically significant sites are treated as noise sensitive depending on their land-use activities. Sites of 

national significance with considerable outdoor use required for site interpretation would be in 

Category 1. Historical sites that are currently used as residences would be in Category 2. Historic

buildings with indoor use of an interpretive nature involving meditation and study fall into Category 3. 

Category 3 sites include museums, significant birthplaces, and buildings in which significant historical 

events occurred.

Most busy downtown areas have buildings that are historically significant because they represent a 

particular architectural style or are prime examples of the work of a historically significant designer. If 

the buildings or structures are used for commercial or industrial purposes and are located in busy 

commercial areas, they are not considered noise sensitive, and the noise impact criteria do not apply. 

Similarly, historical transportation structures, such as terminals and railroad stations, are not considered 

noise-sensitive sites. These buildings or structures are, of course, afforded special protection under 

Section 4(f) of the DOT Act and Section 106 of the National Historic Preservation Act. However, based 

strictly on how they are used and the settings in which they are located, these types of historical buildings 

are not considered noise-sensitive sites.

Although parks are considered in general to be noise-sensitive sites, in some cases, actual noise sensitivity 

depends on how the park is being used. Parks used for passive purposes such as reading, meditation, and 

conversation would be considered more noise sensitive than ones used for sports or other active 

recreational pursuits.

Undeveloped land may also need to be considered for noise impact assessment and mitigation if plans are 

under way to develop the land for noise-sensitive use. The policy for considering such land for 

assessment and mitigation should be determined on a project-specific basis by the project sponsor.

3.2.2 Considerations in Applying the Noise Impact Criteria

The procedure for assessing noise impact is to determine the existing noise exposure and the predicted 

project noise exposure at a given site, in terms of either Ldn or Leq(h) as appropriate, and to plot these 

levels on Figure 3-1. The location of the plotted point with respect to the three impact ranges is an 

indication of the magnitude of the impact. A more accurate determination of noise impact can be made 

by using Table 3-1, rounding the existing noise level values to the nearest whole decibel before using the 

table. Note that the impact ranges are defined within one-tenth of a decibel. This level of precision is 

normally more than necessary for determining noise impacts at specific locations but allows for accurate 

definition of the impact curves. More precise determination of noise impact may be appropriate in some 

situations, such as calculating the distance from the project to which noise impact extends. In such cases, 

more precise noise limits can be determined using the criteria equations provided in Appendix A.

The noise criteria are to be applied at the exterior façade of building locations for residential land use and 

at the nearest point of use for parks and other significant nonresidential outdoor use. It should be noted 

that although noise impact is always evaluated based on exterior noise levels, interior noise levels may 
Chapter 3: Noise Impact Criteria 3-9

need to be evaluated when considering the need for mitigation at locations where land-use activity is 

solely indoors.

It is important to note that the criteria specify a comparison of future project noise with existing noise and 

not with projections of future “no-build” noise exposure (i.e., without the project). This is because 

comparison of a projection with an existing condition is more accurate than comparison of a projection 

with another projection. Furthermore, it should be emphasized that it is not necessary and it is not 

recommended that the existing noise exposure be determined by taking measurements at every noisesensitive location in the project area. Rather, the recommended approach is to characterize the noise 

environment for “clusters” of sites based on measurements or estimates at representative locations in the 

community. In view of the sensitivity of the noise criteria to the existing noise exposure, careful 

characterization of the existing noise is important. Guidelines for determining ambient noise are provided 

in Appendix B.

Application of criteria for livestock and wildlife provides information on the exposed area in which noise 

could have an effect, even if the consequences of those effects are not fully known. Researchers have 

observed both behavioral and physiological effects with the approximate single-event sound levels listed 

in Table 3-3. The noise descriptors used by the researchers are not always well defined, but the best 

descriptor for a single event that incorporates both level and duration is the SEL. Procedures for 

calculating SEL for varying distances from high-speed train passbys are described in Chapters 4 and 5. 

Criteria are not yet fully developed to the point where dose-response relationships can be fully described 

for different animal species. However, the assessment is based on the assumption that impact occurs 

when a noise event is sufficiently loud to generate an observable effect in domestic livestock or wildlife. 

The term “wildlife” is assumed to include all endangered species until species-specific information can be 

developed.

3.2.3 Mitigation Policy Considerations

FRA’s traditional approach to abatement of noise sources from high-speed train systems is embodied in 

its Railroad Noise Emission Compliance Regulation.14 Rather than specific environmental regulations, 

the compliance regulation is intended to enforce the Noise Emission Standards for Transportation 

Equipment: Interstate Rail Carriers promulgated by the U.S. Environmental Protection Agency.15 These 

standards limit the amount of noise emitted from power cars and rail cars under stationary and moving 

conditions. In addition, NEPA establishes a broad mandate for Federal agencies to incorporate 

environmental protection and enhancement measures into the programs and projects they help promote, 

approve, and/or finance.16 FRA strongly encourages noise abatement on high-speed train projects, 

especially where severe noise impacts are identified according to methods of this manual.

 

14 U.S. DOT, FRA. Railroad Noise Emission Compliance Regulations, Final Rule, 48 Federal Register 56756-

56761; December 23, 1983 (49 Code of Federal Regulations 210).

15 U.S. Environmental Protection Agency. Noise Emission Standards for Transportation Equipment: Interstate Rail 

Carriers, 40 Code of Federal Regulations 201, July 1, 1984.

16 U.S. Congress. National Environmental Policy Act of 1969; P.L. 91-190, January 1, 1970.
Chapter 3: Noise Impact Criteria 3-10

3.2.4 Determining the Need for Noise Mitigation

Noise is frequently among the most significant environmental concerns of planned high-speed rail 

projects. Consequently, FRA requires the project sponsor to make every reasonable effort to reduce the 

predicted noise to levels considered acceptable for affected noise-sensitive land uses. The noise impact 

criteria discussed in this chapter provide the framework for identifying the magnitude of the impacts. The 

need for noise mitigation is determined based on the magnitude of the impacts and consideration of other 

factors such as feasibility, cost-effectiveness, and community views. There are many safety concerns that 

must be addressed during the engineering design of mitigation phase such as maintaining sufficient linesof-sight around noise barriers for pedestrians, cyclists, and motorists and maintaining sufficient warning 

devices (i.e., audible and visual warning devices) at grade crossings. Mitigation should be constructed 

only if they are found to be practical, prudent, and safe.

The magnitude of the impacts is the first consideration for noise mitigation. Project-generated noise in the 

“No Impact” range is not likely to be found annoying, and mitigation is not required. At the other 

extreme, noise projections in the “Severe Impact” range represent the most compelling need for 

mitigation. Impacts in this range have the greatest adverse impact on the community. In these cases, FRA 

strongly recommends that mitigation be incorporated in the project unless there are truly extenuating 

circumstances which prevent it. 

Project noise levels in the “Moderate Impact” range may also require consideration and adoption of 

mitigation measures. Although impacts in this range are not of the same magnitude as Severe Impacts, 

there can be situations that make a compelling argument for mitigation. It can be helpful for project 

sponsors to prepare a noise mitigation policy to delineate a consistent approach to mitigating Moderate 

and Severe impacts early in the planning process. FRA can provide guidance on the content of a 

mitigation policy. The content of such a policy should have the following considerations:

• The number of noise-sensitive sites affected – A row or cluster of residences adjacent to a rail line 

establishes a greater need for mitigation than one or several isolated residences. .

• The increase over existing noise levels – Since the noise impact criteria are delineated as bands or 

ranges, project noise can vary 5–7 dB within the band of Moderate Impact at any specific ambient 

noise level. If the noise impact falls just below the severe range, the need for mitigation is the 

strongest. Similarly, if the plot falls just above the No Impact threshold, there is less need.

• Noise sensitivity at affected land uses – There can be differences in noise sensitivity based on 

individual circumstances. For example, parks and recreational areas vary in their sensitivity 

depending on the type of use they experience and the settings in which they are located.

• Minimum effectiveness of mitigation measures – Can sufficient noise reduction be achieved?

• Community views – The NEPA compliance process provides the framework for hearing the 

community’s concerns about a proposed project and then making a good-faith effort to address 

those concerns. Decisions regarding mitigation should be made only after considering input from 

the affected public, relevant government, agencies and community organizations. For example, 

there have been cases where the solution to the noise problem—a sound barrier—was rejected by 

community members because of perceived adverse visual effects.
Chapter 3: Noise Impact Criteria 3-11

• Costs versus benefits – Cost is an important consideration in reaching decisions about noise 

mitigation measures. Thus, it is appropriate to establish guidelines for gauging the 

reasonableness of noise mitigation measures in terms of cost per benefited residence.

• Design limitations – Are there limitations on the application of noise mitigation measures (e.g.,

structural constraints for noise barriers or track treatments on aerial guideways)?

• Determination of wayside mitigation versus building sound insulation – Are there conditions 

under which building sound insulation should be considered (e.g., for high-rise buildings or 

where noise barrier effectiveness is limited)?

• Indoor land-use activity – For locations where land-use activity is solely indoors, such as upper 

floors of apartment buildings, noise impact may be less significant if the outdoor-to-indoor 

reduction is greater than for typical buildings (approximately 25 dB with windows closed). Under 

these conditions, an indoor Ldn criterion of 45 dBA is considered acceptable for residential 

buildings. Thus, if the project sponsor can demonstrate that this is the case, mitigation may not 

be needed.

Chapter 4: Initial Noise Evaluation 4-1

CHAPTER 4. INITIAL NOISE EVALUATION

This chapter contains procedures for an initial evaluation of potential noise impacts from a high-speed 

train project. The goals of an initial noise evaluation are to identify the potential for impacts and to 

determine their order of magnitude so that a more detailed analysis can be done in areas where significant 

impacts are found during later phases of the design processes. The initial evaluation includes two parts: a 

preliminary screening of the project corridor to identify areas of potential impact, especially when the 

technology or alignments have not been selected, and a general noise assessment for when more details 

are known or when representative cases are required. The Screening Procedure is described in 

Section 4.1 and the General Assessment procedures are described in Section 4.2. An example of an initial 

noise evaluation appears at the end of this chapter. The initial evaluation results in an inventory of 

buildings where noise impact could occur and where noise mitigation measures, such as noise barriers, 

may be needed. In this regard, the method is designed to generally overstate the potential impact. This 

information is useful for comparing alternatives and selecting those with the least potential for noise 

impacts.

Noise from high-speed trains passing near noise-sensitive receptors is the focus of an initial evaluation. 

Except for special cases, other ancillary project noise sources, such as electrical substations, roadway 

traffic near passenger stations, and maintenance facilities, generally should not be considered at this stage 

of planning. Usually, a lack of detail on the design and placement of these types of noise sources 

precludes a meaningful noise assessment.

The screening procedure of the initial evaluation is based on the type of technology and the type of area 

the alignment is passing through. The screening procedure identifies areas where impacts may occur, but 

it does not attempt to predict noise exposure at specific receptors or to estimate the mitigation 

requirements. The screening procedure is appropriate for very early phases of a project when the 

alternatives are still at a conceptual stage.

The General Assessment portion of the initial evaluation is based on noise source and land-use 

information likely to be available at early stages in the project development process. The General 
Chapter 4: Initial Noise Evaluation 4-2

Assessment includes selecting source levels for the high-speed rail technology being considered, 

estimating existing noise exposure using a simplified procedure, determining noise impact based on the 

criteria given in Chapter 3, and preparing an inventory of the potential impacts and mitigation 

requirements. At the comparatively early planning stage, the General Assessment can help establish the 

most promising corridor locations.

For programmatic environmental reviews of long transportation corridors that cover extensive 

geographical areas, a programmatic noise assessment can be accomplished by adapting the screening 

procedure to incorporate some aspects of the general assessment procedure. Once the general noise 

assessment procedure is applied to representative cases in the project area, screening distances can be 

adjusted to a specific high-speed train technology and to regional geographic conditions. In some 

instances, a general noise assessment of representative cases can be used to define additional or more 

detailed screening categories that better reflect regional land development patterns and existing noise 

sources.

4.1 NOISE-SCREENING PROCEDURE

The Screening Procedure is based on very general assumptions and can be applied in the early phases of a 

project before specific project elements have been defined. The screening distances appropriate for the 

project are used to define the study area for any subsequent noise impact assessment. Distances for 

project types are listed in Table 4-1. When there are noise-sensitive receptors within the screening 

distance, impact is possible, and as the project definition evolves, the procedures for General (this 

chapter) and Detailed (Chapter 5) Noise Assessments are used to determine the extent and severity of 

impact. 

The Screening Procedure indicates whether any noise-sensitive receivers are close enough to the proposed 

alignments for noise impact to be possible, and it identifies locations where the project has little 

possibility of noise impact. Screening can be useful when making a broad-brush comparison of potential 

impacts for different corridors. Screening also can be used to select the corridors that will be studied in 

more detail and to define the study area of any subsequent noise impact assessment. This selection can be 

a key element of a noise impact study because high-speed rail corridors may extend over hundreds of 

miles. Where no noise-sensitive land uses are within the screening distance, no further noise assessment 

is necessary. This approach allows the noise analysis to focus on locations where impacts may occur. 

The Screening Procedure takes into account the noise impact criteria, the type of project, and noisesensitive land uses. For screening purposes, all noise-sensitive land uses are considered to be in a single 

category. The distances given in Table 4-1 delineate a project’s noise study area. The distances were 

developed using typical noise emissions of high-speed trains, the typical number of operations and speeds 

of a given project type, and the lowest applicable impact threshold from Chapter 3 to obtain worst-case 

conditions. This approach gives a conservative estimate of impact. With the greater refinement in the 

general and detailed procedures, the noise impact distances should generally be less than the screening 

distances listed in Table 4-1.

The Screening Procedure is applicable to high-speed rail projects using either steel-wheeled or maglev 

technologies. Screening distances by the type of corridor or alignment involved, either shared with an 

existing rail or highway corridor or newly built through undeveloped land, are listed in Table 4-1.
Chapter 4: Initial Noise Evaluation 4-3

The steps for the Screening Procedure are as follows:

Step 1. Project Setting. Determine the type of project corridor, and ambient noise environment, and 

locate them on Table 4-1. Review the assumptions given in Table 4-2. If known operations vary by a 

factor of 2 or more from the assumptions for railroad or highway corridors, adjust the existing noise 

environments using FTA or FHWA methods described in Appendix G. For many high-speed rail 

projects, the corridor can vary from one type to another, both in alignment characteristics and ambient 

environment, over the length of the project corridor. These variations should be identified and included 

when screening an entire project corridor.

Step 2. Technology. Determine the appropriate column (steel-wheel on steel rail or maglev and speed 

regime) under Screening Distance in Table 4-1. If speed regimes are not known, use regime III (highest 

speed). If operations are expected to differ significantly (factor of 2) from the assumptions in Table 4-2, 

calculate project noise according to Section 4.2 and determine the distance to the threshold of moderate 

impact. Apply this distance from the guideway centerline. 

Step 3. Study Area Characteristics. Within the distance noted above, locate any of the noise-sensitive 

land uses listed in Table 3-2.

Step 4. Assessment. If it is determined that none of the listed land uses are within the distances noted in 

Table 4-1, then no further noise analysis is needed. In contrast, if one or more of the noise-sensitive land 

uses are within the screening distances noted in Table 4-1, then the project will require further analysis 

using the General Noise Assessment procedures described in the following section.

Table 4-1 Screening Distances for Noise Assessments

Corridor

Type

Existing Noise

Environment

Screening Distance in Feet for Project Type 

and Speed Regime*

Steel-Wheeled Maglev

Reg. II Reg. III Reg. II Reg. III

Railroad Urban/Noisy Suburban - unobstructed 300 ft 700 ft 50 ft 400 ft

Urban/Noisy Suburban - intervening buildings** 200 300 50 250

Quiet Suburban/Rural 500 1,200 50 700

Highway Urban/Noisy Suburban - unobstructed 250 600 50 400

Urban/Noisy Suburban - intervening buildings** 200 350 50 250

Quiet Suburban/Rural 400 1,100 50 600

New Urban/Noisy Suburban - unobstructed 350 700 75 450

Urban/Noisy Suburban - intervening buildings** 250 350 75 300

Quiet Suburban/Rural 600 1,300 150 800

* Measured from centerline of guideway or rail corridor. Minimum distance is assumed to be 50 ft.

** Rows of buildings assumed to be at 200, 400, 600, 800, and 1,000 ft parallel to guideway.
Chapter 4: Initial Noise Evaluation 4-4

Table 4-2 Assumptions for Screening Distances*

Corridor Type Assumed Operations

Railroad 10 daytime, 2 nighttime

1 locomotive, 40 cars

55 mph

Highway 4 lanes, 1,450 peak-hour volume

95% automobiles, 2% medium trucks, 3% heavy trucks

55 mph

New No major rail or road corridors

Urban/noisy suburban Ldn = 60 dB

Quiet suburban/rural Ldn = 50 dB

Corridor Type Operations Speeds

Steel Wheel 2 power cars, 10 coaches

45 daytime, 12 nighttime

Regime II at 100 mph

Regime III at 180 mph

Maglev 10 cars

45 daytime, 12 nighttime

Regime II at 100 mph

Regime III at 200 mph

* See Appendix G for details.

4.2 GENERAL NOISE ASSESSMENT

The General Noise Assessment determines the potential for noise impact by applying simplified models 

to estimate train noise and existing ambient noise and then comparing the results with the impact criteria 

in Chapter 3. The procedure involves noise predictions commensurate with the level of detail of available 

data in the early stages of major investment planning and environmental clearance. For projects in the 

preliminary stages of planning, a general assessment may be all that is needed to evaluate noise impacts 

and to propose mitigation measures. The General Assessment can also be used to compare alternatives, 

such as locations of alignments or candidate high-speed transportation modes (steel-wheeled versus 

maglev technology), and can provide the appropriate level of detail about noise impacts for a corridor or 

subarea study. A combination of the Screening Procedure and General Assessment may be applied to 

long transportation corridors in programmatic environmental assessments.

The general noise assessment procedure starts with determining the project noise level at a reference 

distance for the various project alternatives. This reference noise source level differs depending on the 

type of high-speed vehicle chosen for the project. The noise generated by each vehicle depends on the 

source characteristics described in Chapter 2. The reference noise source level is then used to compute 

noise exposure, accounting for anticipated operating conditions based on information about the project. 

At an early project stage, the information available may include:

• candidate technology or vehicle type

• guideway variations

• hours of operation
Chapter 4: Initial Noise Evaluation 4-5

• headways

• design speed

• alternative alignments

The available information may not be sufficient to predict noise levels at all locations along the right-ofway, but by using conservative estimates (e.g., maximum design speeds and operations at design 

capacities), it will allow estimates of worst-case noise impacts.

The steps in the general noise assessment are described in detail in the following sections and are 

summarized below:

Step 1. Source Levels

• Place the alternative under study into one of three categories: steel-wheeled electric-powered, 

steel-wheeled fossil fuel-powered, or maglev.

• Determine the source reference level, which pertains to a typical passby of the project vehicle in a 

given speed range under reference operating conditions. Use Table 4-3. The noise descriptor, 

SEL, used to define the reference level is discussed in Chapter 2. If Lmax or Passby Level is 

available from source measurements or specifications, a conversion to SEL is necessary. Use the 

methods described in Appendix C.

Step 2. Project Operating Conditions

• Convert the source reference level to noise exposure in terms of Leq(h) or Ldn at the reference 

distance of 50 ft under anticipated project operating conditions. Use the appropriate equations 

contained in Table 4-5, depending on the type of source. 

• Correct the noise exposure to account for vertical terrain effects, such as embankments and 

trenches. Use the method described in Section 4.2.2.

Step 3. Propagation Characteristics

• Draw a noise exposure-versus-distance curve for this source, which will show the project noise 

exposure as a function of distance, ignoring shielding. Use the method described in Section 4.2.3.

• Estimate the reduction in noise level to account for shielding attenuation from rows of buildings. 

Use the general rule given at the bottom of Table 4-6. It is important to include adjustments for 

shielding attenuation from rows of buildings; omitting them can result in unrealistically high 

estimates of noise impact.

• Draw an adjusted exposure-versus-distance curve.

Step 4. Study Area Characteristics

• Estimate the existing noise exposure for areas adjacent to the project. Use the methods described 

in Section 4.2.4.
Chapter 4: Initial Noise Evaluation 4-6

Step 5. Noise Impact Estimation

• Locate the distance at which project noise exposure results in impact corresponding to the 

estimated existing noise exposure, on a point-by-point basis. Use the impact criteria from 

Chapter 3. 

• Connect the points to obtain a contour line around the project, which signifies the outer limits of 

impact.

Alternatively, when it is desired to compare different technologies:

• Determine contours corresponding to specific noise levels from the exposure-versus-distance 

curves (e.g., 60-, 65-, 70-decibal A contours).

• Identify noise-sensitive locations very close to the tracks where receivers may be startled by rapid 

onset rates of noise from high-speed trains. The distance defining a potential startle zone is 

identified in Figure 4-2. 

Step 6. Noise Impact Inventory

• Tabulate noise-sensitive land uses within the specific contours.

Step 7. Noise Mitigation

• Estimate the noise reduction that would be achieved with mitigation in the community areas 

where potential for impact has been identified.

• Repeat the tabulation of noise impacts after mitigation has been applied.

4.2.1 Noise Source Levels for General Assessment

The procedure starts with establishing the noise source levels, expressed in terms of SEL under reference 

conditions of speed, distance, and length of train. These quantities are given in Table 4-2 for the two 

general categories of high-speed trains: steel-wheeled (including both electric-and fossil fuel-powered 

locomotives) and maglev trains. Electric-powered technologies include electric locomotive-hauled 

passenger coach trains and EMU trains. High-speed fossil fuel-powered source levels are based on gasturbine locomotive-hauled trains operating up to 150 mph. Although some diesel-electric locomotivehauled trains with tilting technology and diesel multiple unit (DMU) trains can approach speeds of 

150 mph, the fossil-fuel model is not based on reference noise levels of these trains. The FTA guidance 

manual includes methodologies and noise source reference levels of DMU and diesel-electric locomotivehauled trains operating at speeds below 90 mph. Noise source levels of these trains operating at speeds 

above 90 mph are not currently available.

Reference SELs for each type of high-speed rail vehicle are given in Table 4-3 for the three speed regimes 

corresponding to propulsion, mechanical, and aerodynamic noise sources dominating the overall wayside 

noise. The speed regimes were discussed in Chapter 2. These speed regimes are defined by transition 

speeds, St1 and St2, as well as speed-dependency coefficients K, which represent the slopes of the SEL 

versus speed curve in each regime. These parameters are included in Table 4-3. For each speed regime, 

the table also lists the reference SEL, reference speed, and reference length. These parameters are used in 
Chapter 4: Initial Noise Evaluation 4-7

the equations of Table 4-5 to predict the noise exposure at 50 ft. A reference distance of 50 ft is used to 

minimize propagation effects. 

Table 4-3 Reference Parameters at 50 ft from Track/Guideway

Reference 

Quantity Abbreviation Speed Regime

Vehicle Type

Steel-Wheeled Maglev***

Electric* Fossil Fuel**

Reference SEL SELref

I 86 dBA 87 dBA 72 dBA

II 93 dBA 94 dBA 73 dBA

III 99 dBA n/a 78 dBA

Speed Coefficient K

I 3 5 2

II 17 16 17

III 47 n/a 50

Reference Speed Sref

I 20 mph 20 mph 20 mph

II 90 mph 90 mph 60 mph

III 180 mph n/a 120 mph

Reference Length lenref

I 70 ft 70 ft 82 ft

II 664 ft 664 ft 82 ft

III 70 ft n/a 82 ft

Transition Speed

St1 I → II 60 mph 60 mph 60 mph

St2 II → III 170 mph n/a 120 mph

* Electric steel-wheeled model is based on train speeds up to 220 mph.

** Fossil-fuel steel-wheeled model is based on train speeds up to 125 mph, and the model can be extended up to speeds of 

150 mph. More detailed information on reference source levels is required for these technologies above 150 mph.

*** Maglev model is based on train speeds up to 250 mph.

Detailed modeling results and measurement data are presented in Appendix D.

A generalized plot of SEL as a function of speed, with each of the three speed regimes identified, is 

shown in Figure 4-1. This plot illustrates use of several of the parameters listed in Table 4-3 in each of 

the three speed regimes. It differs from Figure 2-7 in that it plots SEL, not Lmax, versus speed and 

represents the relationship as three discrete straight-line segments to approximate the smooth curve. The 

general equation relating SEL to speed for each speed regime at the reference distance (50 ft) is defined 

as:

SEL = SELref + K log � S

Sref�

where S = train speed in miles per hour, and all other quantities are defined by the reference parameters 

given in Table 4-2. As indicated in Figure 4-1, the speed coefficient K represents the “slope” of the line 

in each speed regime.
Chapter 4: Initial Noise Evaluation 4-8

Figure 4-1 Generalized SEL vs. Speed for a High-Speed Train Passby

4.2.2 Project Operating Conditions

After the reference level is determined for the candidate high-speed rail technology, the next step is to 

verify noise exposure at 50 ft under project operating conditions and expressed in terms of Ldn and Leq(h). 

The additional data needed includes the following:

• number of train passbys during daytime hours (defined as 7 a.m.–10 p.m.) and nighttime hours 

(defined as 10 p.m.–7 a.m.),

• maximum number of train passbys during hours that Category 1 or Category 3 land uses are 

normally in use (usually the peak-hour train volume),

• number and unit length of locomotives (power cars) and passenger coaches per train,

• speed (maximum expected), and

• guideway configuration.

Shielding. Attenuation from various types of shielding including noise barriers also should be accounted 

for at this step of the process. Shielding attenuation depends primarily on geometrical factors relating the 

noise source, receiver, and intervening terrain or structures. The approximate noise reductions provided 

from the shielding effects of track layout such as trenches and embankments as well as from “negative”
Chapter 4: Initial Noise Evaluation 4-9

shielding (i.e., noise increase) for elevated structures are provided in Table 4-4. These noise reductions 

are given in terms of a correction factor, Cs, to be added to the reference SEL.

If noise mitigation is determined necessary at the end of the first pass of the General Assessment, 

Table 4-4 also gives the nominal noise reduction achieved by a 10-foot-high wayside noise barrier, the 

most common mitigation measure for railway noise.

The equations necessary for calculating these quantities based on the reference SEL, adjusted to account 

for operating conditions, and the parameters listed here are listed in Table 4-5.

4.2.3 Propagation Characteristics

The process described in Section 4.2.2 results in estimates of noise exposure at 50 ft for the proposed 

project. This section describes the procedure used to estimate the project noise exposure at other 

distances, resulting in a noise exposure versus distance relationship sufficient for use in a general 

assessment. The procedure is as follows:

1. Noise exposure at 50 ft. Determine the Ldn or Leq at 50 ft for the appropriate vehicle type using 

the equations in Table 4-5.

2. Attenuation with distance. Adjust for the distance to the receiver using the equation:

Ldnor Leqat distance, d = Ldnor Leqat 50 ft − 15log �

d

50�

where d is the perpendicular distance from the receiver to the track centerline in feet. This 

equation gives an approximate relationship between noise exposure and distance that can be used 

to determine the noise impact contour for the first row of unobstructed buildings. This 

relationship can be plotted to display noise from both unmitigated and mitigated conditions to 

assess the benefits from mitigation measures.

3. Shielding from Rows of Buildings. Account for shielding attenuation from rows of intervening 

buildings for second-row receivers and beyond. Without accounting for shielding, impacts may 

be substantially overestimated. Use the following general rules to determine the effect of 

shielding from intervening rows of buildings:

• Assign 3 dB of shielding attenuation for the first row of intervening buildings only. (Attenuation 

means a subtraction from the sound level.)

• Assign 1.5 dB of shielding attenuation for each subsequent row, up to a maximum total 

attenuation of 10 dB.
Chapter 4: Initial Noise Evaluation 4-10

Table 4-4 Shielding Corrections for Track Geometry

CASE Speed

Regime

Shielding

Correction

(CS)

1) Tracks in Shallow Cut I 0 dBA

II -10 dBA

III -3 dBA

2) Tracks in Deep Trench or Cut

I -10 dBA

II -15 dBA

III -10 dBA

3) Tracks on Aerial Structure

I +4 dBA

II +4 dBA

III +2 dBA

4) Tracks on Embankment

I 0 dBA

II -5 dBA

III 0 dBA

5) Noise Barrier I 0 dBA

II -10 dBA

III -5 dBA
Chapter 4: Initial Noise Evaluation 4-11

Table 4-5 Computation of Noise Exposure at 50 ft for General Assessment

Quantity Equation

SEL at 50 ft SEL = SELref + Klog � S

Sref� + 10 log � lenlenref�

Hourly Leq at 50 ft Leq(h) = SEL + 10logV + CS − 35.6

Daytime Leq at 50 ft Leq(day) = Leq(h) V = Vd

Nighttime Leq at 50 ft Leq(night) = Leq(h) V = Vn

Ldn at 50 ft Ldn = 10 log �15 ∗ 10�

Leq (day)

10 � �

+ 9 ∗ 10�

Leq (night)+10

10 � �

� − 13.8

9

number of trainsfrom10 p.m. to 7 a.m.

average hourly nighttime volume of train traffic,in trains per hour

15

number of trainsfrom 7 a.m. to10 p.m.

average hourly daytime volume of train traffic,in trains per hour

average hourly volume of train traffic,in trains per hour

train speed, in miles per hour

length of leading power unit, ft in Speed Regime III

 total train length,ft in Speed Regime II

total length of power unit(s)*,ft in Speed Regime I

=

=

=

=

=

=











→

→

→

=

n

V

dV

V

S

len

* Use a maximum of two power units for electric locomotive trains, gas-turbine trains, or EMUs. 

4.2.4 Study Area Characteristics

The impact criteria described in Chapter 3 base the threshold of impact on estimates of existing noise 

exposure in the vicinity of the project. Impact is assessed using a combination of the existing noise 

exposure and the additional noise exposure that will be caused by the project. The Detailed Analysis 

procedures presented in Chapter 5 base the existing noise exposure on noise measurements at 

representative locations in the community. It is generally a good idea to base all estimates of existing 

noise on measurements, especially at locations known to be noise sensitive. However, measurements are 

not always possible at the general assessment stage. This section gives procedures for estimating existing 

noise in the project study area from general data available early in project planning. The procedure uses 

Table 4-6, where a neighborhood’s existing noise exposure is based on proximity to transportation 

sources such as nearby major roadways or railroads or on population density in locations away from 

major sources of noise. The process is as follows:
Chapter 4: Initial Noise Evaluation 4-12

1. Mapping: Obtain scaled mapping and aerial photographs showing the project location and 

alternatives. A scale of 1 inch (in) = 200 or 400 ft is appropriate for the accuracy needed in the 

noise assessment. The size of the base map should be sufficient to show distances of at least 

1,000 ft from the center of the alignment. Mapped areas are now available in GIS formats that 

provide great accuracy.

2. Sensitive Receivers: Review the maps, together with land-use information, to determine the 

proximity of the noise-sensitive land uses to the project and to the nearest major roadways and 

railroad lines. When necessary, windshield surveys or more detailed land-use maps may confirm 

the location of sensitive receivers. For land uses more than 1,000 ft from major roadways or 

railroad mainlines (see definitions in Table 4-6), obtain an estimate of the population density in 

the immediate area, expressed in people per square mile. When using population density, take 

care to exclude areas where there are no residences or sensitive land uses.

3. Existing Noise Exposure: Use Table 4-6 to estimate existing noise exposure. Existing noise 

exposure is estimated by first looking at a site’s proximity to major roads and railroad lines. If the 

site is located far enough from any major “linear” sources so that ambient noise is dominated by 

local streets and community activities, then the estimate should be based on population density 

alone. If the site is within approximately 1,000 ft of a major linear source, an estimate of the 

noise exposure from that source should be made based on generalized assumptions. Compare the 

noise levels from each of the three categories (roadways, railroads, and population density) and 

select the highest level to estimate the current exposure. In all cases, the noise levels are 

underestimated to provide a conservative impact assessment.

Major roadways are separated into two categories: interstates, or roadways with four or more 

lanes that allow trucks; and “others,” parkways without trucks and city streets with the equivalent 

of 75 or more heavy trucks per hour or 300 or more medium trucks per hour. The estimated 

roadway noise levels are based on data for light to moderate traffic on typical highways and 

parkways using the FHWA17 highway noise prediction model. Where a range of distances is 

given, the predictions are made at the outer limit, thereby underestimating the traffic noise at the 

inner distance. For highway noise, distances are measured from the centerline of the near lane for 

roadways with two lanes, while for roadways with more than two lanes the distance is measured 

from the geometric mean of the roadway, computed as follows:

DGM = �(DNL)(DFL)

where:

DGM is the distance to the geometric mean, DNL and DFL are distances to the nearest lane and 

farthest lane centerlines, respectively.

For railroads, the estimated noise levels are based on an average train traffic volume of 

5–10 trains per day at 30–40 mph for mainline railroad corridors, and the noise levels are 

provided in terms of Ldn only. Distances are referenced to the track centerline or, in the case of 

 

17 U.S. DOT, FHWA. FHWA Highway Traffic Noise Prediction Model, FHWA-RD-77-108, December 1978.
Chapter 4: Initial Noise Evaluation 4-13

multiple tracks, to the centerline of the rail corridor. Because of the intermittent nature of train 

operations, train noise will affect the Leq only during certain hours of the day, and these hours 

may vary from day to day. To reduce the chance of inaccurate estimates of noise impact when 

using the 1-hour Leq descriptor, the Leq at sites near rail lines should be estimated based on nearby 

roadways or population density unless very specific train information is available.

In areas away from major roadways, noise from local noise sources is estimated using a 

relationship determined by the U.S. Environmental Protection Agency (EPA).

18 EPA determined 

that ambient noise can be approximately related to population density in locations away from 

transportation corridors, such as airports, major roads, and railroad tracks, according to the 

following relation:

LDN = 22 + 10 log(p) (in dBA)

where p = population density in people per square mile. 

4. Measurements to estimate existing noise from a shared rail transit corridor: If the proposed highspeed rail project corridor is to be shared with an existing rail transit corridor (rapid transit, 

commuter rail, etc.), the methods described in Steps 1 through 3 are not adequate to characterize 

existing noise exposure accurately. Because existing noise exposure is a strong function of 

distance from the existing rail corridor, general estimates such as those presented in Table 4-6 are 

difficult to make, given the high variability in the operational characteristics of transit systems. 

In such cases, noise measurements at representative locations along the corridor are essential to 

estimate existing noise accurately.

The procedure for the Detailed Noise Analysis (Chapter 5) recommends that these measurements 

be supplemented and/or substantiated through noise prediction methods developed specifically 

for different transit modes. These methods are provided in the guidance manual published by 

FTA.

19

 

18 U.S. EPA. Population Distribution of the United States as a Function of Outdoor Noise Level, Report 550/9-74-

009, June 1974.

19 U.S. DOT, FTA. Transit Noise and Vibration Impact Assessment, Report No. FTA-VA-90-1003-06, May 2006.
Chapter 4: Initial Noise Evaluation 4-14

Table 4-6 Estimating Existing Noise Exposure for General Assessment

Distance from Major Noise Source1 (ft) Population 

Density (people 

per square mile)

Noise Exposure Estimates (dBA)

Interstate 

Highways2

Other 

Roadways3

Railroad 

Lines4 Leq Day LeqEvening Leq Night Ldn

10–49

50–99

100–199

200–399

400–799

800 and up

75

70

65

60

55

50

70

65

60

55

50

45

65

60

55

50

45

40

75

70

65

60

55

50

10–49

50–99

100–199

200–399

400 and up

70

65

60

55

50

65

60

55

50

45

60

55

50

45

40

70

65

60

55

50

10–29

30–59

60–119

120–239

240–499

500–799

800 and up

--

--

--

--

--

--

--

--

--

--

--

--

--

--

--

--

--

--

--

--

--

75

70

65

60

55

50

45

1–99

100–299

300–999

1,000–2,999

3,000–9,999

10,000–29,999

30,000 and up

35

40

45

50

55

60

65

30

35

40

45

50

55

60

25

30

35

40

45

50

55

35

40

45

50

55

60

65
Chapter 4: Initial Noise Evaluation 4-15

Notes:

1 Distances do not include shielding from intervening rows of buildings. General rule for estimating shielding attenuation in 

populated areas: Assume 1 row of buildings every 100 ft; -4.5 dB for the first row, -1.5 dB for every subsequent row up 

to a maximum of -10 dB attenuation.

2 Roadways with four or more lanes that permit trucks, with traffic at 60 mph.

3 Parkways with traffic at 55 mph, but without trucks, and city streets with the equivalent of 75 or more heavy trucks per hour

and 300 or more medium trucks per hour at 30 mph.

4 Mainline railroad corridors typically carrying 5–10 trains per day at speeds of 30–40 mph.

4.2.5 Noise Impact Estimation

It is often desirable to draw noise impact contours on land-use maps to aid the impact inventory. Once 

the contours are on the map, the potential noise impacts can be estimated by counting the buildings inside 

the contours. The process is as follows:

1. Project versus Existing Noise Exposure. Identify the noise-sensitive neighborhoods and buildings 

and estimate existing noise exposure following the procedures described in Section 4.2.4. Use 

the estimate of existing noise exposure and the noise impact criteria in Figure 3-1 to determine 

how much additional noise exposure would need to be created by the project before there would 

be Impact or Severe Impact. 

2. Noise Impact Contours. Determine the distances from the project boundary to the two impact 

levels using the noise exposure-versus-distance relationships from Section 4.2.2. Plot points on 

the land-use map corresponding to those distances in the neighborhood under study. Continue 

this process for all areas surrounding the project. Connect the plotted points by lines to represent 

the noise impact contours.

3. Noise Exposure Contours. Alternatively, if it is desired to plot specific noise contours at, for 

example, 65 dBA, the distances also can be determined directly from the approach described in 

Section 4.2.2. Again, plot the points associated with a given noise level on the land-use map and 

connect by lines to represent that contour.

The impact contour will change with respect to the project boundary as the existing ambient exposure 

changes, as project source levels change, and as the amount of acoustical shielding changes. In general, 

the points should be placed close enough to allow a smooth curve to be drawn. For a General 

Assessment, the contours may be drawn through buildings and salient terrain features as if they were not 

present. This practice is acceptable considering the level of detail associated with a project in its early 

stages of development.

Rapid Onset Rate

As discussed in Chapter 2, there is considerable evidence that increased annoyance is likely to occur for 

train noise events with rapid onset rates. The relationship of speed and distance to define locations where 

the onset rate for high-speed train operations may cause surprise, assuming open flat terrain with 

unobstructed view of the tracks in both directions is shown in Figure 4-2. The potential for increased 

annoyance for the most part is confined to an area very close to the tracks. For example, Figure 4-2 

shows that 150-mile per hour high-speed train operations would have the potential for surprise within 

32 ft of the track centerline. Therefore, the area where rapid onset rates may cause surprise is typically 
Chapter 4: Initial Noise Evaluation 4-16

within the right-of-way limits of the rail corridor. Area that rapid onset rate may be of concern within the 

right-of-way includes station platforms where high-speed through operations occur or pedestrian bridges. 

For these locations, high-speed rail systems may include advanced audible and visual warning of 

oncoming trains to minimize potential surprise.

For the purposes of a General Noise Assessment, it is necessary only to identify noise-sensitive locations 

where surprise may be an additional annoyance. The speed information contained in Figure 4-2 should be 

used to determine the distance within which surprise could occur. Any noise-sensitive land use within 

that distance should be identified as a candidate for increased annoyance.

Figure 4-2 Distance from Tracks within which Surprise Can Occur for HST
Chapter 4: Initial Noise Evaluation 4-17

4.2.6 Noise Impact Inventory

The steps for developing the inventory are as follows:

1. Construct tables for all the noise-sensitive land uses identified in the three land-use categories 

from Chapter 3.

2. For each alternative, tabulate buildings and sites that lie within the impact contours. For 

residential buildings, estimate either the number of buildings or number of dwelling units. Other 

pertinent information, such as existing noise levels, corridor segment delineations, and expected

train speed, also may be useful in tabulating the impacts. An example table is shown in 

Table 4-7.

3. Prepare summary tables showing the number of buildings and dwelling units within each impact 

zone for each alternative. Use the summary table to compare the alternatives, including those 

with and without noise mitigation measures.

4. Determine the possible need for mitigation based on the degree of impact and appropriate policy 

considerations.
Chapter 4: Initial Noise Evaluation 4-18

Table 4-7 Sample Noise Impact Inventory Table

Alignment: 1

Scenario: HS-Electric

Corridor Segment Existing 

Ldn

(dBA)

Avg 

Train 

Speed 

(mph)

Distance to 

Contour (ft)

Impact Inventory without 

Mitigation (number of buildings)

Description Milepost Impact Severe 

Impact

Impact Severe Impact

From To SF MF Inst SF MF Inst

Downtown Area 0.0 4.6 70 50 45 25 0 2 0 0 0 0

Inside I-95 4.6 5.7 65 80 70 40 6 1 0 0 0 0

To Rt. 100 5.7 9.5 65 100 80 45 12 0 0 2 0 0

To Pleasant St. 9.5 12.0 65 60 60 30 1 0 0 0 0 0

Smithtown Station 12.0 12.2 60 25 40 20 0 0 0 0 0 0

Lakeville 

Mountains

12.2 20.8 55 80 80 40 1 0 0 0 0 0

Central Valley 20.8 26.9 60 110 100 55 7 0 0 4 0 0

To Rt. 66 Crossing 26.9 33.4 60 125 110 65 6 0 1 2 0 0

I-84 Corridor 33.4 41.6 65 140 125 75 14 0 1 5 0 1

To South St. 41.6 44.2 65 80 70 40 2 0 0 1 0 0

Business District 44.2 46.2 65 55 60 30 0 1 0 0 0 0

Springfield Station 46.2 46.4 65 25 40 20 0 0 0 0 0 0

SF: Single-Family Residential

MF: Multifamily Residential

Inst: Institutional (Schools, Churches, 

hospitals)

4.2.7 Noise Mitigation Requirements

The final step of the General Assessment is to estimate the noise mitigation measures required to 

minimize the number of impacts. The primary noise control treatment for steel-wheeled high-speed rail 

systems is the installation of wayside noise barriers.20 The approximate noise barrier lengths and 

locations developed in a general assessment will provide a preliminary basis for evaluating the costs and 

benefits of impact mitigation. This section provides guidelines for making order-of-magnitude cost 

estimates for noise barriers based on the length of barrier required. A more complete description of noise 

mitigation, with consideration given to other available mitigation treatments applied at the source, path, or 

receiver, and the benefits resulting from each, is provided in Chapter 5.

Train noise barriers need to be high enough to effectively block the line of sight between the noise source 

and the receiver. The dominant source of train noise over most operating speeds for steel-wheeled high-

 

20 Because of the unique characteristics of maglev systems, noise control considerations are likely to be made at the 

outset as an integral part of the system design. Retrofitting a maglev system for noise mitigation measures such as 

sound barriers is likely to incur great costs. Design options such as building sidewalls into the guideway structure, 

using a concrete rather than a steel guideway, and minimizing structural vibrations of the guideway and vehicle 

through design are noise control measures that can be taken as a baseline condition. As a result, it may not be 

applicable to estimate preliminary mitigation without more detailed information on system design. 
Chapter 4: Initial Noise Evaluation 4-19

speed rail, as with conventional rail systems, is wheel-rail interaction. To shield this noise effectively, 

relatively low barriers located close to the track are usually sufficient. A barrier with its top edge 6–8 ft 

above the top of rail at the right-of-way line usually achieves effective shielding. A barrier at this height 

above the top of rail can reduce wheel-rail noise by 8–10 dBA.

The attenuation of sound by a barrier is frequency dependent; all other things being equal, the higher the 

frequency of the noise, the greater the barrier attenuation. Because the sound energy for aerodynamic 

sound sources is in the low frequencies (below 500 Hz), these sources are inherently difficult to shield 

with a barrier. Furthermore, because the sound level due to aerodynamic sources increases rapidly with 

increasing speed, a standard 8-foot barrier is less effective at high speeds, where aerodynamic sources 

dominate the overall sound level.

A relatively low barrier will not shield sound sources located high above the guideway, since such 

sources would protrude above the top of the barrier. This noise includes noise from propulsion sources, 

such as cooling fans, as well as aerodynamic noise generated at the upper part of the train. A description 

of these sources is presented in Chapter 2.

The following steps can be applied in making a preliminary estimate of the noise mitigation measures that 

might be required following an initial evaluation of noise impact:

1. Barrier Height. Assume an average noise barrier height of 8 ft as a cost-effective mitigation 

measure for high-speed rail noise impact. If shielding noise from higher noise sources (such as 

propulsion units) or protecting higher floors of residences is required, assume a 16-foot-high 

barrier.

2. Barrier Length. In addition to height, determine the length of noise barriers needed to extend far 

enough to each side of the affected receiver so that train noise from beyond the ends of the barrier 

does not significantly degrade its acoustical performance. As a rule, the barrier should be long 

enough to shield the entire train length for an angle of at least 60 degrees in either direction. 

3. Barrier Cost. Make a mitigation cost estimate based on the average height and length, assuming a 

unit cost of $20/ft2

. Use this cost to perform a cost-benefit analysis, if required.

4. Barrier Effectiveness. Assume an overall net barrier attenuation of 5 dBA for an 8-foot-high 

barrier and 8 dBA for a 16-foot-high barrier. These attenuations are applicable to both Leq and 

Ldn. Reassess impact with mitigation based on these reductions using the methods in this chapter.

It is important to note that the barrier estimates made in the initial evaluation are preliminary. Detailed 

barrier designs should be developed during the final engineering phase of the project. Some of the factors 

to be addressed during the final engineering phase are the structural, aesthetic, safety, and acoustical 

feasibility of the barriers, as well as their cost-effectiveness with respect to their acoustical benefits. 

There are many safety concerns that must be addressed during the engineering design phase such as 

maintaining sufficient lines-of-sight around noise barriers for pedestrians, cyclists, and motorists and 

maintaining sufficient warning devices (i.e., audible and visual warning devices) at grade-crossings. 

Mitigation should be constructed if it is found to be practical, prudent and safe.

Examples 4-1 and 4-2 provide two examples of noise analyses using the procedures presented in this 

chapter. Example 4-1 illustrates the Initial Noise Evaluation procedure for a representative high-speed 

rail project alternatives analysis, including both the Noise Screening and General Assessment. The source 
Chapter 4: Initial Noise Evaluation 4-20

reference levels used in the analysis are taken directly from Table 4-2, because it is assumed that at this 

stage, measurements or specifications for the equipment are unavailable. Example 4-2 demonstrates the 

conversion of a measured or specified Lmax to the appropriate source reference level in SEL for use in the 

General Assessment procedure, using the methods presented in Appendix C.

Example 4-1. Initial Noise Evaluation Comparing Two High-Speed Rail Alignments

This example illustrates the initial noise evaluation procedure for a hypothetical high-speed rail project. 

The project involves an alternatives analysis of a proposed steel-wheeled high-speed rail system to serve 

a 200-mile intercity corridor. Two alignment options are available, characterized by the following typical 

corridor segments:

Alignment Alternative 1: A direct route through primarily undeveloped, rural areas with farmland, and 

scattered residences within 1,000 ft of the corridor. The track would be welded rail on ballast and 

concrete ties at-grade, designed for a maximum speed of 160 mph.

Alignment Alternative 2: Along the median of a busy multilane interstate highway (typical vehicle speeds 

of 60–70 mph during freely flowing conditions), passing through a densely developed area with mixed 

residential and commercial land use. The alignment would be fully grade-separated, with welded rail on 

aerial structure (direct-fixation track on concrete slab) and with a maximum design speed of 160 mph. An 

example of a typical corridor segment is illustrated by the plan map in Figure 4-3. The closest 

unobstructed residences are 80–200 ft from the median centerline.

Figure 4-3 Typical Corridor Segment for Example 4-1, Alignment Alternative 2

Assumptions

The assumptions for the project are the same for both alignment alternatives and are as follows:
Chapter 4: Initial Noise Evaluation 4-21

Proposed System: Steel-wheeled electrically powered high-speed train consisting of two power cars 

(one on each end) and 10 passenger coaches. Unit length of each power car is 73 ft, unit length of each 

passenger coach is 63 ft.

Proposed Service: Total of 57 trains per day operating between 5 and 12 a.m. Headways are 

20 minutes (min) during daytime hours (7 a.m.–10 p.m.) and 20 min during nighttime hours (10 p.m.–

12 a.m., 5 a.m.–7 a.m.) This service results in the following average hourly volumes:

VD = 3 trains/hour (h)

VN = 1.33 trains/h

Procedure

For steel-wheeled systems, the screening procedure (Table 4-1) calls for additional analysis for noisesensitive land use within 450 ft of a shared corridor-type right-of-way and 900 ft of a new corridor through 

undeveloped land, thereby requiring further noise analysis for both alternatives. The procedure is 

summarized as follows:

Determination of Noise Exposure at 50 ft

1. Determine reference SEL at 50 ft and parameters for proposed system

Table 4-3 indicates that the maximum design speed of 160 mph puts the system in speed regime II. 

Thus, the following parameters are applied:

SELref = 93 dBA

K = 17

Sref = 90 mph

lenref = 664 ft

The actual source length is defined in Table 4-5 as the total train length, which is calculated as:

len = power cars + coaches = 776 ft

With the first equation in Table 4-5, adjust to SEL at 50 ft for actual operating conditions,

SEL = SELref + K log(S/Sref) + 10 log(len/lenref)

= 93 + 17 log(160/90) + 10 log(776/664)

= 97.9 dBA or 98 dBA (rounded)

2. Calculate Leq(h) and Ldn at 50 ft, adjusting for track geometry

For Alignment 1, the track is at-grade, so there is no shielding adjustment for track geometry (i.e., Cs = 0). 

Thus, using the equations in Table 4-4, 

Leq(day)= SEL + 10 log(Vd) + Cs - 35.6

= 98 + 10 log(3) + 0 - 35.6 = 67.2 dBA

Leq(night) = SEL + 10 log(Vn) + Cs - 35.6

= 98 + 10 log(1.33) + 0 - 35.6 = 63.6 dBA

Ldn = 70.7 dBA or 71 dBA (rounded)

For Alignment 2, speed regime II, Table 4-3 indicates that Cs = +4 dBA for aerial structure. Thus, 
Chapter 4: Initial Noise Evaluation 4-22

Leq(day)= 98 + 10 log(3) + 4 - 35.6 = 71.2 dBA

Leq(night) = 98 + 10 log(1.33) + 4 - 35.6 = 67.6 dBA

Ldn = 74.7 dBA or 75 dBA (rounded)

Estimate Propagation of Project Noise Exposure with Distance

3. Apply Noise Exposure-versus-Distance Relationship

With the method described in Section 4.2.3, the distance correction equation is applied to the project Ldn

at 50 ft. A resulting curve of Ldn versus distance is obtained for each alignment option, as shown in 

Figure 4-4.

Estimate Existing Noise Exposure

4. Estimate existing noise at noise-sensitive sites

For Alignment 1, there are no major roadways or rail lines contributing to the existing ambient noise. 

Thus, the existing noise exposure should be estimated based on population density. For a predominantly 

rural area, a population density of 300–1,000 people/square mile can be assumed, yielding an ambient 

Ldn of 45 dBA (from Table 4-6). From Figure 3-1, the corresponding project noise exposure Ldns causing 

impact for Category 2 land uses (residential) are 52 and 59 dBA for Impact and Severe Impact, 

respectively.

For Alignment 2, the highway (the dominant noise source) is a major linear source from which noise 

attenuates rapidly with distance. Thus, it would be inaccurate in this case to assign a single "generalized" 

noise level to characterize a large area, as for Alignment 1. The existing noise exposure should be 

estimated as a function of distance from the highway on a site-specific basis.

From Figure 4-3, unobstructed residences range from 80 to 200 ft from the highway. On the basis of the

information in Table 4-6, the Ldn is 70 dBA for residences closer than 100 ft from a major interstate

highway and 65 dBA for residences between 100 and 200 ft.

Figure 4-4 Noise Exposure vs. Distance for Example 4-1
Chapter 4: Initial Noise Evaluation 4-23

Applying the impact criteria curves in Figure 3-1, the project noise levels that cause impact for 

Alignment 2 are listed in the following table:

Distance to 

Highway

Existing Noise,

Ldn

Project Ldn Criterion

Onset of 

Moderate 

Onset of 

Severe Impact

50-99 ft 70 dBA 64 dBA 69 dBA

100-200 ft 65 dBA 61 dBA 66 dBA

Although the criteria allow for a higher project Ldn for Alignment 2 than for Alignment 1 because of the 

higher existing noise environment, the net allowable increase is less for Alignment 2 (1–4 dB) than for 

Alignment 1 (8–14 dB).

Noise Impact Contours

5. Determine Distances to Impact and Severe Impact

Distance-to-impact contours for each alignment are determined by extrapolating along the curves in 

Figure 4-4 and the project impact thresholds defined in Step 4. The results are summarized as follows for 

the residences:

Alternative Distance Existing Noise,

Ldn

Distance to Noise Impact 

Threshold (ft)

Moderate 

Impact

Severe Impact

Alignment 1 1,000 ft 45 dBA 980 330

Alignment 2 50–99 ft 70 dBA 250 110

100–200 ft 65 dBA 450 200

6. Draw Noise Impact Contours

Draw contours for each affected residence based on the distances given in the table in Step 5. The 

impact distances are defined in terms of distance from the project corridor centerline. 

For Alignment 2, the impact contours are shown in Figure 4-3. The severe impact contours do not go 

beyond the edge of the highway and are thus omitted for simplicity. The impact noise contours are drawn 

at the two different distances, 250 and 450 ft, resulting from the change in existing noise based on 

distance to the highway. Thirty-eight residential buildings are located within the contours defining impact 

(shaded in Figure 4-3).

7. Estimate Startle Effects/Wildlife

For either alignment, the distance within which startle could occur is the same. With a speed of 160 mph 

in Figure 4-2 results in a distance of approximately 33 ft within which a person could be startled by a highspeed train. None of the buildings in Alignment 2 is within that distance. 
Chapter 4: Initial Noise Evaluation 4-24

The distance within which wildlife could be disturbed also should be evaluated. According to Table 3-3, 

whenever the SEL exceeds 100 dBA there is a potential for effects on animals. With Alignment 1 as a 

likely example, the SEL at 50 ft is 98 dBA. Using the propagation equation given in Section 4.2.3 with 

SEL in place of Leq (which is valid because both are sound energy descriptors), the distance “d” becomes 

37 ft for SEL = 100 dBA. Consequently, wildlife could be disturbed within 37 ft of the tracks in Alignment 

1.

End of Example 4-1

Example 4-2. Conversion of Specified Lmax to Source Reference Level in SEL

In the previous example, Alignment 2 is chosen as the preferred project alternative. The proposed 

system is modeled on a high-speed electric trainset with the following noise performance:

Lmax = 86 dBA, measured at a distance of 82 ft from track centerline and a speed of 100 mph, which puts 

us in Regime II for the General Assessment.

The steps to convert Lmax to the equivalent source reference levels for use in the General Assessment, 

instead of the tabulated value in Table 4-3, are as follows:

1. Convert to SEL under specified conditions

The parameters needed to evaluate the second equation in Table C-2 of Appendix C are:

len = 776 ft

S = 100 mph

d = 82 ft

α = arctan �

len

2d � = 1.36

sin(2α) = 0.41

Substituting into this equation we get SEL at the specified distance and speed:

SEL = 86 + 10log �

776

100� − 10 log(2 × 1.36 + 0.41) + 3.3 = 93.2(dBA), or 93 dBA (rounded)

2. Normalize to reference conditions of Table 4-3

Use the fourth equation in Table C-2 to normalize the SEL to the appropriate reference parameters in 

Table 4-3 for comparison with the tabulated level. The following values are required from Table 4-3:

K = 17

Sref = 90 mph

lenref = 664 ft

Evaluating the fourth equation in Table C-2 yields:

SELref = SEL + Klog �

Sref

S � + 10log �

lenref

len � − 15log �

50

d �

 SELref = 94.8 dBA, or 95 dBA (rounded)

Thus, this value of SELref, based on the specified Lmax, is 2 dBA higher than the tabulated value, 93 dBA, 

in Table 4-3 for a steel-wheeled electric train in this speed regime.
Chapter 4: Initial Noise Evaluation 4-25

End of Example 4-2

Chapter 5: Detailed Noise Analysis 5-1

CHAPTER 5. DETAILED NOISE ANALYSIS

Procedures for performing a comprehensive assessment of noise impact for proposed high-speed train 

projects are presented in this chapter. The Detailed Noise Analysis allows site-specific noise predictions 

and mitigation evaluations. Considerably more precision can be achieved with the Detailed Noise 

Analysis than is possible with the General Assessment described in Chapter 4. Although the General 

Assessment involves the use of generalized overall noise source levels and simplified noise projection 

models, a Detailed Noise Analysis considers the noise from each subsource component, with each 

component defined in terms of a noise-generating mechanism (e.g., propulsion, wheel-rail, aerodynamic), 

reference noise level, location along the train, and speed dependency. The Detailed Noise Analysis also 

uses more precise methods to estimate adjustments for horizontal and vertical geometry, ground 

absorption, and shielding. Furthermore, the method can be adapted to conventional freight and passenger 

train operations by using information provided in Appendix E. Although the Detailed Noise Analysis 

procedures present all the information needed to predict noise and assess impact under “normal”

circumstances, sometimes it will be appropriate to adapt the procedures by using practical engineering 

judgment to reflect a project’s specific design parameters.

The Detailed Noise Analysis is appropriate for assessing noise impacts for high-speed train projects after 

the preferred alignment and candidate high-speed train technologies have been selected. At this point, the 

preliminary engineering has been initiated, and the preparation of an environmental document (usually an 

Environmental Impact Statement) has begun. Information required to perform a Detailed Noise Analysis 

includes type of vehicle equipment to be used, train schedules, speed profiles, plan and profiles of 

guideways, locations of access roads, and landform topography, including adjacent terrain and building 

features. 

Equations, rather than graphs or tables of numbers, are used in these procedures as the primary mode of 

computation to allow the use of spreadsheets and/or programmable calculators. These equations and their 

supporting text have been streamlined in this chapter to provide a concise view of the Detailed Noise 

Analysis. Background information on noise concepts and the basics of high-speed train noise are 

presented in Chapter 2 and Appendix A.
Chapter 5: Detailed Noise Analysis 5-2

The steps in performing the Detailed Analysis parallel the steps for the General Noise Assessment, 

although more refined procedures are used to predict project noise and evaluate mitigation measures. The 

steps are outlined below.

Existing Conditions

Step 1. Noise-Sensitive Receivers: Guided by the information in Section 5.1.1, identify noise-sensitive 

receivers. The number of receivers will depend on the land use in the vicinity of the proposed 

project and the extent of the study area defined by the screening procedure described in 

Chapter 4. An initial evaluation (using the procedures presented in Chapter 4) will provide a 

good indication of the extent of potential impacts.

Step 2. Existing Noise Exposure: Estimate the existing noise exposure at each noise sensitive receiver 

or cluster of receivers using the methods presented in Section 5.1.2.

Projections of High-Speed Rail Noise

Step 3. Source Reference Levels: Determine the technology applicable to the project: steel-wheeled 

high-speed or very high-speed electric (locomotive hauled or EMU), steel-wheeled fossil fuel, or 

maglev. For each noise subsource, determine noise exposure in terms of SEL under reference 

operating conditions. These reference levels should incorporate source-noise mitigation that will 

be incorporated into the system specifications. 

Step 4. Project Operating Conditions: Adjust the subsource reference SELs to the anticipated 

operating conditions of the project (i.e., train consist and speed).

Step 5. Propagation of Noise to Receivers: Develop an SEL-versus-distance relationship for each 

subsource that includes the effects of shielding along the path. Include any sound barriers when 

assessing propagation-path mitigation in the project.

Step 6. Total Noise Exposure: Determine total SEL at each receiver by combining the levels from all 

subsources. Use the SEL to calculate total noise exposure [Ldn or Leq (h)] by using project 

operating parameters, including train schedule, speed, and length.

Step 7. Maximum Noise Level for Train Passbys: (optional) If determining compliance with vehicle 

noise limits, project specifications, or comparison with measured noise levels is desired, calculate 

the Lmax using equations provided in Appendix C.

Noise Impact Assessment

Step 8. Noise Impact Assessment: Assess noise impact at each receiver or cluster of receivers using the 

criteria described in Chapter 3. If a GIS database is available, incorporating the noise projections 

and the impact assessment into the GIS database can be an effective means of identifying and 

displaying where noise impact is expected to occur and comparing the relative impacts for 

different alternatives. 

Mitigation of Noise Impact

Step 9. Mitigation of Noise Impact: Where the assessment shows impact, evaluate alternative 

mitigation measures; then, return to Step 3, modify the project noise computations, and reassess 
Chapter 5: Detailed Noise Analysis 5-3

the remaining noise impact. The locations where noise mitigation is needed and any residual 

impacts with mitigation also can be effectively displayed with GIS databases.

A conceptual approach for using GIS as a tool in assessing noise impact is provided.

5.1 EXISTING CONDITIONS

5.1.1 Step 1: Noise-Sensitive Receivers

The basic steps in identifying noise sensitive receptors are: 

• Identify all noise-sensitive land uses.

• Find individual receivers, such as isolated residences and schools.

• Group residential neighborhoods into “clusters” that have similar levels of existing noise and 

would have similar levels of project noise. 

The steps in identifying noise-sensitive receivers, both the number of receivers needed and their locations, 

are shown in Figure 5-1.

Figure 5-1 Guide to Selecting Receivers of Interest

Identify Noise-Sensitive Land Uses

A Detailed Noise Analysis usually should be performed for all noise-sensitive land uses where impact is 

identified in a General Noise Assessment. If a General Noise Assessment has not been done, all noisesensitive sites within the area defined by the noise screening procedure should be included. In areas 

where ambient noise is low, the assessment will include land uses that are farther from the proposed 

project than for areas with higher ambient levels.

Three categories of land most likely to be affected by noise from high-speed rail projects are listed in 

Table 5-1. If noise impact was identified at other types of buildings/areas with noise-sensitive use by the 

general noise assessment, these types also should be identified.
Chapter 5: Detailed Noise Analysis 5-4

Table 5-1 Noise-Sensitive Land Uses

Land Uses Specific Use Selecting Receivers

Outdoor noisesensitive areas• Parks with passive recreation

• Historic sites used for interpretation

• Amphitheaters

• Cemeteries

• Select each noise-sensitive site

Residences • Single-family residences

• Multifamily residences (apartment

 buildings, duplexes, etc.)

• Select each isolated residence

• For residential areas with uniform noise 

levels, cluster as described in text

Indoor noisesensitive sites• Places of worship

• Schools

• Hospitals/nursing homes 

• Libraries

• Public meeting halls

• Concert halls/auditoriums/theaters

• Recording/broadcast studios

• Museums and certain historic buildings

• Hotels and motels 

• Select each noise-sensitive building

Sources of information that can be helpful in locating noise-sensitive land uses in the vicinity of the 

proposed project include:

• Land-use maps prepared by regional or local planning agencies or by the project staff. 

Particularly useful are project-specific maps (track plans, right-of-way plan and profile), which 

provide building-by-building detail for land uses bordering the project.

• GIS databases are often available from State, county, or local planning departments which 

include the latest information (i.e., zoning information) on existing properties and proposed 

developments.

• Maps prepared by the U.S. Geological Survey (USGS), generally at a 2,000-foot scale. These 

maps show individual buildings except in highly urbanized areas, and generally show the location 

of all schools and places of worship, plus many other public-use buildings. The topographic 

contours on these maps can be useful for estimating acoustical shielding.

• Road and town maps. These maps can supplement the USGS maps. They are generally more 

current and may be of a larger scale.

• Aerial photographs are valuable in locating potential noise-sensitive land uses close to the 

proposed project and for determining the distances between receivers and the project alignment. 

Web-based tools offer aerial, bird’s-eye, ground-level, and street-level views to identify sensitive 

land uses in study areas.

• Windshield surveys of the corridor can provide the most current information on existing 

properties. Definitive identification of noise-sensitive sites often requires driving the corridor and 

annotating land uses on base maps. Driving the corridor may be the only way to identify new 

construction, to confirm land uses very close to the project boundary, and to identify site 

characteristics such as topography and terrain features that are not readily apparent from maps.
Chapter 5: Detailed Noise Analysis 5-5

Selecting Individual Receivers

Typically, major noise-sensitive public buildings, isolated residences, and relatively small outdoor noisesensitive areas will be selected as individual receivers. Some judgment in selection is required to avoid a 

noise analysis where it is obviously not needed. In contrast, buildings and outdoor areas that the 

community considers to be particularly noise sensitive must be included. Isolated residences that are 

particularly close to the project should certainly be included, whereas those at some distance may often be 

omitted or clustered together with other land uses, as described in the next section. 

Relatively small outdoor noise-sensitive areas should be evaluated using judgment and common sense. 

For example, parks with active recreation (e.g., playgrounds) can often be omitted unless they directly 

abut the proposed project, because noise sensitivity in such parks is generally low.

Clustering Noise-Sensitive Land Uses

Residential neighborhoods and relatively large outdoor noise-sensitive areas often can be clustered, 

simplifying the analysis without compromising accuracy. These neighborhoods/areas should be 

subdivided into clusters of approximately uniform noise, each containing a collection of noise-sensitive 

sites. Uniformity of both project noise and ambient noise should be attained, guided by these receiver-tosource distance considerations: 

• In general, noise drops off with distance from the project. For this reason, project noise 

uniformity requires nearly equal distances between the source and all points within the cluster. 

Such clusters will usually be shaped as narrow strips parallel to the rail corridor. Clusters within 

which the noise exposure will vary over a range of 2 dB or less are suggested. The fact that noise 

exposure from rail operations drops off approximately 3–4.5 dB per doubling of distance from the 

tracks, assuming propagation over open terrain, should be used as guidance. The dropoff will be 

faster when rows of buildings, terrain, or other obstacles offer acoustical shielding.

• Ambient noise usually drops off from nonproject sources in the same manner as noise from 

project sources. For this reason, clustering for uniform ambient noise will usually result in long 

narrow strips parallel to major roadways or circling major point sources of ambient noise, such as 

a manufacturing facility. Clusters within which the ambient noise will vary over a range of 

3–5 dB or less are recommended, although this may be hard to judge without measurements. 

After the cluster is defined, one receiver should be selected as representative of the cluster. Generally, the 

receiver closest to the project and at an intermediate distance from the predominant sources of existing 

noise should be selected.

5.1.2 Step 2: Existing Noise Exposure

In estimating existing noise exposure, one must first decide whether, and how thorough, a noise survey 

will be performed. Some noise monitoring should be performed unless extenuating circumstances make 

measurements impractical. Project schedule, bad weather, and limited budget are typical reasons that 

measurements may not be possible. The most common approach is to use measurements at representative 

sites to characterize existing noise. When measurements are not possible, the existing noise exposure can 

be estimated by using Table 4-6 in Chapter 4. A penalty for using the convenient tabular estimates is a 
Chapter 5: Detailed Noise Analysis 5-6

built-in conservatism in the projections. That is, the projections underpredict the ambient noise somewhat 

and thereby overpredict relative noise impact. 

Guidelines for noise measurements to characterize existing noise exposure for both residential and 

nonresidential land uses include:

• For institutional land uses, measure for 30–60 min at the receiver, preferably on at least two 

nonsuccessive weekdays (generally between Monday morning and Friday afternoon). Select the 

hour of the day when the project activity is expected to be at a maximum and the property is in 

use.

• For residential land uses, measure for a full 24 h at the receiver for one or more weekday periods 

(generally between Monday morning and Friday afternoon).

• Use judgment in positioning the measurement microphone. Location of the microphone at the 

receiver depends on the proposed location of the high-speed rail alignment. If, for example, a 

new rail line will be in front of the house, do not locate the microphone in the back yard. 

Recommended measurement positions corresponding to various locations of the project source 

are illustrated in Figure 5-2.

• Undertake all measurements in accordance with good engineering practice, following guidelines 

contained in ASTM and American National Standards Institute (ANSI) Standards.21,22

 

21ASTM. Standard Guide for Measurement of Outdoor A-Weighted Sound Levels, E 1014-84, Philadelphia, 

1984.

22ANSI. Method for the Measurement of Sound Pressure Levels, ANSI S1.13-1971 (R1976), New York, 

1971.
Chapter 5: Detailed Noise Analysis 5-7

Figure 5-2 Recommended Microphone Locations for Existing Noise Measurements
Chapter 5: Detailed Noise Analysis 5-8

Measurements made at representative receivers often are used to estimate noise exposure at other similar 

receivers. In other situations, several hourly Leq measurements at a receiver can be used to estimate Ldn. 

Both of these options require the intuition gained from experience and knowledge of acoustics to select 

representative measurement sites.

Measurements at one receiver can be used to represent the noise environment at other sites, but only when 

proximity to major noise sources is similar among the sites. For example, a residential neighborhood 

with otherwise similar homes may have greatly varying noise environments. One part of the 

neighborhood may be located where the ambient noise is clearly due to highway traffic. A second part, 

toward the interior of the neighborhood, may have highway noise as a factor but also will receive a 

significant contribution from other community noise. In a third part of the neighborhood, located deep in 

the residential area, local street traffic and other community activities could dominate the ambient noise. 

In this example, three or more measurement sites would be required to represent the varying ambient 

noise conditions in a single neighborhood.

Representative measurement sites typically can be used to estimate noise levels at other sites when both 

share the following characteristics:

• proximity to the same major transportation noise sources, such as highways, rail lines, and 

aircraft flight patterns,

• proximity to the same major stationary noise sources, such as power plants, industrial facilities, 

rail yards and airports, and

• similar type and density of housing, such as single-family homes on quarter-acre lots and 

multifamily housing in apartment complexes.

Acoustical professionals are often adept at such computations from partial data and are encouraged to use 

their experience and judgment in fully utilizing the measurements in their computations. In contrast, 

people lacking a background in acoustics should use the procedures in Appendix B to accomplish this 

same aim. The procedures contained in Appendix B are an attempt to systematize such computations 

from partial measurements. As a safety factor, these procedures underestimate ambient noise to account 

for reduced precision compared with full noise measurements.

5.2 PROJECTIONS OF HIGH-SPEED RAIL NOISE

Once receivers have been selected, projections of noise from high-speed trains can be developed for each 

receiver. The subsequent steps in the computation procedure are described in detail in Sections 5.2.1 

through 5.2.5.

5.2.1 Step 3: Source Reference Levels

The wayside noise level generated by a high-speed train passby depends primarily on system design and 

its operating conditions. The SEL used to describe a given system under a fixed set of operating 

conditions (speed, consist, track configuration) at a reference distance is called the source reference 

level. Because a number of high-speed rail systems are in existence worldwide, with design variations 

ranging from the type of propulsion mechanism to the car body shape, it is necessary to develop a set of 
Chapter 5: Detailed Noise Analysis 5-9

generalized source reference levels for use in the prediction model established in this manual. A review 

of available data resulted in grouping existing high-speed rail systems into four categories. 

The representative trainsets listed in each category are generally applicable for their respective models. 

These trainsets are assumed to be running on ballast and tie track, with wheels and rails in good running 

condition (i.e., meet wheel and rail roughness standards such as those in International Standards 

Organization 3095 and European Union High-Speed Rail Technical Standards for Interoperability (TSI)). 

The noise models assume that these trainsets do not have noise source mitigation measures such as wheel 

skirts on all bogies, sound absorptive materials inside wheel skirts or underneath the car body, elimination 

of all surface discontinuities to reduce aerodynamic noise (i.e., closing the gaps between cars and other 

streamlining features), specially designed pantographs (i.e., sound absorptive materials on the structure, 

covers, shrouds, or barriers on the sides of the train or pantographs that have the ability to lower behind 

covers so that only one pantograph in the rear of the train is necessary for operations) or special track 

features such as rail vibration absorbers. Introduction of the aforementioned features to high-speed trains 

would be expected to generate lower noise emissions than these models. These noise source mitigation 

measures and their typical effectiveness are discussed in greater detail in Section 5.4.1.

• High-Speed and Very High-Speed, Steel-Wheeled Electric

This category includes electric-powered, locomotive-hauled trains with maximum operating 

speed of 150 mph (high-speed) and 250 mph (very high-speed). The model is based on trains 

including the Amtrak Acela, French TGV (Thayls, Atlantique, Reseau, and Duplex), Swedish 

X2000, Eurostar, and Korean KTX-II.

• High-Speed and Very High-Speed, Steel-Wheeled EMU

This category includes EMU trains with maximum operating speeds of 150 mph (high-speed) and 

250 mph (very high-speed). The model is based on EMU trains including the German IC T, ICE 

3, AVE S103, Pendolino ETR450, and Korean KTX-III. 

• High-Speed, Steel-Wheeled Fossil Fuel

This category includes fossil-fuel-powered, locomotive-hauled trains with maximum operating 

speeds of 150 mph. This model is based on gas-turbine-powered locomotive-hauled trains 

including the Bombardier Jet-Train and the Rohr RTL-II. Although some diesel-electric 

locomotive hauled trains with tilting technology and DMU trains can approach speeds of 

150 mph, the fossil-fuel model is not based on reference noise levels of these trains. The FTA 

guidance manual includes methodologies and noise source reference levels of DMU and dieselelectric locomotive hauled trains operating at speeds below 90 mph. Noise source levels of these 

trains operating at speeds above 90 mph are not currently available.

• Maglev

This category includes magnetically levitated trains, such as the German Transrapid (TR08) with 

maximum operating speed of 300 mph.

Once the appropriate system category is selected, the first action in the detailed noise prediction 

procedure for high-speed train passbys is to establish the source reference level and the corresponding 

reference conditions for that category. Depending on the system category, this source reference level can 
Chapter 5: Detailed Noise Analysis 5-10

be broken down into two or more subsources as described in Chapter 2. These subsources relate directly 

to the various location-specific noise-generating mechanisms on the train and can be categorized into one 

of the following three component categories:

• propulsion, 

• mechanical, or

• aerodynamic noise.

The relevant subsources and their nominal noise reference levels to be used in computing noise exposure 

for each of the four system categories of high-speed trains are listed in Table 5-2 and for conventional 

trains in Table E-1. In these tables, the reference SEL for each subsource is given for the reference 

distance of 50 ft from the track centerline. Also given in the tables are the definition and reference value 

of the associated length of each subsource; for example, wheel-rail noise is associated with the entire train 

length, whereas propulsion noise originates only from the power cars. The subsource length is an 

important parameter, because SEL is an energy descriptor and for a train is always defined normalized to 

some reference length. The subsource heights, expressed in terms of the height above the rails (or 

guideway), are also listed in Tables 5-2 and E-1 and are used in evaluating shielding and other 

propagation effects as described in Section 5.2.3.

The levels in Table 5-2 are based on the results of background measurement and research programs 

including data collected for the initial development of these models and more recent data collected on 

high-speed train systems around the world. See Appendix D for more detail. The resulting data is an 

extensive database of noise data on most existing high-speed rail systems, ensuring that Table 5-2 is 

reasonably accurate for the existing technologies. However, when specific equipment has been selected 

for a project, it will be more accurate to base the impact assessment on noise measurements of that 

equipment. 

To obtain detailed reference noise levels of each subsource on a high-speed train, as provided in 

Table 5-2, it is generally necessary to conduct complex microphone-array measurements with a large

number of microphones. These measurements provide an acoustic map of the locations and sound 

intensities of different noise sources. The procedures for conducting microphone-array measurements are 

outside the scope of this guidance manual. If single-level measurements are performed for obtaining 

overall noise levels from all subsources, methods for converting these levels to the simplified reference 

levels used in the General Assessment procedure (Chapter 4) are given in Appendix C. The measurement 

standard International Standards Organization 3095-2005: Railway Applications - Acoustics -

Measurement of Noise Emitted by Railbound Vehicles23 provide a good reference for determining how to 

conduct reliable single-microphone reference noise measurements for consideration of atmospheric 

conditions, site conditions, track conditions, and train operating conditions.

For some projects, source-noise levels will be predefined; for example, noise limits are usually included 

in the specifications for purchase of new vehicles. Compliance with such specifications, almost always 

 

23 International Standards Organization. Railway Applications - Acoustics - Measurement of Noise Emitted by 

Railbound Vehicles, ISO-3095, 2005.
Chapter 5: Detailed Noise Analysis 5-11

defined in terms of Lmax or Passby Level, can be checked using the equations found in Appendix C. This 

option is addressed further in Section 5.2.5, accompanied by an example in which noise projections are 

used to determine compliance with a noise specification given in terms of Lmax.

Table 5-2 Noise Source Reference Levels for High-Speed Trains (SELs at 50 ft)

System Category 

and Features (a)

Example 

Systems

Subsource 

Component

Subsource Parameters Reference Quantities

Length 

Definition, 

len

Height 

above 

rails (ft)

SELref

(dBA)

lenref

(ft)

Sref

(mph) K

HS and VHS 

ELECTRIC 

LOCOMOTIVEHAULED TRAINS

Amtrak Acela

TGV

Eurostar

X2000

KTX-I /KTX-II

ETR 500

Propulsion lenpower 12 86 73 (b) (b)

Wheel-rail lentrain 1 91 634 90 20

A

E

R

O

Train Nose lenpower 10 89 73 180 60

Wheel Region lentrain 5 89 634 180 60

Pantograph (c) 15 86 (c) 180 60

(Only include aerodynamic subsources for very high-speed trains above 150 mph.)

HS and VHS EMU

TRAINS

IC T

ICE 3

AVE S103

ETR450

KTX-III

Propulsion lenpower 2 86 634 (b) (b)

Wheel-rail lentrain 1 91 634 90 20

A

E

R

O

Train Nose lenpower 10 89 73 180 60

Wheel Region lentrain 5 89 634 180 60

Pantograph (c) 15 86 (c) 180 60

(Only include aerodynamic subsources for very high-speed trains above 150 mph.)

HS GAS-TURBINE 

LOCOMOTIVEHAULED TRAINS

Rohr RTL-2

Bombardier 

Jet-Train

Propulsion lenpower 10 83 73 20 10

Wheel-rail lentrain 1 91 634 90 20

MAGLEV TR08

Propulsion lentrain 1.5 68 165 90 8

Guideway/Structural lentrain -5 80 295 90 30

A

E

R

O

Train Nose (c) 0 61 (c) 90 50

TBL (d) lentrain 10 78 295 120 50

(a) HS (High-Speed) = maximum speed 150 mph

VHS (Very High-Speed) = maximum speed 250 mph

MAGLEV = maximum speed 300 mph

(b) Source level is not adjusted for train speed

(c) Source level is not adjusted for train length

(d) Turbulent Boundary Layer

5.2.2 Step 4: Project Operating Conditions

Because the source reference levels given in Table 5-2 are for a specific train length and speed, they must 

be normalized to reflect the actual operating conditions of the project. In other words, trains whose 

consists are different from the reference consists assumed in Table 5-2 require conversion because they 

will produce different noise exposure. The same is true for trains at speeds other than those listed in 
Chapter 5: Detailed Noise Analysis 5-12

Table 5-2. As guidance, a 40-percent change in the number of power cars or coaches per train, or a 

15-percent change in train speed, will produce an approximate 2-decibel change in noise exposure. 

Once the appropriate system category and reference quantities are established, the following input 

parameters are required to adjust each reference SEL to the appropriate operating conditions:

• number of passenger cars in the train, Ncars

• number of power units in the train, Npower

• length of one passenger car, ulencar

• length of one power unit, ulenpower

• train speed in miles per hour, S

The following equation should be used to adjust each “nth” subsource SEL to the operating conditions 

identified above:

SELn = �SELref�

n + 10log � len

lenref�

n

+ K log � S

Sref�

n

The consist adjustment in the above equation is reflected in the “10 log(len/lenref)” term, where len

represents the subsource length (lenpower, lentrain) specified in Table 5-2. These variables are defined as:

lenpower = Npower × ulenpower

lentrain = (Npower × ulenpower) + (Ncars × ulencar)

The speed adjustment is given by the K log � S

Sref� term, using the appropriate value for K in Table 5-2.

5.2.3 Step 5: Propagation of Noise to Receivers

Propagation characteristics must now be considered to compute the noise exposure at specific receivers, 

using the project SEL at 50 ft for each subsource as the basis for calculation. The sequence in this 

process is as follows: 

• Determine the propagation characteristics between each subsource and the receiver. 

• Develop an SEL-distance relationship for each subsource.

• Add a final adjustment using the appropriate shielding term based on intervening barriers and/or 

terrain features between subsource and receiver. 

The steps required to carry out this sequence, resulting in calculation of a specific noise exposure-versusdistance relationship for each noise subsource, are described below: 

1. Set up cross-sectional geometries: Draw several approximate topographic sections, each 

perpendicular to the path of moving sources or radially outward from point sources, similar to 

those shown in Figure 5-3. Draw separate sections, if necessary, to account for significant 
Chapter 5: Detailed Noise Analysis 5-13

changes in topography and/or track geometry. Use judgment to reasonably limit the number of 

cross sections required. 

2. Estimate Ground Effects:24 For each topographic cross section, use the relationships illustrated 

in Figure 5-3 to determine the effective path height, Heff, and from it the ground factor, G, for the 

wheel-rail and propulsion noise subsources only. For aerodynamic noise subsources, ground 

absorption has little attenuating effect and can be disregarded. 

Larger values of G mean larger amounts of ground attenuation with increasing distance from the source. 

As shown in Figure 5-3, Heff depends on subsource heights, which are defined in terms of height above 

rails in Table 5-2, and upon receiver heights, which is usually taken as 5 ft above ground for both outdoor 

receivers and first floor receivers. 

Because of the different effective source heights for the wheel-rail and propulsion noise subsources, each 

will have a different Heff and therefore ground factor. For acoustically “hard” (i.e., nonabsorptive) 

ground conditions, and for all aerodynamic noise subsources, G should be taken to be zero. Application 

of the computations in Figure 5-3 is restricted to topographies for which horizontal distances are much 

greater than the vertical distances. In cases where the vertical distance, such as the elevation of the source 

or receiver, is of the same order of magnitude as any of the horizontal distances, G can be taken as zero if 

the line of sight is unbroken. Otherwise use the shielding method described in the next step.

3. Estimate Shielding due to Terrain and Noise Barriers: If the line of sight between subsource 

and receiver is unbroken, calculation of the ground factor (G) alone is sufficient to describe the 

attenuation of noise with increasing distance. However, if shielding between source and receiver 

in the form of intervening noise barriers and/or terrain features due to natural topography or to 

track geometry (e.g., track in cut or on embankment) breaks the line of sight, an additional 

attenuation must be included in the calculation of propagation effects.

Equations for computing the attenuation due to shielding (Ashielding) are provided in Table 5-3 for the basic 

cross-sectional geometry shown in the figure at the bottom of the table. This fundamental source-barrierreceiver geometry can also be used to model the barrier effect of terrain features that protrude above the 

line of sight, such as the edge of a deep cut, an embankment, or an earth berm. Examples of application 

of the shielding model are shown in Figure 5-4.

 

24Ontario Ministry of Environment. ORNAMENT: Ontario Road Noise Analysis Method for Environment 

and Transportation, November 1988.
Chapter 5: Detailed Noise Analysis 5-14

IN GENERAL: Heff = sum of average path heights on either side of barrier 

 Hb = 0 for no barrier

 Heff = Hs+2Hb+Hr

2

Example 1: Source in shallow cut For B < A

2�

Heff = Hs + 2Hb + Hr

2

* Otherwise use Equation (1)

Example 2: Receiver elevated For Hb > Hc

Heff = Hs + 2Hb − Hc + Hr

2

For Hb < Hc

Heff = Hs + Hc + Hr

2

Example 3: Source in sloped cut For A < B

2�

Use Equation (1)

For A > B

2�

Heff = Hs + 2Hb + Hc + Hr

2

Example 4: Source and receiver separated by trench

For A > B

2�

Heff = Hs + 2Hc + Hr

2

For A < B

2�

Heff = Hs + Hr

2

Ground Factor

For soft ground: For hard ground:

G = �

0.66

0.75 �1 − Heff

42 �

0

 

Heff < 5

5 < Heff < 42

Heff > 42

 G = 0

Notes:

• Values for subsource heights (Hs) 

are given in Table 5-2.

• Equations for Heff remain valid 

even when Hb = 0.

Figure 5-3 Computation of Ground Factor G for Ground Attenuation
Chapter 5: Detailed Noise Analysis 5-15

Table 5-3 Computation of Shielding: Barriers and Terrain

Subsource Type Equation for Barrier Attenuation

PROPULSION Abarrier = min �15or �20log � 2.51√P

tanh�4.46√P�

� + 5��

WHEEL-RAIL Abarrier = min �20or �20log � 3.54√P

tanh�6.27√P�

� + 5��

AERODYNAMIC Abarrier = min �15or �20log � 1.25√P

tanh�2.22√P�

� + 5��

Barrier Insertion Loss:

Ashielding = ILbarrier = Abarrier − 10(GNB − GB)log �

D

50�

D = closest distance between the receiver and the source, in feet

P = path length difference, in feet (see figure below)

GNB = Ground factor G computed without barrier (see Figure 5-3)

GB = Ground factor G computed with barrier (see Figure 5-3)

Basic Cross-Sectional Geometry:

A = �DSB2 + (HB − HS)2

B = �DBR2 + (HB − HR)2

C = �(DSB + DBR)2 + (HS − HR)2
Chapter 5: Detailed Noise Analysis 5-16

(b) Barrier Geometry for Depressed Tracks:

Figure 5-4 Barrier Geometry Models of Terrain for Computation of Shielding
Chapter 5: Detailed Noise Analysis 5-17

4. Calculate SEL versus Distance. For each subsource SEL at 50 ft developed earlier in the 

analysis, plot a noise exposure-versus-distance curve, with SEL represented on the vertical axis 

and distance on the horizontal axis, by evaluating one of the following equations over a range of 

distances D:

• for wheel-rail subsources,

• for propulsion subsources, and

• for aerodynamic subsources.

5.2.4 Step 6: Cumulative Noise Exposure

The procedures followed in Step 5 (Section 5.2.3) result in calculation of subsource SELs as a function of 

distance from the project corridor. The next step is to combine the subsources to yield a total SEL value 

for a train passby and convert from SEL to a measure of cumulative noise exposure based on a specific 

operating schedule. As guidance, a 40-percent change in either the number of trains per hour or the 

number of trains per day will produce an approximate 2-decibel change in cumulative noise exposure (Leq

or Ldn). The procedure is as follows:

1. Total Passby SEL: Calculate the total passby SEL by combining the subsource SELs obtained 

following Step 4 (Section 5.2.2), using the third equation in Table 5-4. The equations for 

subsource SEL at 50 ft and at distance D are repeated in Table 5-4 for clarity and to illustrate the 

continuity of the procedure.

2. Noise-Sensitive Hours: Determine the relevant time periods for all receivers that may be 

affected by the project. For residential receivers, the two time periods of interest for computation 

of Ldn are daytime (7 a.m.–10 p.m.) and nighttime (10 p.m.–7 a.m.). For nonresidential receivers, 

choose the loudest project hour during noise-sensitive activity. Several different hours may be of 

interest for nonresidential receivers, depending on the hours the facility is used. 

3. Train Operations: Determine number of trains per hour. 

For residential receivers:

Vd, the average hourly daytime (7 a.m.–10 p.m.) train volume, and

Vn, the average hourly nighttime (10 p.m.–7 a.m.) train volume.

For nonresidential receivers: 

V, the hourly train volume for each hour of interest.

4. Hourly Leq: Compute Leq(h) using the fourth equation in Table 5-4 for each hour of interest.

5. Day-Night Sound Level (Ldn): If the project noise will affect any residential receivers, compute 

the total train Ldn using the last three equations in Table 5-4.
Chapter 5: Detailed Noise Analysis 5-18

Table 5-4 Computation of Leq and Ldn

Quantity Equation

nth Subsource:

†

Subsource SEL 

at 50 ft:

SELn = �SELref�

n + 10log � len

lenref�

n

+ K log � S

Sref�

n

Subsource SEL 

at distance D: SELn =

⎩

⎪

⎨

⎪

⎧SELn|at 50 ft − 10log � D

50� − 10 G log � D42� − Ashielding (Wheel − Rail)

SELn|at 50 ft − 10log � D

50� − 10 G log � D29� − Ashielding (Propulsion)

SELn|at 50 ft − 10log � D

50� − Ashielding (Aerodynamic)

N Subsources:

Total SEL for 

train passby

SEL = 10 log ��10

SELi 10 �

N

i=1

�

Hourly Leq: Leq(h) = SEL + 10 log(V) − 35.6 − Aexcess

Daytime Leq: Leq(day) = Leq(h)|V=Vd

Nighttime Leq: Leq(night) = Leq(h)|V=Vn

Ldn: Ldn = 10 log �15 ∙ 10Leq(day)

10 � + 9 ∙ 10

(Leq(night)+10)

10 � � − 13.8

V = average hourly volume of train traffic, in trains per hour

Vd = average hourly daytime volume of train traffic, in trains per hour

= number of trains, 7 a. m.to 10 p. m.

15

Vn = average hourly nighttime volume of train traffic, in trains per hour

= number of trains, 10 p. m.to 7 a. m.

9

† See Section 5.2.2 for definition of terms

6. Excess Shielding: If necessary, adjust for excess shielding. At this point, excess shielding 

(Aexcess) that is site-specific and not directly related to the vertical geometry of the source relative 

to the receiver (as computed in Step 5) can be applied to the overall noise exposure. Such excess 

shielding can be caused by intervening rows of buildings, dense tree zones, and any other 

obstruction between the source and the receiver. The attenuations are applied to overall Leq and 

Ldn and not to the individual subsource contributions. Equations for computing these attenuations 

are given in Table 5-5.
Chapter 5: Detailed Noise Analysis 5-19

Table 5-5 Computation of Excess Shielding: Rows of Buildings and Dense Tree Zones

Condition Equation

If gaps in the row of buildings constitute less than

35% of the length of the row: Abuildings = min{10 or [1.5(R − 1) + 5]}

If gaps in the row of buildings constitute between 

35 and 65% of the length of the row: Abuildings = min{10 or [1.5(R − 1) + 3]}

If gaps in the row of buildings constitute more than 

65% of the length of the row: Abuildings = 0

Where at least 100 ft of trees intervene between 

source and receiver, and if no clear line-of-sight 

exists between source and receiver, and if the trees 

extend 15 ft or more above the line-of-sight:

Atrees = min �10 or

W

20�

If above conditions do not occur: Atrees = 0

NET ATTENUATION Aexcess = max{Abuildings or Atrees}

R = number of rows of houses that intervene between source and receiver

W = width of the tree zone along the line-of-site between source and receiver, in feet

An example of application of Steps 1 through 6 of the Detailed Noise Analysis procedure for a 

hypothetical proposed high-speed rail project follows.

Example 5-1. Detailed Noise Projection Procedure

Consider the following system:

Proposed Equipment: The project will use a steel-wheeled electric train with two power cars (one on 

each end) and eight passenger coaches. The maximum design speed will be 180 mph, placing it in the 

“Very High-Speed” category in Table 5-2. The locomotives are 73 ft long each, and the cars are each 61 

ft long. 

Proposed Service: Hours of revenue service from 5 a.m. to midnight. Hourly volumes are:

Daytime (7 a.m.–10 p.m.): 

Vd = 4 trains/h

Nighttime (10 p.m.-12 a.m., 5–7 a.m.):

Vn = 1 train/h

In the corridor segment of concern, the train will pass through a deep cut with sloped walls, and we are 

concerned with the sound exposure at a 5-foot receiver standing 80 ft from the edge of the cut (200 ft 

from the centerline of the near track).

The geometry is illustrated in case 3 of Figure 5-3, with the following parameter values:

A = 105 ft

B = 200 ft

Hr = 5 ft

Hc = 49 ft

Hb = 0 ft

Hs = subsource heights as given in Table 5-2 for Very High-Speed trains
Chapter 5: Detailed Noise Analysis 5-20

1. Calculate the ground factor, G, for the wheel-rail and propulsion subsources by using the 

equations in Figure 5-3:

Heff = Hs + 2Hb + Hc + Hr

2

Heff = (1) + (2 × 0) + (49) + (5)

2 = 27.5 for wheel − rail

Heff = (12) + (2 × 0) + (49) + (5)

2 = 33 for propulsion

Using the equation for G, again from Figure 5-3,

G = 0.75 �1 − Heff

42 �

G = 0.75 �1 − 27.5

42 � = 0.26 for wheel − rail

G = 0.75 �1 − 33

42� = 0.16 for propulsion

2. Because the line of sight between the receiver and the source may be broken by the cut (see 

Figure 5-4(b)), determine the shielding as a result of the terrain. Using the geometry from Table 5-3, with 

the barrier height represented by the height of the cut, 

DSB = 120 ft,

DBR = 80 ft,

HR = 54 ft (receiver height + height of cut),

HB = 49 ft, and

HS = heights of wheel-rail, propulsion, and aerodynamic subsources from Table 5-2.

Use these values to obtain the lengths A, B, C, and P in Table 5-3:

Propulsion Wheel-Rail Train Nose Wheel Region Pantograph

A 125.6 129.2 126.2 127.8 124.7

B 80.2 80.2 80.2 80.2 80.2

C 204.4 206.9 204.8 205.9 203.8

P 1.4 2.5 1.6 2.1 1.1

Insert the path length difference, P, into the equations for Barrier Attenuation from Table 5-3, which 

yields:

Abarrier,propulsion = 14.4

Abarrier,wheel-rail = 20.0

Abarrier,train nose = 8.9

Abarrier,wheel region = 10.1

Abarrier,pantograph = 7.6

Solve for the insertion loss using the fourth equation in Table 5-3. Because this system does not have a 

man-made barrier, set GNB and GB = 0. This yields:

Ashielding,propulsion = 14.4

Ashielding,wheel-rail = 20.0

Ashielding,train noise = 8.9
Chapter 5: Detailed Noise Analysis 5-21

Ashielding,wheel region = 10.1

Ashielding,pantograph = 7.6

3. To calculate the noise exposure as a function of distance, normalize the reference quantities in 

Table 5-2 to the actual operating conditions of the proposed system, using the method from Section 5.2.2. 

This results in the following subsource SELs:

Propulsion = 89 dBA

Wheel-rail = 97 dBA

Train nose = 92 dBA

Wheel region = 89 dBA

Pantograph = 86 dBA

Using these values, evaluate the equations in Section 5.2.3 at a distance of 200 ft at each subsource. 

Add the subsource SELs together to obtain the total SEL exposure. A plot of the total SEL versus 

distance for this example is given below. At 200 ft, the sound exposure level at the receiver will be 

approximately 80 dBA.

4. Using the Leq and Ldn equations in Table 5-4, compute the cumulative noise exposure at the 

receiver:

Leq(day) = 51 dBA

Leq(night) = 45 dBA

Ldn = 52 dBA

End of Example 5-1
Chapter 5: Detailed Noise Analysis 5-22

5.2.5 Step 7: Maximum Noise Level for Train Passbys

Noise impact assessment in this manual is based on either Ldn or Leq; therefore, normally it is not 

necessary to determine and tabulate the Lmaxs. However, often it is desirable to include estimates of Lmax

because:

• it is representative of what people hear at any particular instant;

• it is straightforward to measure with a standard sound level meter;

• noise limits in vehicle specifications are usually in terms of Lmax; and

• Lmax represents the sound level heard during a transportation vehicle passby, and then people can 

relate this metric with other environmental noises, such as an aircraft flyover or a truck passby.

Although Lmax is not used in this manual as a basis for assessing noise impact, when used in conjunction 

with Leq(h) or Ldn, it can provide a more complete description of the noise effects of a proposed project. 

Lmax also may be necessary in determining compliance with the project noise limits. Equations for 

computing Lmax from SEL and also for estimating a single-reference SEL (for use in the General 

Assessment method presented in Chapter 4) from a specified or measured value of Lmax are given in 

Appendix C. Application of these equations is illustrated in Example 5-2.

Example 5-2. Calculation of Lmax Using Detailed Noise Analysis Procedure

This example demonstrates how to compute Lmax combining the methods described in Chapter 5 and the 

equations given in Appendix C. The segment in question will use an electric locomotive-hauled train with 

a maximum design speed of 150 mph, which places it in the “high-speed” category of Table 5-2. The 

land abutting the rail corridor is flat with no shielding, and the tracks are on a 3-foot-high embankment. 

The receiver is assumed to be 5 ft high, and the noise specification requires Lmax at a distance of 50 ft 

away from the centerline of the tracks. The trainset is made up 2 power units (one at each end of the set) 

and 10 passenger coaches. The parameters for this train are as follows:

SELref,propulsion = 86 dBA

SELref,wheel-rail = 91 dBA

Nlocos = 2

Ncars = 10

Llocos = 73 ft

Lcars = 61 ft

Ltotal,locos = 146 ft

Ltotal,cars = 610 ft

S = 150 mph

D = 50 ft

The SELs for each subsource must be computed for the proposed consist and speed by using the 

methods described in Section 5.2. Then, Lmax from each subsource can be calculated by using the 

equations in Appendix C. The highest subsource Lmax is used in the noise specification for this trainset.

First, the effective path heights must be calculated to determine the ground attenuation. As shown in 

Figure 5-3, the effective ground height is as follows:
Chapter 5: Detailed Noise Analysis 5-23

Heff = Hs + 2Hb + Hr

2

Heff = (1) + (2 × 0) + (49) + (5)

2 = 27.5 for wheel − rail

Heff = (12) + (2 × 0) + (49) + (5)

2 = 33 for propulsion

Using the equation for G, again from Figure 5-3,

G = 0.75 �1 − Heff

42 �

G = 0.75 �1 − 27.5

42 � = 0.26 for wheel − rail

G = 0.75 �1 − 33

42� = 0.16 for propulsion

The reference parameters given in Table 5-2 must now be adjusted to actual speed and distance 

conditions by using the equations from Section 5.2.2. It should be noted that for cases where the 

locomotives are located on opposite ends of the train, they should be treated separately; the equations in 

Section 5.2.2 assume the locomotives are in groups. In other words,

SELpropulsion = SELref,propulsion + 10 log �

73

73�

= 86 for each power unit, and

SELwheel/rail = SELref,wheel/rail + 10 log �

(146 + 610)

634 � + 20 log �

150

90 �

= 96.2 for the wheel − rail componentof the train

Using the equations in Section 5.2.3, the SEL at 50 ft for each power unit is:

SEL = SELpropulsion − 10 log �

D

50� − 10 G log �

D

29� , which yields

= 86 − 10 log �

50

50� − 10(. 59)log �

50

29� = 84.6

and for the wheel-rail subsource is:

SEL = SELwheel/rail − 10 log �

D

50� − 10 G log �

D

42� , which yields

= 96.2 − 10 log �

50

50� − 10(. 66)log �

50

42� = 95.7

These SELs can now be used in the equations given in Table C-1. First, α corresponding to propulsion 

and wheel-rail noise must be calculated:

α = arctan � L

2D�

 = 0.63 for propulsion noise and
Chapter 5: Detailed Noise Analysis 5-24

= 1.4 for wheel − rail noise.

Lmax,propulsion = 84.6 − 10 log �

73

150� + 10 log(2 × 0.63) − 3.3

= 85.4 dBA or 85 dBA (rounded)

Lmax,wheel/rail = 95.7 − 10 log �

610

150� + 10 log[(2 × 1.44) + sin(2 × 1.44)] − 3.3

= 91.3 dBA or 91 dBA (rounded)

The total Lmax is the larger of the two:

Lmax,total = 91 dBA at 50 ft and 150 mph

End of Example 5-2

5.3 STEP 8: NOISE IMPACT ASSESSMENT

This section outlines procedures for assessing noise impact using the existing and projected noise results 

developed using the methodologies described in the previous sections. These procedures can be applied 

not only to noise impact from high-speed rail operations, including projects built within a highway or 

railroad corridor, but also to impacts from fixed facilities such as storage and maintenance yards, 

passenger stations and terminals, parking facilities, and substations.

5.3.1 Assessment Procedure

Noise impact should be assessed at each receiver of interest by using the criteria for high-speed train 

projects described in Chapter 3 as follows:

1. Existing Noise Exposure: Tabulate existing ambient noise exposure (rounded to the nearest 

whole decibel) at all receivers of interest identified earlier in the analysis.

2. Project Noise Exposure: Tabulate project noise exposure at these receivers using the analytical 

procedures described in this chapter. In the tabulation, account for added annoyance from startle 

for receivers located within the distances given in Figure 4-2 (Chapter 4).

3. Noise Impact Criteria: Determine the level of noise impact (no impact, impact, or severe 

impact) by comparing the existing and project noise exposure based on the impact criteria in 

Chapter 3.

4. Noise Impact Inventory: Document the results in noise-assessment inventory tables. These 

tables should include the following types of information:

• receiver identification and location,

• land-use description,

• number of noise-sensitive sites represented (usually the number of residential buildings or 

dwelling units),
Chapter 5: Detailed Noise Analysis 5-25

• closest distance to the project,

• existing noise exposure,

• project noise exposure,

• level of noise impact (No Impact, Impact, or Severe Impact), and

• potential for startle.

In addition, these tables should indicate the total number of receivers predicted to experience 

Impact or Severe Impact.

5. Graphical Illustration of Noise Impact: Illustrate the areas of Impact and Severe Impact on 

maps or aerial photographs. This illustration could consist of noise impact contours on the maps 

or aerial photographs, along with the impact areas highlighted. This is done by delineating two 

impact lines: one between the areas of No Impact and Impact and the second between Impact and 

Severe Impact. To conform with the practices of other agencies (e.g., FHWA, U.S. Federal 

Aviation Administration (FAA)), include several contour lines of constant project noise, such as 

Ldn 65, Ldn 70, and Ldn 75. 

6. Magnitude of Noise Impact: Determine the magnitude of the impacts as the basis of the 

assessment, defined by the two threshold curves delineating onset of Impact and Severe Impact. 

Interpretation of the two impact regimes is discussed in Chapter 3.

7. Maximum Noise Level: Evaluate and tabulate Lmax at sensitive receivers and locations where 

SEL exceeds the interim criteria for effects on animals as discussed in Chapter 3.

1.5 STEP 9: MITIGATION OF NOISE IMPACT

This section provides guidance for evaluating noise reduction measures at locations where the noise 

impact assessment shows either Severe or Moderate Impact. Severe Impacts are likely to generate 

considerable annoyance and activity interference and are therefore considered to be adverse effects in the 

context of most environmental regulations. Consequently, remedies in terms of alternative alignments or 

mitigation measures must be proposed and analyzed for locations for which impacts are assessed to be 

severe. The Moderate Impact category ranges from Threshold to Severe. In this range, other factors may 

be considered, such as costs and benefits, practicality, prior exposure, severity of impact, and land-use 

sensitivity in decisions regarding the application of noise mitigation. In general, mitigation options are 

chosen from those listed below, and then, relevant portions of the project noise are recomputed and 

reassessed to account for this mitigation. This reassessment provides an accurate prediction of the noise 

reduction and the resulting net impact of the project, assuming the incorporation of mitigation measures 

either in the initial project plans by the project proponent or as a condition imposed by the approving 

public agency. 

The source levels used in this manual are typical of high-speed rail systems designed according to current 

engineering practice, but they do not include special noise control features that could be incorporated in 

the specifications at extra cost (e.g., wheel skirts, pantograph shrouds). Such measures could further 

reduce noise impact and warrant consideration by project proponents and public agencies where the Initial 

Noise Evaluation indicates the potential for extensive areas of severe impact.
Chapter 5: Detailed Noise Analysis 5-26

Mitigation of noise impact from high-speed train projects may involve treatments at the three 

fundamental components of the noise problem: (1) at the noise source, (2) along the source-to-receiver 

propagation path, or (3) at the receiver. A list of practical noise mitigation measures that should be 

considered is summarized in Table 5-6. This table is organized according to whether the treatment 

applies to the source, path, or receiver and includes estimates of the acoustical effectiveness of each 

treatment. The treatments are discussed in Sections 5.4.1 through 5.4.3. Note the mitigation treatments 

are not additive within each group. Professional judgment is required to determine the total effectiveness, 

but one can usually add the effectiveness of one treatment from each group.

There are many safety concerns must be addressed during the engineering design phase of mitigation such 

as maintaining sufficient lines-of-sight around noise barriers for pedestrians, cyclists, and motorists and 

maintaining sufficient warning devices (i.e., audible and visual warning devices) at grade-crossings. 

Noise mitigation measures should be implemented only if they are found to be practical, prudent, and 

safe.
Chapter 5: Detailed Noise Analysis 5-27

Table 5-6 High-Speed Train Noise Mitigation Measures

Application Mitigation Measure Effectiveness

SOURCE Stringent vehicle & equipment noise specifications Varied

Placement of HVAC systems Varied

Sound-absorptive duct lining for air intake/exhaust Varied

Operational restrictions Varied

Resilient or damped

wheels

For rolling noise on tangent track: 2 dB

For wheel squeal on curved track: 10–20 dB

Vehicle skirts 6–10 dB

Under-car absorption 5 dB

Spin-slide control (prevents flats) *

Wheel truing (removes wheel flats) *

Rail Grinding (removes corrugations) *

Turn radii greater than 1,000 ft (Avoids squeal)

Rail lubrication on sharp curves (Reduces squeal)

Movable-point frogs (reduce rail gaps at crossovers) (Reduces impact noise)

Elimination of all surface discontinuities/edges on vehicle 3–6 dB

Pantograph cover or shroud 5 dB 

PATH Sound barriers close to vehicles 6–10 dB

Sound barriers at right-of-way line 5–8 dB

Alteration of horizontal & vertical alignments Varied

Acquisition of buffer zones Varied

Ballast on at-grade guideway 3 dB**

Ballast on aerial guideway 5 dB**

Resilient track support on aerial guideway Varied

RECEIVER Acquisition of property rights for construction of sound 

barriers

5–10 dB

Building noise insulation 5–15 dB

* These mitigation measures work to maintain a high-speed rail system in its as-new condition. Without incorporating them 

into the system, noise levels could increase by up to 10 dB.

** The General and Detailed noise models are based on high-speed trains operating on ballast and tie track. For systems 

which use slab track (i.e., with direct fixation), noise levels would be approximately 3 dB higher at-grade and 5 dB higher 

on an aerial guideway.

5.4.1 Source Treatments

Vehicle Noise Specifications

Incorporating noise control features during the specification and design of the vehicle is among the most 

effective noise mitigation treatments. The development and enforcement of stringent but achievable 

noise specifications by the project sponsor is a major step in controlling noise everywhere on the system. 

It is important to ensure that noise levels quoted in the specifications are achievable with the application 

of best available technology during the development of the vehicle and reasonable in light of the noise 

reduction benefits and costs. Effective enforcement includes imposing significant penalties for 

noncompliance with the specifications.
Chapter 5: Detailed Noise Analysis 5-28

Wheel Treatments

A major source of noise from steel-on-steel high-speed train systems is the wheel-rail interaction, which 

has three components: roar, impact, and squeal. Roar is the rolling noise caused by small-scale 

roughness on the wheel tread and rail running surface. Impact is caused by discontinuities in the running 

surface of the rail or by flat spots on the wheels. Squeal occurs when a steel-wheel tread or its flange rubs 

across the rail, setting up resonant vibrations in the wheel, which cause it to radiate a screeching sound. 

Various wheel designs and other mitigation measures to reduce the noise from each of these three 

mechanisms include:

• Resilient and damped wheels to reduce rolling noise, but only slightly. A typical reduction is 

2 dB on tangent track. This treatment is more effective in eliminating wheel squeal in tight 

curves; reductions of 10–20 dB for high-frequency squeal noise is typical.

• Spin-slide control systems, similar to antilocking brake systems on automobiles, reduce the 

incidence of wheel flats (localized flat spots on wheels), a major contributor of impact noise. 

Trains with smooth wheel treads can be up to 20 dB quieter than those with wheel flats. To be 

effective, the antilocking feature should be in operation during all braking phases, including 

emergency braking. Wheel flats are more likely to occur during emergency braking than during 

dynamic braking.

• Maintenance of wheels by truing eliminates wheel flats from the treads and restores the wheel 

profile. An effective maintenance program includes the installation of equipment to detect and 

correct wheel flats on a continuing basis.

Vehicle Treatments

Vehicle noise mitigation measures are applied to the various mechanical systems associated with 

propulsion, ventilation, and passenger comfort; these include:

• Propulsion systems of high-speed train vehicles include electric traction motors and fossil-fuel 

turbine engines. Noise from the propulsion system depends on the type of unit and the level of 

noise mitigation is built into the design. 

• Ventilation requirements for vehicle systems are related to the noise generated by a vehicle. Fan 

noise often remains a major noise source after other mitigation measures have been instituted 

because of the need to have direct access to cooling air. This problem applies to heat exchangers 

for electric traction motors and air-conditioning systems. Fan quieting can be accomplished by 

installation of one of several new designs of quiet, efficient fans. Forced-air cooled electric 

traction motors can be quieter than self-cooled motors at operating speeds. Placement of fans on 

the vehicle can make a significant difference in the noise radiated to the wayside or to patrons on 

the station platforms. 

• Vehicle body design can provide shielding and absorption of the noise generated by the vehicle 

components. Acoustical absorption under the car has been demonstrated to provide up to 5 dB of 
Chapter 5: Detailed Noise Analysis 5-29

mitigation for wheel-rail noise and propulsion-system noise on rapid transit trains. 25 Similarly, 

vehicle skirts over the wheels can provide more than 5 dB of mitigation. If the carbodies are 

outfitted with their own noise barriers, vehicles with these features can provide cost-effective 

noise reduction.

The Shinkansen 700T and Fastech360Z are examples of high-speed trains that include several noise 

source mitigation measures and have been found to generate lower noise emissions than other EMU trains 

without such noise mitigation measures. See Appendix D for more details.

Guideway Support

The smoothness of the running surface is critical in the mitigation of noise from a moving vehicle. 

Because of the high train speeds, smooth rail running surfaces are essential for controlling noise at 

acceptable levels on high-speed rail systems. Roughness of rail surfaces can be reduced by grinding rails, 

thereby reducing noise levels by up to 10 dB. 

Operational Restrictions

Restrictions on operations are not a desirable mitigation option because of service demands. However, in 

extreme cases, they can be a viable option. Two changes in operations that can mitigate noise are 

decreasing speed in selected, noise-sensitive areas and reducing nighttime (10 p.m. to 7 a.m.) operations. 

Because noise from high-speed trains depends on speed, a reduction of speed results in lower noise levels. 

The effect can be considerable. For example, each halving of speed on a steel-wheel/steel-rail system 

results in a 6-decibel reduction in noise exposure (see Table 5-2). Complete elimination of nighttime 

operations has a strong effect on reducing the Ldn, because nighttime noise is increased by 10 dB when 

calculating Ldn. 

It is expected that most new high-speed rail systems will be grade-separated, eliminating the need for 

grade crossings and their associated noise levels. However, when grade crossings are present in lower

speed track segments, other operational restrictions that can reduce noise impact include minimizing or 

eliminating horn blowing and other types of audible warning signals. These mitigation options must be 

compliant with safety regulations and FRA guidelines.

5.4.2 Path Treatments

Sound Barriers

Sound barriers are probably the most common noise mitigation measure used in surface transportation 

modes. Sound barriers are effective in mitigating noise when they break the line-of-sight between source 

and receiver. The mechanism of sound shielding is described in Chapter 2. The necessary height of a 

barrier depends on factors such as the source height and the distance from the source to the barrier. For 

example, a barrier located very close to the nearest track need only be 3–4 ft above the top of rail to 

 

25C. E. Hanson. Noise control for rapid transit cars on elevated structures. Journal of Sound and Vibration, 87(2):

285-294 (1983).
Chapter 5: Detailed Noise Analysis 5-30

effectively reduce wheel-rail noise, providing noise reductions of 6–10 dB. The height of barriers farther 

away from the adjacent track, such as on the right-of-way line or for trains on the far track, or for 

screening aerodynamic noise sources, must be increased to provide equivalent effectiveness. Otherwise, 

the effectiveness of the barrier could drop to 5 dB or less, even if it breaks the line of sight. Where the 

barrier is very close to the vehicle or where the vehicles travel between sets of parallel barriers, barrier 

effectiveness can be increased by as much as 5 dB by applying sound-absorbing material to the inner 

surface of the barrier. 

Similarly, the length of the barrier wall is important in its effectiveness. The barrier must be long enough 

to screen out a moving train along most of its visible path. This length is necessary so that train noise 

from beyond the ends of the barrier will not severely compromise noise-barrier performance at sensitive 

locations.

Noise barriers can be made of any outdoor weather-resistant solid material that meets a minimum sound 

transmission loss requirement. The sound requirements are not particularly strict; they can be met by 

many commonly available materials, such as 16-gauge steel, 1-inch-thick plywood, and any reasonable 

thickness of brick or concrete. The normal minimum requirement is a surface density of 4 pounds (lb)/ft2

. 

To sustain wind loads, structural requirements are more stringent. Most importantly, achieving the 

maximum possible noise reduction requires careful sealing of gaps between barrier panels and between 

the barrier and the ground or elevated guideway deck.

Costs for noise barrier materials, based on highway installations, range from $15 to $25/ft2

, not counting 

design, installations, and construction inspection costs. The cost of installation on an aerial structure is 

approximately the same as at-grade, unless the structure has to be strengthened to accommodate the added 

weight and wind load.

Locating a rail alignment in a reasonably deep cut or trench, as part of a grade separation, can accomplish 

the same result as installing a noise barrier. The walls of the trench serve the same function as barrier 

walls in breaking the line-of-sight between source and receiver.

Noise Buffers

Because noise levels attenuate with distance, increasing the distance between noise sources and the 

closest sensitive receivers can be an effective mitigation measure. This buffer can be accomplished by 

locating alignments away from sensitive sites. In areas of severe impact, acquiring land or easements for 

noise buffer zones is an option that may be considered.

Ground Absorption

Propagation of noise over ground is affected by whether the ground surface is absorptive or reflective. 

Noise from vehicles at-grade is strongly affected by the character of the ground in the immediate vicinity 

of the vehicle. Guideways for rail systems can be either reflective or absorptive, depending on whether 

they are concrete or ballast. Ballasted track construction can reduce train noise 3 dB at-grade and up to 

5 dB on aerial structure. The noise models are based on high-speed trains operating on ballast and tie 

track. Therefore, for systems that use slab track (i.e., with direct fixation), noise levels would be 

approximately 3 dB higher at-grade and 5 dB higher on aerial guideway.
Chapter 5: Detailed Noise Analysis 5-31

5.4.3 Receiver Treatments

Sound Barriers

In certain cases it may be possible to acquire limited property rights for the construction of sound barriers 

at the receiver. As discussed above, barriers need to break the line of sight between the noise source and 

the receiver to be effective and are most effective when they are closest to either the source or the 

receiver. Procedures for estimating barrier effectiveness are given earlier in this chapter.

Building Insulation

In cases where rights-of-way are restricted, the only practical noise mitigation measure may be to provide 

sound insulation for the building. Sound insulation improvements should be considered if interior noise 

levels would be 45 Ldn or greater from project noise sources prior to mitigation. The most effective 

treatments are to caulk and seal gaps in the building envelope and to install windows and doors that are 

specially designed to meet acoustical transmission-loss requirements. These windows are usually made 

of multiple layers of glass and are beneficial for heat insulation as well as for sound insulation. 

Depending on the quality of the original windows, the new windows can improve noise reduction by 5 to 

15 dB. Because improving the sound transmission performance of windows and doors would only be 

effective when they are closed, it may be necessary to ensure that heating and cooling can be provided 

with the closed windows (i.e., central ventilation or air conditioning). Additional sound insulation, if 

needed, can be provided by sealing vents and ventilation openings and relocating them to a side of the 

building away from the noise source.

5.5 EXAMPLE OF GIS IMPLEMENTATION

GIS technology can be a useful tool in graphically identifying and displaying noise impacts, as well as 

simplifying the mapping and inventorying work that is needed to complete the impact assessment. One of 

the key benefits to using GIS tools is that once the receiver and geographic information has been entered 

into the system, it is possible to change any number of variables such as track alignments, train 

configuration, train speeds and shielding, and updated noise impact and mitigation results can be obtained 

with little effort. GIS technology could be integrated into public outreach tools to allow residents who 

live near a corridor to see the specific impact that a rail project would have on them. Because most highspeed rail projects cover relatively long distances, using GIS technology can facilitate in the volume of 

sensitive receptors that may be near proposed projects. An example showing a conceptual method of 

implementing GIS is given in this section. 

Procedure

The following outlines the steps typically required to conduct a noise impact assessment using GIS:

1. Collect GIS Data: GIS data layers must be gathered from project sources, local or State 

planning departments, or sometimes third-party vendors. Data that is helpful when conducting 

the analysis include base maps such as aerial photography or USGS maps, land parcels, building 

footprints (including number of units for multifamily housing and the type of building 

construction), land-use information (e.g., zoning, tax, or census maps), topography (e.g.,

elevation contours), proposed track alignments including curve radii, type of track form (e.g.,
Chapter 5: Detailed Noise Analysis 5-32

ballast and tie versus slab track), type of guideway (e.g., at-grade, elevated or in trench), special 

track-work locations, grade-crossing locations, and train speed information (e.g., design speeds of 

track segments or speed profiles).

2. Identify Sensitive Receivers and Cluster Receivers: Identify all sensitive land uses and create 

a data layer of receiver points and clusters following the guidelines presented in Section 5.1.1. 

Each cluster must reference the receivers within. Distances from each receiver to the track 

centerlines can be computed using the GIS tool.

3. Analyze Topography: On the basis of elevation contours and type of guideway, assign a terrain 

condition category based on examples shown in Figure 5-3 to each receptor. Some GIS tools 

offer advanced three-dimensional functions that can facilitate this analysis. This process should 

also result in the height and distance parameters necessary for computing ground effect values. 

4. Project Noise Levels and Assess Impact: Predictions of noise levels can be programmed within 

GIS tools following the methods described in this chapter or Chapter 4 for an Initial Noise 

Evaluation, or data can be drawn from the GIS tool for separate calculations in a spreadsheet. 

Commercially available GIS-based acoustic models are available to predict train noise. These 

models as with all tools should follow the methods and procedures presented in this manual, and 

the results of these models must be consistent with the results obtained from this manual. GIS 

tools also have the capacity to generate noise contours based on the modeling results and the track 

alignment. An example of noise impact contours within a GIS tool is presented in Figure 5-5. A 

spreadsheet for computing noise and assessing impact based on the Initial Noise Evaluation 

chapter is available from the FRA Web site. 

5. Analyze Noise Mitigation: A data layer of noise mitigation, such as sound barriers, can be 

developed within GIS. Similar to the noise projections, the effect of noise mitigation can be 

programmed within GIS tools or separately with spreadsheets. 

6. Prepare Figures of Potential Noise Impact and Mitigation: On the basis of the impact 

assessment and mitigation results, figures showing locations of potential noise impact and 

mitigation can easily be prepared.
Chapter 5: Detailed Noise Analysis 5-33

Figure 5-5 Determining Noise Impact Using GIS
Chapter 6: Ground-Borne Vibration Concepts 6-34

CHAPTER 6. GROUND-BORNE VIBRATION CONCEPTS

Noise and vibration are traditionally linked in environmental impact assessments because the two 

disciplines are perceived to have many physical characteristics in common. For example, noise can be 

generated by vibration of surfaces. Both involve fluctuating motion: noise is oscillating motion of air,

and vibration is oscillating motion of structures or the ground. Both are analyzed as wave phenomena: 

noise is made up of sound waves in air and vibration travels as waves in the ground. Both can be 

measured in decibels. Both are considered sensory effects: noise is related to hearing, and vibration is 

related to feeling. Despite their similarities, however, noise and vibration require entirely different kinds 

of analyses. The fact that ground-borne vibration travels through a succession of solid media, such as 

various kinds of soil, rock, building foundation, and building structure, to reach the receiver makes 

vibration more complicated to measure and to predict than noise.

This chapter provides a general background on ground-borne vibration and summarizes the available data 

on ground-borne vibration caused by high-speed trains. The material presented is based largely on 

empirical data, because ground-borne vibration is a more complex phenomenon than that of airborne 

noise. The information contained in this chapter forms the basis of the assessment procedures presented 

in Chapters 7, 8, and 9.

The effects of ground-borne vibration include perceptible movement of the building floors, rattling of 

windows, shaking of items on shelves or hanging on walls, and rumbling sounds. In extreme cases, such 

vibration can damage buildings and other structures. Building damage is not a factor for most surface 

transportation projects, except during construction when there may be occasional blasting and pile 

driving. Annoyance from vibration often occurs when the vibration exceeds the threshold of perception 

by 5–10 dB. This vibration level is an order of magnitude below the damage threshold for normal 

buildings.

The basic concepts of ground-borne vibration are illustrated for a high-speed rail system in Figure 6-1. 

The train wheels rolling on the rails create vibration energy transmitted through the track support system 

into the track bed or track structure. The amount of energy that is transmitted into the track structure 
Chapter 6: Ground-Borne Vibration Concepts 6-35

depends strongly on factors such as how smooth the wheels and rails are and the resonance frequencies of 

the vehicle suspension system and the track support system. 

Although a maglev train has no direct contact with its guideway, dynamic loads on the guideway structure 

during its motion do create vibration energy in the structure. This energy is transmitted through the 

guideway supports to the ground.

Figure 6-1 Propagation of Ground-Borne Vibrations into Buildings

The vibration of the track or guideway structure excites the adjacent ground, creating vibration waves that 

propagate through the various soil and rock strata to the foundations of nearby buildings. The vibration 

propagates from the foundation throughout the remainder of the building structure. The maximum 

vibration amplitudes of floors and walls of a building often occur at the resonance frequencies of those 

building elements. 

The vibration of floors and walls may cause perceptible vibration, rattling of items such as windows or 

dishes on shelves, or a rumble noise. The rumble is the noise radiated from the motion of the room 

surfaces. In essence, the room surfaces act like a giant loudspeaker. This is called ground-borne noise.

Ground-borne vibration is almost never annoying to people who are outdoors. Although the motion of 

the ground may be perceived, the motion does not provoke the same adverse human reaction without the 

effects associated with the shaking of a building. In addition, the rumble noise that usually accompanies 

the building vibration can only occur inside buildings.

6.1 DESCRIPTORS OF GROUND-BORNE VIBRATION AND NOISE

6.1.1 Vibratory Motion

Vibration is an oscillatory motion, which can be described in terms of displacement, velocity, or 

acceleration. Because the motion is oscillatory, there is no net movement of the vibration element, and 

the average of any of the motion descriptors is zero. Displacement is the easiest descriptor to understand. 
Chapter 6: Ground-Borne Vibration Concepts 6-36

For a vibrating floor, the displacement is simply the distance that a point on the floor moves away from 

its static position. The velocity represents the instantaneous speed of the floor movement, and 

acceleration is the rate of change of the speed.

Although displacement is easier to understand than velocity or acceleration, it is rarely used to describe 

ground-borne vibration. This is because most transducers used for measuring ground-borne vibration 

measure either velocity or acceleration, and, even more importantly, the response of humans, buildings, 

and equipment to vibration is more accurately described by using velocity or acceleration.

6.1.2 Amplitude Descriptors

Vibration consists of rapidly fluctuating 

motions with an average motion of zero. The 

various methods used to quantify vibration 

amplitude are shown in Figure 6-2. The raw 

signal is the lighter weight curve in the top 

graph. This is the instantaneous vibration 

velocity, which fluctuates about the zero 

point. The peak particle velocity (PPV) is 

defined as the maximum instantaneous 

positive or negative peak of the vibration 

signal. PPV often is used in monitoring of 

blasting vibration because it is related to the 

stresses that are experienced by buildings.

Although PPV is appropriate for evaluating 

the potential for building damage, it is not 

suitable for evaluating human response. It 

takes some time for the human body to 

respond to vibration signals. In a sense, the 

human body responds to an average vibration 

amplitude. Because the net average of a 

vibration signal is zero, the root mean square 

(RMS) amplitude is used to describe the 

“smoothed” vibration amplitude. The RMS 

of a signal is the average of the squared 

amplitude of the signal. The average is 

typically calculated over a 1-second period. The 

RMS amplitude is shown superimposed on the Figure 6-2 Different Methods of Describing a 

Vibration Signal
Chapter 6: Ground-Borne Vibration Concepts 6-37

vibration signal in Figure 6-2. The RMS amplitude is always less than the PPV and is always positive.26

The PPV and RMS velocities are normally described in inches per second in the United States and in 

meters per second in the rest of the world. Although it is not universally accepted, decibel notation is in 

common use for vibration. Decibel notation serves to compress the range of numbers required to describe 

vibration. The bottom graph in Figure 6-2 shows the RMS curve of the top graph expressed in decibels. 

Vibration velocity level in decibels is defined as:

Lv = 20 × log10 � v

vref�

where “Lv” is the velocity level in decibels, “v” is the RMS velocity amplitude, and “vref” is the reference 

velocity amplitude. A reference always must be specified whenever a quantity is expressed in terms of 

decibels. The accepted reference quantities for vibration velocity are 1 × 10–6 in/s in the United States

and either 1 × 10–8 or 5 × 10–8 m/s in the rest of the world. Because of the variations in the reference 

quantities, it is important to state clearly the reference quantity being used whenever velocity levels are 

specified. All vibration levels in this manual are referenced to 1 × 10–6 in/s. Although not a universally 

accepted notation, the abbreviation “VdB” is used in this document for vibration decibels to reduce the 

potential for confusion with sound decibels.

6.1.3 Ground-Borne Noise

As discussed above, the rumbling sound caused by the vibration of room surfaces is called ground-borne 

noise. The annoyance potential of ground-borne noise is usually characterized by using the A-weighted 

sound level. Although the A-weighted level is almost exclusively used as the descriptor for community 

noise, there are potential problems when characterizing low-frequency noise using A-weighting. This is 

because of the nonlinearity of human hearing, which causes sounds dominated by low-frequency 

components to seem louder than broadband sounds that have the same A-weighted level. The result is 

that a ground-borne noise level of 40 dBA sounds louder than 40-decibel A broadband airborne noise. 

This anomaly is accounted for by setting the limits for ground-borne noise lower than would be the case 

for broadband noise.

6.2 HUMAN PERCEPTION OF GROUND-BORNE VIBRATION AND NOISE

This section gives some general background on human response to different levels of building vibration, 

thereby establishing the basis for the criteria for ground-borne vibration and noise that are presented in 

Chapter 7.

 

26 The ratio of PPV to maximum RMS amplitude is defined as the crest factor for the signal. The crest factor is 

always greater than 1.71, although a crest factor of 8 or more is not unusual for impulsive signals. For ground-borne 

vibration from trains, the crest factor is usually 4 to 5.
Chapter 6: Ground-Borne Vibration Concepts 6-38

6.2.1 Typical Levels of Ground-Borne Vibration and Noise

In contrast to airborne noise, ground-borne vibration is not a phenomenon that most people experience 

every day. The background vibration velocity level in residential areas is usually 50 VdB or lower, well 

below the threshold of perception for humans, which is around 65 VdB. Most perceptible indoor 

vibration is caused by sources within buildings such as operation of mechanical equipment, movement of 

people, or slamming of doors. Typical outdoor sources of perceptible ground-borne vibration are 

construction equipment, steel-wheeled trains, and traffic on rough roads. If the roadway is smooth, the 

vibration from traffic is rarely perceptible.

Common vibration sources and the human 

and structural response to ground-borne 

vibration are illustrated in Figure 6-3. The 

range of interest is from approximately 

50–100 VdB. Background vibration is 

usually well below the threshold of human 

perception and is of concern only when the 

vibration affects very sensitive 

manufacturing or research equipment, such 

as electron microscopes and highresolution photolithography equipment.

The relationship between ground-borne 

vibration and ground-borne noise depends 

on the frequency content of the vibration 

and the acoustical absorption of the 

receiving room. The more acoustical 

absorption in a room, the lower the noise 

level will be. For a room with average 

acoustical absorption, the sound pressure level is approximately 5 dB less than the average vibration 

velocity level of the room surfaces.

27 Hence, the A-weighted level of ground-borne noise can be 

estimated by applying A-weighting to the vibration velocity spectrum. Because the A-weighting at 

31.5 Hz is -39.4 dB, if the vibration spectrum peaks at 30 Hz, the A-weighted sound level will be 

approximately 45 dB lower than the velocity level. Correspondingly, if the vibration spectrum peaks at 

60 Hz, the A-weighted sound level will be approximately 30 dB lower than the velocity level.

 

27 This relationship applies only when the velocity level is referenced to 1 microinch (μin)/s. When velocity level is 

expressed using the international standard of 1 × 10–8 m/s, the sound level is approximately 13 dB lower than the 

average velocity level.

Figure 6-3 Typical Levels of Ground-Borne Vibration
Chapter 6: Ground-Borne Vibration Concepts 6-39

6.2.2 Quantifying Human Response 

to Ground-Borne Vibration and 

Noise

One of the major problems in developing 

suitable criteria for ground-borne vibration 

is that there has been relatively little 

research into human response to vibration,

in particular, human annoyance with 

building vibration. However, experience 

with U.S. rapid transit projects over many

years represents a good foundation for 

developing suitable limits for residential 

exposure to ground-borne vibration and 

noise from high-speed rail operations.

The relationship between the vibration 

velocity level measured in 22 homes and the general response of the occupants to vibration from rapid 

transit trains is illustrated in Figure 6-4. The data points shown were assembled from measurements that 

had been performed for several transit systems. The subjective ratings are based on the opinion of the 

person who took the measurements and the response of the occupants.

These data were previously published in the State-of-the-Art Review of Ground-borne Noise and 

Vibration.

28 Both the occupants and the people who performed the measurements agreed that floor 

vibration in the "Distinctly Perceptible" category was unacceptable for a residence. The data in 

Figure 6-4 indicate that residential vibration exceeding 75 VdB is unacceptable if trains are passing every 

5–15 min, as is usually the case with urban transit trains. Additional social survey data is provided by a 

Japanese study on vibration pollution conducted in 1975.

29 The percent of people annoyed by vibration 

from high-speed trains in Japan is shown by the “% annoyed” curve in Figure 6-4. Note that the scale 

corresponding to the percent annoyed is on the right-hand axis of the graph. The results of the Japanese 

study confirm the conclusion that at vibration velocity levels ranging from 75 to 80 VdB, many people 

will find the vibration annoying. A more recent study of human response to vibration also supports this 

finding.30

 

28 J. T. Nelson and H. J. Saurenman. State-of-the-Art Review: Prediction and Control of Ground-Borne Noise and 

Vibration from Rail Transit Trains, U.S. DOT, Urban Mass Transportation Administration, Report No. UMTA-MA06-0049-83-4, DOT-TSC-UMTA-83-3, December 1983.

29 Y. Tokita. “Vibration Pollution Problems in Japan,” Inter-Noise 75 Proceedings, Sendai, Japan, pp. 465-472, 

1975.

30 J. A. Zapfe, H. Saurenman, and S. Fidell. Ground-Borne Noise and Vibration in Buildings Caused by Rail Transit, 

Transportation Research Board, Final Report for TCRP Project D-12, December 2009.

Figure 6-4 Occupant Response to Urban Transit-Induced 

Residential Vibration
Chapter 6: Ground-Borne Vibration Concepts 6-40

6.3 FACTORS THAT INFLUENCE GROUND-BORNE VIBRATION AND NOISE

Developing accurate estimates of ground-borne vibration is complicated by the many factors that can 

influence vibration levels at the receiver position. Factors that have significant effects on the levels of 

ground-borne vibration are discussed in this section. Some of these factors that are known to have, or are 

suspected of having, a significant influence on the levels of ground-borne vibration and noise are 

summarized in Table 6-2. As the table indicates, the physical parameters of the track, trainsets, geology, 

and receiving building all influence vibration levels. The important physical parameters can be divided 

into the following four categories:

Operational and Vehicle Factors: This category includes all of the parameters that relate to rail 

vehicles and the operation of trains. Factors such as high speed, stiff primary suspensions on the vehicle, 

and flat or worn wheels will increase the possibility of ground-borne vibration problems.

Guideway: The type and condition of the rails, the type of guideway, the rail support system, and the 

mass and stiffness of the guideway structure can all influence the level of ground-borne vibration. Worn 

rail and wheel impacts at special track work can substantially increase ground-borne vibration. A highspeed rail system guideway will be in tunnel, in open trench, at-grade, or on aerial viaduct. It is rare for 

ground-borne vibration to be a problem with aerial railways, except when guideway supports are located 

within 50 ft of buildings. Directly radiated airborne noise is usually the dominant problem from 

guideways at-grade or in cut, although ground-borne noise can sometimes be a problem. For tunnels that 

are under residential areas, however, ground-borne noise and vibration are often among the most 

significant environmental problems.

Geology: Soil conditions are known to have a strong influence on the levels of ground-borne vibration. 

Among the most important factors are the stiffness and internal damping of the soil and the depth to 

bedrock. Experience has shown that vibration propagation is more efficient in stiff clay soils as well as 

areas with shallow bedrock; the latter condition seems to channel or concentrate the vibration energy 

close to the surface, resulting in ground-borne vibration problems at large distances from the track. 

Factors such as layering of the soil and depth to water table can also have significant effects on the 

propagation of ground-borne vibration.

Receiving Building: Ground-borne vibration problems occur almost exclusively inside buildings. 

Therefore, the characteristics of the receiving building are a key component in the evaluation of groundborne vibration. The train vibration may be perceptible to people who are outdoors, but it is very rare for 

outdoor vibration to cause complaints. The vibration levels inside a building depend on the vibration 

energy that reaches the building foundation, the coupling of the building foundation to the soil, and the 

propagation of the vibration through the building structure. The general guideline is that the more 

massive a building is, the lower its response to incident vibration energy in the ground.

The human response to different levels of ground-borne noise and vibration is described in Table 6-1. 

The first column lists vibration velocity levels, and the next two columns list the corresponding noise 

levels, assuming that the vibration spectrum peaks at either 30 or 60 Hz. As discussed above, the Aweighted noise level will be approximately 45 dB less than the vibration velocity level if the spectrum 

peak is around 30 Hz and 30 dB lower if the spectrum peak is around 60 Hz. However, human response 

measures illustrate that achieving either the acceptable vibration or acceptable noise levels does not 
Chapter 6: Ground-Borne Vibration Concepts 6-41

guarantee that the other will be acceptable. The noise caused by vibrating structural components may be 

very annoying even though the vibration cannot be felt or the other way around.
Chapter 6: Ground-Borne Vibration Concepts 6-42

Table 6-1 Human Response to Different Levels of Ground-Borne Noise and Vibration

RMS 

Vibration 

Velocity Level

Noise Level

Human Response Low 

Freq1

Mid 

Freq2

65 VdB 20 dBA 35 dBA

Approximate threshold of vibration perception for many humans. 

Low-frequency sound usually inaudible, mid-frequency sound 

marginally acceptable for quiet sleeping areas.

75 VdB 30 dBA 45 dBA

Approximate dividing line between barely perceptible and distinctly 

perceptible. Many people find train vibration at this level 

unacceptable. Low-frequency noise acceptable for sleeping areas, midfrequency noise annoying in most quiet occupied areas.

85 VdB 40 dBA 55 dBA

Vibration acceptable only if there are an infrequent number of events 

per day. Low-frequency noise generally unacceptable for sleeping 

areas, mid-frequency noise unacceptable even for infrequent events 

with institutional land uses such as schools and churches.

Notes:

1. Approximate noise level when vibration spectrum peak is near 30 Hz.

2. Approximate noise level when vibration spectrum peak is near 60 Hz.

Table 6-2 Factors that influence Levels of Ground-Borne Vibration and Noise

Factors Related to Vibration Source

Factors Influence

Vehicle Suspension If the suspension is stiff in the vertical direction, the effective vibration forces 

will be higher. On transit cars, only the primary suspension affects the 

vibration levels, the secondary suspension that supports the carbody has no 

apparent effect. Similar effects are likely to occur with high-speed trainsets.

Wheel Condition Wheel roughness and flat spots are the major cause of vibration from steelwheel/steel-rail train systems.

Track Surface Rough track is often the cause of vibration problems. Maintaining a smooth 

track surface will reduce vibration levels.

Track Support System On rail systems, the track support system is one of the major components in 

determining the levels of ground-borne vibration. The highest vibration levels 

are created by track that is rigidly attached to a concrete track bed. The 

vibration levels are much lower when special vibration control track systems 

such as resilient fasteners, ballast mats, and floating slabs are used.

Speed As intuitively expected, higher speeds result in higher vibration levels. 

Doubling speed usually results in vibration levels 4–6 dB higher.

Track Structure The general rule of thumb is that the heavier the track structure, the lower the 

vibration levels. The vibration levels from a lightweight bored tunnel will 

usually be higher than from a poured concrete box tunnel.

Depth of Vibration Source There are significant differences in the vibration characteristics when the 

source is underground compared to at the ground surface.
Chapter 6: Ground-Borne Vibration Concepts 6-43

6.4 GROUND-BORNE VIBRATION FROM HIGH-SPEED TRAINS

Available data on ground-borne vibration from high-speed trains is from measurements of test programs 

involving the Acela in the United States and the TransRapid TR08 in Germany, and revenue service 

operations of the X2000 in Sweden, the Pendolino in Italy, and the TGV and Eurostar trains in France. 

Acela and TR08 tests were performed in 2000–2001. The European revenue service data were obtained 

in May 1995 as part of the data collection task involved in preparing this manual. Vibration 

measurements were made at two or three sites in each country, with vibration propagation testing done at 

one primary site in each country. This measurement program represents one of the first times that the 

same detailed ground-borne vibration testing procedure has been carried out in several different countries 

for high-speed trains operating under normal revenue conditions. 

One of the major problems in characterizing ground-borne vibration from trains is that geology has a 

major influence in vibration levels, and there are no analytical methods of factoring out the effects of 

geology. This makes it very difficult to compare the levels of ground-borne vibration from different types 

of trains, unless they are operating on the same track. An experimental method of characterizing 

Factors Related to Vibration Path

Factors Influence

Soil Type It is generally expected that vibration levels will be higher in stiff clay type 

soils than in loose sandy soils.

Rock Layers Vibration levels often seem to be high near at-grade track when the depth to 

bedrock is 30 ft or less. Tunnels founded in rock will result in lower vibration 

amplitudes close to the tunnel. Because of efficient propagation, the vibration 

level does not attenuate as rapidly in rock as it does in soil.

Soil Layering Soil layering will have a substantial, but unpredictable, effect on the vibration 

levels because each stratum can have significantly different dynamic

characteristics.

Depth-to-Water Table The presence of the water table is often expected to have a significant effect on 

ground-borne vibration, but evidence to date cannot be expressed with a 

definite relationship.

Frost Depth There is some indication that vibration propagation is less efficient when the 

ground is frozen.

Factors Related to Vibration Receiver

Factors Influence

Foundation Type The general rule of thumb is that the heavier the building foundation, the 

greater the coupling loss as the vibration propagates from the ground into the 

building.

Building Construction Because ground-borne vibration and noise almost always are evaluated in 

terms of indoor receivers, the propagation of the vibration through the building 

must be considered. Each building has different characteristics relative to 

structure-borne vibration, although the general rule of thumb is that the more 

massive a building is, the lower the levels of ground-borne vibration will be.

Acoustical Absorption The amount of acoustical absorption in the receiver room affects the levels of 

ground-borne noise.
Chapter 6: Ground-Borne Vibration Concepts 6-44

vibration propagation characteristics at a specific site that was developed to work around this problem31

was applied during the tests in Sweden, Italy, and France.

This propagation test procedure basically consists of dropping a weight on the ground and measuring the 

force of the impact and the vibration pulses at various distances from the impact point. The transfer 

functions between the force impulse and the vibration pulses are then used to characterize vibration 

propagation. Assuming a reasonably linear system, these transfer functions define the relationship 

between any type of exciting force and the resulting ground vibration.

The end result of the propagation test is a measure of the transmissibility of ground vibration, or line 

source transfer mobility, as a function of distance from the train. Measurements of train vibration and 

line source transfer mobility at the same site can be used to derive a “force-density” function that 

characterizes the vibration forces of a train independent of the geologic conditions at the site. The test is 

discussed in greater detail in Chapter 9.

The steps used to analyze the train vibration and ground transfer mobility data to derive force densities 

were as follows:

1. Transfer mobility and train vibration were expressed in terms of frequency-dependent 

representations, or frequency spectra.

2. Raw transfer mobility data for point sources were combined to approximate line source transfer 

mobility at each test site. 

3. Best-fit curves of level versus distance for each frequency band were derived using linear 

regression or other curve-fitting technique, to obtain line-source transfer mobility, and train 

vibration spectra as a function of distance from the source.

The difference between the train vibration spectrum and the transfer mobility spectrum at the same 

distance, or the force-density spectrum, was calculated. Theoretically, the force density should be 

independent of distance. In practice, however, force density is calculated at each measurement distance, 

and the average force density is used to characterize each type of trainset. For all of the trainsets, the 

force densities at the six measurement distances converged to within 3–4 dB of the average.

 

31 U.S. DOT, FTA. Chapter 11: Detailed vibration analysis. In Transit Noise and Vibration Impact Assessment, 

Report FTA-VA-90-1003-06, May 2006.
Chapter 7: Vibration Impact Criteria 7-1

CHAPTER 7. VIBRATION IMPACT CRITERIA

The environmental impacts of vibration from high-speed trains are similar to those from other types of 

trains. The resulting building vibration can be perceptible and intrusive to building occupants and can 

cause secondary rattling of windows, items on shelves, and pictures hanging on walls. In addition, the 

sound reradiated from vibrating room surfaces, referred to as ground-borne noise, often will be audible in 

the form of a low-frequency rumbling sound.

Because of the relatively rare occurrence of annoyance due to ground-borne vibration and noise, there has 

been only limited sponsored research of human response to building vibration and structure-borne noise. 

However, with the construction of new rail rapid transit systems in the past 30 years (yr), considerable 

experience has been gained as to how people will react to various levels of building vibration. This 

experience, combined with the available national and international standards,

32,33,34 represents a good 

foundation for predicting annoyance from ground-borne noise and vibration in residential areas as well as 

interference with vibration-sensitive facilities caused by a high-speed rail project. The criteria for 

ground-borne vibration and noise included in this chapter are based on the FTA manual Transit Noise and 

Vibration Impact Assessment35 with only minor modifications.

The criteria for environmental impact from ground-borne vibration and noise presented in Table 7-1 are 

based on the maximum levels for a single event. The criteria account for variation in land use as well as 

 

32 Acoustical Society of America. American National Standard: Guide to Evaluation of Human Exposure to 

Vibration in Buildings, ANSI S3.29-1983 (ASA 48-1983).

33 International Standards Organization. Evaluation of Human Exposure to Whole-Body Vibration, Part 2: 

Continuous and Shock-Induced Vibrations in Buildings (1-80 Hz), ISO-2361-2, 1989.

34 Institute of Environmental Sciences and Technology. Considerations in Clean Room Design, RR-CC012.1, 1993.

35 U.S. DOT, FTA. Transit Noise and Vibration Impact Assessment, Report No. FTA-VA-90-1003-06, May 2006.
Chapter 7: Vibration Impact Criteria 7-2

the frequency of events, which can differ widely among high-speed rail projects. Most experience is with 

the community response to ground-borne vibration from rail rapid transit systems with typical headways 

in the range of 3–10 min and each vibration event lasting less than 10 s. Intuition suggests that with many 

fewer events each day, as is typical for high-speed rail projects, it should take higher vibration levels to 

evoke the same community response. This was accounted for in the criteria by distinguishing between 

projects with varying numbers of events, where Frequent Events are defined as more than 70 events per 

day, Occasional Events range between 30 and 70 events per day, and Infrequent Events are fewer than 

30 events per day. The dividing line between frequent and occasional events was originally selected in 

the FTA manual such that most commuter rail projects fall into the occasional or infrequent event 

categories. Intercity rail operations typically fall into these categories as well.

Table 7-1 Ground-Borne Vibration (GBV) and Ground-Borne Noise (GBN) Impact Criteria for 

General Assessment

Land Use Category

GBV Impact Levels

(VdB re 1 μin/s) GBN Impact Levels (dB re 20 μPa)

Frequent

Events1

Occasional

Events2

Infrequent

Events3

Frequent

Events1

Occasional

Events2

Infrequent

Events3

Category 1: Buildings where 

vibration would interfere with 

interior operations.

65 VdB4 65 VdB4 65 VdB4 N/A5 N/A5 N/A5

Category 2: Residences and 

buildings where people normally 

sleep.

72 VdB 75 VdB 80 VdB 35 dBA 38 dBA 43 dBA

Category 3: Institutional land 

uses with primarily daytime use. 75 VdB 78 VdB 83 VdB 40 dBA 43 dBA 48 dBA

Notes:

1. Frequent Events is defined as more than 70 vibration events of the same kind per day.

2. Occasional Events is defined as between 30 and 70 vibration events of the same kind per day.

3. Infrequent Events is defined as fewer than 30 vibration events of the same kind per day.

4. This criterion limit is based on levels that are acceptable for most moderately sensitive equipment such as optical 

microscopes. Vibration-sensitive manufacturing or research will require detailed evaluation to define the acceptable 

vibration levels. Ensuring lower vibration levels in a building often requires special design of the HVAC systems 

and stiffened floors.

5. Vibration-sensitive equipment is not sensitive to ground-borne noise.

The criteria are primarily based on experience with passenger train operations, rather than freight train 

operations. The difference is that passenger train operations, whether rapid transit, commuter rail, or

moderate to high-speed intercity rail, create vibration events that last less than approximately 10 s. A 

typical line-haul freight train is approximately 5,000 ft long. At a speed of 30 mph, it takes a 5,000-foot 

freight train approximately 2 min to pass. Even though the criteria are primarily based on experience with 

shorter vibration events and this manual is oriented toward high-speed rail projects, there will be some 

situations where potential impacts from freight train ground-borne vibration will need to be evaluated. 

The prime example is the operation of high-speed trains within an existing freight railroad right-of-way. 

Some guidelines for applying these criteria to rail corridors with existing freight or passenger trains are 

given later in this chapter.
Chapter 7: Vibration Impact Criteria 7-3

7.1 VIBRATION IMPACT CRITERIA FOR GENERAL ASSESSMENT

7.1.1 Sensitive-Use Categories

The criteria for acceptable ground-borne vibration are expressed in terms of RMS velocity levels in 

decibels, and the criteria for acceptable ground-borne noise are expressed in terms of A-weighted sound 

level. The criteria apply to train-generated ground-borne vibration and noise whether the trains run 

underground, at the surface, or on elevated guideway. The limits are specified for the three land-use 

categories defined below:

Vibration Category 1 - High Sensitivity: Included in Category 1 are buildings where vibration would 

interfere with operations within the building, including levels that may be well below those associated 

with human annoyance. Concert halls and other special-use facilities are covered separately in Table 7-2. 

Typical land uses covered by Category 1 are vibration-sensitive research and manufacturing, hospitals 

with vibration-sensitive equipment, and university research operations. The degree of sensitivity to 

vibration will depend on the specific equipment that will be affected by the vibration. Equipment such as 

electron microscopes, high-resolution lithographic equipment and magnetic resonance imaging devices 

can be very sensitive to vibration, and even normal optical microscopes will sometimes be difficult to use 

when vibration is well below the human annoyance level. Manufacturing of computer chips is an example 

of a vibration-sensitive process.

The vibration limits for Vibration Category 1 are based on an acceptable vibration for moderately 

vibration-sensitive equipment, such as optical microscopes and electron microscopes with vibration 

isolation systems. Defining limits for equipment that is even more sensitive requires a detailed review of 

the specific equipment involved. This type of review is usually performed during the Detailed Analysis 

associated with the final design phase and not as part of the environmental impact assessment. Mitigation 

of train vibration that affects sensitive equipment typically involves modification of the equipment 

mounting system or relocation of the equipment rather than applying vibration control measures to the 

high-speed rail project. 

Note that this category does not include most computer installations or telephone switching equipment. 

Although the owners of this type of equipment often are very concerned about the potential of groundborne vibration interrupting smooth operation of their equipment, it is rare for a computer or other 

electronic equipment to be particularly sensitive to vibration. Most such equipment is designed to operate 

in typical building environments where it may experience occasional shock from bumping and continuous 

background vibration caused by other equipment.

Vibration Category 2 – Residential: This category covers all residential land uses and any buildings 

where people sleep, such as hotels and hospitals. No differentiation is made between different types of 

residential areas. This is primarily because ground-borne vibration and noise are experienced indoors, 

and building occupants have practically no means to reduce their exposure. Even in a noisy urban area, 

the bedrooms often will be quiet in buildings that have effective noise insulation and tightly closed 

windows. Moreover, street traffic often abates at night when trains continue to operate. Hence, an 

occupant of a bedroom in a noisy urban area is likely to be just as exposed to ground-borne noise and 

vibration as someone in a quiet suburban area.
Chapter 7: Vibration Impact Criteria 7-4

Vibration Category 3 – Institutional: Vibration Category 3 includes schools, places of worship (e.g.,

churches), other institutions, and quiet offices that do not have vibration-sensitive equipment, but still 

have the potential for activity interference. Although it is generally appropriate to include office 

buildings in this category, it is not appropriate to include all buildings that have any office space. For 

example, most industrial buildings have office space, but it is not intended that buildings primarily for 

industrial use be included in this category.

There are some buildings, such as concert halls, television and recording studios, and theaters, that can be 

very sensitive to vibration and noise but do not fit into any of the three categories. Because of the 

sensitivity of these buildings, they usually warrant special attention during the environmental assessment

of a high-speed rail project. Table 7-2 gives criteria for acceptable levels of ground-borne vibration and 

noise for various types of special buildings. 

Table 7-2 Ground-Borne Vibration and Noise Impact Criteria for Special Buildings

Type of Building or Room

Ground-Borne Vibration Impact Levels

(VdB re 1 μin/s)

Ground-Borne Noise Impact Levels

(dB re 20 μPa)

Frequent

Events1

Occasional or 

Infrequent

Events2

Frequent

Events1

Occasional or 

Infrequent

Events2

Concert Halls

TV Studios

Recording Studios

Auditoriums

Theaters

65 VdB

65 VdB

65 VdB

72 VdB

72 VdB

65 VdB

65 VdB

65 VdB

80 VdB

80 VdB

25 dBA

25 dBA

25 dBA

30 dBA

35 dBA

25 dBA

25 dBA

25 dBA

38 dBA

43 dBA

Notes:

1. Frequent Events is defined as more than 70 vibration events per day. 

2. Occasional or Infrequent Events is defined as fewer than 70 vibration events per day. 

The criteria in Tables 7-1 and 7-2 are related to ground-borne vibration causing human annoyance or 

interfering with use of vibration-sensitive equipment. It is extremely rare for vibration from train 

operations to cause any sort of building damage, even minor cosmetic damage. However, there is 

sometimes concern about damage to fragile historic buildings located near the right-of-way. Even in 

these cases, damage is unlikely, except when the track will be very close to the structure. Damage 

thresholds that apply to these structures are discussed in Chapter 10.

7.1.2 Existing Vibration Conditions

One factor not incorporated in the criteria is how to account for existing vibration. In most cases, except 

near railroad tracks, the existing environment does not include a significant number of perceptible 

ground-borne vibration or noise events. However, it is common for high-speed rail projects to use parts 

of existing rail corridors. When the project will cause vibration more than 5 VdB greater than the existing 

source, the existing source can be ignored, and the standard vibration criteria can be applied to the project. 

Following are methods of handling representative scenarios:

1. Infrequently used rail corridor (fewer than five trains per day): Use the general vibration criteria, 

Tables 7-1 and 7-2.

2. Moderately used rail corridor (5 to 12 trains per day): If the existing train vibration exceeds the 

impact criteria given in Tables 7-1 and 7-2, there will be no impact from the project vibration if 
Chapter 7: Vibration Impact Criteria 7-5

the levels estimated using the procedures outlined in either Chapter 8 or 9 are at least 5 VdB less 

than the existing train vibration. Otherwise, the vibration criteria in Tables 7-1 and 7-2 apply to 

the project. The existing train vibration can be either measured or estimated by using the General 

Assessment procedures in Chapter 8; however, it is usually preferable to measure vibration from 

existing train traffic.

3. Heavily used rail corridor (more than 12 trains per day): If the existing train vibration exceeds 

the impact criteria given in Tables 7-1 and 7-2, the project will cause additional impact if the 

project significantly increases the number of vibration events. Approximately doubling the 

number of trains is required for a significant increase.

If there is not a significant increase in vibration events, there will be additional impact only if the 

project vibration, estimated using the procedures of Chapter 8 or 9, will be 3 VdB or more than 

the existing vibration. In locations where the new trains will be operating at much higher speeds 

than the existing rail traffic, it is likely that the high-speed trains will generate substantially higher 

levels of ground-borne vibration. When the project will cause vibration more than 5 VdB greater 

than the existing source, the existing source can be ignored, and the vibration criteria in 

Tables 7-1 and 7-2 can be applied to the project.

4. Moving existing tracks: Another scenario where existing vibration can be significant is when a 

new high-speed rail line will use an existing rail right-of-way and results in shifting the location 

of existing tracks. The track relocation and reconstruction can result in lower vibration levels, in 

which case this aspect of the project represents a benefit rather than an adverse impact. If the 

track relocation will cause higher vibration levels at sensitive receptors, then the projected 

vibration levels from both rail systems must be compared with the appropriate impact criterion to 

determine whether there will be new impacts. If impact is judged to have existed prior to moving 

the tracks, new impact will be assessed only if the relocation results in more than a 3-vibration 

decibel increase in vibration level.

7.1.3 Application to Freight Trains

The impact thresholds given in Tables 7-1 and 7-2 are based on experience with vibration from rail transit 

systems. They have been used to assess vibration from freight trains because no specific impact criteria 

exist for freight railroads. However, the significantly greater length, weight, and axle loads of freight 

trains make it problematic to use these impact criteria for freight rail. Nevertheless, in shared right-ofway situations where the proposed high-speed rail alignment causes the freight tracks to be moved closer 

to sensitive sites, these impact criteria will have to be used. In assessing the freight train vibration, a dual 

approach is recommended with separate consideration of the locomotive and rail car vibration. Because 

the locomotive vibration only lasts for a very short time, the few-event criterion is appropriate for fewer 

than 30 events per day. However, for a typical line-haul freight train where the rail car vibration lasts for 

several minutes, the many-event limits should be applied to the rail car vibration. Some judgment must 

be exercised to make sure that the approach is reasonable. For example, some spur rail lines carry very 

little rail traffic (sometimes only one train per week) or have short trains, in which case the criteria may 

be disregarded altogether.

Finally, it should be noted that the vibration control measures developed for passenger rail systems are 

not effective for freight trains. Consequently, any decision to relocate freight tracks closer to sensitive 
Chapter 7: Vibration Impact Criteria 7-6

sites should be made with the understanding that the increased vibration impact due to freight rail will be 

very difficult, if not impossible, to mitigate.

7.2 VIBRATION IMPACT CRITERIA FOR DETAILED ANALYSIS

7.2.1 Ground-Borne Vibration

Specification of mitigation measures requires more detailed information and more refined impact criteria 

than those used in the General Assessment. A frequency distribution, or spectrum, of the vibration energy 

determines whether the vibrations are likely to generate a significant response in a receiving building or 

structure. The Detailed Analysis method in this manual provides an estimate of building response in 

terms of a one-third octave band frequency spectrum. This section provides criteria for assessing the 

potential for interference or annoyance from building response and for determining the performance of 

vibration reduction methods.

International standards have been developed for the effects of vibration on people in buildings with 

ratings related to annoyance and interference with activities based on frequency distribution of acceptable 

vibrations.36 These criteria have been supplemented by industry standards for vibration-sensitive 

equipment.37 Both sets of criteria are expressed in terms of one-third octave band spectra, with transient 

events like train passbys described in terms of the maximum RMS vibration velocity level with a 

1-second averaging time. The measurement point is specified as the floor of the receiving building at the 

location of the prescribed activity.

The vibration impact criteria are shown in Figure 7-1 where the international standard curves and the 

industry standards are plotted on the same figure. Interpretations of the various levels are presented in 

Table 7-3. Detailed Analysis results in one-third octave band spectra levels that are plotted over the 

curves shown in Figure 7-1. Band levels that exceed a particular criterion curve indicate the need for 

mitigation and the frequency range within which the treatment needs to be effective.

These criteria use a frequency spectrum because vibration-related problems generally occur because of

resonances of the structural components of a building or vibration-sensitive equipment. Resonant 

response is frequency dependent. A Detailed Analysis can provide an assessment that identifies potential 

problems resulting from resonances.

The detailed vibration criteria are based on generic cases when people are standing or equipment is 

mounted on the floor in a conventional manner. Consequently, the criteria are less stringent at very low 

frequencies below 8 Hz. Where special vibration isolation has been provided in the form of pneumatic 

isolators, the resonant frequency of the isolation system is very low. Thus, in this special case, the curves 

may be extended flat at lower frequencies. In general, the curves may also be extended flat at higher 

frequencies than shown in Figure 7-1 (i.e., above 80 Hz).

 

36 International Standards Organization. Evaluation of Human Exposure to Whole-Body Vibration, Part 2: 

Continuous and Shock-Induced Vibrations in Buildings (1–80 Hz), ISO-2361-2, 1989.

37 Institute of Environmental Sciences and Technology. Considerations in Clean Room Design, RR-CC012.1, 1993.
Chapter 7: Vibration Impact Criteria 7-7

Figure 7-1 Criteria for Detailed Vibration Analysis
Chapter 7: Vibration Impact Criteria 7-8

Table 7-3 Interpretation of Vibration Criteria for Detailed Analysis

Criterion Curve1

(See Figure 7-1)

Max Lv

(VdB)2 Description of Use

Workshop 90 Distinctly feelable vibration. Appropriate to workshops and nonsensitive 

areas.

Office 84 Feelable vibration. Appropriate to offices and nonsensitive areas.

Residential Day 78 Barely feelable vibration. Adequate for computer equipment and lowpower optical microscopes (up to ×20).

Residential Night,

Operating Rooms 72

Vibration not feelable, but ground-borne noise may be audible inside quiet 

rooms. Suitable for medium power optical microscopes (×100) and for 

other equipment of low sensitivity.

VC-A 66 Adequate for medium high-power optical microscopes (×400), 

microbalances, optical balances, and similar specialized equipment.

VC-B 60 Adequate for high-power optical microscopes (×1,000), inspection, and 

lithography equipment to 3-micron line widths.

VC-C 54 Appropriate for most lithography and inspection equipment to 1-micron 

detail size.

VC-D 48 Suitable in most instances for the most demanding equipment, including 

electron microscopes operating to the limits of their capability.

VC-E 42 The most demanding criterion for extremely vibration-sensitive 

equipment. 1 Descriptors on curves are those provided by References 2 and 3.

2 As measured in one-third octave bands of frequency over the frequency range 8–100 Hz.

7.2.2 Ground-Borne Noise

Ground-borne noise impacts are assessed based on criteria for human annoyance and activity interference. 

The results of the Detailed Analysis provide vibration spectra inside a building. These vibration spectra 

can be converted to sound pressure level spectra in the occupied spaces by using the method described in 

Section 9.3.4. For residential buildings, the criteria for acceptability are given in terms of the A-weighted 

sound level in Table 7-1. For special buildings listed in Table 7-2, a single-valued level may not be 

sufficient to assess activity interference at the Detailed Analysis stage. Each special building may have a 

unique specification for acceptable noise levels. For example, a recording studio may have stringent 

requirements for allowable noise in each frequency band. Therefore, the ground-borne noise criteria for 

each sensitive building in this category will have to be determined on a case-by-case basis.
Chapter 8: Preliminary Vibration Assessment 8-1

CHAPTER 8. PRELIMINARY VIBRATION ASSESSMENT

Procedures that can be used to develop generalized predictions of ground-borne vibration and noise are 

described in this chapter. There are three different levels of detail for projecting ground-borne vibration:

Screening – The screening procedure uses a table of distances to determine whether noise-sensitive land 

uses are close enough to the proposed high-speed train system for impact from ground-borne vibration to 

be possible. More detailed analysis is required if any sensitive land uses are within the screening 

distances. The screening procedure does not require any specific knowledge about the vibration 

characteristics of the system or the geology of the area.

General Assessment – The general level of assessment uses generalized data to develop a curve of 

vibration level as a function of distance from the track. The vibration levels at specific buildings are 

estimated by reading values from the curve and applying adjustments to account for factors such as track 

support system, train speed, track and wheel condition, type of building, and receiver location within the 

building. The general level deals only with the overall vibration velocity level and the A-weighted sound 

level. It does not consider the frequency spectrum of the vibration or noise.

Detailed Analysis – The detailed analysis involves applying all of the available tools for accurately 

projecting the vibration impact at specific sites. The procedure outlined in this manual includes a test of 

the trainset (or similar trainset) to define the forces generated by the vibration source and tests at the sites 

in question to define how the local geology affects vibration propagation. Developing detailed projections 

of ground-borne vibration is considerably more complex than developing detailed projections of airborne 

noise. The vibration projection procedure is not only complex but also has not yet been standardized. 

Accurate projections of ground-borne vibration require professionals with experience in performing and 

interpreting vibration propagation tests. As such, detailed vibration predictions are usually performed 

during the final design phase of a project when there is sufficient reason to suspect adverse vibration 

impact from the project. 
Chapter 8: Preliminary Vibration Assessment 8-2

The Screening and General Assessment methods are discussed in this chapter. The Detailed Analysis 

procedure, which is based on measurements to characterize vibration propagation at specific sites, is 

presented in Chapter 9.

General and detailed predictions do not always have a clear distinction. For example, it is often 

appropriate to use several representative measurements of vibration propagation along the planned 

alignment in developing generalized propagation curves. At other times, generalized prediction curves 

may be sufficient for most of an alignment, with detailed analysis applied to particularly sensitive 

buildings, such as a concert hall.

The purpose of the General Assessment is to provide a relatively simple method of developing estimates 

of the overall levels of ground-borne vibration and noise that can be compared with the acceptability 

criteria given in Chapter 7. For many projects, particularly when comparing alternatives, this level of 

detail will be sufficient for the environmental assessment. Where potential problems exist, the Detailed 

Analysis is then undertaken during final design of the selected alternative to define accurately the level of 

impact and design mitigation measures. A Detailed Analysis usually will be required when designing 

special track-support systems, such as floating slabs or ballast mats. Detailed Analysis is not usually 

required if the mitigation measure consists of relocating a crossover or turnout.

8.1 VIBRATION SCREENING PROCEDURE

The screening method is intended to be applied early in project development before many details on the 

system have been defined. It allows a quick check to identify whether and where impacts from groundborne vibration are likely. Screening distances for three different speed ranges and two general types of 

land use are given in Table 8-1.

Table 8-1 Screening Distances for Vibration Assessments

(applicable to steel-wheel/steel-rail high-speed rail systems)

Land Use Train 

Frequency*

Screening Distance, ft

Train Speed

Less than

100 mph

100 to 

200 mph

200 to 

300 mph

Residential Frequent or 

Occasional

120 220 275

Infrequent 60 100 140

Institutional Frequent or 

Occasional

100 160 220

Infrequent 20 70 100

*Frequent = greater than 70 passbys per day.

 Infrequent = less than 70 passbys per day.

The screening distances given in Table 8-1 are based on the criteria presented in Chapter 7 and the 

Generalized Assessment procedures discussed in Section 8.2, assuming “normal” vibration propagation 

conditions. “Efficient” vibration propagation conditions, characterized by the transmission of ground 

vibration at low rates of attenuation with distance, can result in substantially higher vibration levels. 

Efficient propagation has not been assumed in developing the screening distances, because it is a 

relatively unusual condition and assuming efficient propagation would overestimate the potential for 
Chapter 8: Preliminary Vibration Assessment 8-3

vibration impact. However, by not accounting for the possibility of efficient vibration propagation, some 

potential impact areas may not be identified in the screening process. When there is evidence of efficient 

propagation, such as previous complaints about existing rail facilities or a history of problems with 

construction vibration, the distances in Table 8-1 should be increased by a factor of 2.

8.2 GENERALIZED VIBRATION ASSESSMENT PROCEDURE

The basic approach of the General Assessment procedure is to use a base curve of overall ground-surface 

vibration as a function of distance from the source, then to apply adjustments to this curve to account for 

factors such as track support system, train speed, track and wheel condition, building type, and receiver 

location within the building. Steel-wheel/steel-rail technology has, in terms of ground-borne vibration, 

similar characteristics to existing intercity passenger train and transit trains. Maglev technology has some 

unique characteristics based on measurements at the test facility in Germany.

8.2.1 Base Curve

The generalized projection curves for high-speed trains are shown in Figure 8-1. These curves represent 

typical ground-surface vibration levels assuming equipment in good condition and speeds of 150 mph. 

The levels must be adjusted to account for factors such as different speeds, equipment, and geologic 

conditions than those assumed in the figure. The curves in Figure 8-1 are based on the ground-borne 

vibration measurement data discussed in Appendix D.

The steel-wheel curve in Figure 8-1 is applicable to high-speed trains both at-grade and in tunnel. The 

rationale for applying the same curve to these two very different conditions is based on the analysis done 

for the FTA manual Transit Noise and Vibration Impact Assessment.

38 In developing generalized 

prediction curves for the FTA manual, investigators found that transit trains operating at grade and in 

tunnel had similar overall vibration levels. This finding was rather surprising because transit trains 

operating in tunnels tend to generate more vibration complaints than those operating on at-grade track. 

This tendency is probably due to two factors: (1) tunnels are usually located close to buildings, often 

directly under them, in densely developed areas, and (2) for at-grade systems, airborne noise from train 

passbys is usually more noticeable than the ground-borne vibration generated. Although the overall 

vibration levels from trains operating in tunnel and above grade are similar, there are differences in the 

frequency spectra of the vibration. The ground-borne vibration from trains in tunnels tends to be of a 

higher frequency than the vibration from at-grade track, and higher frequencies make the ground-borne 

noise from tunnels more noticeable in nearby buildings.

 

38 U.S. DOT, FTA. Transit Noise and Vibration Impact Assessment, Report No. FTA-VA-90-1003-06, May 2006.
Chapter 8: Preliminary Vibration Assessment 8-4

Figure 8-1 Generalized Ground-Borne Vibration Curve

The steel-wheel curve in Figure 8-1 is the same as the curve in the FTA manual that is applicable to urban 

transit trains, except that this curve is 10 VdB higher to account for the speed adjustment from 50 mph for 

urban transit to 150 mph for high-speed rail. This curve represents the high range of the available 

measurement data of high-speed train ground-borne vibration. Only data from locations known to have 

unusual vibration propagation conditions was consistently above the curve. 

Experience with ground-borne vibration data from trains has shown that a 5- to 10-decibel fluctuation in 

vibration levels under apparently similar conditions is not uncommon. The curves in Figure 8-1 represent 

the upper range of the measurement data. Although actual levels fluctuate widely, ground-borne vibration 

rarely will exceed the curves in Figure 8-1 by more than 1 or 2 dB unless there are extenuating 

circumstances, such as rail corrugations or flat spots on wheels for the steel-wheel mode or efficient 

vibration propagation for all technologies.

It is not recommended to show projections of normal fluctuation as a “range” of vibration levels. For 

example, the projected level from Figure 8-1 at a train speed of 150 mph is approximately 72 VdB, the 

threshold for acceptable ground-borne vibration for residential land uses, at a distance of 180 ft from the 

track centerline. If shown as a range to reflect normal fluctuations, the projected level of ground-borne 

vibration might be given as a range between 67 and 72 VdB, and the interpretation of whether the 

projected vibration levels exceed the impact threshold becomes unclear. However, because actual levels 

of ground-borne vibration will sometimes differ substantially from the projections, some care must be 

taken when interpreting projections. Some guidelines are given:
Chapter 8: Preliminary Vibration Assessment 8-5

1. Projected vibration is below the impact threshold. Vibration impact is unlikely in this case.

2. Projected ground-borne vibration is 0–5 dB greater than the impact threshold. In this range, there 

is still a significant chance (at least 50 percent) that actual ground-borne vibration levels will be 

below the impact threshold. In this case, the impact would be reported in the environmental 

document as exceeding the applicable threshold, and a commitment would be made to conduct 

more detailed studies to refine the vibration impact analysis and determine appropriate mitigation 

during final design. A site-specific Detailed Analysis may show that vibration control measures 

are not needed.

3. Projected ground-borne vibration is 5 dB or more greater than the impact threshold. Vibration 

impact is probable and some type of vibration control should be incorporated into the final design 

of the project.

The two most important factors that must be accounted for in a General Assessment are the type of 

vibration source and the vibration propagation characteristics. It is well known that there are situations in 

which ground-borne vibration propagates much more efficiently than normal. The result is unacceptable 

vibration levels at distances two to three times the normal distance. Unfortunately, the geologic 

conditions that promote efficient propagation have not been well documented and are not fully 

understood. Shallow bedrock or clay soils often are involved. One possibility is that shallow bedrock 

acts to keep the vibration energy near the surface. Much of the energy that would normally radiate down 

is directed back toward the surface by the rock layer, with the result that the ground surface vibration is 

higher than normal.

8.2.2 Adjustment Factors

Once the vibration levels have been projected by using the base curves in Figure 8-1, the adjustments 

listed in Table 8-2 can be used to develop vibration projections for specific receiver positions inside 

buildings. All of the adjustments are given as numbers to be added to, or subtracted from, the base level. 

The adjustment parameters are speed, wheel and rail type and condition, type of track or guideway 

support system, type of building foundation, and number of floors above the basement level. Many of 

these adjustments depend heavily on the frequency spectrum of the vibration source and the frequency 

dependence of the vibration propagation. The single numbers given are suitable for generalized 

evaluation of the vibration impact and vibration mitigation measures because they are based on typical 

vibration spectra. However, the general adjustments are not adequate for detailed evaluations of impact 

of sensitive buildings or for detailed specification of mitigation measures. Careful consideration of the 

shape of the actual vibration spectra will avoid selection of an inappropriate vibration control measure, 

which in some cases could actually cause an increase in the vibration levels.
Chapter 8: Preliminary Vibration Assessment 8-6

Table 8-2 Adjustment Factors for Generalized Predictions of Ground-Borne Vibration and Noise

Factors Affecting Vibration Source for Steel-Wheel Technology

Source Factor Adjustment to Propagation Curve Comment

Speed

Vehicle Speed

300 mph

200 mph

150 mph

100 mph

75 mph

Adjustment

(Ref Speed=150 mph)

+6.0 dB

2.5 dB

0.0 dB

-3.5 dB

-6.0 dB

Vibration level is approximately proportional to 

20*log(speed/speedref). Sometimes the variation 

with speed has been observed to be as low as 10 to 

15 log(speed/speedref).

Resilient Wheels 0 dB

Resilient wheels do not generally affect groundborne vibration except at frequencies greater than 

approximately 80 Hz.

Worn Wheels or 

Wheels with Flats

Select highest 

one that 

applies

{

+10 dB

Wheel flats or wheels that are unevenly worn can 

cause high vibration levels. This problem can be 

prevented with wheel truing and slip-slide detectors 

to prevent the wheels from sliding on the track.

Worn or Corrugated 

Track +10 dB

If both the wheels and the track are worn, only one 

adjustment should be used. Corrugated track is a 

common problem; however, it is difficult to predict 

the conditions that cause corrugations to occur. 

Rail grinding can remove rail corrugations.

Crossovers and Other 

Special Track Work +10 dB

Wheel impacts at special track work with standard 

frogs will significantly increase vibration levels. 

The increase will be less at greater distances from 

the track. Moveable point frogs mitigate this 

problem.

Floating Slab 

Track Bed

Select highest 

one that 

applies

{

-15 dB

The reduction achieved with a floating slab track

bed is strongly dependent on the frequency 

characteristics of the vibration.

Ballast Mats -10 dB Actual reduction is strongly dependent on 

frequency of vibration.

High-Resilience 

Fasteners -5 dB

Slab track with track fasteners that are very 

compliant in the vertical direction can reduce 

vibration at frequencies greater than 40 Hz.

Resiliently Supported 

Ties -10 dB

Resiliently supported tie systems in tunnel have 

been found to provide very effective control of lowfrequency vibration.

Type of Track 

Structure

Relative to at-grade tie & ballast

The general rule is the heavier the structure, the 

lower the vibration levels. Putting the track in cut 

may reduce the vibration levels slightly. Rockbased tunnels will shift vibration to a higher 

frequency.

Aerial/Viaduct structure -10 dB

Open Cut 0 dB

Relative to bored tunnel in soil

Station -5 dB

Cut and Cover -3 dB

Rock-Based -15 dB
Chapter 8: Preliminary Vibration Assessment 8-7

Table 8-2 Continued...

Factors Affecting Vibration Source for Maglev Technology

Source Factor Adjustment to Propagation Curve Comment

Speed Vehicle Speed

300 mph

200 mph

150 mph

100 mph

75 mph

Adjustment

(Ref. Speed=150 mph)

+14 dB

+ 4 dB

 0 dB

- 8 dB

- 10 dB

Speed relationship is highly dependent on structural 

response of guideway.

Type of Guideway 

Structure

Concrete

Steel

Hybrid

At-Grade

Switch

Reference

+ 1 dB

+ 2 dB

+ 0 dB

+10 dB

Adjustments are based on limited data on prototype 

structure. Vibration levels depend on structural 

design.

Factors Affecting Vibration Path

Path Factor Adjustment to Propagation Curve Comment

Geologic Conditions 

that Promote 

Efficient Vibration 

Efficient propagation in 

soil

+10 dB Refer to the text for guidance on identifying areas 

where efficient propagation is possible. 

Propagation Propagation in 

Rock Layer

Dist.

50 ft

100 ft

150 ft

200 ft

Adjust.

+2 dB

+4 dB

+6 dB

+9 dB

The positive adjustment accounts for the lower 

attenuation of vibration in rock compared with soil. 

Because it is more difficult to get vibration energy 

into rock, propagation through rock usually results 

in lower vibration than propagation through soil.

Coupling to Building 

Foundation

Wood Frame

1-2 Story Masonry

2-4 Story Masonry

Large Masonry - on Piles

 -on Spread Footings

Foundation in Rock

-5 dB

-7 dB

-10 dB

-10 dB

-13 dB

 0 dB

The general rule is the heavier the building 

construction, the greater the coupling loss.

Factors Affecting Vibration Receiver

Receiver Factor Adjustment to Propagation Curve Comment

Floor-to-Floor 

Attenuation

1–5 floors above grade:

5–10 floors above grade:

-2 dB/floor

-1 dB/floor

This factor accounts for dispersion and attenuation 

of the vibration energy as it propagates through a 

building.

Amplification Due to 

Resonances of 

Floors, Walls, and 

Ceilings

+6 dB

The actual amplification will vary greatly 

depending on the type of construction. The 

amplification is lower near the wall-floor and wallceiling intersections.

Factors Affecting Ground-Borne Noise

Receiver Factor Adjustment to Propagation Curve Comment

Radiated Sound Peak frequency of ground vibration: Use these adjustments to estimate the A-weighted 

sound level given the average vibration velocity 

level of the room surfaces. See text for guidelines 

for selecting low-, typical-, or high-frequency 

characteristics. Use the high-frequency adjustment 

for subway tunnels in rock or if the dominant 

frequencies of the vibration spectrum are known to 

be 60 Hz or greater.

Low frequency (<30 Hz):

Typical (peak 30–60 Hz):

High frequency (>60 Hz):

(These adjustments are 

conservative compared to 

the Detailed Assessment.)

-50 dB

-35 dB

-20 dB
Chapter 8: Preliminary Vibration Assessment 8-8

The following guidelines are used to select the appropriate adjustment factors. Note that the adjustments 

for wheel and rail condition for the steel-wheel technology are not cumulative. When more than one 

adjustment may apply, the general rule is to apply only the largest adjustment. For example, the 

adjustment for corrugated rail is 10 dB and the adjustment for flat spots on wheels is 10 dB. In an area 

with both, the projected vibration levels should be increased by 10 dB and not 20 dB. Similarly, only one 

of the vibration mitigation treatments is applied.

Factors Affecting Vibration Source

Train Speed: The levels of ground-borne vibration and noise vary approximately at 20 times the 

logarithm of speed. This relationship means that doubling train speed will increase the vibration levels 

approximately 6 dB and halving train speed will reduce the levels by 6 dB. The adjustments for 

75–300 mph using a reference speed of 150 mph are given in Table 8-2. The relationship:

adjustment (VdB) = 20 × log � speed

speedref�

should be used to calculate the adjustments for other speeds.

Steel-Wheel Trainsets: The levels of ground-borne vibration and noise generated by a train passby 

depend heavily on the trainset’s suspension system, wheel condition, and wheel type. The vehicle 

suspension consists of springs and dampers that affect the vibration transmitted to the track support 

system by the wheel-rail interaction. Generally, stiff springs tend to increase the frequency and amplitude 

of vibrations. Deteriorated wheel condition also will increase vibration levels. It can be assumed that a 

high-speed rail system will have wheels in good condition. However, when older vehicles will be used on 

new track, it may be appropriate to include an adjustment for wheel condition. Wheels with flat spots or 

corrugations can cause vibration levels that are 10 dB higher than normal. Resilient wheels will reduce 

vibration levels at frequencies greater than the effective resonance frequency of the wheel. Because this 

resonance frequency is relatively high, often greater than 80 Hz, resilient wheels usually have a marginal 

effect only on ground-borne vibration.

Track System and Support: The type of rail (welded or special track work), the track support system, 

and the condition of the rail all affect the vibration generated by the track system. The base curve 

(Figure 8-1) assumes the welded rail in good condition. Jointed rail causes higher vibration levels than 

welded rail; however, track on new high-speed rail systems virtually always will be welded. The wheel 

impacts at special track work, especially frogs at crossovers, create much higher vibration forces than 

normally experienced on tangent track. Because of the higher vibration levels at special track work, 

crossovers often are the principal areas of vibration impact on new systems. Special spring- or movablepoint frogs are used as a method of mitigating the vibration impact. These special frogs eliminate the 

gaps in the running rail.

Modifying the track support system is another method of mitigating vibration impact. Special track 

support systems such as ballast mats, highly resilient track fasteners, resiliently supported ties, and 

floating slabs all have been shown to be effective in reducing vibration levels.

The condition of the running surface of the rails can strongly affect vibration levels. Factors such as 

corrugations, general wear, or mill scale on new track can cause vibration levels that are 5–15 dB higher 
Chapter 8: Preliminary Vibration Assessment 8-9

than normal. Mill scale usually will wear off after some time in service. However, the track must be 

ground to remove corrugations or to reduce the roughness from wear.

Track Structure: The weight and size of the track structure affects the vibration radiated by that 

structure. Vibration levels will generally be lower for heavier track structures. Hence, the vibration 

levels from a cut-and-cover concrete double-box tunnel can be assumed to be lower than the vibration 

from a lightweight, concrete-lined bored tunnel. Whether or not the tunnel will be founded in bedrock is 

another factor affecting the radiated vibration. Bedrock is considered to be hard rock. It is usually 

appropriate to consider soft siltstone and sandstone to be more similar to soil than hard rock. As seen in 

Table 8-2, whether the tunnel is founded in soil or rock will make up to a 15-decibel difference in the 

vibration levels. The vibration from aerial structures is lower than from at-grade track because of the 

mass of the structure, the reduced coupling to the ground, and the extra distance that the vibration must 

travel before it reaches the receiver.

Guideway Structure (Maglev): Vibration from maglev systems is not well documented. Limited data is

available from measurements conducted on the prototype system operating in Germany. This data 

indicates that ground-borne vibrations depend on guideway structural design details. Lowest vibration 

levels are associated with the prototype concrete guideway. Higher levels are obtained near the steel and 

hybrid (concrete beam, steel deck) guideways. Vibration levels are even higher near the switch. A true 

at-grade maglev guideway has yet to be measured.

Factors Affecting Vibration Path

Propagation Characteristics: The General Assessment process requires the selection of one general 

propagation characteristic. When at-grade vibration sources are considered, the selection is between 

“normal” vibration propagation and “efficient” vibration propagation. Efficient vibration propagation 

results in vibration levels approximately 10 dB higher than normal vibration propagation, which more 

than doubles the potential impact zone for ground-borne vibration. 

Although geologic conditions are known to have a significant effect on the vibration levels, it is rarely 

possible to develop more than a broad-brush understanding of the vibration propagation characteristics for 

a General Assessment. The conservative approach would be to use the 10-decibel adjustment for efficient 

propagation to evaluate all potential vibration impact. The problem with this approach is that it tends to 

overstate greatly the potential for vibration impact. Hence, it is best to review available geological data 

and any complaint history from existing rail lines and major construction sites near the high-speed rail 

corridor to identify areas where efficient propagation is possible. If there is any reason to suspect 

efficient propagation conditions, then a Detailed Analysis during final design should include vibration 

propagation tests at the areas identified as potentially efficient propagation sites.

Some geologic conditions are repeatedly associated with efficient propagation. Shallow bedrock, less 

than 30 ft below the surface, is likely to cause efficient propagation. Other factors that can be important 

are soil type and stiffness. In particular, soils with heavy clay content have sometimes been associated 

with efficient vibration propagation. Investigation of soil-boring records can be used to estimate depth to 

bedrock and the presence of problem soil conditions. 

Coupling-to-Building Foundation: Because annoyance from ground-borne vibration and noise is an 

indoor phenomenon, the effects of the building structure and its foundation on the vibration propagation 

path must also be considered. Wood frame buildings, such as the typical residential structure, are more 
Chapter 8: Preliminary Vibration Assessment 8-10

easily excited by ground-borne vibration than heavier buildings. In contrast, large masonry buildings 

with spread footings have a low response to ground-borne vibration.

Factors Affecting Vibration Receiver

Type of Building and Receiver Location in Building: Vibration generally reduces in level as it 

propagates through a building. As indicated in Table 8-2, a 1- to 2-decibel attenuation per floor is usually 

assumed. Resonances of the building structure, particularly the floors, will tend to counteract this 

attenuation and will cause some amplification of the vibration. Consequently, for a wood-frame structure, 

the building-related adjustments nearly cancel out. The adjustments for the first floor assuming a 

basement are -5 dB for the coupling loss, -2 dB for the propagation from the basement to the first floor,

and +6 dB for the floor amplification. The total adjustment is -1 dB.

Vibration Radiated as Ground-Borne Noise: The levels of radiated noise can be estimated given the 

average vibration amplitude of the room surfaces (floors, walls, and ceiling) and the total acoustical 

absorption in the room. The average result is that the numerical value of sound-pressure level is 

approximately 5 dB less than the vibration velocity level when the velocity level is referenced to 

1 × 10–6 in/s.

39 However, to estimate the A-weighted sound level from the velocity level, it is necessary 

to have some information about the frequency spectrum. The A-weighting adjustment drops rapidly at 

low frequencies, reflecting the relative insensitivity of human hearing to low frequencies. For example, 

A-weighting is -16 dB at 125 Hz, -26 dB at 60 Hz, and -40 dB at 30 Hz. Conservative adjustments for 

vibration, depending on whether it has low-frequency, typical, or high-frequency characteristics are 

provided in Table 8-2. Some general guidelines for classifying the frequency characteristics are as 

follows:

• Low Frequency: Low-frequency vibration characteristics can be assumed for most surface track, 

tunnels surrounded by sandy soil with low cohesion, or a track support system with vibration 

isolation. 

• Typical: The typical vibration characteristic is the default assumption to be used for tunnels 

unless information indicates that one of the other assumptions is appropriate. It should be used 

for surface track when the soil is very stiff with a high clay content.

• High Frequency: High-frequency characteristics should be assumed for tunnels whenever the 

transit structure is founded in rock or when there is very stiff clay soil.

A factor that can be particularly complex to address is the effect of vibration propagation through rock. 

Three factors from Table 8-2 need to be included when a tunnel will be founded in rock:

• The -15-decibel adjustment in the “Type of Track Structure” category. 

• The adjustment based on the propagation distance in the “Geologic Conditions” category. This 

positive adjustment increases with distance because vibration attenuates more slowly in rock than 

in soil.

 

39 J. A. Zapfe, H. Saurenman, and S. Fidell. Ground-Borne Noise and Vibration in Buildings Caused by Rail Transit, 

Transportation Research Board, Final Report for TCRP Project D-12, December 2009.
Chapter 8: Preliminary Vibration Assessment 8-11

• The “Coupling to Building” category. When a building foundation is directly on the rock layer, 

there is no “coupling loss” because of the weight and stiffness of the building. The standard 

coupling factors should be used if there is at least an 8-foot layer of soil between the building 

foundation and the rock layer.

8.3 INVENTORY OF VIBRATION IMPACT

The results of the General Assessment are expressed in terms of an inventory of all sensitive land uses 

where either ground-borne vibration or ground-borne noise from the project exceeds the impact 

thresholds described in Chapter 7. The General Assessment may include a discussion of mitigation 

measures likely be needed to reduce vibration to acceptable levels at impacted locations.

The purpose of the General Assessment procedure is to develop a reasonably complete inventory of the 

buildings that may experience ground-borne vibration or ground-borne noise that exceed the impact 

criteria. At this point, a conservative assessment of the impact is preferred. It is better to include some 

buildings where ground-borne vibration may be below the impact threshold than to exclude buildings 

where it may exceed the impact threshold.

The steps for developing the inventory are as follows:

Step 1: Identification of Vibration-Sensitive Land Uses

1) Identify all vibration-sensitive land uses within Screening Distance from Table 8-1.

2) Categorize vibration-sensitive land uses according to the categories in Table 7-1.

3) Construct tables of land uses by category.

Step 2: Estimation of Vibration Impact

1) Apply General Assessment procedure to obtain ground-borne vibration and ground-borne noise 

levels at each sensitive land use identified in Step 1.

2) Compare estimation with impact thresholds in Table 7-1.

3) Identify vibration-sensitive land uses where impact thresholds are exceeded.

Step 3: Preparation of Impact Inventory

1) Prepare summary tables showing the number of buildings in each category impacted by groundborne vibration and ground-borne noise. This tabulation is done for each alternative.

2) Utilize the summary tables to compare alternatives by the number of buildings impacted.

Step 4: Mitigation of Impact

1) Select appropriate mitigation method from Section 9-4.

2) Reassess impacts based on application of mitigation measures.
Chapter 8: Preliminary Vibration Assessment 8-12

An example of a receiver-specific General Vibration Assessment for a hypothetical high-speed rail 

project follows. The assumed parameters of the project and receiver are typical of the preliminary 

planning stage of a project, and it is assumed that no project-specific vibration measurements have been 

performed.

Example 8-1 General Vibration Assessment of High-Speed Train Alignment

A high-speed train proposed for a corridor in the Midwest passes through a suburb an average of once an 

hour. A hospital is located 30 ft from the right-of-way line. The train speed is projected to be 120 mph in 

this section. The tracks are continuously welded on concrete tie-and-ballast in this at-grade section. The 

distance from track centerline to the right-of-way is 50 ft. Soil conditions are unknown. Determine 

whether ground-borne vibration and noise from the train will cause impact on the second floor of this 

three-story brick building.

Step 1: Identification of Vibration-Sensitive Land Use

1) Category. A hospital is categorized in “Vibration Category 2: Residential” according to 

Chapter 7.

2) Screen. The “Vibration Screening Procedure” in Section 8.1 shows that for a 120-mile per hour

train with “infrequent” service (less than 70 passbys per day), a residential land use within 

100 ft should be identified as a potentially affected location. The hospital is located 80 ft from the 

tracks, well within the screening distance.

Step 2: Estimation of Vibration Impact

1) Base Curve. The “Generalized Ground-Borne Vibration Curve” (Figure 8-1) shows a vibration 

level of 78 VdB at 80 ft for a train at 150 mph.

2) Adjustments. Refer to Table 8-2.

2.1 Speed Adjustment. Adjustments for speeds other than 150 mph are included in 

Table 8-2. Unfortunately, 120 mph is not one of the adjustments given. Therefore, the speed 

correction of 20 log (speed/150) is used.

20 log (120/150) = -1.9 dB

Round off to -2 dB

2.2 Trainsets. Assume wheels in good condition. No adjustment is applied.

2.3 Track System. Assume rails are in good condition. No adjustment. 

2.4 Track Structure. At-grade tie and ballast is the reference condition. No adjustment is 

applied.

2.5 Propagation Characteristics. Propagation is considered to be normal unless proven 

otherwise. The soil conditions are unknown, so assume no adjustment.

2.6 Type of Building and Receiver Location. The hospital building falls into the category of 

“2-4 Story Masonry” so the coupling adjustment is -10 dB. The receiver is on the second 

floor so the “Floor-to-Floor Attenuation” is -2 dB. Low-frequency characteristics can be 
Chapter 8: Preliminary Vibration Assessment 8-13

assumed for most surface track, so the “Radiated Sound” adjustment is -50 dB to convert 

the vibration level in vibration decibels to sound level in decibel A-weighted.

2.7 Calculation

i. Ground-Borne Vibration:

Base vibration level = 78 VdB

Speed adjustment = -2 dB

Wheel condition = 0 dB

Track system = 0 dB

Track structure = 0 dB

Propagation = 0 dB

Foundation coupling = -10 dB

Receiver location = -2 dB

Floor response = +6 dB

_______

Estimated Vibration

Level = 70 VdB

ii. Ground-Borne Noise:

Vibration Level = 70 VdB

Radiated Sound = -50 VdB to dBA adjustment

________

Estimated Sound Level = 20 dBA

2.8 Impact Assessment. Ground-borne vibration and noise impact criteria are given in 

Table 7-1. The hospital in this case falls under “Category 2: Residential” land uses 

exposed to “Infrequent Events.” The corresponding threshold for ground-borne vibration 

impact is 80 VdB and for ground-borne noise impact is 43 dBA. Neither threshold is 

exceeded at the hospital.

End of Example 8-1

Chapter 9: Detailed Vibration Assessment 9-1

CHAPTER 9. DETAILED VIBRATION ASSESSMENT

The Detailed Assessment approach presented in this chapter provides a means to determine general 

vibration propagation conditions along a proposed high-speed rail corridor and to develop specific 

projections for sensitive buildings where vibration impact is predicted by a General Assessment. The 

goal of the Detailed Assessment is to develop accurate projections of ground-borne vibration by using all 

available tools and, when necessary, to design mitigation measures.

Local geologic conditions can have a very large effect on the impact distances of ground-borne vibration. 

This effect was dramatically demonstrated by the vibration test results described in Appendix D. 

Vibration measurements of the X2000 trains in Sweden indicate that, at the test site, impacts could occur 

at distances greater than 300 ft from the tracks. In contrast, the tests also showed that the X2000 trains at 

the TGV test site in France would not cause vibration impacts beyond approximately 60 ft. The 

difference appears to be entirely due to the geologic conditions. 

Projections using the General Assessment procedures described in Chapter 8 are based on the high range 

of data from sites that appear to have “normal” geology. This means that the actual levels of groundborne vibration will usually be 5 VdB or more lower than projections developed by using the General 

Assessment curve and adjustments and will rarely exceed projections developed by using the General 

Assessment approach. However, an important qualification is that there will be some, apparently rare, 

conditions where the actual levels of ground-borne vibration will be substantially higher than those 

projected using the General Assessment procedures.

As indicated above, it can be appropriate to use the Detailed Assessment procedures at several locations 

along the proposed corridor during the preliminary phases of a high-speed rail project to refine the 

General Assessment projection curves. A Detailed Assessment is also appropriate during the final design 

and engineering phases for areas where a General Assessment has indicated the potential for impact. 

Procedures for developing detailed assessments of ground-borne vibration are constantly evolving. 

Analytical techniques for solving vibration problems are complex and the technology continually 

advances. The material contained in this chapter is not intended to provide the novice with a complete 
Chapter 9: Detailed Vibration Assessment 9-2

methodology for conducting a Detailed Assessment. Rather, the approach presented focuses on the key 

steps usually taken by a qualified professional.

Three examples of cases where Detailed Vibration Assessment might be required are as follows:

1. A particularly sensitive building, such as a major concert hall, is within the impact zone. A 

Detailed Assessment would ensure that effective vibration mitigation is feasible and economically 

reasonable.

2. The General Assessment indicates that a proposed high-speed rail project may create vibration 

impact for a large number of residential buildings adjacent to the alignment. The projections for

many of the buildings exceed the impact threshold by less than 5 dB, which means that more 

accurate projections may show that vibration levels will be below the impact criterion. If the cost 

of measures to mitigate vibration would significantly increase project costs, a Detailed 

Assessment to determine the vibration impact as accurately as possible is warranted.

3. A high-speed rail alignment will be close to university research buildings where vibrationsensitive optical instrumentation is used. Vibration from the trains could make it impossible to 

continue to use the building for this type of research. A Detailed Assessment would determine 

whether it is possible to control the vibration from the trains so that sensitive instrumentation 

would not be affected.

A Detailed Vibration Assessment consists of three main steps:

Step 1. Survey Existing Vibration. Although knowledge of the existing levels of ground-borne 

vibration is not usually required for the assessment of vibration impact, a survey of the existing vibration 

may be valuable in some instances. Examples include documenting existing background vibration at 

sensitive buildings, measuring the vibration levels created by sources such as existing rail lines, and, in 

some cases, characterizing the general background vibration in the project corridor. Characterizing 

existing vibration conditions is discussed in Section 9.1.

Step 2. Predict Future Vibration and Vibration Impact. All of the available analytical tools should be 

applied in a Detailed Assessment to develop the best possible estimates of the potential for vibration 

impact. An approach to projecting ground-borne vibration that consists of measuring vibration 

propagation characteristics at specific sites is discussed in Section 9.3. The vibration propagation test 

procedure is described in Section 9.3, and the assessment of vibration impact is discussed in Section 9.1.

Step 3. Develop Mitigation Measures. Controlling the impact from ground-borne vibration requires 

developing cost-effective measures to reduce the vibration levels. The Detailed Assessment can identify 

practical vibration control measures that will be effective at the dominant vibration frequencies and 

compatible with the given trackway structure (aerial, at-grade, and subway) and track support system. 

Vibration mitigation measures are discussed in Section 9.4.

The discussion in this chapter generally assumes vibration analysis of steel-wheel rail systems. The 

procedures are equally applicable to maglev systems. 
Chapter 9: Detailed Vibration Assessment 9-3

9.1 ASSESSMENT OF VIBRATION IMPACT

The purposes of the vibration impact assessment are to inventory all sensitive land uses that may be 

adversely affected by the ground-borne vibration and noise from a proposed high-speed rail project and to 

determine the mitigation measures that will be required to eliminate or minimize the impacts. This 

requires projecting the levels of ground-borne vibration and noise, comparing the projections with the 

appropriate impact criteria, and developing a list of suitable mitigation measures. The General 

Assessment is incorporated as an intermediate step in the impact assessment because of its relative 

simplicity and potential to narrow the areas requiring Detailed Assessment.

The assessment of vibration impact proceeds according to the following steps:

Step 1: Screening. Screen the entire proposed high-speed rail corridor to identify areas where there is 

the potential for impact from ground-borne vibration. The vibration screening method is described in 

Chapter 8. If sensitive land uses are not located within the screening distances, it is not necessary to 

perform any further assessment of ground-borne vibration. 

Step 2: Vibration Source Levels. Define a curve of ground-surface vibration level as a function of 

distance that can be used with the General Assessment. Usually this will mean selecting the generalized 

curve from Figure 8-1 or adapting measurements from an existing facility.

Step 3: Vibration Propagation Characteristics. Use the General Assessment Procedure to estimate 

vibration levels for specific buildings or groups of buildings. 

Step 4: Study Area Characteristics. In some cases, a vibration survey to characterize existing ambient

vibration may be necessary. As discussed in Section 9.2, although knowledge of the existing ambient 

vibration is not generally required to evaluate vibration impact, there are times when a survey of existing 

conditions is valuable. One common example is when the rail project will be located in an existing rail 

right-of-way shared by freight trains. Guidelines on the procedure to be used to account for existing 

vibration that is higher than the impact limit for the project vibration are provided in Chapter 7.

Step 5: Vibration Impact Estimation and Inventory. Compare the projected levels with the impact 

criteria given in Table 7-1 to determine whether vibration impact is likely. The goal of this step is to 

develop a reasonably accurate catalog of the buildings that will experience ground-borne vibration or 

noise levels that exceed the criteria. In the General Assessment, it is best to make a conservative 

assessment of the impact by including some buildings where the actual vibration ultimately is at or

slightly below the impact threshold. Usually it is far easier to control vibration during design and 

construction rather than to retrofit vibration control measures to solve unanticipated problems that 

develop once the system is operational. In locations where General Assessment indicates impact, the 

more refined techniques of Detailed Assessment should be used. 

Step 6: Vibration Mitigation. For areas where the impact criteria may be exceeded, review potential 

mitigation measures and assemble a list of feasible approaches to vibration control. To be feasible, the 

measure, or combination of measures, must be capable of providing a significant reduction of the 

vibration levels, usually at least 4 dB, while being cost-effective. 

Because vibration control is frequency-dependent, specific recommendations of vibration control 

measures can be made only after the frequency characteristics of the vibration have been evaluated. Use 
Chapter 9: Detailed Vibration Assessment 9-4

the Detailed Vibration Assessment to develop specific mitigation recommendations where it is important 

to estimate the spectrum of ground-borne vibration at potentially affected buildings. This type of 

assessment is often performed during final design rather than during the environmental assessment stage. 

Because a Detailed Assessment is more accurate than a General Assessment, there will be cases where the 

Detailed Assessment will show that the vibration and noise levels will be below the applicable criteria and 

that mitigation is not required. If the projected levels are still above the limits, the spectra provided by the 

Detailed Assessment should be used to evaluate mitigation measures.

9.2 CHARACTERIZING EXISTING VIBRATION CONDITIONS

Ambient vibration is rarely of sufficient magnitude to be perceptible or to cause audible ground-borne 

noise unless there is a major vibration source close by, such as a rail line. In most cases, perceptible 

vibration inside a building is caused by equipment or activities within the building itself, such as heating 

and ventilation systems, footsteps, or doors closing. Because the existing ambient vibration is usually 

below human perception, a limited survey is sufficient even for a Detailed Assessment. This contrasts 

with analysis of noise impact, where documenting the existing ambient noise level is required to assess 

the impact. 

Examples of situations where measurements of the ambient vibration are valuable include:

• Determining existing vibration at sensitive buildings. Serious vibration impact may occur 

when there are vibration-sensitive manufacturing, research, or laboratory activities within the 

screening distances. Careful documentation of the existing vibration will provide valuable 

information on the real sensitivity of the activity to external vibration and will provide a reference 

condition under which vibration is acceptable.

• Using existing vibration sources to characterize propagation. Existing vibration sources such 

as freight trains, industrial processes, quarrying operations, or normal traffic sometimes can be 

used to characterize vibration propagation. Carefully designed and performed measurements may 

eliminate the need for more complex propagation tests.

• Documenting existing levels of general background vibration. Some measurements of the 

existing levels of background vibration can be useful simply to document that, as expected, the 

vibration is below the normal threshold of human perception. Existing vibration in urban and 

suburban areas is usually due to traffic. If a measurement site has existing vibration approaching 

the range of human perception (e.g., the maximum vibration velocity levels are greater than 

approximately 65 VdB), then this site should be carefully evaluated for the possibility of ground 

conditions causing “efficient” vibration propagation. Areas with efficient vibration propagation 

could have vibration problems when the project is built.

• Documenting vibration from existing rail lines. Measurements to document the levels of 

vibration created by existing rail lines can be important in evaluating the impact of the new 

vibration source and determining vibration propagation characteristics in the area. As discussed 

in Chapter 7, if vibration from an existing rail line will be higher than that from the high-speed 

rail trains, there may not be impact even though the normal impact criterion would be exceeded.
Chapter 9: Detailed Vibration Assessment 9-5

Although ground-borne vibration is almost exclusively a problem inside buildings, measurements of 

existing ambient vibration generally should be performed outdoors. Two important reasons for this are 

(1) equipment inside the building may cause more vibration than exterior sources, and (2) the building 

structure and the resonances of the building can have strong, but difficult to predict, effects on the 

vibration. However, there are situations where measurements of indoor vibration are appropriate. For 

example, documenting vibration levels inside a vibration-sensitive building can be important because

equipment and activities inside the building may cause vibration greater than that from external sources 

such as street traffic or aircraft overflights. Floor vibration measurements should be taken near the center

of a floor span where the vibration amplitudes are the highest.

The goal of most ambient vibration tests is to characterize the RMS vertical vibration velocity level at the 

ground surface. In almost all cases, it is sufficient to measure only vertical vibration and to ignore the 

transverse components of the vibration. Although transverse components can transmit significant 

vibration energy into a building, the vertical component usually has greater amplitudes than transverse 

vibration. Moreover, vertical vibration is usually transmitted more efficiently into building foundations 

than transverse vibration.

The manner in which a transducer used to measure vibration is mounted can affect the measured levels of 

ground-borne vibration. However, research has shown that, at the frequencies usually of concern for 

ground-borne vibration (generally less than 200 Hz), straightforward methods of mounting transducers on 

the ground surface or on pavement are adequate for vertical vibration measurements.

40,41,42 Quick-drying 

epoxy or beeswax can be used to mount transducers to smooth, paved surfaces or to metal stakes driven 

into the ground. Rough concrete or rock surfaces require special mountings. One approach is to use a 

liberal base of epoxy to attach small aluminum blocks to the surface and then mount the transducers on 

the aluminum blocks.

Selecting sites for an ambient vibration survey primarily requires good common sense. Sites selected to 

characterize a high-speed rail corridor should be distributed along the entire project and should be 

representative of the types of vibration environments found in the corridor. These would commonly 

include the following: 

• sites in quiet residential areas removed from major traffic arterials to characterize low-ambient 

vibrations,

• sites along major traffic arterials and highways or freeways to characterize high vibration areas,

• sites in any area with vibration-sensitive activities, and

 

40 J. T. Nelson, H. J. Saurenman, and G. P. Wilson. Metrorail Operational Sound Level Measurements: GroundBorne Vibration and Noise Levels. Prepared by Wilson Ihrig & Associates for Washington Metropolitan Area 

Transit Authority, December 1979.

41 T. G. Gutowski, L. E. Wittig, and C. L. Dym. Some aspects of the ground vibration problem. Noise Control 

Engineering, 10(3), 94–101 (1978).

42 H. Nolle. High frequency ground vibration measurements. Shock and Vibration Bulletin, 48(Part 4), 95–103

(1978).
Chapter 9: Detailed Vibration Assessment 9-6

• sites near any significant existing source of vibration such as a railroad line.

The transducers should be located near the building setback line for background vibration measurements. 

Ambient measurements along railroad lines ideally will include multiple sites, several distances from the 

rail line at each site, and 4 to 10 train passbys for each test. Because of the irregular schedule for freight 

trains and, on many rail lines, the low number of operations each day, it is often impractical to perform 

tests at more than two or three sites along the rail line or to measure more than two or three passbys at 

each site. Rail type and condition strongly affect the vibration levels. Consequently, the track at each 

measurement site should be inspected by experienced personnel to locate any switches, bad rail joints, 

corrugations, or other factors that could be responsible for higher than normal vibration levels.

The appropriate methods of characterizing ambient vibration are dependent on the type of information 

required for the analysis. Some examples are as follows:

Ambient Vibration: Ambient vibration is usually characterized with a continuous 10- to 30-minute 

measurement of vibration. The equivalent energy level, or Leq, of the vibration velocity level over the 

measurement period gives an indication of the average vibration energy. Leq is equivalent to a long 

averaging time RMS level. Specific events can be characterized by the maximum RMS level (Lmax) of the 

event or by performing a statistical analysis of RMS levels over the measurement period. An RMS 

averaging time of 1 s should be used for statistical analysis of the vibration level.

Specific Events: Specific events such as train passbys should be characterized by the RMS level during 

the time that the train passes by. If the locomotives have vibration levels more than 5 VdB higher than 

the vehicles, a separate RMS level for the locomotives should be obtained. The locomotives usually can 

be characterized by the Lmax during the train passby. The RMS averaging time or time constant should be 

1 s when determining Lmax. Sometimes it is adequate to use Lmax to characterize the train passby, which is 

simpler to obtain than the RMS averaged over the entire train passby.

Frequency Analysis: When the vibration data will be used to characterize vibration propagation or for 

other special analysis, a frequency analysis of the vibration is required. An example would be if vibration 

transmission characteristics of the ground are suspected of having particular frequency characteristics. 

For many analyses, one-third octave band charts are best for describing the vibration characteristics. 

Narrowband spectra also can be valuable, particularly for identifying pure-tone characteristics and 

designing mitigation measures.

It is preferable that ambient vibration be characterized in terms of the RMS velocity level and not the 

PPV, which is commonly used to monitor construction vibration. As discussed in Chapter 6, RMS

velocity level is considered to be better correlated to human response than PPV.

9.3 VIBRATION PREDICTION PROCEDURE

9.3.1 Background

Predicting ground-borne vibration associated with a transportation project is a developing field. Because 

ground-borne vibration is a complex phenomenon that is difficult to model and predict accurately, most 

projection procedures that have been used for high-speed rail and other types of rail projects rely on 

empirical data. Although no single method stands out as the best approach for all situations, the 
Chapter 9: Detailed Vibration Assessment 9-7

procedure described in this section is one of the most promising because it is based on site-specific tests 

of vibration propagation. The procedure, which was developed under an FTA (formerly UMTA) research 

contract,

43 is recommended for detailed evaluations of ground-borne vibration. The same procedure is 

discussed in Chapter 11 of the FTA manual Transit Noise and Vibration Impact Assessment.

44 Other 

approaches to predicting ground-borne vibration have included pure analytical and pure numerical 

approaches. Some of these approaches were presented at an international workshop on railway noise.

45

There is still work to be done before a comprehensive prediction method will be available that can be 

confidently applied on sensitive projects. The measurements of high-speed rail vibration performed in 

France, Italy, and Sweden as part of preparation of this manual are discussed in Appendix D. An 

important observation from those tests is that vibration from high-speed trains is not caused by 

mechanisms that are substantially different than vibration from lower speed trains such as rapid transit 

and light rail trains. This means that procedures for predicting vibration from transit and passenger trains 

are equally applicable to high-speed trains, following scaling to the appropriate speed. The data shows

that vibration amplitudes are approximately proportional to 20 × log(speed) from 50 mph to over 

150 mph.

Perhaps the biggest problem for most prediction approaches is that vibration propagation through the soil 

and rock layers that are between the source and the receiver is extremely difficult to define. Attenuation 

along the propagation path is a critical component of any prediction procedure. Even when boreholes are 

made at regular intervals along a rail alignment, unless the geology is very uniform, they do not uncover 

geologic variations along the vibration propagation path from the rail line to receiver, which is 

perpendicular to the tracks. A primary goal of the procedure presented in this section is to characterize 

vibration propagation with empirical tests. This makes it unnecessary to infer propagation characteristics 

from standard geologic parameters such as soil classification, wave speed, and density. Experience has 

shown that the test procedure provides a reasonable estimate of vibration propagation characteristics and 

that it can identify areas where ground-borne vibration will be higher than normal because of geologic 

conditions that promote efficient propagation.

9.3.2 Overview of Prediction Procedure Using Measured Transfer Mobility

The prediction method described in this section was developed to enable train vibration measurements 

collected in one city to be used to predict vibration levels in another city where the geologic conditions 

may be completely different. The procedure uses a special measured function, called transfer mobility, 

which defines the relationship between an exciting force and the resulting vibration velocity at the ground 

surface. The transfer mobility combines the effects of the media the vibration waves pass through, the 

 

43 J. T. Nelson and H. J. Saurenman. A Prediction Procedure for Rail Transportation Ground-Borne Noise and 

Vibration, Transportation Research Record 1143, National Research Council, Transportation Research Board 

(Washington, DC), August 1988.

44 U.S. DOT, FTA. Transit Noise and Vibration Impact Assessment, Report FTA-VA-90-1003-06, May 2006.

45 “The Fifth International Workshop on Railway and Tracked Transit System Noise,” Voss, Norway, June 21–24, 

1995. (Proceedings published in J. Sound Vib. 193(1) (1996)).
Chapter 9: Detailed Vibration Assessment 9-8

types of vibration waves, and all possible paths the vibration can take to go from the source to the 

receiver. 

Transfer mobility is a function of both frequency and distance from the source. The transfer mobility 

between two points completely defines the composite vibration propagation characteristics between the 

two points. In most practical cases, receivers are close enough to the train tracks that the vibration cannot 

be considered to be originating from a single point; the vibration source is more appropriately 

characterized as a line source. Consequently, the point transfer mobility must be modified to approximate 

a line source. In the text that follows, TMpoint is used to indicate the measured point source transfer 

mobility and TMline is used for the line source transfer mobility derived from TMpoint. Both are assumed 

to be in decibels with consistent reference quantities.

Predicting ground-borne vibration at a specific site requires the transfer mobility function for the site and 

an applicable force-density function. The force-density function is usually derived from measurements at 

an existing high-speed rail line. In essence, the force density is the normalized ground-borne vibration 

with the effects of geology removed. The measured transfer mobility of a site along an existing highspeed rail system can be used to estimate the force-density function that is independent of the geology. 

The prediction procedure considers ground-borne vibration to be divided into the following components:

1. Excitation Force (Force Density): The vibration energy is created by oscillatory and impulsive 

forces. Steel wheels rolling on smooth steel rails create random oscillatory forces. When a wheel 

encounters a discontinuity such as a rail joint, an impulsive force is created. The force excites the 

track structure, such as the railway tunnel, or the ballast for at-grade track. In the prediction 

method, the combination of the actual force generated at the wheel-rail interface and the vibration 

of the track structure are usually combined into an equivalent force-density level. The forcedensity level describes the force that excites the soil/rock surrounding the track structure.

2. Vibration Propagation (Transfer Mobility): The excitation of the track structure causes 

vibration waves in the soil that propagate away from the track structure. Vibration energy can 

propagate through the soil or rock in a variety of wave forms. All ground vibration includes shear 

and compression waves. In addition, Rayleigh waves, which propagate along the ground surface, 

can be a major carrier of vibration energy. The mathematical modeling of vibration is 

complicated when, as is usually the case, there are soil strata with different elastic properties. 

The propagation through the soil/rock is modeled by using the experimentally determined transfer 

mobility.

3. Building Vibration: When the ground vibration excites a building foundation, it sets the 

building into motion and starts vibration waves propagating throughout the building structure. 

The interaction between the ground and the foundation causes some reduction in vibration levels. 

The amount of reduction depends on the mass and stiffness of the foundation. The more massive 

the foundation, the lower the response to ground vibration. As the vibration waves propagate 

through the building, they can create perceptible vibration and cause annoying rattling of 

windows and decorative items either hanging on walls or located on shelves. 

4. Audible Noise: In addition to perceptible vibration, the vibration of room surfaces radiates lowfrequency sound that may be audible. The sound level is affected by the amount of acoustical 

absorption in the receiver room.
Chapter 9: Detailed Vibration Assessment 9-9

The combination of the force-density level and the transfer mobility is used to predict the ground-surface 

vibration. A fundamental assumption of the prediction approach outlined here is that the force density, 

transfer mobility, and the building coupling to the ground are all independent factors. The following 

equations are the basis for the prediction procedure, where all of the quantities are in decibels with 

consistent reference values:

Lv = LF + TMline + Cbuild

LA = Lv + Krad + KA−wt

where:

Lv = RMS vibration velocity level in one one-third octave band,

LA = A-weighted sound level in one one-third octave band,

LF = force density for a line vibration source such as a train,

TMline = line source transfer mobility from the tracks to the sensitive site,

Cbuild = adjustments to account for ground-building foundation interaction 

and attenuation of vibration amplitudes as vibration propagates 

through buildings,

Krad = adjustment to convert from vibration to sound-pressure level, 

which also for the amount of acoustical absorption inside the room 

(A value of -5 dB can be used for Krad for typical residential rooms 

when the decibel reference value for Lv is 1 μin/s), and

KA-wt = A-weighting adjustment at the one-third octave band center 

frequency.

All of the quantities given above are functions of frequency. The standard approach to dealing with the 

frequency dependence is to develop projections on a one-third octave band basis by using the average 

values for each one-third octave band. The result of the analysis is the one-third octave band spectra of 

the ground-borne vibration and the ground-borne noise. The spectra are then used to calculate overall 

vibration velocity level and the A-weighted sound level. This is in contrast to the General Assessment 

procedures, where the overall vibration velocity level and A-weighted sound level are predicted without 

any consideration of the particular frequency characteristics of the propagation path.

9.3.3 Measuring Transfer Mobility and Force Density (Vibration Propagation Testing)

The overall purpose of vibration propagation testing is to obtain data that can be used to estimate the 

following quantities: 

1. Point Source Transfer Mobility. This is basically an intermediate quantity that is applicable to 

point vibration sources. It is a function of both frequency and distance from the source.

2. Line Source Transfer Mobility. The measured point source transfer mobilities are used to 

estimate an equivalent line source transfer mobility for each test site.

3. Force Density. The force density characterizes the vibration-generating characteristics of the 

train/track system that will be used. It can be based on previous measurements, or testing can be
Chapter 9: Detailed Vibration Assessment 9-10

done at an existing facility to measure the force density. If no suitable measurements are 

available, testing should be done at a high-speed rail facility with equipment similar to the 

planned vehicles. Adjustments for factors such as train speed, track support system, and vehicle 

suspension will usually be needed to match the force density to the conditions at specific sites. 

The force density represents an incoherent line of vibration force equal to the length of the trains. 

The unit of force density is force divided by square root of train length, represented here in 

decibels relative to 1 lb/(ft)1/2. 

The basic field procedure for at-grade and tunnel testing of transfer mobility is illustrated in Figure 9-1. 

The goal of the test is to create vibration pulses that travel from the source through the ground to the 

receiver, using the same path that will be taken by ground-borne vibration from the train. As shown in 

Figure 9-1, a weight is dropped from a height of 3 to 4 ft onto a load cell, which is calibrated to measure 

force. Accelerometers are placed on the ground along a line leading away from the point-of-force 

application. The responses of the load cell and accelerometers are recorded on a multichannel tape 

recorder for subsequent analysis in the laboratory.

Figure 9-1 Impact Method for Measuring Transfer Mobility

When the procedure is applied to tunnels, the force must be located at the approximate depth of the 

tunnel. This is done by drilling a bore hole and locating the load cell at the bottom of the hole. The tests 

are usually performed at the same time that the bore holes are drilled. This allows using the soil-sampling 

equipment on the drill rig for the transfer mobility testing. The load cell is attached to the bottom of the 

drill string and lowered to the bottom of the hole. A standard soil sampling hammer, which is usually a 

140-pound weight dropped 18 in onto a collar attached to the drill string, is used to excite the ground. 
Chapter 9: Detailed Vibration Assessment 9-11

The load cell must be capable of operating underwater if the water table is near the surface or if a slurry 

drilling process is used.

For point sources, such as the columns of a maglev guideway, a point source force spectrum is used 

instead of force density.

Field Procedures

The process of measuring transfer mobility involves impacting the ground and measuring the resulting 

vibration pulse at various distances from the impact. Two different methods, shown in Figure 9-2, that 

have been used to estimate equivalent line source transfer mobility from point source transfer mobility 

are:

1. Lines of transducers: A site is characterized by tests using one or more lines of transducers with 

the impact at one end of the line. The total length of the line ranges from 150 to 300 ft. 

Figure 9-2a shows a site being characterized using three lines perpendicular to the rail line. 

Regression techniques are applied to the one-third octave band transfer function data to obtain 

smooth point-source transfer mobility function curves. Once the point source transfer mobility 

has been defined, the line source transfer mobility can be calculated using numerical integration 

techniques. Optimal use of a single borehole can be made by running three or four transducer 

lines in a radial pattern from each borehole.

2. Lines of impacts: This configuration is shown in Figure 9-2b. One line of transducers is used 

and the ground is impacted at evenly-spaced intervals along a line perpendicular to the transducer 

line. Since the impacts represent a train, it is best if the line of impacts can be along the track 

centerline. When this is not possible, the impact line should parallel the tracks. After the onethird octave band point source transfer mobilities are obtained, the equivalent line source transfer 

mobility is obtained by combining the point source transfer mobilities to approximate a numerical 

integration. This procedure was used to derive force density functions for X2000, Pendolino, and 

TGV high speed trains. Experience has shown that this approach is more accurate and more 

repeatable than the first approach. Unfortunately, this approach is usually impractical for tunnels 

since the ground must be impacted at the bottom of boreholes to approximate propagation from a 

tunnel structure.
Chapter 9: Detailed Vibration Assessment 9-12

 

Figure 9-2 Schematic of Two Approaches for Transfer Mobility Measurements

Instrumentation

Performing a vibration propagation test requires specialized equipment. Most of the equipment is readily 

available from several commercial sources. Commercially available load cells can be used as the force 

transducer. For borehole testing, the load cells must be hermetically sealed and capable of sustaining 

impact forces at the bottom of a 30- to 100-foot-deep hole partially filled with water. A typical 

instrumentation array for field testing and laboratory analysis of transfer mobility is shown in Figure 9-3. 

The force transducer should be capable of impact loads of up to 10,000 lb. Either accelerometers or 

geophones can be used as the vibration transducers. A requirement is that the transducers with associated 

amplifiers be capable of accurately measuring levels of 0.0001 in/s at 40 Hz and have flat frequency 

response from 6 to 400 Hz. The recorder also must have flat response over the 6- to 400-hertz frequency 

range.
Chapter 9: Detailed Vibration Assessment 9-13

Figure 9-3 Equipment Required for Field Testing and Laboratory Analysis

The narrowband spectrum analyzer is the key element of the laboratory instrumentation. The analyzer 

must be capable of capturing impulses from at least two channels and calculating the frequency spectrum 

of the transfer function between the force and vibration channels. All transfer functions should include 

the average of at least 20 impulses. Averaging more impulses will improve signal enhancement at a rate 

of 3 dB improvement for each doubling of the number of impacts. Signal enhancement is particularly 

important when the vibration transducer is more than 100 ft from the impact.

As illustrated in Figure 9-3, the spectrum analyzer usually is interfaced to a computer, which is required 

to adapt the narrowband transfer function data into a format suitable for evaluating one-third octave band 

transfer mobility. The raw transfer function data usually include several hundred frequency bands. By 

transforming from narrowband to one-third octave band spectra, each spectrum is reduced to 

15–20 bands. This step reduces the amount of data that must be evaluated to develop the generalized 

curves. There are specialized multichannel spectrum analyzers that have built-in capabilities that are 

sufficient for this data analysis.

Analysis of Transfer Mobility Data

Transfer mobility functions are developed from field measurements in following steps:

Step 1. Analyze the field data to generate narrowband point source transfer mobilities.

Step 2. Calculate one-third octave band transfer mobilities at each measurement point from the 

narrowband results. Because typical spectrum analyzers are not capable of obtaining one-third octave 

band transfer functions, this processing is performed after transferring the data to a computer. 
Chapter 9: Detailed Vibration Assessment 9-14

Step 3. Calculate the transfer mobility as a function of distance for each one-third octave band. 

Step 4. For steel-wheel technology at grade, use the point source transfer mobilities to compute the line 

source transfer mobility as a function of distance in each one-third octave band.

The two field test procedures that have been used to develop estimates of line source transfer mobility are 

shown in Figure 9-2. Of the two procedures, the first, involving a single impact point for each line of 

accelerometers, requires considerably more analysis and professional judgment to develop line source 

transfer mobility. However, there are some situations, such as elevated guideway columns, where a 

single impact point is the only practical method to apply.

The steps in developing line source transfer mobility curves with field data from the first procedure are 

illustrated in Figure 9-4. The analysis starts with the narrowband transfer function between source and 

receiver at each measurement position. There should be a minimum of four distances in any test line. 

Because of the possibility of local variations in propagation characteristics, when feasible, three or more 

lines should be used to characterize a site. A total of 10–20 transducer positions are often used to 

characterize each site. Assuming that the spectrum analyzer calculates 400 line narrowband transfer 

functions for each position, a total of 4,000–8,000 numbers must be calculated for each site.

Figure 9-4 Analysis of Transfer Mobility

The next step in the analysis procedure is to calculate the equivalent one-third octave band transfer 

functions. This reduces each spectrum from 400 to 15 numbers. As shown in Figure 9-4, the one-third

octave band spectrum is much smoother than the narrowband spectrum. The third step is to calculate a 

best-fit curve of transfer mobility as a function of distance for each one-third octave band. When 

analyzing a specific site, the best-fit curve will be based on 10–20 data points. Up to several hundred 

points could be used to determine average best-fit curves for a number of sites.
Chapter 9: Detailed Vibration Assessment 9-15

The one-third octave band best-fit curves can be applied directly to point vibration sources. However, 

because trains are better represented as line vibration sources, a fourth step is necessary: calculate an 

equivalent line source transfer mobility using numerical integration. 

The analysis involving the second field procedure is slightly different from the first. In this approach, the 

train is represented by impacts at equally spaced intervals along a line perpendicular to the transducer 

line. This approach is particularly suited to characterizing a specific building because, by placing a 

transducer inside the building, it is possible to measure line source transfer mobility from the tracks to 

this point in the building. The resulting transfer mobility combines the vibration path to the building 

foundation, coupling to the building, and propagation of the vibration energy through the building. This 

approach can greatly improve the accuracy of projections for that building.

Using the second procedure, a segment of a train can be represented by a line of impact positions along 

the track centerline at 10- or 20-foot intervals. The one-third octave band point source transfer mobilities 

for each transducer location can then be summed following the trapezoidal rule for numerical integration 

to directly calculate line source transfer mobility. The following equation should be used to perform the 

numerical integration:

TMline = 10 × log10 �h × �

10

TMpi

10

2 + 10

TMp2

10 + ⋯ + 10

TMPn−1

10 +

10

TMPn

10

2 ��

where: h = impact interval,

TMpi = point source transfer mobility for ith impact location, and

n = last impact location.

This approach is considerably more direct than is possible with lines of vibration transducers. An 

important feature of this approach is that the impact line usually can be shorter, sometimes much shorter 

than the train. For example, at a distance of 50 ft from a 600-foot train, most of the vibration energy will 

come for the part of the train closest to the receiver. In this case, the 600-foot train could be accurately 

modeled by using a 200-foot impact line. Judgment must be used in deciding on an appropriate length for 

the impact line in balancing accuracy of the results, available test conditions in the field, budget, and time 

constraints.

Deriving Force Density

Force density is not a quantity that can be measured directly. It must be inferred from measurements of 

transfer mobility and train vibration at the same site. Using a line of impacts to measure line source 

transfer mobility (developed using the second transfer mobility test procedure) will give the best forcedensity results. The force density for each one-third octave band is then simply:

LF = Lv – TMline

where: LF = force density,

LV = measured train ground-borne vibration, and

TMline = line source transfer mobility.

The standard approach is to develop force density from the average of measurements at three or more 

positions. 
Chapter 9: Detailed Vibration Assessment 9-16

Track-bed force densities developed from measurements of the Acela, TGV, X2000, and Pendolino trains 

are shown in Figure 9-5. Adjustments must be made to the force density to account for differences 

between the facility where the force density was measured and the new system. Guidance for making 

these adjustments can be found in a U.S. DOT report.

46

A force spectrum developed from measurements of the Transrapid TR08 is shown in Figure 9-6.

9.3.4 Vibration and Structure-Borne Noise in Buildings

The propagation of vibration from the building foundation to the receiver room is a very complex 

phenomenon, dependent on the specific design of the building. Detailed evaluation of the vibration 

propagation requires extensive use of numerical procedures, such as finite element modeling. An 

evaluation this detailed generally is not practical for individual buildings considered in this manual. The 

propagation of vibration through a building and the radiation of sound by vibrating building surfaces 

consequently are estimated by using simple empirical or theoretical models. The recommended 

procedures are outlined in the Handbook of Urban Rail Noise and Vibration Control47 with a revised 

procedure for converting vibration to radiated noise based on more recent research.48 The approach 

consists of adding the following adjustments to the one-third octave band spectrum of the projected 

ground-surface vibration:

1. Building response or coupling loss. This represents the change in the incident ground-surface 

vibration because of the presence of the building foundation. The adjustments in the handbook 

are shown in Figure 9-7.

2. Transmission through the building. The vibration amplitude will decrease as the vibration 

energy propagates from the foundation through the remainder of the building. The normal 

assumption is that vibration attenuates by 1–2 dB for each floor.

3. Floor resonances. Vibration amplitudes will be amplified because of resonances of the 

floor/ceiling systems. For a typical wood frame residential structure, the fundamental resonance 

is usually in the 15- to 20-hertz range. Reinforced-concrete slab floors in modern buildings will 

have fundamental resonance frequencies in the 20- to 30-hertz range. An amplification resulting 

in a gain of approximately 6 dB should be used in the frequency range of the fundamental 

resonance.

4. Radiated noise. The projected floor vibration is used to estimate the levels of ground-borne 

noise. The primary factors affecting noise level are the average vibration level of the room 

surfaces and the amount of acoustical absorption within the room. As discussed above, the 

radiation adjustment is -5 dB for typical rooms, which gives:

 

46 J. T. Nelson and H. J. Saurenman. State-of-the-Art Review: Prediction and Control of Ground-Borne Noise and 

Vibration from Rail Transit Trains, Report Number UMTA-MA-06-0049-83-4, U.S. DOT, UMTA, December 1983. 47 H. J. Saurenman, J. T. Nelson, and G. P. Wilson. Handbook of Urban Rail Noise and Vibration Control, prepared 

under contract to U.S. DOT/Transportation Systems Center, Report UMTA-MA-06-0099-82-2, February 1982. 48 J. A. Zapfe, H. Saurenman, and S. Fidell. Ground-Borne Noise and Vibration in Buildings Caused by Rail Transit, 

Transportation Research Board, Final Report for TCRP Project D-12, December 2009.
Chapter 9: Detailed Vibration Assessment 9-17

LA ≈ Lv + KA-wt – 5

where: LA = A-weighted sound level in a one-third octave band,

Lv = average RMS vibration velocity level, and

KA-wt = A-weighting adjustment at the center frequency of the one-third octave band.

The A-weighted levels in the one-third octave bands are then combined to give the overall A-weighted 

sound level.

Figure 9-5 Force Densities for High-Speed Trains
Chapter 9: Detailed Vibration Assessment 9-18

Figure 9-6 Characteristics Force Spectra for the TR08 on Each Type of Guideway

Figure 9-7 Approximate Foundation Response for Various Types of Buildings

9.4 VIBRATION MITIGATION

Mitigation can minimize the adverse effects of project ground-borne vibration on sensitive land uses. 

Available data indicate that ground-borne vibration from steel-wheel/steel-rail high-speed trains is caused 

by the same mechanisms as vibration from lower speed trains. Consequently, the approaches to 

controlling ground-borne vibration from transit systems generally are applicable to high-speed trains. 
Chapter 9: Detailed Vibration Assessment 9-19

Because ground-borne vibration is not as common a problem as environmental noise, the mitigation 

approaches have not been as well defined. In some cases, it has been necessary to develop innovative 

approaches to control the impact. Examples are the floating slab systems that were developed for the 

Washington, DC, and Toronto transit systems and wheel-flat detectors that have been used to identify 

vehicles in need of maintenance. 

The importance of adequate wheel and rail maintenance in controlling levels of ground-borne vibration 

cannot be overemphasized. Problems with rough wheels or rails can increase vibration levels by as much 

as 20 dB, negating the effects of even the most effective vibration control measures. It is rare that 

practical vibration control measures will provide more than 15- to 20-decibel attenuation. When groundborne vibration problems are associated with existing rails and rolling stock, often the best control 

measure is to implement new or improved maintenance procedures. Grinding rough or corrugated rail 

and implementing wheel truing to restore the wheel surface and contour may reduce vibration more than 

completely replacing the existing track system with floating slabs.

Assuming that the track and vehicles are in good condition, the options to further reduce ground-borne 

vibration fit into one of seven categories: (1) maintenance procedures, (2) location and design of special

track work, (3) vehicle modifications, (4) changes in the track support system, (5) building modifications, 

(6) adjustments to the vibration transmission path, and (7) operational changes.

Maintenance

As discussed previously, effective maintenance programs are essential for keeping ground-borne vibration 

levels under control. When the wheel and rail surfaces are allowed to degrade, the vibration levels can 

increase by as much as 20 dB compared with a new or well-maintained system. Maintenance procedures 

that are particularly effective at avoiding increases in ground-borne vibration include the following:

• Rail grinding on a regular basis, particularly for rail that develops corrugations. Rail condition 

monitoring systems are available to optimize track conditions.

• Wheel truing to re-contour the wheel, provide a smooth running surface, and remove wheel flats. 

The most dramatic vibration reduction results from removing wheel flats. However, significant 

improvements also can be observed simply from smoothing the running surface. Wheel condition 

monitoring systems are available to optimize wheel conditions.

• Reconditioning vehicles, particularly when components such as suspension system, brakes, and 

wheels will be improved and slip-slide detectors will be installed.

• Installing wheel condition monitoring systems to identify those vehicles most in need of wheel 

truing.

Location and Design of Special Track Work

Most vibration impact from a new train system is caused by wheel impacts at the special track work for 

turnouts and crossovers. Careful review of crossover and turnout locations during the preliminary 

engineering stage is an important step in minimizing potential for vibration impact. When feasible, the 

most effective vibration control measure is to relocate the special track work to a less vibration-sensitive 

area. Sometimes this requires adjusting the location by several hundred feet and will not have a 

significant adverse impact on the operation plan for the system. Another approach is to install movable-
Chapter 9: Detailed Vibration Assessment 9-20

point or spring frogs that eliminate the gaps that occur when standard railbound frogs are used. These 

special frogs have been shown to significantly reduce vibration levels near crossovers, and they are often 

specified because of their longer lifespan under repetitive high-speed conditions.

Vehicle Suspension

The ideal rail vehicle, with respect to minimizing ground-borne vibration, should have a low unsprung 

weight, a soft primary suspension, a minimum of metal-to-metal contact between moving parts of the 

truck, and smooth wheels that are perfectly round. A thorough dynamic analysis, including the expected 

track parameters, should be part of the specifications for any new high-speed trainset.

Special Track Support Systems

When the vibration assessment indicates that vibration levels will be excessive, it is usually the track 

support system that is modified to reduce the vibration levels. Floating slabs, resiliently supported ties, 

high-resilience fasteners, ballast mats, and tire-derived aggregate (shredded tires) all have been used to 

reduce the levels of ground-borne vibration. To be effective, these measures must be optimized for the 

frequency spectrum of the vibration. In addition, care must be taken in applying these measures on atgrade and elevated track because exposure to outdoor weather conditions requires special drainage 

designs. 

The major vibration control measures for track support are discussed below:

• Resilient Fasteners: Resilient fasteners are used to fasten rails to concrete track slabs. Standard 

resilient fasteners are very stiff in the vertical direction, usually in the range of 200,000 lb/in, 

although they do provide some vibration reduction. On urban transit systems, special fasteners 

with vertical stiffness in the range of 40,000–75,000 lb/in have reduced vibration by as much as 5 

to 10 dB at frequencies above 30–40 Hz. 

• Ballast Mats: A ballast mat consists of a rubber or other type of elastomer pad that is placed 

under the ballast. The mat generally must be placed on a thick concrete or asphalt pad to be 

effective. It will not be as effective if placed directly on the soil or the subballast. Ballast mats 

can provide 10- to 15-decibel attenuation at frequencies above 25–30 Hz. An installation of 

ballast mat in a tunnel in France near Vouvray in TGV’s Atlantique line prevents vibrations from 

affecting storage and aging of wines in a nearby wine cave. Ballast mats are often a good retrofit 

measure for existing tie-and-ballast track where there are vibration problems.

• Tire-Derived Aggregate (TDA): Also known as shredded tires, a typical TDA installation 

consists of an underlayment of 12 in of nominally 3-inch-size tire shreds or chips wrapped with 

filter fabric, covered with 12 in of subballast and 12 in of ballast above that to the base of the ties. 

Tests suggest that the vibration reduction effectiveness of this low-cost treatment is equal to or 

greater than that of a ballast mat. However, TDA has only been installed and tested at a limited 

number of locations on U.S. light rail transit systems, and its applicability to high-speed rail 

systems has not been evaluated.

• Resiliently Supported Ties: A resiliently supported tie system, like the one used in the Channel 

Tunnel between England and France, consists of concrete ties supported by rubber pads. The 

rails are fastened directly to the concrete ties by using standard rail clips. Some measurement 

data suggest that resiliently supported ties may reduce low-frequency vibration in the 15- to 
Chapter 9: Detailed Vibration Assessment 9-21

40-hertz range, which would make them particularly appropriate for rail systems with vibration 

problems in the 20- to 30-hertz range. The frequency range over which this type of track support 

system can affect levels of ground-borne vibration depends on the pad stiffness and the 

interaction between the pads, ties, and rails.

• Floating Slabs: Floating slabs can be very effective at controlling ground-borne vibration and 

noise. They basically consist of a concrete slab supported on resilient elements, usually rubber or 

a similar elastomer. A variant that was first used in Toronto and is generally referred to as the 

double tie system consists of 5-foot slabs with four or more rubber pads under each slab. Floating 

slabs are effective at frequencies greater than their single-degree-of-freedom vertical resonance 

frequency. The floating slabs used in the Washington, DC, Atlanta, and Boston transit systems 

were all designed to have a vertical resonance in the 14- to 17-hertz range. A special London 

Transport floating slab that is under the Barbican Redevelopment uses a very heavy design with a 

resonance frequency in the 5- to 10-hertz frequency range.

49 The primary disadvantage of 

floating slabs is that they tend to be the most expensive of the track-related vibration control 

treatments.

• Other Treatments: Changing any feature of the track support system can change the levels of 

ground-borne vibration. Approaches such as using heavier rail, thicker ballast, heavier ties, or 

resilient elements beneath the tracks can be expected to reduce the vibration levels. Also, there is 

some indication that vibration levels are lower with wood ties compared with concrete ties. 

However, there is little confirmation that any of these approaches will make a significant change 

in the vibration levels. This is unfortunate since modifications to the ballast, rails, or ties are 

virtually the only options for typical track systems (at-grade, ballast-and-tie) without resorting to 

a different type of track support system or widening the right-of-way to provide a buffer zone.

Building Modifications

In some circumstances, it is practical to modify an affected building to reduce the vibration levels. 

Vibration isolation of buildings basically consists of supporting the building foundation on elastomer pads 

similar to bridge bearing pads. Vibration isolation is seldom an option for existing buildings. However, 

building vibration isolation can be particularly important for shared-use facilities such as office space 

above a train station or terminal. When vibration-sensitive equipment such as electron microscopes will 

be affected by train vibration, specific modifications to the building structure may be the most costeffective method of controlling the impact. For example, the floor upon which the vibration-sensitive 

equipment is located could be stiffened and isolated from the remainder of the building.

Trenches

Use of trenches to control ground-borne vibration is analogous to controlling airborne noise with sound 

barriers. Although this approach has not received much attention in the United States, a trench can be a 

practical method for controlling vibration from at-grade track. A rule of thumb given by Richert and 

 

49 P. Grootenhuis. Floating track slab isolation for railways. Journal of Sound and Vibration, 51(3), 443–448 (1977).
Chapter 9: Detailed Vibration Assessment 9-22

Hall50 is that if the trench is located close to the source, the trench bottom must be at least 0.6 times the 

Rayleigh wavelength below the vibration source. For most soils, Rayleigh waves travel at around 

600 ft/s, which means that the wavelength at 30 Hz is 20 ft. This means that the trench would have to be 

approximately 12 ft deep to be effective at 30 Hz. 

A trench can be an effective vibration barrier if it changes the propagation characteristics of the soil. It 

can be either open or solid. The Toronto Transit Commission did a test with a trench filled with

Styrofoam to keep it open. They reported successful performance over a period of at least 1 yr.51 Solid 

barriers can be constructed with sheet piling, rows of drilled shafts filled with either concrete or a mixture 

of soil and lime,

52 or concrete poured into a trench. Although experimental research is continuing, 

practical application of such measures has been limited.

Operational Changes

The most obvious operational change is to reduce the vehicle speed. Reducing the train speed by a factor 

of 2 will reduce vibration levels approximately 6 dB. Other operational changes that can be effective in 

special cases are:

• Use the equipment that generates the lowest vibration levels during the nighttime hours when 

people are most sensitive to vibration and noise.

• Adjust nighttime schedules to minimize train movements during the most sensitive hours.

Although there are tangible benefits from reducing speed and limiting operations during the most 

sensitive time periods, these measures may not be practical from the standpoint of trip time and service 

frequency requirements. Furthermore, vibration reduction achieved through operating restrictions 

requires continuous monitoring and will be negated if the signal system does not enforce compliance with 

the speed restriction.

Buffer Zones

Expanding the rail right-of-way sometimes will be the most economical method of controlling the 

vibration impact. A similar approach is to negotiate a vibration easement from the affected property 

owners.

 

50 F. E. Richert and J. R. Hall. Vibrations of Soils and Foundations, Prentice-Hall, Inc., Englewood Cliffs, NJ, 1970.

51 S. T. Lawrence. “TTC-LRT Trackbed Studies, Ground-borne Vibration Testing, Measurement and Evaluation 

Program,” American Public Transit Association Rapid Transit Conference, San Francisco, CA, 1980.

52 The Lime Column Method, Report No. 31, Swedish Geotechnical Institute, Linkoping, Sweden, 1994.
Chapter 10: Noise and Vibration During Construction 10-1

CHAPTER 10. NOISE AND VIBRATION DURING CONSTRUCTION

This chapter discusses the procedures for assessing the temporary noise and vibration impacts associated 

with the construction of a new high-speed rail facility. Methods for estimating noise and vibration levels 

from construction equipment by using tabulated source levels, as well as procedures for assessing and 

mitigating potential noise and vibration impacts, are provided. It is important to note that the guidelines 

in this manual represent recommended practices and are not intended to specify construction noise and 

vibration criteria, which should be developed on a project-specific basis in consideration of applicable 

local ordinances. Although both construction noise and vibration are included in this chapter, there is 

generally no overlap between them in the methodology, and they are covered in separate sections. This 

chapter is intended to provide similar guidance on construction noise and vibration as Chapter 12 in the 

FTA Transit Noise and Vibration Impact Assessment guidance manual.53

Construction often generates community noise/vibration complaints, even when it takes place over a 

limited timeframe. In recent years, public concerns about construction noise and vibration have increased 

significantly, due partly to lengthy periods of heavy construction on some “mega-projects” and also to the 

increasing prevalence of nighttime construction that is undertaken to avoid disrupting workday road and 

rail traffic. Noise and vibration complaints typically arise from interference with people’s activities, 

especially when the adjacent community has no clear understanding of the extent or duration of the 

construction. Misunderstandings can arise when the contractor is considered to be insensitive by the 

community, even though the contractor believes the work is being performed in compliance with local 

ordinances. This situation underscores the need for early identification and assessment of potential 

problem areas. 

An assessment of noise and vibration impact during construction can be made by following procedures 

outlined in this chapter. The type of assessment—qualitative or quantitative—and the level of analysis 

 

53 U.S. DOT, FTA. Transit Noise and Vibration Impact Assessment, Report FTA-VA-90-1003-06, May 2006.
Chapter 10: Noise and Vibration During Construction 10-2

will be determined based on the scale of the project and surrounding land use. In cases where a full 

quantitative assessment is not warranted, a qualitative assessment of the construction noise and vibration 

environment can lead to greater understanding and tolerance in the community. For major projects with 

extended periods of construction at specific locations, a quantitative assessment can aid contractors in 

making bids by allowing changes in construction approach and including mitigation costs before the 

construction plans are finalized.

10.1 CONSTRUCTION NOISE ASSESSMENT

Noise impacts from construction may vary greatly depending on the duration and complexity of the 

project. The level of detail of a construction noise assessment depends on the scale and the type of 

project and the stage of environmental review. Many small projects need no construction noise 

assessment at all. Examples include installation of safety features like grade-crossing signals, track 

improvements within the right-of-way, and installation of small buildings and facilities, which are similar 

in scale to the surrounding development. For projects like these, it would suffice to describe the length of 

time of construction, the loudest equipment to be used, expected truck access routes, and nighttime 

activity. 

Other projects involving a limited period of construction time—less than a month in a noise-sensitive 

area—may warrant a qualitative treatment because of nearby noise-sensitive land uses. In these cases, the 

assessment may simply be a qualitative description of the equipment to be used, the duration of 

construction, and any mitigation requirements placed on particularly noisy operations. Where the length 

of construction in noise-sensitive areas is expected to last for more than several months, or particularly 

noisy equipment will be involved, then construction noise impacts may be determined in detail.

A likely scenario of the planned construction methods should be described in the environmental 

document. At this early stage, it may be possible to describe certain basic measures that would be taken 

to reduce the potential impact, for example, limiting the noisiest construction activities during nighttime. 

Final decisions on noise control measures may require project and construction plans to be defined in 

greater detail during final design. 

Qualitative Assessments. In cases where a qualitative construction noise assessment is appropriate, the 

following descriptions would be included:

• Duration of construction (overall and at specific locations)

• Equipment expected to be used (e.g., noisiest operations)

• Schedule with limits on times of operation (e.g., daytime use only)

• Monitoring of noise

• Forum for communicating with the public

• Commitments to limit noise levels to certain levels, including any local ordinances that apply

• Consideration of application of noise control treatments used successfully in other projects
Chapter 10: Noise and Vibration During Construction 10-3

Community relations will be important in these cases; early information disseminated to the public about 

the kinds of equipment and expected noise levels and durations will help to forewarn potentially affected 

neighbors about the temporary inconvenience. In these cases, a general description of the variation of 

noise levels during a typical construction day may be helpful. The criteria in Section 10.1.2 are not 

applied to qualitative assessments.

Quantitative Assessments. Factors that influence the decision to perform a quantitative construction noise 

assessment include the following:

• Scale of the project

• Intensity of construction noise

• Proximity of noise-sensitive land uses to the construction zones

• Number of noise-sensitive receptors in the project area

• Duration of construction activities near noise-sensitive receptors

• Schedule (the construction days, hours, and time periods)

• Construction methods (e.g., cut-and-cover versus bored tunneling)

• Concern about construction noise expressed in comments by the general public (scoping, public 

meetings)

A quantitative construction noise assessment requires information about source levels, operations, 

proximity of noise sensitive locations, and criteria against which the levels will be compared. These 

elements of assessment are described in the following sections.

10.1.1 Noise from Typical Construction Equipment and Operations

The noise levels generated by construction equipment will vary greatly depending on factors such as the 

type of equipment, the specific model, the operation being performed, and the condition of the equipment. 

The equivalent sound level (Leq) of the construction activity also depends on the fraction of time that the 

equipment is operated over the time period of construction. The dominant source of noise from most 

construction equipment is the engine, usually a diesel, often without sufficient muffling. In a few cases, 

such as impact pile driving or pavement breaking, noise generated by the process dominates. 

For considerations of noise assessment, construction equipment can be considered to operate in two 

modes, stationary and mobile. Stationary equipment operates in one location for one or more days at a 

time, with either a fixed-power operation (pumps, generators, compressors) or a variable noise operation 

(pile drivers, pavement breakers). Mobile equipment moves around the construction site with power 

applied in cyclic fashion (bulldozers, loaders) or to and from the site (trucks). The movement around the 

site is handled in the construction noise prediction procedure discussed later in this chapter. Variation in 

power imposes additional complexity in characterizing the noise source level from a piece of equipment. 

This is handled by describing the noise at a reference distance from the equipment operating at full power 

and adjusting it based on the duty cycle of the activity to determine the Leq of the operation. Standardized 

procedures for measuring the exterior noise levels for the certification of mobile and stationary
Chapter 10: Noise and Vibration During Construction 10-4

construction equipment have been developed by the Society of Automotive Engineers.54,55 Typical noise 

levels generated by representative pieces of equipment are listed in Table 10-1. These levels are based on 

EPA and U.S. DOT reports,

56,57,58 measured data from railroad construction equipment, and other 

measured data. Some of these source levels have been updated based on more recent data referenced in 

FHWA’s Construction Noise Handbook.

59

Construction activities are characterized by variations in the power expended by equipment, with 

resulting variation in noise levels over time. Variation in power is expressed in terms of the “usage 

factor” of the equipment, the percentage of time during the workday that the equipment operates at full 

power. Time-varying noise levels are converted to a single number (Leq) for each piece of equipment 

during the operation. Besides having daily variations in activities, major construction projects are 

accomplished in several different phases. Each phase has a specific equipment mix, depending on the 

work to be accomplished during that phase. 

As a result of the equipment mix, each phase has its own noise characteristics; some will have higher 

continuous noise levels than others, and some have high-impact noise levels. The purpose of the 

quantitative assessment is to determine not only the levels but also the duration of the noise. The Leq of 

each phase is determined by combining the Leq contributions from each piece of equipment used in that 

phase. The impact and the consequent noise mitigation approaches depend on the criteria to be used in 

assessing impact, as discussed in the next section.

 

54 Society of Automotive Engineers. Exterior Sound Level Measurement Procedure for Powered Mobile 

Construction Equipment, SAE Recommended Practice J88a, 1976.

55 Society of Automotive Engineers. Sound Levels for Engine Powered Equipment, SAE Standard J952b, 1976.

56 U.S. EPA. Noise from Construction Equipment and Operations, Building Equipment and Home Appliances,

NTID300.1, December 31, 1971.

57 U.S. DOT. Final Environmental Impact Statement, 4(f) Statement; Replacement of Shaw's Cove Bridge and 

Approaches, FRA-RNC-EIS-80-02-F, September 16, 1981.

58 W. R. Fuller and R. Brown. Analysis and Abatement of Highway Construction Noise, EPA 550/9-81-314-A, U.S. 

EPA, Office of Noise Abatement and Control and U.S. DOT, FHWA, June 1981.

59 U.S. DOT, FHWA. Construction Noise Handbook, Final Report, FHWA-HEP-06-015, August 2006.
Chapter 10: Noise and Vibration During Construction 10-5

Table 10-1 Construction Equipment Noise Emission Levels

Equipment Typical Noise Level (dBA)

50 ft from Source

Air Compressor 80

Backhoe 80

Ballast Equalizer 82

Ballast Tamper 83

Compactor 82

Concrete Mixer 85

Concrete Pump 82

Concrete Vibrator 76

Crane, Derrick 88

Crane, Mobile 83

Dozer 85

Generator 82

Grader 85

Impact Wrench 85

Jack Hammer 88

Loader 80

Paver 85

Pile Driver (Impact) 101

Pile Driver (Vibratory) 95

Pneumatic Tool 85

Pump 77

Rail Saw 90

Rock Drill 85

Roller 85

Saw 76

Scarifier 83

Scraper 85

Shovel 82

Spike Driver 77

Tie Cutter 84

Tie Handler 80

Tie Inserter 85

Truck 84
Chapter 10: Noise and Vibration During Construction 10-6

10.1.2 Construction Noise Criteria

FRA does not have standardized criteria for assessing construction noise impact. Consequently, criteria 

must be developed unless local ordinances are appropriate and found to apply. Generally, local noise 

ordinances are not very useful in evaluating construction noise. They usually relate to nuisance and hours 

of allowed activity and sometimes specify limits in terms of maximum levels, but they are generally not 

practical for assessing the impact of a construction project. Project construction noise criteria should take 

into account the existing noise environment, the absolute noise levels during construction activities, the 

duration of the construction, and the adjacent land use. Although it is not the purpose of this manual to 

specify standardized criteria for construction noise impact, the following guidelines can be considered for 

assessment purposes. If these criteria are exceeded, adverse community reaction is very likely and 

appropriate steps to mitigate the impact should be evaluated and implemented.

General Assessment: Identify land uses in the vicinity of the construction project according to 

residential, commercial, and industrial land use activities. Estimate the combined noise level in 1 h from 

the two noisiest pieces of equipment, assuming they both operate at the same time. Then identify 

locations where the level exceeds the levels specified in Table 10-2:

Table 10-2 General Assessment Criteria for Construction Noise

Land Use

1-Hour Leq (dBA)

Day Night

Residential 90 80

Commercial 100 100

Industrial 100 100

Detailed Assessment: Where a more refined analysis is needed, predict the noise level in terms of 8-hour 

Leq and 30-day averaged Ldn and compare to levels specified in Table 10-3:

Table 10-3 Detailed Assessment Criteria for Construction Noise

Land Use

8-Hour Leq (dBA) Ldn (dBA)

Day Night 30-Day Average

Residential 80 70 75

Commercial 85 85 80*

Industrial 90 90 85*

*Twenty-four-hour Leq, not Ldn.

10.1.3 Quantitative Noise Assessment Methods

A quantitative construction noise assessment is performed by comparing the predicted noise levels with 

impact criteria appropriate for the construction stage. The approach requires an appropriate descriptor, a 

standardized prediction method, and a set of recognized criteria for assessing the impact. 

The descriptor used for construction noise is the Leq. This unit is appropriate for the following reasons:
Chapter 10: Noise and Vibration During Construction 10-7

• It can be used to describe the noise level from operation of each piece of equipment separately 

and is easily combined to represent the noise level from all equipment operating during a given 

period.

• It can be used to describe the noise level during an entire phase.

• It can be used to describe the average noise over all phases of the construction.

The recommended method for predicting construction noise impact for major urban transit projects is 

similar to that suggested by FHWA.60 The FHWA prediction method is used to estimate the construction 

noise levels associated with the construction of a highway, but it can be used for any transportation 

project. The method requires:

1. An emission model to determine the noise generated by the equipment at a reference distance

2. A propagation model that shows how the noise level will vary with distance

3. A way of summing the noise of each piece of equipment at locations of noise sensitivity

The first two components of the model are related by the following equation:

Leq(equip) = E. L. +10 log(U. F. ) − 20log �

D

50� − 10Glog �

D

50�

where: Leq (equip) = Leq at a receiver resulting from the operation of a single piece of 

equipment over a specified time period

E.L. = noise emission level of the particular piece of equipment at the 

reference distance of 50 ft (taken from Table 10-1)

G = constant that accounts for topography and ground effects (taken 

from Chapter 5, Figure 5-3)

D = distance from the receiver to the piece of equipment

U.F. = usage factor that accounts for the fraction of time that the 

equipment is in use over the specified time period

The combination of noise from several pieces of equipment operating during the same time period is 

obtained from decibel addition of the Leq of each single piece of equipment calculated by using the above

equation.

General Assessment

The approach can be as detailed as necessary to characterize the construction noise by specifying the 

various quantities in the equation. For projects in an early assessment stage when the equipment roster 

and schedule are undefined, only a rough estimate of construction noise levels is practical.

The following assumptions are adequate for a general assessment of each phase of construction:

 

60 U.S. DOT. FHWA. FHWA Roadway Construction Noise Model User’s Guide, Final Report, FHWA-HEP-05-054, 

January 2006.
Chapter 10: Noise and Vibration During Construction 10-8

• Full power operation for a time period of 1 h is assumed because most construction equipment 

operates continuously for periods of 1 h or more at some point in the construction period. 

Therefore, U.F. = 1 and 10 log(U.F.) = 0.

• Free-field conditions are assumed and ground effects are ignored. Consequently, G = 0.

• Emission level at 50 ft, E.L., is taken from Table 10-1.

• All pieces of equipment are assumed to operate at the center of the project, or centerline, in the 

case of a guideway or highway construction project.

• The predictions include only the two noisiest pieces of equipment expected to be used in each 

construction phase.

Detailed Assessment

A more detailed approach can be used if warranted, such as when a large number of noise-sensitive sites 

are adjacent to a construction project or where contractors are faced with stringent local ordinances or 

heightened public concerns expressed in early outreach efforts. Additional details include:

• Duration. Long-term construction project noise impact is based on a 30-day average Ldn, the 

times of day of construction activity (nighttime noise is penalized by 10 dB in residential areas), 

and the percentage of time the equipment is to be used during a period of time that will affect 

U.F. For example, an 8-hour Leq is determined by making U.F. the percentage of time each 

individual piece of equipment operates under full power in that period. Similarly, the 30-day 

average Ldn is determined from the U.F. expressed by the percentage of time the equipment is 

used during the daytime hours (7 a.m.–10 p.m.) and nighttime (10 p.m.–7 a.m.), separately over a 

30-day period. However, to account for increased sensitivity to nighttime noise, the nighttime 

percentage is multiplied by 10 before performing the computation.

• Site Characteristics. Taking into account the site topography, natural and artificial barriers and 

ground effects will involve the factor G. Use Figure 5-3 (Chapter 5) to calculate G.

• Noise Sources. Measuring or certifying the emission level of each piece of equipment will refine 

E.L.

• Site Layout. Determining the location of each piece of equipment while it is working will specify 

the distance factor D more accurately.

• Combined Sources. Including all pieces of equipment in the computation of the 8-hour Leq and 

the 30-day average Ldn will determine the total noise levels using Table 10-4 below.

Table 10-4 Computing Total Noise Exposure

Total Leq from All Sources Combined, for the hour of interest: 



 



 = ∑

allsources

L

eq

eq

L total 10 ( ) 10log 10

Total Ldn from All sources Combined: 



 



 = ∑

allsources

L

dn

dn

L total 10 ( ) 10log 10
Chapter 10: Noise and Vibration During Construction 10-9

10.1.4 Mitigation of Construction Noise

After the approaches mentioned previously are used to locate potential impacts from construction noise, 

the next step is to identify appropriate control measures. Three categories of noise control approaches, 

with examples, are given below:

1. Design considerations and project layout:

• Construct noise barriers, such as temporary walls or piles of excavated material, between noisy 

activities and noise-sensitive receivers.

• Route truck traffic away from residential streets, if possible. Select streets with the fewest homes, 

if no alternatives are available.

• Site equipment on the construction lot as far away from noise-sensitive sites as possible.

• Construct walled enclosures around especially noisy activities or around clusters of noisy 

equipment. For example, shields can be used around pavement breakers and loaded vinyl 

curtains can be draped under elevated structures.

2. Sequence of operations:

• Combine noisy operations so they occur in the same time period. The total noise level produced 

will not be significantly greater than the level produced if the operations were performed 

separately.

• Avoid nighttime activities. Sensitivity to noise increases during the nighttime hours in residential 

neighborhoods.

3. Alternative construction methods:

• Avoid impact pile driving where possible in noise-sensitive areas. Drilled piles or the use of a 

sonic or vibratory pile driver are quieter alternatives where the geological conditions permit their 

use.

• Use specially quieted equipment, such as quieted and enclosed air compressors, and mufflers on 

all engines.

• Select quieter demolition methods, where possible. For example, sawing bridge decks into 

sections that can be loaded onto trucks results in lower cumulative noise levels than impact 

demolition by pavement breakers.

If possible, the environmental impact assessment should include descriptions of how each impacted 

location will be treated with one or more mitigation measure. However, with a large, complex project, 

the information available during the preliminary engineering phase may not allow final decisions to be 

made on all specific mitigation measures. In such cases, it is appropriate to describe and commit to a 

mitigation plan that will be developed during final design. The objective of the plan should be to 

minimize construction noise using all reasonable (i.e., cost versus benefit) and feasible (i.e., physically 

achievable) means available. Components of the plan may include some or all of the following 

provisions which would be specified in construction contracts:
Chapter 10: Noise and Vibration During Construction 10-10

• Equipment noise emission limits. These are absolute noise limits applied to generic classes of 

equipment at a reference distance (typically 50 ft). The limits should be set no higher than what 

is reasonably achievable for well-maintained equipment with effective mufflers. Lower limits 

that require source noise control may be appropriate for certain equipment when needed to 

minimize community noise impact, if reasonable and feasible. Provisions could also be included 

to require equipment noise certification testing prior to use on site.

• Lot-line construction noise limits. These are noise limits that apply at the lot line of specific 

noise-sensitive properties. The limits are typically specified in terms of both noise exposure 

(usually Leq over a 20- to 30-minute period) and maximum noise level. They should be based on 

local noise ordinances, if applicable, as well as pre-construction baseline noise levels; limits that 

are 3–5 dB above the baseline are often used.

• Operational and/or equipment restrictions. It may be necessary to prohibit or restrict certain 

construction equipment and activities near residential areas during nighttime hours. This is 

particularly true for activities that generate tonal, impulsive, or repetitive sounds, such as back-up 

alarms, hoe ram demolition, and pile driving.

• Noise abatement requirements. In some cases, specifications may be provided for particular 

noise control treatments, based on the results of the design analysis and/or prior commitments 

made to the public by civic authorities. An example would be the requirement for a temporary 

noise barrier to shield a particular community area from noisy construction activities.

• Noise monitoring plan requirements. Plans can be developed for preproject noise monitoring to 

establish baseline noise levels at sensitive locations, as well as for periodic equipment and lot-line 

noise monitoring during the construction period. The plan should outline the measurement and 

reporting methods that will be used to demonstrate compliance with the project noise limits.

• Noise control plan requirements. For major construction projects, specifications have required 

the preparation and submission of noise control plans on a periodic basis (e.g., every 6 months). 

These plans should predict the construction noise at noise-sensitive receptor locations based on 

the proposed construction equipment and methods. If the analysis predicts that the specified 

noise limits will be exceeded, the plan should specify the mitigation measures that will be applied 

and should demonstrate the expected noise reductions these measures will achieve. The objective 

of this proactive approach is to minimize the likelihood of community noise complaints by 

ensuring that any necessary mitigation measures are included in the construction plans.

• Compliance enforcement program. If construction noise is a significant issue in the community, 

it is important that a program be put in place to monitor contractor compliance with the noise 

control specifications and mitigation plan. It is best that this function be performed by a 

construction management team on behalf of the public agency.

• Public information and complaint response procedures. To maintain positive community 

relations, the public should be kept informed about the construction plans and efforts to minimize 

noise, and procedures should be established for prompt response and corrective action with regard 

to noise complaints during construction.
Chapter 10: Noise and Vibration During Construction 10-11

Most of the above provisions are appropriate for very large projects where construction activity will 

continue for many months, if not years. The FHWA Construction Noise Handbook contains details on 

dealing with construction noise on major transportation projects.61

10.2 CONSTRUCTION VIBRATION ASSESSMENT

Construction activity can result in varying degrees of ground vibration, depending on the equipment and 

methods employed. Operation of construction equipment causes ground vibrations that spread through 

the ground and diminish in strength with distance. Buildings founded on the soil in the vicinity of the 

construction site respond to these vibrations with varying results, ranging from no perceptible effects at 

the lowest levels, low rumbling sounds and perceptible vibrations at moderate levels, and slight damage at 

the highest levels. As expressed previously in this chapter with respect to construction noise, the type of 

assessment—qualitative or quantitative—and the level of construction vibration analysis will be 

determined by factors related to the scale of the project and the sensitivity of the surrounding land use. A 

quantitative analysis should be conducted in cases where construction vibration may result in prolonged 

annoyance or building damage.

Ground vibrations from construction activities do not often reach the levels that can damage structures, 

but they can be within the audible and perceptible ranges in buildings very close to the site. A possible 

exception is the case of fragile buildings, many of them old, where special care must be taken to avoid 

damage. The construction vibration criteria should include special consideration for such buildings. The 

construction activities that typically generate the most severe vibrations are blasting and impact pile 

driving. 

10.2.1 Vibration Source Levels from Construction Equipment

Ground-borne vibration related to human annoyance is generally related to RMS velocity levels expressed 

in vibration decibels. However, a major concern with regard to construction vibration is building damage. 

Consequently, construction vibration is generally assessed in terms of PPV, as defined in Chapter 6. The 

relationship of PPV-to-RMS velocity is expressed in terms of the “crest factor,” defined as the ratio of the 

PPV amplitude to the RMS amplitude. Peak particle velocity is typically a factor of 1.7 to 6 times greater 

than RMS vibration velocity.

Various types of construction equipment have been measured under a wide variety of construction 

activities with an average of source levels reported in terms of velocity as shown in Table 10-5. In this 

table, a crest factor of 4 (representing a PPV-RMS difference of 12 VdB) has been used to calculate the 

approximate RMS vibration velocity levels from the PPV values. Although the table gives one level for 

each piece of equipment, it should be noted that there is a considerable variation in reported ground 

vibration levels from construction activities. The data provides a reasonable estimate for a wide range of 

soil conditions.

 

61 U.S. DOT, FHWA. Construction Noise Handbook, Final Report, FHWA-HEP-06-015, August 2006.
Chapter 10: Noise and Vibration During Construction 10-12

Table 10-5 Vibration Source Levels for Construction Equipment (from 

measured data62.63,64,65)

Equipment PPV at 25 ft 

(in/s)

Approximate

Lv

† at 25 ft

Pile driver (impact)

Upper range 1.518 112

Typical 0.644 104

Pile driver (vibratory)

Upper range 0.734 105

Typical 0.170 93

Clam shovel drop (slurry wall) 0.202 94

Hydromill (slurry wall)

In soil 0.008 66

In rock 0.017 75

Vibratory roller 0.210 94

Hoe ram 0.089 87

Large bulldozer 0.089 87

Caisson drilling 0.089 87

Loaded trucks 0.076 86

Jackhammer 0.035 79

Small bulldozer 0.003 58

† RMS velocity in decibels (VdB) re 1 μin/s.

10.2.2 Construction Vibration Criteria

For evaluating potential annoyance or interference with vibration-sensitive activities as a result of

construction vibration, the criteria for General Assessment in Chapter 7 can be applied. In most cases, 

however, the primary concern regarding construction vibration relates to potential damage effects. 

Guideline vibration damage criteria are given in Table 10-6 for various structural categories. In this table, 

a crest factor of 4 (representing a PPV-RMS difference of 12 VdB) has been used to calculate the 

approximate RMS vibration velocity limits from the PPV limits. These limits should be viewed as 

criteria that should be used during the environmental impact assessment phase to identify problem 

locations that must be addressed during final design.

 

62 D. J. Martin. Ground Vibrations from Impact Pile Driving during Road Construction, Supplementary Report 544, 

United Kingdom Department of the Environment, Department of Transport, Transport and Road Research 

Laboratory, 1980.

63 J. F. Wiss. Vibrations during construction operations. Journal of Construction Division, Proc. American Society of 

Civil Engineers, 100(CO3), 239–246, September 1974.

64 J. F. Wiss. Damage Effects of Pile Driving Vibrations, Highway Research Record, No. 155, Highway Research 

Board, 1967.

65 D. A. Towers. Ground-Borne Vibration from Slurry Wall Trench Excavation for the Central Artery/Tunnel 

Project Using Hydromill Technology, Proceedings of Inter-Noise 95, Newport Beach, CA, July 1995, pp. 227–232.
Chapter 10: Noise and Vibration During Construction 10-13

Table 10-6 Construction Vibration Damage Criteria66

Building Category PPV (in/s) Approximate Lv

†

I. Reinforced-concrete, steel or timber (no plaster) 0.5 102

II. Engineered concrete and masonry (no plaster) 0.3 98

III. Nonengineered timber and masonry buildings 0.2 94

IV. Buildings extremely susceptible to vibration damage 0.12 90

† RMS velocity in decibels (VdB) re 1 μin/s.

10.2.3 Quantitative Construction Vibration Assessment Methods

Construction vibration should be assessed in cases where there is a significant potential for impact from 

construction activities. Such activities include blasting, pile driving, vibratory compaction, demolition, 

and drilling or excavation in close proximity to sensitive structures. The recommended procedure for 

estimating vibration impact from construction activities is as follows:

Damage Assessment

• Select the equipment and associated vibration source levels at a reference distance of 25 ft from 

Table 10-5.

• Make the propagation adjustment according to the following formula (this formula is based on 

point sources with normal propagation conditions):

PPVequip = PPVref × (25/D)1.5

where: PPV (equip) is the peak particle velocity in inches per second of the equipment adjusted for 

distance

PPV (ref) is the reference vibration level in inches per second at 25 ft from Table 10-5

D is the distance from the equipment to the receiver

• Apply the vibration damage criteria from Table 10-6.

Annoyance Assessment

• If desired for consideration of annoyance or interference with vibration-sensitive activities, 

estimate the vibration level Lv at any distance D from the following equation and apply the 

vibration impact criteria for General Assessment in Chapter 7 for vibration-sensitive sites:

Lv(D) = Lv(25 ft) – 30log(D/25)

 

66 Swiss Consultants for Road Construction Association. Effects of Vibration on Construction, VSS-SN640-312a, 

Zurich, Switzerland, April 1992.
Chapter 10: Noise and Vibration During Construction 10-14

10.2.4 Construction Vibration Mitigation

After the methods mentioned previously were used to locate potential human impacts (or building 

damage) from construction vibrations, the next step is to identify control measures. Similar to the 

approach for construction noise, mitigation of construction vibration requires consideration of equipment 

location and processes, as follows:

1. Design considerations and project layout:

• Route heavily loaded trucks away from residential streets, if possible. Select streets with fewest 

homes, if no alternatives are available.

• Operate earthmoving equipment on the construction lot as far away from vibration-sensitive sites 

as possible.

2. Sequence of operations:

• Phase demolition, earthmoving, and ground-impacting operations so as not to occur in the same 

time period. Unlike noise, the total vibration level produced could be significantly less when 

each vibration source operates separately.

• Avoid nighttime activities. People are more aware of vibration in their homes during the 

nighttime hours.

3. Alternative construction methods:

• Avoid impact pile driving where possible in vibration-sensitive areas. Drilled piles or the use of a 

sonic or vibratory pile driver causes lower vibration levels where the geological conditions permit 

their use (however, see cautionary note below). 

• Select demolition methods not involving impact, where possible. For example, sawing bridge 

decks into sections that can be loaded onto trucks results in lower vibration levels than impact 

demolition by pavement breakers, and milling generates lower vibration levels than excavation 

using clam shell or chisel drops.

• Avoid vibratory rollers and packers near sensitive areas.

Pile driving is potentially the greatest source of vibration associated with equipment used during 

construction of a project. The source levels in Table 10-5 indicate that vibratory pile drivers may provide 

substantial reduction of vibration levels. However, there are some additional vibration effects of 

vibratory pile drivers that may limit their use in sensitive locations. A vibratory pile driver operates by 

continuously shaking the pile at a fixed frequency, literally vibrating it into the ground. However, 

continuous operation at a fixed frequency may be more noticeable to nearby residents, even at lower 

vibration levels. Furthermore, the steady-state excitation of the ground may increase resonance response 

of building components. Resonant response may be unacceptable in cases of fragile buildings or 

vibration-sensitive manufacturing processes. Impact pile drivers, in contrast, produce a high vibration 

level for a short time (0.2 s) with sufficient time between impacts to allow any resonant response to 

decay.
Chapter 10: Noise and Vibration During Construction 10-15

As with construction noise, in many cases the information available during the preliminary engineering 

phase will not be sufficient to define specific construction vibration mitigation measures. In such cases, it 

is appropriate to describe and commit to a mitigation plan that will be developed and implemented during 

the final design and construction phases of the project. The objective of the plan should be to minimize 

construction vibration damage using all reasonable and feasible means available. The plan should 

provide a procedure for establishing threshold and limiting vibration values for potentially affected 

structures based on an assessment of each structure’s ability to withstand the loads and displacements 

because of construction vibrations. The plan should also include the development of a vibration 

monitoring plan during final design, preconstruction surveys to document the condition of potentially

affected buildings prior to construction, and the implementation of a compliance monitoring program 

during construction.

Chapter 11: Documentation of Noise and Vibration Assessment 11-1

CHAPTER 11. DOCUMENTATION OF NOISE AND VIBRATION ASSESSMENT

To be effective, noise and vibration analyses must be presented to the public in a clear, comprehensive 

manner. The mass of technical data and information necessary to withstand scrutiny in the environmental 

review process must be documented in a manner that remains intelligible to the public. Justification for 

all assumptions used in the analysis, such as selection of representative measurement sites and all baseline 

conditions, must be presented for review. For large-scale projects, the environmental document normally 

contains a condensation of essential information to maintain a reasonable size. For these projects, 

separate technical reports are usually prepared as supplements to the environmental impact statement

(EIS) or environmental assessment (EA). For smaller projects, or ones with minimal noise or vibration 

impact, all the technical information may be presented in the environmental document itself. This chapter 

gives guidance on how the necessary noise and vibration information should be incorporated in the 

project’s environmental documentation.

11.1 THE TECHNICAL REPORT ON NOISE AND VIBRATION

A separate technical report is often prepared as a supplement to the environmental document (EIS or EA). 

A technical report is appropriate when all of the data cannot be placed in the environmental document. 

The details of the analysis are important for establishing the basis for the assessment. Consequently, all 

the details in the technical report should be contained in a well-organized format for easy access to the 

information. Although the technical report is not intended to be a primer on the subject, the technical data 

and descriptions should be presented in a manner that can be understood by the general public. All the 

necessary background information should be included in the technical report, including tables, maps, 

charts, drawings, and references that may be too detailed for the environmental document but that are 

important in helping to draw conclusions about the project’s noise and vibration impacts and mitigation 

options.
Chapter 11: Documentation of Noise and Vibration Assessment 11-2

11.1.1 Organization of Technical Report

The technical report on noise and vibration should contain the following major subject headings, along 

with the key information content described below. If both noise and vibration have been analyzed, it is 

generally preferable to separate the noise and vibration sections; as shown in this manual, the approaches 

to the two topics are quite different.

Overview – This section contains a brief description of the project and an overview of the noise/vibration 

concerns. It sets forth the initial considerations in framing the scope of the study.

Inventory of Noise and Vibration-Sensitive Sites – The approach for selecting noise/vibration-sensitive 

sites should be described in sufficient detail to demonstrate completeness. Sites and site descriptions are 

to be included.

Measurements of Existing Noise and Vibration Conditions – The basis for selecting measurement sites 

should be documented, along with tables of sites coordinated with maps showing locations of sites. If the 

measurement data are used to estimate existing conditions at other locations, the rationale and the method 

should be included. Measurement procedures should be fully described. Tables of measurement 

instruments should include manufacturer, type, serial number, and date of most recent calibration by 

authorized testing laboratory. Measurement periods, including time of day and length of time at each site, 

should be shown to demonstrate adequate representation of the ambient conditions. The measurement 

data should be presented in a well-organized form in tables and figures. A summary and interpretation of 

measured data should be included.

Special Measurements Related to the Project – Some projects may require specialized measurements at 

sensitive sites, such as outdoor-to-indoor noise level reduction of homes or transmission of vibrations into 

concert halls and recording studios. Other projects may need special source level characterization. Full 

descriptions of the measurements and the results should be included.

Predictions of Noise/Vibration from the Project – The prediction model used for estimating future 

project conditions should be fully described and referenced. Any changes or extensions to the models 

recommended in this manual should be fully described so that the validity of the adjustments can be 

confirmed. Specific data used as input to the models should be listed. Computed levels should be 

tabulated and illustrated by contours, cross sections, or shaded mapping. It is important to illustrate noise 

and vibration impacts on base maps at a scale sufficient to provide location reference for the reader. 

Noise and Vibration Criteria – Impact criteria for the project should be fully described and referenced 

(refer to Chapters 3 and 8). In addition, any applicable local ordinances should be described. Tables 

specifying the criteria levels also should be included. If the project involves considerable construction, 

and a separate construction noise and vibration analysis will be included, then construction criteria should 

appear in a separate section with its own assessment.

Noise and Vibration Impact Assessment – The impact assessment should be described according to the 

procedures outlined in this manual. A resulting impact inventory should be presented for each alternative 

mode or alignment to enable ready comparison among alternatives. The inventory should be tabulated 

according to the different types of land uses affected. For noise, Moderate and Severe impacts should be 

tabulated separately, along with any potential additional impacts from surprise (i.e., startle) because of

rapid noise onset rates. The results of the assessment may be presented both before and after mitigation.
Chapter 11: Documentation of Noise and Vibration Assessment 11-3

Noise and Vibration Mitigation – The mitigation section of the report should begin with a summary of 

all treatments considered, even if some are not carried to final consideration. Final candidate mitigation 

treatments should be considered separately, with descriptions of the features of the treatment, costs, 

expected benefits in reducing impacts, locations where the benefit would be realized, and discussions of 

practicality of implementing alternative treatments. With respect to noise impacts, enough information 

should be included to allow the project sponsor and FRA to reach decisions on mitigation prior to 

issuance of the final environmental document.

Construction Noise and Vibration Impacts – Criteria adopted for construction noise or vibration should 

be described, if appropriate. In accordance with Chapter 10, these may be adopted on a project-specific 

basis. The method used for predicting construction noise or vibration should be described, along with 

inputs to the models, such as equipment roster by construction phase, equipment source levels, assumed 

usage factors, and other assumed site characteristics. The predicted levels should be shown for sensitive 

sites and short-term impacts should be identified. In cases where construction impacts appear to be 

problematic, feasible abatement methods should be discussed in enough detail such that construction 

contract documents could include mitigation measures.

References – References should be provided for all criteria, approaches and data used in the analyses, 

including other reports related to the project which may be relied on for information (e.g., geotechnical 

reports).

11.2 THE ENVIRONMENTAL DOCUMENT

The environmental document typically includes noise and vibration information in three places: a section 

of the chapter on the affected environment (existing conditions) and two sections in the chapter on 

environmental consequences (long-term and short-term impacts). The noise and vibration information 

presented in the environmental document is a summary of the comprehensive information from the 

technical report, with emphasis on presenting the salient points of the analysis in a format and style that 

affected property owners and other interested citizens can understand. Smaller projects may have all of 

the technical information contained within the environmental document; special care should be taken in 

summarizing technical details to convey the information adequately. 

The environmental document provides full disclosure of noise and vibration impacts, including 

identification of locations where impacts cannot be mitigated satisfactorily. An EIS describes significant 

impacts and tells what the Federal agency intends to do about them. For projects handled with EAs, 

completion of the environmental review with a finding of no significant impact (FONSI) may depend on 

mitigation being incorporated in the proposed project. The specific way mitigation is handled in the 

environmental document depends on the type of impact (noise or vibration) and the stage of project 

development and environmental review.

In general, airborne noise impacts can be accurately predicted in the preliminary engineering stage. 

Because the environmental review for major investment projects is completed during preliminary 

engineering, it is possible to specify, and commit to implement, appropriate noise mitigation measures in 

the final environmental document (Final EIS or FONSI). With major investments, as well as small 

projects like bus terminals and garages, it is expected that decisions on noise mitigation will be made 

before the final document is approved; thus, timely development of design, feasibility, and cost 

information needed to reach decisions on noise mitigation is essential. For major investments in the 
Chapter 11: Documentation of Noise and Vibration Assessment 11-4

Alternatives Analysis/Draft EIS stage, the emphasis is not on mitigation but rather a broad comparison 

among the alternatives concerning the magnitude and extent of noise impacts. If it seems likely that 

mitigation would be required for at least some major investment alternatives, this can be discussed in a 

general way while touching on the remaining stages of project development and how decisions on 

mitigation fit in. Finally, there are other projects for which the preferred alternative is identified at the 

outset in the Draft EIS or EA. With the focus on a single alternative, noise impacts can be accurately 

identified in the draft document. If mitigation is needed, mitigation options should be explored in the 

draft; however, firm decisions on mitigation can be deferred to the final document.

Predicting vibration impacts accurately is a more complex undertaking because ground-borne vibration is 

strongly influenced by subsurface conditions. The geotechnical studies that reveal these conditions are 

normally undertaken during the final design stage after the NEPA process has been completed. Thus, for 

ground-borne vibration and noise, the final environmental document will usually not be able to state with 

certainty whether mitigation is needed. The final environmental document will rely on a General 

Assessment for ground-borne vibration and noise to identify potential problem areas. If there are such 

areas, there should be a commitment in the final document to conduct a Detailed Analysis during final 

design to complete the impact assessment and to help determine the need for mitigation. The final 

environmental document should present a preliminary assessment of whether the impact criteria can be 

met. If it appears the criteria cannot be met, the document would also discuss various control measures 

that could be used and the likelihood that the criteria could be met through the use of one or more of the 

measures. It may be possible to state a commitment in the final environmental document to adhere to the 

impact criteria while deferring the selection of specific vibration control measures until the completion of 

detailed studies in final design.

After a final environmental document is approved, the described mitigation measures are incorporated by 

reference in the actual grant agreements signed by FRA and the project sponsor. Thus, they become 

contractual conditions that must be adhered to by the project sponsor. As a project advances into 

preliminary engineering and final design, future noise and vibration conditions may be affected by 

changes in the design such as minor shifts in alignment, relocation of special track work, or other physical 

changes to the proposed project. With these changes, the potential for noise and vibration impact and the 

need for mitigation may change. Therefore, noise and vibration should be continually analyzed 

throughout the engineering process. If significant changes to potential impact or mitigation occur, they 

should be documented in a similar manner to that of the NEPA documentation. FRA may review these 

documented changes to the impact assessment and proposed mitigation and additional public outreach to 

convey such changes to affected stakeholders may be required.

11.2.1 Organization of Noise and Vibration Sections

Chapter on Affected Environment (Existing Conditions)

This chapter describes the preproject setting, including the existing noise and vibration conditions that

will likely be affected by one or more of the alternatives. The primary function of this chapter is to 

establish the focus and baseline conditions for later chapters discussing environmental impacts. 

Consequently, this chapter is a good place to put basic information on noise and vibration descriptors and 

effects, as well as for describing the characteristics in the vicinity of the project. Again, it is preferable to 

separate the noise and vibration sections.
Chapter 11: Documentation of Noise and Vibration Assessment 11-5

• Description of Noise and Vibration Descriptors, Effects, and Typical Levels: Information 

from Chapters 2 and 6 of this manual can be used to provide a background for the discussions of 

noise/vibration levels and characteristics to follow. Illustrative material to guide the reader in 

understanding typical levels is helpful. 

• Inventory of Noise and Vibration-Sensitive Sites: The approach for selecting noise and 

vibration-sensitive sites should be described in sufficient detail to demonstrate completeness. 

Site locations and descriptions are to be included.

• Noise and Vibration Measurements: A summary of the site selection procedure should be 

included, along with tables of sites coordinated with maps showing locations of sites. The 

measurement approach should be summarized, with justification for the measurement procedures 

used. The measurement data should be presented in well-organized form in tables and figures. 

To save space, the results are often included with the table of sites described above. In some 

cases, measurements may be supplemented or replaced by collected data relevant to the noise and 

vibration characteristics of the area. For example, soils information for estimating ground-borne 

vibration propagation characteristics may be available from other projects in the area. 

Fundamental to this section are a summary and interpretation of how the collected data define the 

project setting. 

Chapter on Environmental Consequences.

The section on long-term impacts, the impacts due to operation of the project should be organized 

according to the following order:

• Overview of Approach. A summary of the assessment procedure for determining noise and 

vibration impacts is provided as a framework for the following sections.

• Estimated Noise and Vibration Levels. A general description of prediction models used to 

estimate project noise/vibration levels should be provided. Any distinguishing features unique to 

the project, such as source levels associated with various technologies, should be described. The 

results of the predictions for various alternatives should be described in general terms first, 

followed by a detailed accounting of predicted noise levels. This information should be 

supplemented with tables and illustrated by contours, cross sections, or shaded mapping. If 

contours are included in a technical report, then it is not necessary to repeat them here.

• Criteria for Noise and Vibration Impact. Impact criteria for the project should be fully 

described and referenced (refer to Chapters 3 and 7). In addition, any applicable local ordinances 

should be described. Tables listing the criterion levels should be included.

• Impact Assessment. The impact assessment can be a section by itself or can be combined with 

the section above. It is important to provide a description of locations where noise and vibration 

impact is expected to occur without implementation of mitigation measures, based on the 

predicted future levels, existing levels, and the criteria for impact. Inventory tables of impacted 

land uses should be used to quantify the impacts for comparisons among alternatives. The 

comprehensive list of noise- and vibration-sensitive sites identified in the “Affected 

Environment” chapter should be included in this inventory table.
Chapter 11: Documentation of Noise and Vibration Assessment 11-6

• Noise and Vibration Mitigation. Perhaps the most significant difference between the technical 

report and the environmental document is in the area of mitigation. Whereas the technical report 

discusses options and may make recommendations, the environmental document provides the 

vehicle for reaching decisions on appropriate mitigation measures, with consideration given to 

environmental benefits, feasibility, and cost. This section should begin with a summary of all 

noise and vibration mitigation measures considered for the impacted locations. The specific 

measures selected for implementation should be fully described. Reasons for dismissing any 

abatement measures should be clearly stated, especially if such nonimplementation results in 

significant adverse effects. In cases where it is not possible to commit to a specific mitigation 

measure in the final environmental document, it may be possible to commit to a certain level of 

noise or vibration reduction, for example, adherence to the impact criteria specified in Chapters 3 

and 7.

• Unavoidable Adverse Environmental Effects. If it is projected that adverse noise and vibration 

impacts will result after all reasonable abatement measures have been incorporated, the impacts 

should be identified in this section.

Impacts During Construction

The environmental document may have a separate section on short-term impacts because of project 

construction, depending on the scale of the project. For a major project there may be a special section on 

construction noise and vibration impacts; this section should be organized according to the 

comprehensive outline described above. For projects with relatively minor effects, a briefer format 

should be used, with a section included in the chapter on “Environmental Consequences.”
Appendix A: Background – Noise Concepts A-1

APPENDIX A BACKGROUND – NOISE CONCEPTS

A.1 NOISE METRICS

Environmental noise generally derives from a conglomeration of distant noise sources. Such sources may 

include distant traffic, wind in trees, and distant industrial or farming activities, all part of our daily lives. 

These distant sources create a low-level “background noise” in which no particular individual source is 

identifiable. Background noise is often relatively constant from moment to moment but varies slowly 

from hour to hour as natural forces change or as human activity follows its daily cycle. Superimposed on 

this low level, slowly varying background noise is a succession of identifiable noisy events of relatively 

brief duration. These events may include single-vehicle passbys, aircraft flyovers, screeching of brakes, 

and other short-term events, all causing the noise level to fluctuate significantly from moment to moment.

It is possible to describe these fluctuating noises in the environment by using single-number descriptors. 

To do this allows manageable measurements, computations, and impact assessment. The search for 

adequate single-number noise descriptors has encompassed hundreds of attitudinal surveys and laboratory 

experiments, plus decades of practical experience with many alternative descriptors.

A.1.1 A-Weighted Level: The Basic Noise Unit

As discussed in Chapter 2, the basic noise unit for environmental noise is the A-weighted sound level. It 

describes the magnitude of noise at a receiver at any moment in time and is read directly from noisemeasuring equipment, with the “weighting switch” set on “A.” Typical A-weighted sound levels from 

high-speed rail systems as well as other outdoor and indoor sources are shown in Figure 2-2.

Typical community A-weighted sound levels range from the 30s to the 90s, where 30 is very quiet and 90 

is very loud. An A-weighted sound level measured in decibels is abbreviated “dBA,” where the “dB”

stands for decibels and refers to the general strength of the noise. The decibel is a unit that can be used to 

denote the ratio between any two quantities that are proportional to power. When used to describe sound 
Appendix A: Background – Noise Concepts A-2

level, the number of decibels is 10 times the logarithm (to the base 10) of the ratio (p2/pref

2

), where p is the 

sound pressure (in micropascals) and pref is a reference pressure (20 μPa). The letter “A” indicates that 

the sound has been filtered to reduce the strength of very low and very high frequency sounds, much as 

the human ear does. Without this A-weighting, noise-monitoring equipment would respond to events 

people cannot hear, events such as high-frequency dog whistles and low-frequency seismic disturbances. 

On the average, each A-weighted sound level increase of 10 dB corresponds to an approximate doubling 

of subjective loudness.

A-weighted sound levels are adopted here as the basic noise unit because: (1) they can be easily 

measured, (2) they approximate the human ear’s sensitivity to sounds of different frequencies, (3) they 

match attitudinal-survey tests of annoyance better than do other basic units, (4) they have been in use 

since the early 1930s, and (5) they are endorsed as the proper basic unit for environmental noise by nearly 

every agency concerned with community noise throughout the world.

This manual uses the following single-number descriptors for environmental noise measurements, 

computations, and assessment:

The A-Weighted Sound Level, which describes a receiver’s noise level at any moment in time.

The Maximum Level (Lmax) during a single noise event.

The Sound Exposure Level (SEL), which describes a receiver’s cumulative noise exposure from a 

single noise event.

The Hourly Equivalent Sound Level (Leq(h)), which describes a receiver's cumulative noise 

exposure from all events over a 1-hour period.

The Day-Night Sound Level (Ldn), which describes a receiver’s cumulative noise exposure from 

all events over a full 24 h, with events between 10 p.m. and 7 a.m. increased by 10 dB to account 

for greater nighttime sensitivity to noise.

The following sections illustrate all of these noise descriptors, in turn, and describes their particular 

application in this manual. Graphic illustrations and mathematical definitions are provided to help the 

reader understand and see the interrelationships among descriptors.

A.1.2 Lmax during a Single Noise Event

As a train approaches, passes by, and then proceeds into the distance, the A-weighted sound level rises, 

reaches a maximum, and then fades into the background noise. The maximum A-weighted sound level 

reached during this passby is called the maximum level, abbreviated here as “Lmax.” For noise 

compliance tests of transient sources, such as moving rail vehicles under controlled conditions with 

smooth wheel and rail conditions, Lmax is typically measured with the sound level meter’s switch set on 

“fast,” meaning that the sound level is averaged over a period of 0.125 s. Another use of Lmax (fast), 

abbreviated Lmax,f, is for identifying defective components such as wheel flat spots in a passing train or an 

excessively noisy car in a long consist of freight cars. However, for tests of continuous or stationary 

sources, and for describing short-term noise events for the general assessment of noise impact, it is 

usually more appropriate to use the “slow” setting, where the sound level is averaged over a 1-second 

period. When set on “slow,” sound level meters ignore some of the very transient fluctuations, which are 
Appendix A: Background – Noise Concepts A-3

unimportant to people's overall assessment of the noise. Lmax (slow), abbreviated Lmax,s gives a better 

representation of sound energy of an event and is therefore more directly related to the sound exposure 

level (SEL) described in the next subsection.

Measurements reported as Lmax without designation of “fast” or “slow” meter response often become a 

source of confusion, which leads to errors in interpretation. Measurements of high-speed trains to obtain 

reference levels for this manual consistently showed Lmax,f to be 2 dB higher than Lmax,s. Therefore, in 

general, if it is important to document the sound level of a very short-term event, less than 1 s in duration, 

use the “fast” meter setting; otherwise, use “slow.” The manner in which the Lmax descriptor fits into the 

time history of environmental noise is shown in Figure A-1. 

A.1.3 SEL: The Cumulative Exposure from a Single Noise Event

The quantitative measure of the noise “dose” for single noise events is the Sound Exposure Level, 

abbreviated here as “SEL.” The fact that SEL is a cumulative measure means that (1) louder events have 

higher SELs than quieter ones, and (2) events that last longer in time have higher SELs than shorter ones. 

People react to the duration of noise events, judging longer events to be more annoying than shorter ones, 

assuming equal maximum A-Levels. The SEL is computed as:

SEL = 10log �

total sound energy

during the event �

A more specific mathematical definition is:

SEL = 10log �� 10

LA(t)

10 � dt

∞

−∞

�

where LA(t) represents the time-varying A-weighted sound level during an event. Time base is assumed 

to be 1 s.

• SEL is used in this manual as the measure of each single high-speed train event because unlike 

Lmax,

• SEL increases with the duration of a noise event, which is important to people’s reaction,

• SEL therefore allows a uniform assessment method for differing high-speed rail technologies, and

• SEL can be used to calculate the 1- and 24-hour cumulative descriptors discussed below.

A.1.4 Hourly Equivalent Sound Level [Leq(h)]

The descriptor for cumulative 1-hour exposure is the Hourly Equivalent Sound Level, abbreviated here as 

“Leq(h).” It is an hourly measure that accounts for the moment-to-moment fluctuations in A-weighted 

sound levels as a result of all sound sources during that hour, combined. Sound fluctuation is illustrated 

in the upper frame of Figure A-1 for a single noise event such as a train passing on nearby tracks. As the 

train approaches, passes by, and then proceeds into the distance, the A-Weighted Sound Level rises, 

reaches a maximum, and then fades into the background noise. The area under the curve in this upper 

frame is the receiver’s noise exposure over this 5-minute period.
Appendix A: Background – Noise Concepts A-4

The center frame of Figure A-1 shows sound-level fluctuations over a 1-hour period that includes the 

5-minute period from the upper frame. The area under the curve represents the noise exposure for 1 h. 

The Hourly Equivalent Sound Level is computed as:

Leq(hour) = 10log10 �

Total sound energy

during 1 hour � − 35.6

or mathematically:

Leq(hour) = 10log10 �

1

T � 10

LA(t)

10 �

t2

t1

dt�

where the 1-hour interval extends from t1 to t2, and T = t2 – t1 = 1 h. The constant 35.6 is obtained from 

time normalization: 1 h = 3,600 s, and 10 log (3,600) = 35.6.

Sound energy is totaled here over a full hour; thus, it accumulates from all noise events during that hour. 

Subtraction of 35.6 from the total sound energy during 1 h in the first equation converts it into a time 

average, as does the 1/T factor shown in the second equation. In brief, if the actual fluctuating noise were 

replaced by a constant noise equal to this average value, the receiver would be exposed to the same total 

noise energy. This type of average value is “equivalent” in that sense to the actual fluctuating noise.

A useful, alternative way of computing Leq due to a series of high-speed rail noise events is:

Leq(hour) = 10log10 �

Energy Sum of

all SELs � − 35.6

or mathematically:

Leq(hour) = 10log10 �

1

T�10

SELi

10 �

i

�

This equation concentrates on the cumulative contribution of individual noise events and is the 

fundamental equation incorporated into Chapters 4 and 5.

The bottom frame of Figure A-1 shows the sound level fluctuations over a full 24-hour period. It is 

discussed in Section A.1.5.
Appendix A: Background – Noise Concepts A-5

Figure A-1 Example A-Weighted Sound Level Time Histories

Typical hourly Leqs, both for high-speed rail and non-high-speed rail sources, are shown in Figure A-2. 

These Leqs depend on the number of events during the hour and also upon each event’s duration, which is 

affected by speed. Doubling the number of events during the hour will increase the Leq by 3 dB, as will 

doubling the duration of each individual event.
Appendix A: Background – Noise Concepts A-6

Figure A-2 Typical Hourly Leqs

Hourly Leq is adopted as the measure of cumulative noise impact for non-residential land uses (those not 

involving sleep) because:

• Leqs correlate well with speech interference in conversation and on the telephone, as well as 

interruption of television, radio, and music enjoyment,

• Leqs increase with the duration of events, which is important to people’s reaction,

• Leqs take into account the number of events over the hour, which is also important to people’s 

reaction, and

• Leqs are used by FHWA in assessing highway-traffic noise impact. 

Thus, this noise descriptor can be used to compare and contrast modal alternatives such as highway 

versus rail. Leq is computed for the loudest facility hour during noise-sensitive activity at each particular 

nonresidential land use. 

A.1.5 Day-Night Sound Level (Ldn): The Cumulative 24-Hour Exposure from All Events

The descriptor for cumulative 24-hour exposure is the Day-Night Sound Level, abbreviated as “Ldn.” It is 

a 24-hour measure that accounts for the moment-to-moment fluctuations in A-Levels due to all sound 

sources during 24 h, combined. Such fluctuations are illustrated in the bottom frame of Figure A-1. The 

area under the curve represents the receiver’s noise exposure over a full 24 h. Some vehicle passbys 

occur at night in the figure when the background noise is less. Mathematically, the Day-Night Level is 

computed as:

Ldn = 10log10 �

Total sound energy

during 24 hours � − 49.4

where nighttime noise (10 p.m.–7 a.m.) is increased by 10 dB before totaling. The constant 49.4 is 

obtained from the time normalization: 24 h = 86,400 s, and 10 log (86,400) = 49.4.

Sound energy is totaled over a full 24 h; it accumulates from all noise events during that 24 h. 

Subtraction of 49.4 from this 24-hour exposure converts it into a type of “average.” If the actual 
Appendix A: Background – Noise Concepts A-7

fluctuating noise were replaced by a constant noise equal to this average value, the same total noise 

exposure would enter the receiver’s ears.

An alternative way of computing Ldn from 24 hourly Leqs is:

Ldn = 10log10 �

Energy sum of

24 hourly Leqs � − 13.8

where nighttime Leqs are increased by 10 decibels before totaling, as in the previous equation. 

This is expressed mathematically as:

























+

=

∑ ∑ = =

+

24

10 10

10log

7

10

10

7

10

10

( ) 10

10

( ) am

hour pm

pm

hour am

dn

hour Leq hour Leq

L

where:

the 15-hour period from 7 a.m. to 10 p.m. is defined as daytime (unweighted), and

the 9-hour period 10 p.m.–7 a.m. is defined as nighttime (with 10-decibel weighting).

Ldn due to a series of high-speed train events can also be computed as:

Ldn = 10log10 �

Energy sum of

all SELs � − 49.4

Use of this equation assumes that train noise dominates the 24-hour noise exposure. Here again, 

nighttime SELs are increased by 10 dB before totaling. This last equation concentrates upon individual 

noise events, and is the equation incorporated into Chapters 4 and 5. 

Typical Ldns, both for high-speed rail and conventional transit sources are shown in Figure A-3. As 

shown in the figure, typical Ldns range from the 50s to the 70s—where 50 is a quiet 24-hour period and 70 

is an extremely noisy one. These Ldns depend on the number of events during day and night separately—

and also upon each event’s duration, which is affected by vehicle speed.
Appendix A: Background – Noise Concepts A-8

Figure A-3 Typical Ldns

Ldn is adopted as the measure of cumulative noise impact for residential land uses (those involving sleep), 

because: 

 Ldn correlates well with the results of attitudinal surveys of residential noise impact,

 Ldn increases with the duration of transit events, which is important to people’s reaction,

 Ldn takes into account the number of transit events over the full 24 h, which is also important to 

people’s reaction,

 Ldn takes into account the increased sensitivity to noise at night, when most people are asleep,

 Ldn allows composite measurements to capture all sources of community noise combined,

 Ldn allows quantitative comparison of transit noise with all other community noises,

 Ldn is the designated metric of choice of other Federal agencies such as FTA, the U.S. Department 

of Housing and Urban Development (HUD), FAA, and EPA, and

 Ldn has wide international acceptance.

In terms of individual passbys, some characteristics of both the Leq and the Ldn are as follows:

When passby Lmaxs increase: Both Leq and Ldn increase

When passby durations increase: Both Leq and Ldn increase

When the number of passbys increases: Both Leq and Ldn increase

When some operations shift to louder vehicles: Both Leq and Ldn increase

When passbys shift from day to night: Ldn increases

All of these increases in Leq and Ldn correlate to increases in community annoyance.
Appendix A: Background – Noise Concepts A-9

A.1.6 Passby Level

In Europe, the most widely encountered descriptor for high-speed train noise, is the A-weighted “passby 

level,” or LpAeq,Tp.

67 This descriptor is used to quantify the noise level from a single vehicle passby, and is 

defined as the A-weighted sound level energy-averaged over the time of the event passby. In a sense, it is 

like Leq(hour), except that it is evaluated for only a single event and averaged over the event-specific 

passby time instead of a standardized time period. It is defined mathematically as follows:

LpAeq.Tp = 10log10 �

1

Tp

� 10

LA(t)

10 � dt

t2

t1

�

where:

t1 is the time at the leading edge of the passby

t2 is the time at the trailing edge of the passby

the passby duration Tp = t2 – t1

A.1.7 Other Descriptors

In Japan, different metrics are used to describe the noise from train passages. One such metric, LAmax, is 

defined as the power- or energy-average of the “slow” maximum level (Lmax,s) of 20 consecutive train 

passbys. Mathematically this is expressed as:

LAmax

i

Lmax s i

= 













= 

10 ∑1

20

10 10

1

20

10 log

( , )

A metric known as SEL, but abbreviated LAE, also is used in Japan and has a slightly different definition 

from the SEL used in this manual. It is defined as the energy-averaged value of the sound exposure, or 

energy during the event, measured within 10 dB of LAmax, sampled at a time interval of 5/3 s. The 

mathematical expression is:

L t AE

i

LAi

= ⋅ 















10 ∑ 10 10

10 log ∆

where t = 5/3 s.

 

67 Also sometimes abbreviated Lp,p and Lmax(mean).
Appendix A: Background – Noise Concepts A-10

A.2 RECEIVER RESPONSE TO TRANSPORTATION NOISE

An overview of receiver response to noise is presented in this section. It serves as background 

information for the noise impact criteria presented in Chapter 3 and for the criteria development process 

documented in Section A.3. 

Noise can interrupt ongoing activities and can result in community annoyance, especially in residential 

areas. In general, most residents become highly annoyed when noise interferes significantly with 

activities such as sleeping, talking, noise-sensitive work, and listening to radio or television or music. In 

addition, some land uses, such as outdoor concert pavilions, are inherently incompatible with high noise 

levels. Annoyance to noise has been investigated and approximate exposure-response relationships have 

been quantified by the U.S. EPA.68,69 The selection of noise descriptors in this manual is largely based on 

this EPA work. Beginning in the 1970s, EPA undertook a number of research and synthesis studies 

relating to community noise of all types. Results of these studies have been widely published and 

discussed and referenced by many professionals in acoustics. Basic conclusions of these studies have 

been adopted by the Federal Interagency Committee on Noise, HUD, the American National Standards 

Institute, and even internationally.70,71,72,73 Conclusions from this seminal EPA work remain scientifically 

valid to this day.

A synthesis of actual case studies of community reaction to newly introduced sources of noise in a 

residential urban neighborhood is shown in Figure A-4 (ref. 3). The new noise’s excess above existing 

noise levels is shown in Figure A-4. Both the new and existing noise levels are expressed as Day-Night 

Sound Levels, Ldn, discussed in Section A.1.5. The community reaction to this newly introduced noise 

also is shown in Figure A-4, varying from “No Reaction” to “Vigorous Action,” for newly introduced 

noises averaging from “10 dB below existing” to “25 dB above existing.” Note that these data points 

apply only when the stated assumptions are true. For other conditions, the points shift to the right or left 

somewhat.

In a large number of community attitudinal surveys, transportation noise has been ranked among the most 

significant causes of community dissatisfaction. A synthesis of many such surveys on annoyance appears 

 

68 U.S. EPA. Impact Characterization of Noise Including Implications of Identifying and Achieving Levels of 

Cumulative Noise Exposure, Task group 3, Henning von Gierke, Chairman, Report NTID 73.4, Washington, DC, 

July 27, 1973.

69 U.S. EPA. Information on Levels of Environmental Noise Requisite to Protect Public Health and Welfare with an 

Adequate Margin of Safety, Report No. 550/9-74-004, Washington, DC, March 1974.

70 Federal Interagency Committee on Urban Noise. Guidelines for Considering Noise in Land Use Planning and 

Control, a joint publication of EPA, DOT, HUD, the Department of Defense, and the Veterans Administration, 

Washington, DC, June 1980.

71 HUD. Environmental Criteria and Standards of the Department of Housing and Urban Development, 24 Code of 

Federal Regulations Part 51; 44 Federal Register 40861, Washington, DC, July 12, 1979.

72 American National Standards Institute. American National Standard: Compatible Land Use With Respect to 

Noise, Standard S3.23-1980, New York NY, May 1980.

73 International Standards Organization, “Assessment of Noise with Respect to Community Response,”

Recommendation R-1996, Geneva, 1971.
Appendix A: Background – Noise Concepts A-11

in Figure A-5.74,75 Different neighborhood noise exposures are plotted horizontally. The percentage of 

people who are highly annoyed by their particular level of neighborhood noise is plotted vertically. As 

shown in the figure, the percentage of high annoyance is approximately 0 at 45 dB, 10 percent around 60 

dB, and increases quite rapidly to approximately 70 percent around 85 dB. The scatter about the 

synthesis line is due to variation from community to community and to some wording differences in the 

various surveys. A recent update of the original research, containing several additional railroad, transit 

and street traffic noise surveys, confirmed the shape of the original Schultz curve.76

Figure A-4 Community Reaction to New Noise, Relative to Existing Noise in a Residential Urban 

Environment

 

74 T.J. Schultz, “Noise Rating Criteria for Elevated Rapid Transit Structures,” U.S. Department of Transportation 

Report No. UMTA-MA-06-0099-79-3, Washington DC, May 1979.

75 T. J. Schultz. Synthesis of social surveys on noise annoyance. Journal of the Acoustical Society of America, 63(8), 

August 1978.

76 S. Fidell, D. S. Barber, and T. J. Schultz. Updating a dosage-effect relationship for the prevalence of annoyance 

due to general transportation noise. Journal of the Acoustical Society of America, 89(1), January 1991.
Appendix A: Background – Noise Concepts A-12

Figure A-5 Community Annoyance Because of Noise

As indicated by these two figures, introduction of high-speed rail noise into a community may have two 

undesirable effects. First, it may significantly increase existing noise levels in the community, and 

residents have mostly become accustomed to those levels. This effect is called “relative” noise impact. 

Evaluation of this effect is “relative” to existing noise levels; relative criteria are based upon noise 

increases above existing levels. Second, newly introduced noise may interfere with community activities, 

independent of existing noise levels; it may be simply too loud to converse or to sleep. This effect is 

called “absolute” noise impact, because it is expressed as a fixed level not to be exceeded and is 

independent of existing noise levels. Both of these effects, relative and absolute, enter into the 

assessment of noise impact discussed in Chapters 4 and 5. These two types of impact, relative and 

absolute, are merged into the noise criteria described in Chapter 3.

A.3 NOISE IMPACT CRITERIA DEVELOPMENT

The noise criteria presented in Chapter 3 of this manual have been developed based on well-documented 

criteria and research into human response to community noise. The primary goals in developing these 

noise criteria were to ensure that the impact limits be firmly founded in scientific studies, be realistically 

based on noise levels associated with high-speed rail projects, and represent a reasonable balance between 

community benefit and project costs. This section provides the background information.

A.3.1 Relevant Literature

An annotated list of the documents that are particularly relevant to the noise impact criteria follows:
Appendix A: Background – Noise Concepts A-13

1. US Environmental Protection Agency “Levels Document” (ref. 3): This report identifies noise 

levels consistent with the protection of public health and welfare against hearing loss, annoyance, 

and activity interference. It has been used as the basis of numerous community noise standards 

and ordinances.

2. CHABA Working Group 69, “Guidelines for Preparing Environmental Impact Statements on 

Noise.”:

77 This report was the result of deliberations by a group of leading acoustical scientists 

with the goal of developing a uniform national method for noise impact assessment. Although 

the CHABA’s proposed approach has not been adopted, the report serves as an excellent resource 

documenting research in noise effects. It provides a strong scientific basis for quantifying 

impacts in terms of Ldn. 

3. “Synthesis of Social Surveys on Noise Annoyance” (ref. 9): In 1978, Theodore J. Schultz, an 

internationally known acoustical scientist, synthesized the results of a large number of social 

surveys, each concerning annoyance because of transportation noise. Remarkable consistency 

was found in a group of these surveys, and the author proposed that their average results be taken 

as the best available prediction of transportation noise annoyance. This synthesis has received 

essentially unanimous acceptance by acoustical scientists and engineers. The “universal”

transportation response curve developed by Schultz (Figure A-5) shows that the percentage of the 

population highly annoyed by transportation noise increases from 0 at an Ldn of approximately 50 

dBA to 100 percent when Ldn is about 90 dBA. Most significantly, this curve indicates that for 

the same increase in Ldn, there is a greater increase in the number of people highly annoyed at 

high noise levels than at low noise levels. In other words, a 5 dB increase at low ambient levels 

(40–50 dB) has less impact than at higher ambient levels (65–75 dB). A recent update of the 

original research, containing several railroad, transit and street traffic noise surveys, confirmed 

the shape of the original Schultz curve (ref. 10).

4. HUD Standards:

78 HUD has developed noise standards, criteria and guidelines to ensure that 

housing projects supported by HUD achieve the goal of a suitable living environment. The HUD 

site acceptability standards define 65 dB (Ldn) as the threshold for a normally unacceptable living 

environment and 75 dB (Ldn) as the threshold for an unacceptable living environment.

5. French High Speed Rail Noise Survey:

79 The first comprehensive high-speed rail noise 

annoyance survey was performed along the route of TGV Atlantique south of Paris. Surveys of 

residents along the dedicated high-speed rail line were conducted before and after operation of the 

trains. Results of the study led to recommendations that the noise assessment descriptor should 

be modified to include early morning and nighttime events and that a procedure be developed for 

 

77 National Academy of Sciences. Guidelines for Preparing Environmental Impact Statements on Noise, Report 

from Committee on Bioacoustics and Biomechanics (CHABA) Working Group 69, February 1977.

78 U.S. Department of Housing and Urban Development. Environmental Criteria and Standards, 24 Code of Federal 

Regulations Part 51, July 12, 1979; amended by 49 FR 880, 6 January 1984.

79 J. Lambert, Pl. Champelovier, and I. Vernet. Annoyance from high speed train noise: a social survey. Journal of 

Sound and Vibration, 193(1), 1996.
Appendix A: Background – Noise Concepts A-14

noise assessment of multimodal operations. Both of these objectives are included in the 

development of criteria for this manual. 

A.3.2 Basis for Noise Impact Criteria Curves

The lower curve in Figure 3-1, representing the onset of Impact, is based on the following considerations:

• The EPA finding that a community noise level of Ldn less than or equal to 55 dBA is “requisite to 

protect public health and welfare with an adequate margin of safety” (ref. 2).

• The conclusion by EPA and others that a 5 dB increase in Ldn or Leq is the minimum required for 

a change in community reaction.

• The research finding that there are very few people highly annoyed when the Ldn is 50 dBA, and 

that an increase in Ldn from 50 to 55 dBA results in an average of 2 percent more people highly 

annoyed (see Figure A-5).

Consequently, the change in noise level from an existing ambient level of 50 dBA to a cumulative level of 

55 dBA caused by a project is assumed to be a minimal impact. Expressed another way, this is 

considered to be the lowest threshold where impact starts to occur. Moreover, the 2 percent increment 

represents the minimum measurable change in community reaction. Thus the curve’s hinge point is 

placed at a project noise level of 53 dBA and an existing ambient noise level of 50 dBA, the combination 

of which yields a cumulative level of 55 dBA. The remainder of the lower curve in Figure 3-1 was 

determined from the annoyance curve (Figure A-5) by allowing a fixed 2-percent increase in annoyance 

at other levels of existing ambient noise. As cumulative noise increases, it takes a smaller and smaller 

increment to attain the same 2-percent increase in highly annoyed people. Although it takes a 5 dB noise 

increase to cause a 2-percent increase in highly annoyed people at an existing ambient noise level of 50 

dB, an increase of only 1 dB causes the 2-percent increase of highly annoyed people at an existing 

ambient noise level of 70 dB. 

The upper curve delineating the onset of Severe Impact was developed in a similar manner, except that it 

was based on a total noise level corresponding to a higher degree of impact. The Severe Noise Impact 

curve is based on the following considerations:

• HUD in its environmental noise standards defines an Ldn of 65 as the onset of a normally 

unacceptable noise zone (ref. 7). Moreover, FAA considers that residential land uses are not 

compatible with noise environments where Ldn is greater than 65 dBA.

80

• The common use of a 5 dBA increase in Ldn or Leq as the minimum required for a change in 

community reaction.

• The research finding that the foregoing step represents a 6.5-percent increase in the number of 

people highly annoyed (see Figure A-5).

Consequently, the increase in noise level from an existing ambient level of 60 dBA to a cumulative level 

of 65 dBA caused by a project represents a change from an acceptable noise environment to the threshold 

 

80 U.S. DOT, FAA. Federal Aviation Regulations Part 150: Airport Noise Compatibility Planning, January 1981.
Appendix A: Background – Noise Concepts A-15

of an unacceptable noise environment. This is considered to be the level at which Severe Impact starts to 

occur. Moreover, the 6.5-percent increment represents the change in community reaction associated with 

Severe Impact. Thus the upper curve’s hinge point is placed at a project noise level of 63 dBA and 

existing ambient noise level of 60 dBA, the combination of which yields a cumulative level of 65 dBA. 

The remainder of the upper curve in Figure 3-1 was determined from the annoyance curve (Figure A-5) 

by fixing the increase in annoyance for all existing ambient noise levels at 6.5 percent.

Both curves incorporate a maximum limit for the high-speed rail project noise in noise-sensitive areas. 

Independent of existing noise levels, Impact for land use Categories 1 and 2 is considered to occur 

whenever the high-speed rail Ldn equals or exceeds 65 dBA and Severe Impact occurs whenever the highspeed rail Ldn equals or exceeds 75 dBA. These absolute limits are intended to restrict activity 

interference caused by the project alone.

Both curves also incorporate a maximum limit for cumulative noise increase at low existing noise levels 

(below approximately 45 dBA). This is a conservative measure that reflects the lack of social survey data 

on people's reaction to noise at such low ambient levels. Similar to the FHWA approach in assessing the 

relative impact of a highway project, the transit noise criteria include caps on noise increases of 10 and 

15 dBA for Impact and Severe Impact, respectively, relative to the existing noise level.

Finally, because of the types of land use included in Category 3, the criteria allow the project noise for 

Category 3 sites to be 5 dB greater than for Category 1 and Category 2 sites. This difference is reflected 

by the offset in the vertical scale on the right side of Figure 3-1. With the exception of active parks, 

which are clearly less sensitive to noise than Category 1 and 2 sites, Category 3 sites include primarily 

indoor activities and thus the criteria reflect the noise reduction provided by the building structure.

A.3.3 Equations for Noise Impact Criteria Curves

The noise impact criteria can be quantified through the use of mathematical equations that approximate 

the curves shown in Figure 3-1. These equations may be useful when performing the noise assessment 

methodology through the use of spreadsheets, computer programs, or other analysis tools. Otherwise, 

such mathematical detail is generally not necessary to properly implement the criteria, and direct use of 

Figure 3-1 is likely to be adequate and less time-consuming.

A total of four continuous curves are obtained from the criteria: two threshold curves (“Impact” and 

“Severe Impact”) for Category 1 and 2; and two for Category 3. Note that for each level of impact, the 

overall curves for Categories 1 and 2 are offset by 5 dBA from Category 3. Although each curve is 

graphically continuous, it is defined by a set of three discrete equations that represent three “regimes” of 

existing noise exposure. These equations are approximately continuous at the transition points between 

regimes.

The first equation in each set is a linear relationship, representing the portion of the curve in which the 

existing noise exposure is low and the allowable increase is capped at 10 and 15 dBA for Impact and 

Severe Impact, respectively. The second equation in each set represents the impact threshold over the 

range of existing noise exposure for which a fixed percentage of increase in annoyance is allowed, as 

described in the previous section. This curve, a third-order polynomial approximation derived from the 

Schultz curve, covers the range of noise exposure encountered in most populated areas and is used in 

determining noise impact for most transit projects. Finally, the third equation in each of the four sets 
Appendix A: Background – Noise Concepts A-16

represents the absolute limit of project noise imposed by the criteria, for areas with high existing noise 

exposure. For land-use Categories 1 and 2, this limit is 65 dBA for Impact and 75 dBA for Severe 

Impact. For land-use Category 3, the limit is 70 dBA for Impact and 80 dBA for Severe Impact.

The four sets of equations corresponding to the curves are given below. Each curve represents a threshold 

of noise impact, with impact indicated for points on or above the curve.

Category 3

80 77

101.725 1.992 3.02 10 1.043 10 44 77

22.322 0.940 44

Category 1and 2

75 77

96.725 1.992 3.02 10 1.043 10 44 77

17.322 0.940 44

Category 3

70 71

76.662 1.164 0.018 4.088 10 42 71

16.450 0.953 42

Category 1and 2

65 71

71.662 1.164 0.018 4.088 10 42 71

11.450 0.953 42

2 2 4 3

2 2 4 3

2 5 3

2 5 3





















>

− + × − × ≤ ≤

+ <

=





















>

− + × − × ≤ ≤

+ <

=





















>

− + − × ≤ ≤

+ <

=





















>

− + − × ≤ ≤

+ <

=

− −

− −

−

−

E

E E E E

E E

P

E

E E E E

E E

P

E

E E E E

E E

P

E

E E E E

E E

P

L

L L L L

L L

L

L

L L L L

L L

L

L

L L L L

L L

L

L

L L L L

L L

L

Threshold of Severe Impact :

Threshold of Impact :

where:

LE is the existing noise exposure in terms of Ldn or Leq(h), and

LP is the project noise exposure which determines impact, also in terms of Ldn or Leq(h).

A.4 STARTLE EFFECTS FROM RAPID ONSET RATES

Researchers report that sounds of approaching vehicles with rapidly rising sound signatures carry a sense 

of convergence and cause greater annoyance than receding sounds.81

 

81 G. Rosinger, D. W. Nixon, and H. E. vonGierke. Quantification of the noisiness of ‘approaching’ and ‘receding’ 

sounds. Journal of the Acoustical Society of America, 48, 843–853, October 1970.
Appendix A: Background – Noise Concepts A-17

A.4.1 High-Speed Rail Noise Signatures

The presence of a high-speed rail system in close proximity to homes may result in a new noise unlike 

other existing sources of community noise. The sound signature at a position close to a high-speed train 

passby is characterized by sudden onset of high noise levels for a short duration. A typical example is 

shown in Figure A-6, where the sound rises rapidly at 15 dB/s and falls again within approximately 5 s. 

Shorter trains, such as the two-car test train of the German TransRapid TR07, can have even faster onset 

rates and shorter durations.

The onset rate is related to the rate of approach of a moving vehicle. More correctly, it is related to the 

rate at which the vector distance between the sound source and the receiver diminishes. Both speed and 

distance figure into the process. Measured onset rates from two high-speed rail systems are plotted in 

Figure 2-5.

Figure A-6 Time History of A-weighted Sound Level of Maglev at 25 m

A.4.2 Research on Startle Effects

When the onset of sound is very sudden, people tend to be startled, or surprised, especially when they are 

not expecting it. Researchers have proposed various adjustments to account for the increased annoyance 
Appendix A: Background – Noise Concepts A-18

of fast-rising sound events. One such study into the added annoyance from rapid onset rates has been 

conducted by the U.S. Air Force in connection with low-altitude military test flights.82 On the basis of 

psychoacoustic tests conducted in a real home environment with hired test subjects, a recommended 

adjustment to SEL was developed based on the onset rate. This adjustment is 0 dB up to an onset rate of 

15 dB/s, extending to an addition of 11 dB at an onset rate of 150 dB/s, with the relationship:

Adjustment to SEL = 11 log (onset rate) – 12.9, in decibels

where:

B/s < onset rate < 150 dB/s.

A.4.3 Startle Effects Applied to High-Speed Rail Impact Assessment

Based on results from the U.S. Air Force study, an adjustment for noise from high-speed maglev 

operations was suggested in a report prepared for the FRA-sponsored National Maglev Initiative (NMI).83 

The recommended adjustment was to add 5 dB to the SEL whenever the onset rate from a maglev passby 

exceeded 15 dB/s. Because data is available to show onset rates as a function of speed divided by 

distance, it was possible to develop a curve defining the relationship between speed and distance within 

which the onset rate exceeds 15 dB/s for a maglev train. The proposed onset rate adjustment was 

recommended for assessment of noise impact from maglev trains. 

Applying the same approach, but using the recommended US Air Force onset rate adjustments starting 

with 0 dB at 15 dB/sec, results in the relationships shown in Figure A-7. The Air Force adjustments of 

2–5 dB are plotted along with the NMI proposed adjustment of 5 dB. The Air Force adjustments result in 

the potential for startle to be confined to a much narrower region than was obtained using the NMI 

method.

 

82 E. Stusnick and K. Bradley. The Effect of Onset Rate on Aircraft Noise Annoyance, USAF Report No. AL/OETR-1993-0170, October 1992. 83 C. E. Hanson, P. Abbot, and I. Dyer. Noise from High Speed Maglev Systems, U.S. Department of Transportation, 

FRA, Report No. DOT/FRA/NMI - 92-18, January 1993.
Appendix A: Background – Noise Concepts A-19

Figure A-7 Zones of Potential Startle Effect

There are a number of unresolved issues regarding application of the Air Force research to determine the 

startle effects of high speed rail, such as the scheduled nature, lower sound levels and lower onset rates of 

train passbys compared to military aircraft flights. Thus, without better definition of the application of 

results of noise from aircraft overflights to noise from high-speed rail passbys, it is appropriate to 

consider startle effects as “additional information” included in the impact assessment, rather than to 

include a penalty in the calculation of noise exposure itself. What remains to be determined is an onset 

rate that could be considered significant enough to cause startle on a regular basis. Without further 

direction from research, it is recommended that sensitive receptors that are within the distances to the near 

track-defined by the Air Force 3 dB adjustment be identified as locations where startle may occur. This 

distance versus speed relationship is given in Figure 4-2.

A.5 EFFECTS ON LIVESTOCK AND WILDLIFE

A.5.1 Summary

A wide range of studies have been conducted concerning noise effects on animals. For humans, 

annoyance is considered to be the primary environmental noise effect; thresholds for annoyance in terms 

of sound exposure have been determined by surveys as described in Section A.3. However, for animals, 

the effects are not easily determined. Usually the studies require introduction of a specific noise event 

like an aircraft overflight and a subsequent observation of animal response. Observations of response to 

noise range from no reaction or mild responses such as slight changes in body position to extreme 

responses such as panic and attempts to escape. Long-term effects that might change behavior tend to be 

affected by factors other than short-term noise exposure, such as weather, predation, disease, and other 

disturbances to animal populations. Conclusions from research conducted to date provide only 

preliminary indications of the appropriate descriptor, rough estimates of threshold levels for observed 

animal disturbance, and habituation characteristics of only a few species. Long-term effects continue to 
Appendix A: Background – Noise Concepts A-20

be a matter of speculation. Moreover, most of the noise events used in prior studies are related to aircraft 

overflights. Consequently, any criteria adopted for effects on animals by high-speed rail noise must be 

considered interim until further specific research results are known. Following are discussions of 

descriptors and levels from the literature.

84,85,86,87

A.5.2 Noise Descriptor

A noise descriptor for noise effects on wildlife has not been universally adopted, but recent research 

indicates the SEL is the most useful predictor of responses. Characteristic of the bulk of research to date 

has been lack of systematic documentation of the source noise event. Many studies report “sound levels” 

without specifying the frequency spectrum or duration. A notable exception is a study sponsored by U.S. 

Air Force that identifies SEL as the best descriptor for response of domestic turkey poults to low-altitude 

aircraft overflights (ref. 21). Another report questions whether an A-weighted sound level used in the 

SEL for aircraft overflights is appropriate for animals since their hearing differs from humans (ref. 20). 

However, because no weighting has been established for representing the hearing characteristics of wild 

animals, the A-weighted sound level continues to be used.

A.5.3 Thresholds for Disturbance

Most studies have focused on identifying a noise level associated with disturbance effects, even if the 

type of noise event varied considerably from study to study. In the well-documented study that 

recommended SEL as the preferred descriptor, a threshold of response for disturbance (“100 percent rate 

of crowding”) of domestic turkeys was identified as SEL = 100 dB (ref. 21). Even if the descriptors are 

not the same, many studies report levels in the vicinity of 100 dB as associated with an observable effect, 

as shown in Table A-1. The information in this table is taken from an extensive survey on aircraft noise 

effects.88 Until more definitive information on thresholds can be developed, an interim criterion of SEL = 

100 dB will be used for disturbance by high-speed rail operations.

 

84 K. M. Manci, D. N. Gladwin, R. Villella, and M. G. Cavendish. “Effects of Aircraft Noise and Sonic Booms on 

Domestic Animals and Wildlife: A Literature Synthesis,” U.S. Fish and Wildlife Service National Ecology Research 

Center, Ft. Collins, CO., Report NERC-88/29, 1988.

85 P. Dufour. Effects of Noise on Wildlife and Other Animals: Review of Research Since 1971, U.S. EPA, Report No. 

550/9-80100, July 1980.

86 A. M. McKechnie and D. N. Gladwin. Aircraft Overflight Effects on Wildlife Resources, U.S. National Park 

Service, NPOA Report No. 93-8, November 1993.

87 F. Bradley, C. Book, and A. E. Bowles. Effects of Low-Altitude Aircraft Overflights on Domestic Turkey Poults, 

Report No. HSD-TR-90-034, U.S. Air Force Systems Command, Noise and Sonic Boom Impact Technology 

Program, June 1990.

88 K. M. Manci, D. N. Gladwin, R. Villella, and M. G. Cavendish. Effects of Aircraft Noise and Sonic Booms on 

Domestic Animals and Wildlife: A Literature Synthesis, U.S. Fish and Wildlife Service National Ecology Research 

Center, Ft. Collins, CO., Report No. NERC-88/29, 1988.
Appendix A: Background – Noise Concepts A-21

Table A-1 Summary of Noise Levels Associated with Effects on Animals and Birds

Animal Category Species

Noise Level and Type (if 

known) Associated with 

Effect

Effect

Domestic Mammals Dairy Cow 105 dB Reduction in milk production

97 dB Changes in blood composition

110 dB, 1 kHz Changes in blood composition

Swine 108-120 dB Hormonal changes

93 dB Hormonal changes

120-135 dB Increased heart rate

Sheep 100 dB “white noise” Increased heart rate, respiration

90 dB” white noise” Decreased thyroid activity

100 dB Increase in number of lambs 

per ewe

Wild Mammals Reindeer Sonic booms Startle

Caribou Aircraft Startle, panic running

Pronghorn antelope 77 dBA, helicopter Running

Domestic Birds Chicken 100 dB Blood composition

115 dB Interrupt brooding

Wild Birds Quail 80 dB Accelerated hatching

Canary 95–100 dB Hearing loss

Seabirds (general) Sonic boom Startle, flush from nest

Tern Sonic boom, frequent Reduced reproduction

California condor Blasting, drilling, etc. Flush from nest; abandon area

Raptors Sonic booms Alarm

A.5.4 Habituation

There is evidence that some animals demonstrate reduced response to noise after prior exposure but that a 

few species never become accustomed to, or habituate, to high noise levels. Researchers found that for 

turkeys, previous exposure to sound levels below the 100 dB threshold was sufficient to eliminate panic 

responses to higher level sounds (ref. 21). In contrast, some animals and birds, such as the grizzly bear, 

Dall sheep, and least tern, have not been observed to habituate (ref. 20). Because habituation is found to 

be species-dependent, a general criterion cannot be developed at this time.

Appendix B: Determining Existing Noise B-1

APPENDIX B DETERMINING EXISTING NOISE

This appendix provides additional detail for determining existing noise by (1) full measurement, (2) 

computation from partial measurements, and (3) tabular look-up. The words “existing noise” and 

“ambient noise” are often used interchangeably.

The full set of options for determining existing noise at receivers of interest is as follows:

• OPTION 1: For nonresidential land uses, measure a full hour’s Leq at the receiver of 

interest, during a typical hour of use on two nonsuccessive days. The hour chosen should 

be the one in which maximum project activity will occur. The Leq will be accurately 

represented.

• The three options for residential land uses are –

1. OPTION 2: Measure a full day’s Ldn. The Ldn will be accurately represented.

2. OPTION 3: Measure the hourly Leq for three typical hours: peak traffic, midday and 

late night. Then compute the Ldn from these three hourly Leqs. The computed Ldn

will be slightly underestimated. 

3. OPTION 4: Measure the hourly Leq for 1 h of the day only, preferably during 

midday. Then compute the Ldn from this hourly Leq. The computed Ldn will be 

moderately underestimated.

• OPTION 5: For all land uses, compute either the Leq or the Ldn from a measured value at 

a nearby receiver—one where the ambient noise is dominated by the same noise source. 

The computed value will be represented with only moderate precision.

• OPTION 6: For all land uses, estimate either the Leq or the Ldn from a table of typical 

values, depending upon distance from major roadways or upon population density. The 

resulting values will be underestimated significantly.
Appendix B: Determining Existing Noise B-2

Option 1: For nonresidential land uses, measure the hourly Leq for the hour of interest

Full 1-hour measurements are the most precise way to determine existing noise for nonresidential 

receivers of interest. Such full-duration measurements are preferred over all other options. The following 

procedures apply to full-duration measurements:

• Measure a full hour’s Leq at the receiver of interest on at least two nonsuccessive days 

during a typical hour of use. This would generally be between noon Monday and noon 

Friday, but weekend days may be appropriate for places of worship. On both days, the 

measured hour must be the same as that for which project noise is computed: the loudest 

facility hour that overlaps hours of noise-sensitive activity at the receiver.

• At all sites, locate the measurement microphone as shown in Figure 5-2 (Chapter 5), 

depending on the relative orientation of project and ambient sources. A microphone 

location that is shielded somewhat from the ambient source is preferred. At such 

locations, ambient noise will be measured at the quietest location on the property for 

purposes of noise impact assessment so that noise impact will be assessed most critically.

• Undertake all measurements in accordance with good engineering practice (see 

References 1 and 2 of Chapter 5).

Option 2: For residential land uses, measure the Ldn for a full 24 h

Full 24-hour measurements are the most precise way to determine ambient noise for residential receivers 

of interest. Such full-duration measurements are preferred over all other options. The following 

procedures apply to full-duration measurements:

• Measure a full 24-hour’s Ldn at the receiver of interest, for a single weekday (generally 

between noon Monday and noon Friday).

• At all sites, locate the measurement microphone as shown in Figure 5-2, depending on 

the relative orientation of project and ambient sources. A microphone location that is 

shielded somewhat from the ambient source is preferred. At such locations, ambient 

noise will be measured at the quietest location on the property for purposes of noise 

impact assessment so that noise impact will be assessed most critically.

• Undertake all measurements in accordance with good engineering practice (see 

References 1 and 2 of Chapter 5).

Option 3: For residential land uses, measure the hourly Leq for 3 h and then compute Ldn

An alternative way to determine Ldn, less precise than its full-duration measurement, is to measure hourly 

Leqs for three typical hours of the day and then to compute the Ldn from these three hourly Leqs. The 

following procedures apply to this partial-duration measurement option for Ldn:

• Measure the 1-hour Leq during each of the following time periods: once during peak-hour 

roadway traffic, once midday between the morning and afternoon roadway-traffic peak 

hours, and once between midnight and 5 a.m. For locations with no significant traffic 

patterns, it will be sufficient to measure a morning hour (7–9 a.m.), a midday hour 

(10 a.m.–4 pm), and a late-night hour (10 p.m.–7 a.m.).
Appendix B: Determining Existing Noise B-3

• Compute Ldn with the following equation:

10log (3) 10 (12) 10 (9) 10 13.8 10

( ) 8

10

( ) 2

10

( ) 2

−















 ≈ ⋅ + ⋅ + ⋅

L peakhour − L midday − L latenight +

dn

eq eq eq

L

This value of Ldn will be slightly underestimated, due to the subtraction of 2 dB from each of the 

measured levels before their combination. As explained previously, this underestimate is intended to 

compensate for the reduced precision of the computed Ldn here, compared to its full-duration 

measurement.

• At all sites, locate the measurement microphone as shown in Figure 5-2, depending on 

the relative orientation of project and ambient sources. A microphone location that is 

shielded somewhat from the ambient source is preferred. At such locations, ambient 

noise will be measured at the quietest location on the property for purposes of noise 

impact assessment so that noise impact will be assessed most critically.

• Undertake all measurements in accordance with good engineering practice (see 

References 1 and 2 of Chapter 5).

Option 4: For residential land uses, measure the hourly Leq for 1 h and then compute Ldn

The next level down in precision is to determine Ldn by measuring the hourly Leq for 1 h of the day and 

then to compute Ldn from this hourly Leq. This method is useful when there are many sites in a General 

Assessment or when checking whether a particular receiver of interest represents a cluster in a Detailed 

Analysis. The following procedures apply to this partial-duration measurement option for Ldn:

• Measure the 1-hour Leq during any hour of the day. The loudest hour during the daytime 

period is preferable. If this hour is not selected, then other hours may be used with less 

precision.

• Convert the measured hourly Leq to Ldn with the applicable equation:

For measurements between 10 p.m.and 7 a.m.: 8

For measurements between 7 p.m.and10 p.m.: 3

For measurements between 7 a.m.and 7 p.m.:Ldn 2

≈ +

≈ +

≈ −

dn eq

dn eq

eq

L L

L L

L

The resulting value of Ldn will be moderately underestimated, as a result of the use of the 

adjustment constants in these equations. As explained previously, this underestimate is 

intended to compensate for the reduced precision of the computed Ldn here, compared 

with the more precise methods of determining Ldn.

• At all sites, locate the measurement microphone as shown in Figure 5-2, depending on 

the relative orientation of project and existing sources. A microphone location that is 

shielded somewhat from the ambient source is preferred. At such locations, ambient 

noise will be measured at the quietest location on the property for purposes of noise 

impact assessment so that noise impact will be assessed most critically.

• Undertake all measurements in accordance with good engineering practice (see 

References 1 and 2 of Chapter 5).
Appendix B: Determining Existing Noise B-4

Option 5: For all land uses, compute either Leq or Ldn from a nearby measured value

A computation method comparable in precision to Option 4 is to determine the ambient noise, either 

Leq(h) or Ldn, from a measured value at a nearby receiver—one where the ambient noise is dominated by 

the same noise source. This method is used to characterize noise in several neighborhoods by using a 

single representative receiver. Care must be taken to ensure that the measurement site has a similar noise 

environment to all areas represented. If measurements made by others are available, and the sites are 

equivalent, they can be used to reduce the amount of project noise monitoring. The following procedures 

apply to this computation of ambient noise at the receiver of interest: 

• Choose another receiver of interest, called the “comparable receiver,” at which:

 The same source of ambient noise dominates.

 The ambient LCompRec was measured with either OPTION 1 or OPTION 2 above.

 The ambient measurement at the comparable receiver was made in direct view of 

the major source of ambient noise, unshielded from it by noise barriers, terrain, 

rows of buildings, or dense tree zones.

• From a plan or aerial photograph, determine: (1) the distance DCompRec from the 

comparable receiver to the near edge of the ambient source, and (2) the distance DThisRec

from this receiver of interest to the near edge of the ambient source.

• Also determine N, the number of rows of buildings that intervene between the receiver of 

interest and the ambient source.

• Compute the ambient noise at this receiver of interest with the applicable equation:

If roadway sources dominate:

N

D

D

L L

Comp c

This c

This c Comp c 15log 3

Re

Re

Re Re −















 ≈ −

If other sources dominate:

N

D

D

L L

Comp c

This c

This c Comp c 25log 3

Re

Re

Re Re −















 ≈ −

The resulting value of LThisRec will be moderately underestimated. As explained previously, this 

underestimate is intended to compensate for the reduced precision of the computed Ldn, compared with

the more precise methods of determining ambient noise levels.

Option 6: For all land uses, estimate either Leq(h) or Ldn from a table of typical values 

The least precise way to determine the ambient noise is to estimate it from a table. A tabular look-up can 

be used to establish baseline conditions for a General Noise Assessment if a noise measurement cannot be 

made. It should not be used for a Detailed Noise Analysis. For this estimate of ambient noise:
Appendix B: Determining Existing Noise B-5

• Read the ambient noise estimate from the relevant portion of Table 4-5. These tabulated 

estimates depend upon distance from major roadways, rail lines or upon population 

densities. In general, these tabulated values are significant underestimates. As explained 

previously, underestimates are intended to compensate for the reduced precision of the 

estimated ambients, compared to the options that incorporate some degree of 

measurements. 

Appendix C: Converting Between Lmax or Passby Level and SEL C-1

APPENDIX C CONVERTING BETWEEN Lmax OR PASSBY LEVEL AND SEL

This appendix provides procedures for:

1. computing Lmax for a single high-speed train passby using the source reference levels in SEL and 

methods given in Chapters 4 and 5,

2. estimating source reference levels in SEL for a General Assessment from either measured or 

specified values of the single-passby Lmax, and

3. estimating SEL from the Passby Level (LpAeq,Tp).

The first SEL to Lmax conversion may be useful in determining whether a proposed project or type of 

equipment will meet the noise limit defined in the project specifications, almost always given in terms of 

Lmax. The second procedure, converting from Lmax to SEL, involves computing reference SELs specific to 

a certain trainset or project noise specification, which may be different from the generalized levels given 

in this manual. A General Noise Assessment can then be performed based on measurements, equipment 

specifications, or project noise limits. 

C.1 COMPUTING Lmax FOR A SINGLE TRAIN PASSBY

The Lmax conversion procedure from the reference SELs given in Chapter 4 (Initial Noise Evaluation) or 

Chapter 5 (Detailed Noise Analysis) to a single Lmax value is summarized as follows:

Step 1. Select Source Reference SEL(s). Classify the project into one of the vehicle categories 

defined in Table 4-3 or Table 5-2. For General Assessment, the speed regime (I, II, or III) also 

must be selected from Table 4-3, which identifies the single dominant noise source for the given 

speed and the corresponding reference SEL. For Detailed Analysis, separate subsource SELs are 

listed in Table 5-2.
Appendix C: Converting Between Lmax or Passby Level and SEL C-2

Step 2. Adjust for Project Operating Conditions. Adjust the reference SEL (General 

Assessment) or each applicable subsource reference SEL (Detailed Analysis) at 50 ft for 

operating conditions for the project or for a particular corridor segment, using the methods in 

Section 4.2.1 or 5.2.2. 

Step 3. Adjust for Propagation with Distance. Propagate each adjusted SEL out to the 

specified distance (if other than the reference distance of 50 ft), accounting for attenuation with 

distance, shielding, and ground effect, if necessary, using the methods in Section 4.2.2 or 5.2.3.

Step 4. Convert SEL to Lmax. Compute Lmax using the equations in Table C-1. For the Detailed 

Analysis method, choose the largest of the subsource Lmax values as the overall Lmax for the train 

passby.

Table C-1 Computation of Lmax for a High-Speed Train Passby using General Assessment or 

Detailed Analysis Method

Applicable Parameters SEL–to–Lmax Equation General Assessment Detailed Analysis

Speed Regime I Propulsion 

Subsource 

L SEL ( ) len

S max = − log log . 



 

 10  + 10 2α − 3 3

use len = total length 

of power units, in feet

use len = length of 

one power unit, in 

feet

Speed Regime II

Wheel-Rail or 

Guideway/Structural 

Subsource L SEL [ ( )] len

S max = − log log sin . 



 

 10  + 10 2α + 2α − 3 3

use len = total length 

of train, in feet

use len = length of 

coaches only, in feet

Speed Regime III Aerodynamic 

Subsources 

L SEL ( ) len

S max = − log log . 



 

 use len = total length 10  + 10 2α − 3 3

of leading power car, 

in feet

use len = subsource 

length as defined in 

Table 5-2, in feet

Variables are defined as follows:

S

len

d

len

d

=

= 



 





=

=

−

train speed, in mph,

, in radian s,

length as defined above, and

receiver d istance from track centerline, in feet.

α tan 1

2

C.2 COMPUTING REFERENCE SELs FROM LMAX FOR GENERAL ASSESSMENT 

METHOD

If Lmax for a specific trainset is available from vehicle noise measurements, manufacturer specifications, 

or a specific project limit, it is possible to estimate the equivalent reference SELs to use in the General 

Noise Assessment (Chapter 4) procedure presented in this manual. The Detailed Noise Analysis 

(Chapter 5) method, however, involves the use of detailed component, or subsource, SELs that cannot be 
Appendix C: Converting Between Lmax or Passby Level and SEL C-3

determined accurately from a single passby Lmax value. Determination of subsource SELs requires more 

complex measurement techniques, such as a microphone array or controlled single microphone 

measurements with a low sound barrier to shield wheel-rail noise, to isolate certain source components. 

If a specific Lmax value is available for the proposed trainset and Detailed Noise Analysis procedures are 

to be followed, it is recommended that the subsource SELs provided in Chapter 5 be used to first calculate 

Lmax as described in Appendix C (Section C.1). This calculated Lmax can then be compared with the 

specified or measured Lmax and if necessary, one or more of the subsource SELs can be adjusted to 

account for the discrepancy. This may be an iterative process until the computed Lmax and the specified 

Lmax are the same. This technique should be exercised with caution, however, because judgment and 

understanding of the subsource mechanisms are required to determine which of the subsource SELs 

should be adjusted.

The procedure for converting Lmax to a reference SEL for use in the General Noise Assessment method is 

summarized as follows:

Step 1. Identify Vehicle Category. Classify the project into one of the vehicle type categories listed in 

Table 4-3.

Step 2. Identify Major Sound Source and Parameters. Identify the appropriate speed regime I, II, or 

III from Table 4-3. The speed regime establishes the dominant sound source for the given speed 

(propulsion, wheel-rail or aerodynamic). For the vehicle category, obtain noise model parameters such as 

speed coefficient, reference length, and reference speed corresponding to the speed regime from 

Table 4-3.

Step 3. Convert Lmax to SEL. Compute SEL using the equations in Table C-2. This computation yields 

the SEL for the operating conditions and distance corresponding to the Lmax measurement or specification.

Step 4. Normalize to Reference Conditions. Adjust the resulting SEL to the reference distance and 

operating conditions of Table 4-3, using the equation in Table C-2. This adjustment yields a new 

reference SEL appropriate for comparison with the values listed in Table 4-3.
Appendix C: Converting Between Lmax or Passby Level and SEL C-4

Table C-2 Computation of SEL for a High-Speed Train Passby from Lmax for General Assessment 

To convert from Lmax to SEL:

Speed Regime I

SEL L ( ) len

S = + 



 

 max 10 log  − 10 log 2α + 3.3

where len = total length of power unit(s), in feet

Speed Regime II

SEL L [ ( )] len

S = + 



 

 max 10 log  − 10 log 2α + sin 2α + 3.3

where len = total length of train, in feet

Speed Regime III

SEL L ( ) len

S = + 



 

 max 10 log  − 10 log 2α + 3.3

where len = total length of leading power car, in feet

To normalize back to Reference Conditions of Table 4-2:

SEL SEL K

S

S

len

len d ref

ref ref = + 



 



 + 



 



 − 



 

 log 10 log 15 log  50

SEL SEL

K

S

S

len

d

len

d

ref

ref

ref

=

=

=

=

=

=

= 



 



 −

 adjusted to referen ce parameters of Tab le 4 - 2 at reference distance,

Speed coefficient (from Table 4 - 2),

Reference speed, mph (from Table 4 - 2),

Train speed, mph,

Reference length, feet (fro m Table 4 - 2),

receiver distance from track centerline, feet, and

α tan , radians. 1

2

C.3 ESTIMATING SEL FROM PASSBY LEVEL

The SEL for a single vehicle passby can be estimated from the Passby Level as follows:

SEL ≈ LpAeq,Tp + 10 log10(t2 – t1) + 1

where:

LpAeq,Tp is the Passby Level (dBA)

t1 is the time at the leading edge of the passby (seconds)
Appendix C: Converting Between Lmax or Passby Level and SEL C-5

t2 is the time at the trailing edge of the passby (seconds)

The difference between SEL and time-adjusted Passby level depends on factors such as the distance of the 

measurement position to the alignment. At closer distances, the difference between SEL and timeadjusted Passby level is less than at farther measurement distances. The 1 dB difference shown in the 

equation above is based on typical measured differences at a distance of 100 ft.

Appendix D: High-Speed Train Noise and Vibration Measurements D-1

APPENDIX D HIGH-SPEED TRAIN NOISE AND VIBRATION MEASUREMENTS

D.1 HIGH-SPEED TRAIN NOISE MEASUREMENTS

The data used to develop the high-speed ground transportation noise models are taken from recent 

measurements of revenue service high-speed train operations in the United States, Europe, and 

Asia,89,90,91,92,93,94 and databases of noise measurements from an FRA-sponsored European high-speed rail 

measurement program, U.S. Northeast Corridor (NEC) Electrification Project,

95 the NMI Project,96 and 

 

89 P. Fodiman and P. Gautier. Noise Emission Limits for Railway Interoperability in Europe: Application to HighSpeed and Conventional Rail, Forum Acusticum, 2005.

90 R. Carmen, C. Reyes, and Wilson Ihrig and Associates. HST Noise Level Comparison with FRA Guidance 

Manual Data, Technical Memorandum, February 18, 2010.

91 P. Fodiman and M. Staiger. Improvement of the noise technical specifications for interoperability: The input of 

the NOEMIE project. Journal of Sound and Vibration, 293(3-5), Proceedings of the Eighth International Workshop 

on Railway Noise, 13 June 2006, Pages 475–484.

92 F. Poisson, P. E Gautier, and F. Letourneaux. Noise Sources for High Speed Trains: A Review of Results in the 

TGV Case, Proceedings of the 9th International Workshop on Railway Noise, Munich, Germany, 4-8 September 

2007.

93 C. Mellet, F. Letourneaux, F. Poisson, and C. Talotte. High speed train noise emission: Latest investigation of the 

aerodynamic/rolling noise contribution. Journal of Sound and Vibration, 293(3-5), Proceedings of the Eighth 

International Workshop on Railway Noise, June 13, 2006, Pages 535-546.

94 Siemens, Acoustic, exterior pass-by noise, Velaro E, RENFE S103, Mobility Division, January 25, 2010.

95 U.S. Department of Transportation, Federal Railroad Administration, “Northeast Corridor Improvement Project 

Electrification -New Haven, CT to Boston, MA: Final Environmental Impact Statement/Report, Volume II: 

Technical Studies,” Chapter 4. Noise and Vibration, DOT/FRA/RDV-94/01-B, DOT-VNTSC-FRA-94-6, Final 

Report, October 1994.
Appendix D: High-Speed Train Noise and Vibration Measurements D-2

various other sources on ICE (Germany), TGV, X2000, RTL-2 (gas-turbine powered), and TR07 

(German maglev trainsets). These data are also supplemented by measurements of the Acela,

97 Jet 

Train,

98 and an updated version of the German maglev train TR08.99

Noise emission data have been collected for electrical locomotive hauled trains such as the Amtrak Acela, 

French TGV (Thayls, Atlantique, Reseau, and Duplex), Swedish X2000, Eurostar and Korean KTX-II. 

EMU trains included in the database include the German IC T, ICE 3, AVE S103, Pendolino ETR450 and 

Korean KTX-III. Noise emission data have also been collected on the Shinkansen 800T and Fastech360Z 

EMU trains that are examples of trainsets with several noise source mitigation measures. Gas-turbine 

powered locomotive-hauled trains such as the Bombardier Jet-Train and the Rohr RTL-II are also 

included in the database.

As an overview of the available data, measured noise levels from the various high-speed train categories, 

are plotted over a range of speeds in Figures D-1 through D-4. These figures show the noise level plotted 

in terms of SEL, with the data normalized to a reference distance of 100 feet and a train length of 740 ft

for steel-wheeled technologies. Figures D-1 and D-2 also include the European noise limits for high 

speed trains from the Technical Specifications for Interoperability (TSI) adjusted from Passby Level to 

SEL.100 For the Maglev, the data are referenced to 50 feet and a train length of 295 ft. These figures also 

show the General and Detailed model results based on the same train speed, reference distance and 

reference train length parameters.

It should be noted that the Shinkansen 700T and Fastech360Z are not included in Figure D-2 for EMU 

trains, nor is the EMU model based on these specific trains. This is because these two trains are examples 

of EMUs that have several noise source mitigation measures included and their noise emissions are 

substantially lower than most other EMU trains without such mitigation. Further information on the 

overall effectiveness of these mitigation measures is presented in Section D.2

The results in Figures D-1 through D-4 indicate that there are relatively consistent noise emissions within 

each train technology category and that the models are relatively accurate at projecting noise levels from 

these trains. Furthermore, the measurements and models show that the noise emissions of these trains are 

typically within the TSI noise limits. The models tend to result in levels that are near the upper limit of 

measurement results within each category to provide slightly conservative projections. 

 

96 U.S. DOT, FRA. Noise from High Speed Maglev Systems, DOT/FRA/NMI-92/18, January 1993.

97 U.S. DOT, FRA. Noise Characteristics of Northeast Corridor High-Speed Trainsets, DTFR53-94-A-00060, 

September 2000.

98 U.S. DOT, FRA. High-Speed Non-Electric Locomotive Noise Measurements, HMMH Report 298240, DTFR53-

98-D-00004, October 2001.

99 U.S. DOT, John A. Volpe National Transportation Systems Center. Noise Characteristics of the Transrapid TR08 

Maglev System, DOT-VNTSC-FRA-02-13, July 2002.

100 European Commission. Decision 2008/232/EC concerning a technical specification for interoperability relating to 

the “rolling stock” sub-system of the trans-European high-speed rail system, 21 February 2008.
Appendix D: High-Speed Train Noise and Vibration Measurements D-3

Maglev noise levels are consistently low relative to the steel-wheeled trains, but it is clear that as speeds 

reach the upper limits there is less difference between the steel-wheeled and maglev technologies in the 

level of noise generated as the aerodynamic component becomes significant.

Figure D-1 Measured and Modeled SEL’s vs. Speed from Electric Locomotive-Hauled Trains
Appendix D: High-Speed Train Noise and Vibration Measurements D-4

Figure D-2 Measured and Modeled SELs vs. Speed from EMU Trains

Figure D-3 Measured and Modeled SELs vs. Speed from Fossil Fuel Locomotive-Hauled Trains
Appendix D: High-Speed Train Noise and Vibration Measurements D-5

Figure D-4 Measured and Modeled SELs vs. Speed from Maglev Trains

D.2 EFFECTIVENESS OF NOISE SOURCE MITIGATION

Figure D-5 presents noise levels plotted in terms of SEL versus speed, with the data normalized to a 

reference distance of 100 ft and a train length of 740 ft, for EMU trains including the Shinkansen 700T 

and the Fastech 360Z (square data points); the EMU Detailed model results and the TSI noise limits are 

also shown in the figure. Although the use of wayside noise barriers is very common on the Japanese 

high-speed rail systems and most of the data from these systems have been collected with noise barriers, 

these data have been adjusted to conditions without noise barriers. These trains incorporate several noise 

source mitigation measures such as shrouds around the base of the pantograph; barriers on top of the train 

along the sides of the pantograph, reducing the number of pantographs to one per train with a second 

foldable pantograph; porous materials on the surfaces of the pantograph structure; bogie skirts/side covers 

over the wheelsets; an aerodynamic snowplow cover on the lead car; absorptive materials on the lower 

sides and under sides of the car; use of ballast mats; under tie pads and/or resilient rail fasteners to reduce 

rolling noise; a streamlined nose; elimination of gaps between the cars; door handles that are flush with 

the train body to reduce aerodynamic noise.101,102,103,104,105,106,107,108,109,110,111,112

 

101 A. Ido, T. Kurita, and M. Horiuchi. Countermeasures for Noise from the Lower Car Body with Sound Absorber, 

JR East Technical Review No. 8.
Appendix D: High-Speed Train Noise and Vibration Measurements D-6

Although data are limited, the wheel and rail roughnesses of the Shinkansen system appear to be 

consistent with those for the European systems.

 

102 M. Ikeda, T. Mitsumoji, T. Sueki, and T. Takaishi, “Aerodynamic Noise Reduction in Pantographs by Shapesmoothing of the Pantograph and Its Support and by Use of Porous Material in Surface Coverings,” QR of RTRI, 

Vol. 51, No. 4, Nov. 2010.

103 M. Ikeda, T. Morikawa, K. Manabe, and Railway Technical Research Institute. Development of Low 

Aerodynamic Noise Pantograph for High-Speed Train, Proceedings of Internoise 94, August, 1994.

104 M. Ikeda, et al. Aerodynamic Noise Reduction of a Pantograph by Shape-Smoothing of Panhead and Its Support 

by the Surface Covering with Porous Material, Proceedings of 10th International Workshop on Railway Noise, 

Nagahama, Japan, October 2010.

105 H. Kanda, H. Tsuda, K. Ichikawa, and S. Yoshida. Environmental Noise Reduction of Tokaido Shinkansen and 

Future Prospect, Noise and Vibration Mitigation for Rail Transportation Systems: Proceedings of the 9th 

International Workshop on Railway Noise, Notes on Numerical Fluid Mechanics and Multidisciplinary Design, Vol. 

99 (2008), pp. 1-8.

106 T. Kitagawa and D. J. Thompson. Comparison of wheel/rail noise radiation on Japanese railways using the 

TWINS model and microphone array measurements. Journal of Sound and Vibration, 293(3-5), Proceedings of the 

Eighth International Workshop on Railway Noise, 13 June 2006, Pages 496-509.

107 T. Kurita, T. Wakabayashi, H. Yamada, and M. Horiuchi. Reduction of Wayside Noise from Shinkansen HighSpeed Trains, Journal of Mechanical Systems for Transportation and Logistics, 4(1), 2011.

108 T. Kurita and F. Mizushima. “Environmental Measures along Shinkansen Lines with FASTECH360 High-Speed 

Test Trains,” JR East Technical Review, No. 16.

109 K. Murata, T. Sato, and K. Sasaki. “Countermeasures of Noise Reduction for Shinkansen Electric-Current 

Collecting System and Lower Parts of Cars,” JR East Technical Review, No. 1.

110 K. Nagakura. The methods of analyzing Shinkansen noise. Quarterly Report of Railway Technical Research 

Institute, 37(4), (1996), pp. 210-215.

111 K. Nagakura. Localization of aerodynamic noise sources of Shinkansen trains. Journal of Sound and Vibration, 

293(3-5), Proceedings of the Eighth International Workshop on Railway Noise, 13 June 2006, Pages 547-556.

112 T. Sueki, M. Ikeda, and T. Takaishi. Aerodynamic noise reduction using porous materials and their application to 

high-speed pantographs. QR of RTRI, 50(1), February, 2009.
Appendix D: High-Speed Train Noise and Vibration Measurements D-7

Figure D-5 Measured and Modeled SELs vs. Speed from EMU Trains Including Shinkansen 700T 

and Fastech 360Z

Figure D-6 presents the noise level plotted in terms of SEL versus speed for Shinkansen trains including 

the original 0 Series model in 1964 (which did not include these noise source mitigation measures), the 

Shinkansen 700T from 1990 (which includes many of these noise source mitigation measures) and the 

latest Fastech 360Z train which has been engineered to reduce noise substantially. It should be noted that 

due to the prevalence of wayside noise barriers on Japanese high-speed lines, most noise emission data 

are reported for trains with such barriers. Japanese research also often focuses on relative differences of 

noise emissions with and without noise source mitigation measures. Therefore, some of the data 

presented in Figure D-6 have been adjusted to conditions without a wayside barrier (similar to the 

reference noise parameters presented in Chapters 4 and 5) and interpreted based on relative differences of 

known values. This figure demonstrates that the introduction of several noise source mitigation measures 

can effectively reduce overall noise emissions by up to 10 dB. 
Appendix D: High-Speed Train Noise and Vibration Measurements D-8

Figure D-6 SELs vs. Speed from Shinkansen EMU Trains With and Without Noise Source 

Mitigation Measures

D.3 HIGH-SPEED TRAIN VIBRATION MEASUREMENTS

Vibration velocity measurement results for several different types of high-speed trains are shown in 

Figure D-3. Included in Figure D-3 are the results from: 1) the European measurements in May 1995; 2) 

tests with X2000 equipment on the Northeast Corridor; and 3) measurements on TGV trains in 1991. All 

of the data points have been normalized to 150 mph. The wide spread in the data is partly due to 

differences in the equipment and track conditions, and partly from the differences in geology. To clarify 

the trends, Figure D-4 shows best-fit curves for the same data.

Some observations derived from the measurements presented in Figures D-3 and D-4 are:

• The TGV and Eurostar trainsets measured along the Nord (North) line in France all had very 

similar vibration levels. The TGV data measured on the Atlantique line shows a distinctly 

different characteristic.

• The Pendolino trainsets measured in Italy have vibration levels similar to the TGV trainsets 

operating on the Nord line.

• The X2000 trainsets measured in Sweden show vibration levels much higher than those of the 

TGV or Pendolino trainsets. However, as discussed later, normalizing the data to a single set of 

soil conditions indicate that X2000 trainsets actually generate ground-borne vibration forces 
Appendix D: High-Speed Train Noise and Vibration Measurements D-9

similar to the other high-speed trains. Consequently, the higher levels appear to be primarily due 

to the propagation conditions of the ground at the test site in Sweden.

• The test with the X2000 trainset on the Northeast Corridor show relatively high vibration levels. 

Because propagation tests were not a part of the Northeast Corridor testing, however, it is 

unknown whether these higher vibration levels were due to geology, track condition, wheel 

condition, or other factors.

Figure D-7 Overall Vibration Velocity Level for Different High-Speed Trains
Appendix D: High-Speed Train Noise and Vibration Measurements D-10

Figure D-8 Best-Fit Curves of Vibration Velocity Level vs. Distance

A summary of the overall vibration velocity levels of the trainsets measured in Europe, calculated from 

the smoothed one-third octave band spectra, are shown in Figure D-5. The differences in the vibration 

levels measured with the different types of trainsets are shown clearly. The X2000 had significantly 

higher vibration at all distances, with the levels over 30 dB higher than the TGV trainsets at 100 m from 

the tracks.

Figures D-3, D-4, and D-5 indicate the overall levels of ground-borne vibration as a function of distance, 

but do not indicate the dominant frequency range in the ground-borne vibration generated by each 

trainset. Knowing the dominant frequency range helps determine whether the ground-borne vibration is 

perceived as vibration or audible noise by occupants of buildings near train tracks. The measured 

vibration velocity in terms of one-third octave band levels for the TGV, X2000, and Pendolino trainsets 

normalized to 150 mph are shown in Figure D-6. The X2000 measured at the test site in Sweden showed 

the highest levels of low-frequency vibration below 40 Hz, with the Pendolino data falling between the 

X2000 and the TGV in this range. In fact, the X2000 vibration levels were higher over the entire 

frequency spectrum, except at 50 and 63 Hz, where TGV vibration was highest.
Appendix D: High-Speed Train Noise and Vibration Measurements D-11

Figure D-9 Vibration Velocity vs. Distance Calculated from Smoothed One-Third Octave Bands
Appendix D: High-Speed Train Noise and Vibration Measurements D-12

Figure D-10 Comparison of One-Third Octave Band Spectra

As discussed above, much of the difference between the trainsets is likely to be due to geology variations 

rather than differences in suspension, axle load or wheel conditions of the trainsets. The line source 

transfer mobility spectra, which indicate the frequency-dependent response characteristics of the ground, 

for the three different measurement sites are shown in Figure D-7. It is clear that the transfer mobilities 

are very different between the three primary sites in France, Italy and Sweden. For example, at 100 Hz 

the transfer mobility measured at the site in Sweden is 8 dB higher than the site in France and 

approximately 30 dB higher than the site in Italy. All of the sites were in rural areas where relatively little 

is known about the specific geology at the test sites. The measurements indicated that these differences in 

transfer mobility are fairly consistent out to 100 m from the vibration source.
Appendix D: High-Speed Train Noise and Vibration Measurements D-13

Figure D-11 Line-Source Transfer Mobility at the Test Sites

The force density functions derived for X2000, Pendolino, TGV, and Eurostar trainsets, all normalized to

a speed of 150 mph, are shown in Figure D-8. The force densities are also very different, but the 

differences are not as large as the measured ground vibration levels. The TGV and Eurostar force 

densities are close enough to be considered the same. The X2000 and the Pendolino are surprisingly 

similar, considering the large difference in the vibration spectra.
Appendix D: High-Speed Train Noise and Vibration Measurements D-14

Figure D-12 Force Density Functions Derived from Measurements

The four force density functions can each be combined with the transfer mobility from a single site to 

approximate what the vibration levels would be if all of the trainsets were operating on the same track at 

the same location. The resulting overall vibration levels using the transfer mobility from the primary site 

(Site D) in France are shown in Figure D-9, and the same results using the transfer mobility from the 

primary site (Site 3B) in Sweden are shown in Figure D-10 .

Both figures show that using the same transfer mobility, in effect normalizing the ground vibration from 

the trainsets to one site, substantially reduces the differences in the overall vibration levels. Using the 

transfer mobility from Sweden, the TGV, Eurostar, and X2000 are all within approximately 2 dB, and the 

Pendolino is 3–4 dB lower. In this case, the range of ground-borne vibration from the different trainsets 

is limited to a narrow “band” between 75 and 80 VdB at 30 m from the track. Using the transfer mobility 

from France, the TGV and Eurostar are 2–3 dB lower than the Pendolino, and the X2000 is approximately

4 dB higher than the Pendolino. The levels range from 65 to 73 VdB at 30 m from the track centerline. 

The overall conclusion drawn is that all of the trainsets would generate significantly higher ground 

vibration levels at the Swedish test site than at the French site.
Appendix D: High-Speed Train Noise and Vibration Measurements D-15

Figure D-13 Projected Vibration Velocity, Transfer Mobility from Site in France
Appendix D: High-Speed Train Noise and Vibration Measurements D-16

Figure D-14 Projected Vibration Velocity, Transfer Mobility from Site in Sweden

Finally, to further illustrate the strong effects of the transfer mobility, the results of applying the X2000 

force density to the transfer mobility functions at each of the three primary sites are shown in 

Figure D-11, in terms of overall vibration level as a function of distance. This shows that close to the 

track centerline, the projected vibration levels are all relatively high. However, the levels with the 

transfer mobility from Site 3B in Sweden show considerably slower attenuation with distance than with 

the other two transfer mobilities because of geological factors.
Appendix D: High-Speed Train Noise and Vibration Measurements D-17

Figure D-15 Projected Vibration Velocity, X2000 Force Density

Appendix E: Source Reference Levels for Conventional Trains (Freight and Passenger) E-1

APPENDIX E SOURCE REFERENCE LEVELS FOR CONVENTIONAL TRAINS 

(FREIGHT AND PASSENGER)

Noise source reference levels for conventional freight and passenger trains in service throughout the 

United States are based on measurements of more than 315 trains during the environmental assessments 

associated with recent railroad mergers.113 The measurements were taken on a variety of road 

locomotives in freight service. The results were averaged, adjusted for speed and distance and used in the 

projection models for impact assessments by the Surface Transportation Board. Passenger train data were 

obtained from a variety of environmental assessments. 

The source reference levels are for freight and passenger locomotives, freight cars, passenger coaches, 

and horns. Locomotive, freight car, and passenger coach reference levels are expressed in a form that can 

be used directly in the computations based on Table 5-2. 

Passenger trains in regional and interstate service can be assumed to have similar characteristics, although 

it is recommended to consult the FTA guidance manual for a more detailed treatment of commuter rail 

operations.114 Horn reference levels are applicable to a separate computational model developed by FRA 

in connection with the study on the Use of Locomotive Horns at Highway-Rail Grade Crossings.115 The 

FRA also has available a spreadsheet for modeling freight and passenger diesel-electric locomotive 

hauled trains which was originally developed for the Chicago Region Environmental and Transportation 

Efficiency (CREATE) Program.

 

113 CSX/NS/Conrail merger, 1997; CN/IC merger 1998.

114 U.S. DOT, FTA. Transit Noise and Vibration Impact Assessment, DOT-T-95-16, April 1995.

115 U.S. DOT, FRA. Final Environmental Impact Statement on Use of Locomotive Horns at Highway-Rail Grade 

Crossings, 2003.
Appendix E: Source Reference Levels for Conventional Trains (Freight and Passenger) E-2

Table E-1 Noise Source Reference Levels for Conventional Freight Trains (SEL at 50 ft)

Category Subsource 

Component

Length 

Definition

Height above 

rails (ft)

SELref

(dBA)

len ref (ft) S ref

(mph)

K

Freight 

locomotive

Propulsion lenpower 10 97 90 40 10

Freight car Wheel-rail lentrain 1 100 2,000 40 20

Passenger 

locomotive

Propulsion lenpower 10 92 60 50 -10

Passenger 

coach

Wheel-rail lentrain 1 82 85 50 20

Horn Horn N/A 13 113 N/A N/A N/A
Appendix F: Glossary of Terms F-1

APPENDIX F GLOSSARY OF TERMS

A-weighting – A method used to alter the sensitivity of a sound level meter with respect to frequency so 

that the instrument is less sensitive at frequencies where the human ear is less sensitive. Also written as 

dBA.

Aeroacoustic – Acoustical waves generated by pressure fluctuations in moving air.

Ambient – The preproject background noise or vibration level.

Alignment – The horizontal location of a railroad as described by curved and tangent track.

Auxiliaries – The term applied to a number of separately driven machines, operated by power from the 

main engine. They include the air compressor, radiator fan, traction motor blower, exciter for the main 

generator and the boiler blower.

Ballast Mat – A 2- to 3-inch-thick elastomer mat placed under the normal track ballast on top of a rigid 

slab.

Ballast – Selected material placed on the roadbed for the purpose of holding the track in line and at 

surface.

Cab – The space in the power unit containing the operating controls and providing shelter and seats for 

the engine crew.

Catenary – On electric railroads, the term describing the overhead conductor that is contacted by the 

pantograph or trolley, and its support structure.

Coach – A passenger-carrying rail car, usually with a center aisle and two rows of seats.

Consist – The total number and type of cars and locomotives in a trainset.

Continuous Welded Rail – A number of rails welded together in lengths of 400 ft or longer.
Appendix F: Glossary of Terms F-2

Corrugated Rail – A rough condition on the rail head of alternate ridges and grooves, which develops in 

service.

Cross Tie – The transverse member of the track structure to which the rails are spiked or otherwise 

fastened to provide proper gage and to cushion, distribute, and transmit the stresses of traffic through the 

ballast to the roadbed.

Crossover – Two turnouts with the track between the frogs arranged to form a continuous passage 

between two nearby and generally parallel tracks.

Cut – A term used to describe a railbed at a lower level than the surrounding ground.

dB – see Decibel.

dBA – see A-weighting.

Decibel – A unit of level which denotes the ratio between two quantities that are proportional to power; 

the number of decibels is 10 times the logarithm of this ratio. Also written as dB.

Descriptor – A quantitative metric used to identify a specific measure of sound level.

DNL – see Ldn.

DOT – The Department of Transportation. An agency of the U.S. government having jurisdiction over 

matters pertaining to all modes of transportation.

Electrification – A term used to describe the installation of overhead wire or third rail power distribution 

facilities to enable operation of trains hauled by electric locomotives.

Embankment – A bank of earth, rock or other material constructed above the natural ground surface.

Equivalent Level – The level of a steady sound which, in a stated time period and at a stated location, has 

the same A-weighted sound energy as the time-varying sound. Also written as Leq.

Flange – The vertical projection along the inner rim of a wheel that serves, together with the 

corresponding projection of the mating wheel of a wheel set, to keep the wheel set on the track. 

Flow Separation – Loss of adherence of air to parts of the train’s outer surface.

FRA – The Federal Railroad Administration. An agency of the U.S. Department of Transportation with 

jurisdiction over matters of railroad safety and research.

Frequency – Of a phenomenon that occurs periodically in time, the number of times that the quantity 

repeats itself in 1 s.

Frog – A track structure used at the intersection of two running rails to provide support for wheels and 

passageways for their flanges, thus permitting wheels on either rail to cross the other.

Gage (of track) – The distance between the gage lines, measured at right angles thereto.

Gage Line – A line five eighths of an inch below the top of the center line of head of running rail or 

corresponding location of tread portion of other track structures along that side which is nearer the center 

of the tracks.
Appendix F: Glossary of Terms F-3

Gas-Turbine Electric Locomotive – A power unit in which a gas turbine drives electric generators 

supplying current to electric traction motors on the axles.

Grade Crossing – The point where a rail line and a motor vehicle road intersect.

Guideway – Supporting structure to form a track for rolling- or magnetically-levitated vehicles.

Head-End Power – A system of furnishing electric power for a complete railway train from a single 

generating plant in the power unit.

Hourly Average Sound Level – The time-averaged A-weighted sound level, over a 1-hour period, usually 

calculated between integral hours. Also known as L1h.

Idle – The speed at which an engine runs when it is not under load.

Intermodal Car – A rail car designed specifically for handling piggyback trailers or containers, or both.

Intermodal Traffic – Freight moving via at least two different modes of transport (e.g., truck-to-rail).

Jointed Rail – A system of joining rails with steel members designed to unite the abutting ends of 

contiguous rails.

L1h – see Hourly Average Sound Level.

LAE – Power-averaged value of sound exposure within 10 dB of LAmax, sampled at a time interval of 5/3 

second. Used in Japan.

LAeq,P – Equivalent A-weighted sound-level, energy averaged over the time of passby (train length). Used 

in Europe.

LAeq,1h – Sound-pressure level, energy averaged over one hour. See also Hourly Average Sound Level. 

Used in Europe.

LAmax – Power-averaged “slow” maximum level (Lmax,s) of 20 consecutive train passbys. Used in Japan.

Ldn – The sound exposure level for a 24-hour day calculated by adding the sound exposure level obtained 

during the daytime (7 a.m.–10 p.m.) to 10 times the sound exposure level obtained during the nighttime 

(10 p.m.–7 a.m.). This unit is used throughout the United States for environmental impact assessment. 

Also written as DNL.

Leq – see Equivalent Level.

Lmax(mean) – see LAeq,P (used in Scandinavia) .

Lp,1h – see LAeq,1h.

Lp,p – see Laeq,P.

Locomotive – A self-propelled, non-revenue rail vehicle designed to convert electrical or mechanical 

energy into tractive effort to haul railway cars. (see also Power Unit).

Lead Unit – The first and controlling power unit in a series of locomotives pulling the same train.
Appendix F: Glossary of Terms F-4

Mainline – The principal line or lines of a railway.

Maglev – Magnetically levitated vehicle; a vehicle or train of vehicles with guidance and propulsion 

provided by magnetic forces. Support can be provided by either an electrodynamic system (EDS) 

wherein a moving vehicle is lifted by magnetic forces induced in the guideway, or an electromagnetic 

system (EMS) wherein the magnetic lifting forces are actively energized in the guideway.

Maximum Sound Level – The highest exponential-time-average sound level, in decibels, that occurs 

during a stated time period. Also written as Lmax. The standardized time periods are 1 second for Lmax, slow

and 0.125 s for Lmax, fast.

Multiple Unit (MU) – A term referring to the practice of coupling two or more power units or electric 

passenger cars together with provision for controlling the traction motors on all units from a single 

controller.

Noise – Any disagreeable or undesired sound or other audible disturbance.

Octave – The frequency interval between two sounds whose frequency ratio is 2.

Pantograph – A device for collecting current from an overhead conductor (catenary), consisting of a 

jointed frame operated by springs or compressed air and having a current collector at the top.

Peak Particle Velocity (PPV) – The peak signal value of an oscillating vibration velocity waveform. 

Usually expressed in inches/second.

Peak-to-Peak (P-P) Value – Of an oscillating quantity, the algebraic difference between the extreme 

values of the quantity.

Power Unit – A self-propelled vehicle, running on rails and having one or more electric motors that drive 

the wheels and thereby propel the locomotive and train. The motors obtain electrical energy either from a 

rail laid near to, but insulated from, the track rails, or from a wire suspended above the track. Contact 

with the wire is made by a pantograph mounted on top of the unit.

Radius of Curvature – A measure of the severity of a curve in a track structure based on the length of the 

radius of a circle that would be formed if the curve were continued.

Rail – A rolled steel shape, commonly a T-section, designed to be laid end to end in two parallel lines on 

cross ties or other suitable supports to form a track for railway rolling stock.

Receiver/Receptor – A stationary far-field position at which noise or vibration levels are specified. 

Retarder – A braking device, usually power-operated, built into a railway track to reduce the speed of cars 

by means of brake shoes which, when set in position, press against the sides of the lower portions of the 

wheels.

Right-of-Way – Lands or rights used or held for railroad operation.

Root Mean Square (RMS) – The average or “mean” level of an oscillating waveform. Obtained by 

squaring the value of amplitudes at each instant of time. The squared values are then added and averaged 

over the sample time.

SEL – see Sound Exposure Level.
Appendix F: Glossary of Terms F-5

Siding – A track auxiliary to the main track for meeting or passing trains.

Sound Exposure Level – The level of sound accumulated over a given time interval or event. 

Technically, the sound exposure level is the level of the time-integrated mean square A-weighted sound 

for a stated time interval or event, with a reference time of one second. Also written as SEL.

Sound – A physical disturbance in a medium that is capable of being detected by the human ear.

Sub-Ballast – Any material of a superior character, which is spread on the finished subgrade of the 

roadbed and below the top-ballast, to provide better drainage, prevent upheaval by frost, and better 

distribute the load over the roadbed.

Subgrade – The finished surface of the roadbed below the ballast and track.

Switch – A track structure used to divert rolling stock from one track to another.

Tangent Track – Track without curvature.

Terminal – An assemblage of facilities provided by a railway at a terminus or at an intermediate point for 

the handling of passengers or freight and the receiving, classifying, assembling, and dispatching of trains.

Top-Ballast – Any material of a superior character spread over a sub-ballast to support the track structure, 

distribute the load to the subballast, and provide a good initial drainage.

Turbulent Boundary Layer – Fluctuations in the air adjacent to the body of a vehicle moving at high 

speed.

Track Crossing – A structure, used where one track crosses another at grade, and consisting of four 

connected frogs.

Track – An assembly of rail, ties and fastenings over which cars, locomotives, and trains are moved.

Traction Motor – A specially designed direct current series-wound motor mounted on the trucks of 

locomotives and self-propelled car to drive the axles.

Trainset – A group of coupled cars including at least one power unit.

Truck – The complete assembly of parts including wheels, axles, bearings, side frames, bolster, brake 

rigging, springs and all associated connecting components, the function of which is to provide support, 

mobility and guidance to a railroad car or locomotive.

Turnout – An arrangement of a switch and a frog with closure rails, by means of which rolling stock may 

be diverted from one track to another.

VdB – see Vibration Velocity Level.

Vibration Velocity Level – 10 times the common logarithm of the ratio of the square of the amplitude of 

the vibration velocity to the square of the amplitude of the reference velocity. Also written as VdB.

Vibration – An oscillation wherein the quantity is a parameter that defines the motion of a mechanical 

system.
Appendix F: Glossary of Terms F-6

Vortex Shedding – A flow separation (see definition above) wherein the air departs periodically in a 

spinning motion.

Wheel Flat – A localized flat area on a steel wheel of a rail vehicle, usually caused by skidding on steel 

rails, causing a discontinuity in the wheel radius.

Wheel Squeal – The noise produced by wheel-rail interaction, particularly on a curve where the radius of 

curvature is smaller than allowed by the separation of the axles in a wheel set.

Wye – A triangular arrangement of tracks on which locomotives, cars and trains may be turned.

Yard – A system of tracks within defined limits provided for making up trains, storing cars, and other 

purposes, over which movements not authorized by time table or by train-order may be made, subject to 

prescribed signals and rules, or special instructions.
Appendix G: Background Information for FRA Noise Screening Table G-1

APPENDIX G BACKGROUND INFORMATION FOR FRA NOISE SCREENING TABLE

Screening method requires information regarding: 

1. Project setting 

a. Shared with railroad corridor (primarily freight trains)

b. Shared with highway corridor

c. New transportation corridor

2. Existing Ambient Noise Conditions

a. Urban/Noisy Suburban (U/NS) 

b. Quiet Suburban/Rural (QS/R)

3. Technology

a. Steel wheel high speed trains

b. Maglev trains

Assumptions regarding the development of screening distances:

1. Railroad Corridor has 10 daytime and 2 nighttime freight trains with an average of 1 

locomotive and 40 freight cars running at 55 mph. Using the FTA noise spreadsheet, the Ldn for 

this condition would be 65 dBA at 50 ft from track centerline. Noise levels in the corridor are 

assumed to follow a soft ground propagation rate of 4.5 dB per distance doubling, or 65-

15log(d/50).

2. Highway Corridor has a four-lane highway with a peak hour volume of 1,450 vehicles, made up 

of 95-percent automobiles, 2-percent medium trucks, and 3-percent heavy trucks. “TNM 
Appendix G: Background Information for FRA Noise Screening Table G-2

Lookup” gives Leq = 72 dBA at 50 feet for this condition. FTA manual provides an estimated Ldn

= PH Leq – 2 dB, or 70 dBA for a typical highway traffic pattern. Again, a soft ground 

propagation rate is assumed, or Ldn = 70 – 15log (d/50).

3. New Transportation Corridor is assumed to have no existing transportation facilities other than 

local roads and streets in urban, suburban and rural areas. Noise level is the ambient noise 

associated with the land use.

4. Existing ambient noise is based on the levels identified by US Environmental Protection Agency 

(“Levels Document” p.14) where “small town and quiet suburban” noise levels are given the 

rating of 50 dB Ldn and “urban” is given the rating of 60 dB Ldn. The foregoing descriptions are 

modified and applied to the categories of “Quiet Suburban/Rural” at 50 dB Ldn, and “Urban/Noisy 

Suburban” at 60 dB Ldn. These Ldn values are the noise levels found uniformly in the areas, 

except where the noise environment is affected by the transportation corridors described above –

railroad and highway. In the corridor cases, the railroad noise or highway noise is added to the 

ambient noise, with the result that close to the transportation noise source the ambient noise is 

determined by the transportation and far from the source the ambient is attained. The results are 

shown in the figures below.
Appendix G: Background Information for FRA Noise Screening Table G-3

5. Project Noise is based on the technology selected for assessment—steel wheel high-speed trains 

and maglev trains, and two speed regimes for each. Noise from each technology is computed 

using the FRA noise computation spreadsheet with the following input data based on typical 

conditions expected for a high speed rail project. 

a. Steel Wheel Technology is represented by trains made up of 2 power cars, 10 coaches, 

and a service of 45 daytime trains and 12 night trains. Two speed regimes are assumed, 

Regime II at 100 mph; and Regime III at 180 mph. The FRA model gives Ldn = 70 dBA 

at 50 ft. for Regime II and 75 dBA for Regime III under the foregoing conditions. 

Soft ground propagation was assumed for open terrain—4.5 dB per distance doubling, or 

-15log(d/50). An added condition is the propagation in built-up areas, where the rows of 

buildings provide shielding. This condition applies in urban and densely populated 

suburban locations. Rows of buildings are assumed to occur at 200, 400, 600, 800, and 

1,000 ft from track centerline in urban settings. A shielding factor of 3 dB was subtracted 

at the first row of buildings (200 ft) and 1.5 dB subtracted for each successive row of 

buildings.
Appendix G: Background Information for FRA Noise Screening Table G-4

b. Maglev Technology is represented by trains made up of 10 cars, and a service of 45 

daytime trains and 12 night trains, the same as the steel wheel technology. Again, two 

speed regimes are assumed but with a higher speed in Regime III than steel wheel to 

account for the maglev’s higher speed capability: Regime II at 100 mph and Regime III 

at 200 mph. FRA spreadsheet model gives the result of Ldn = 60 dBA at 50 ft for Regime 

II and 72 dBA for Regime III under these conditions. 

Soft ground propagation was assumed for open terrain – 4.5 dB per distance doubling, or 

-15log(d/50). An added condition is the propagation in built-up areas, where the rows of 

buildings provide shielding. This condition applies in urban and densely populated 

suburban locations. Rows of buildings are assumed to occur at 200, 400, 600, 800, and 

1,000 ft from track centerline in urban settings. A shielding factor of 3 dB was subtracted 
Appendix G: Background Information for FRA Noise Screening Table G-5

at the first row of buildings (200 ft) and 1.5 dB subtracted for each successive row of 

buildings.

6. Results

The projected noise levels from the steel wheel and maglev systems are compared with FRA noise impact 

criteria in order to determine the distance within which noise impact could occur. The noise impact 

criteria are ambient-based, and impact values are tabulated in Chapter 3. Given the existing noise level, 

the project noise level is listed for moderate impact and severe impact. For the screening process, only 

the moderate impact level is used in order to provide an upper bound on the potential for impact. 

The results of the exercise are shown in the table below. 
Appendix G: Background Information for FRA Noise Screening Table G-6

Corridor 

Type EXISTING NOISE ENVIRONMENT

Screening Distance in Feet for Project 

Type and Speed Regime*

Steel-Wheeled Maglev

Reg. II Reg. III Reg. II Reg. III

Railroad U/NS –unobstructed 300 ft. 700 ft. 50 ft. 400 ft.

U/NS – intervening buildings** 200 300 50 250

QS/R 500 1200 50 700

Highway U/NS –unobstructed 250 600 50 400

U/NS – intervening buildings** 200 350 50 250

QS/R 400 1100 50 600

New U/NS –unobstructed 350 700 75 450

U/NS – intervening buildings** 250 350 75 300

QS/R 600 1300 150 800

*Measured from centerline of guideway or rail corridor. 

Minimum distance is assumed to be 50 ft. 

** Rows of buildings assumed to be at 200, 400, 600, 800, and 1,000 ft parallel to guideway.

U = Urban; NS = Noisy Suburban; QS = Quiet Suburban; R = Rural.