Brunswick Layover Environmental Assessment (EA)

Appendix E: Noise and Vibration Technical Report

September 2013

1 

Brunswick Layover Facility 

Environmental Assessment 

Noise and Vibration Technical Report 

April 11, 2013 

Prepared by; Prepared for: 

 
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TABLE OF CONTENTS 

1. Executive Summary ................................................................................................................................. 1 

2. Noise Fundamentals................................................................................................................................ 1 

3. Noise Criteria .............................................................................................................................................. 3 

3.1. FRA/FTA ............................................................................................................................................... 3 

3.2. Maine DEP and Brunswick Ordinance ................................................................................... 5 

4. Community Receptor Sites .................................................................................................................. 6 

5. Existing Ambient Noise Measurements ......................................................................................... 7 

6. Downeaster Train Set Noise Emission Measurements ........................................................12 

7. Noise Assessment Approach .............................................................................................................12 

7.1. Noise Modeling ................................................................................................................................14 

8. Existing Service Levels Noise Assessment .................................................................................15 

8.1. No-Build Scenario ..........................................................................................................................15 

8.2. Project-Generated Noise Assumptions ................................................................................15 

8.3. FRA/FTA Noise Predictions and Impact Assessment ...................................................18 

8.4. Maine DEP and Brunswick Ordinance Noise Predictions...........................................18 

9. Future Service Levels Noise Assessment ....................................................................................21 

9.1. No-Build Scenario ..........................................................................................................................21 

9.2. Project-Generated Noise Assumptions ................................................................................22 

9.3. FRA/FTA Noise Predictions and Impact Assessment ...................................................24 

9.4. Maine DEP and Brunswick Ordinance Noise Predictions...........................................25 

10. Train Horn Noise..................................................................................................................................29 

10.1. Horn Noise Mitigation ...............................................................................................................30 

11. Vibration Assessment ........................................................................................................................31 

11.1. Vibration Fundamentals ..........................................................................................................31 

11.2. Vibration Criteria.........................................................................................................................32 

11.3. Ambient Vibration Measurements ......................................................................................34 

11.4. Project-Generated Vibration Levels ...................................................................................37 

12. Conclusions .............................................................................................................................................38 
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LIST OF FIGURES 

Figure 1. Typical A-Weighted Noise Levels ...................................................................................... 2 

Figure 2. FRA/FTA Project Noise Impact Criteria ......................................................................... 4 

Figure 3. Aerial of Community Receptor Sites ................................................................................ 6 

Figure 4. Ambient Noise Monitoring Data from Site 1 ................................................................ 9 

Figure 5. Ambient Noise Monitoring Data from Site 2 ..............................................................10 

Figure 6. Ambient Noise Monitoring Data from Site 3 ..............................................................10 

Figure 7. Predicted Project Ldn Noise Levels – Existing Service ..........................................21 

Figure 8. Predicted Project Worst-Hour Leq(h) Noise Levels – Existing Service .........21 

Figure 9. Predicted Project Ldn Noise Levels – Future Service ............................................28 

Figure 10. Predicted Project Worst-Hour Leq(h) Noise Levels – Future Service.........28 

Figure 11. FRA/FTA Criteria for Ground-Borne Vibration Impact .....................................33 

Figure 12. Ambient Vibration Levels at Site 1 ...............................................................................35

Figure 13. Ambient Vibration Levels at Site 2 ...............................................................................36

Figure 14. Ambient Vibration Levels at Site 3 ...............................................................................36
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LIST OF TABLES 

Table 1. Community Receptor Site Details ........................................................................................ 7 

Table 2. Noise Monitoring Instrumentation ..................................................................................... 8 

Table 3. Measured Ambient Ldn Noise Levels ..............................................................................11 

Table 4. Measured Noise Emission Level of Idling Downeaster Train Set ......................12 

Table 5. Receptor Noise Impact Criteria ..........................................................................................13 

Table 6. Project-Generated Noise Assumptions – Existing Service.....................................17 

Table 7. Predicted Noise and FRA/FTA Impact Assessment - Existing Service ............20 

Table 8. Predicted Noise and Maine DEP/Brunswick Ordinance - Existing Service ...20 

Table 9. Project-Generated Noise Assumptions – Future Service Levels .........................24 

Table 10. Predicted Noise and FRA/FTA Impact Assessment - Future Service ............27 

Table 11. Predicted Noise and Maine DEP/Brunswick Ordinance - Future Service ...27 

Table 12. FRA/FTA Criteria Limits for Vibration Impact .........................................................33 

Table 13. Vibration Monitoring Instrumentation ........................................................................34 

Table 14. Ambient and Predicted Vibration Levels ....................................................................38 
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1. Executive Summary 

The Preferred Alternative in this project involves the construction of a layover facility in 

Brunswick, Maine to support the overnight storage and turnaround servicing of Amtrak 

Downeaster train sets. The layover facility is proposed to be constructed at the existing 

Brunswick railroad yard, which is situated 0.6 miles west of Brunswick Station, the 

terminus of the recently expanded Downeaster service. 

This assessment evaluates potential noise and vibration impacts due to the introduction of 

the layover facility for both existing and potential future Downeaster service levels. The 

extended operation of Downeaster trains to Brunswick on the mainline tracks, which 

commenced in November 2012, was previously analyzed and approved by others as part of 

the Portland North Expansion Project (2008),. The passage of Downeaster trains on the 

mainline is considered as part of the ambient noise in the study area. 

Both the Federal Railroad Administration1 (FRA) and Federal Transit Administration2

(FTA) have published guidance manuals for the assessment of noise and vibration impacts 

from rail transit projects. This assessment is consistent with the guidance and procedures 

of both agencies. The operational assumptions and definition of the project have evolved 

since previous draft assessments were made public. This report presents the most current 

and accurate noise and vibration impact assessment of the project to date, and thus the 

results and findings of this report supersede those of all previous draft reports. 

The results conclude that the project, as defined, will fully comply with all applicable 

FRA/FTA criteria so additional noise and vibration mitigation measures will not be 

required for this project. 

2. Noise Fundamentals 

Environmental noise is a result of everyday occurrences such as transportation systems, 

industrial processes, building air handling and power generation systems, wind, human 

activities, etc. Noise can be quantified in many different manners, depending on its 

temporal (time), tonal (frequency), or magnitudinal (loudness) characteristics. In general, 

environmental noise assessment addresses relative changes in noise levels over time and 

relates those changes with effects on human beings. 

 

1

 FRA High Speed Ground Transportation Noise and Vibration Impact Assessment, September 2012. 

2

 FTA Transit Noise and Vibration Impact Assessment, May 2006. 
2 

Noise magnitude is expressed in units of decibels (dB) which is a logarithmic quantity 

comparing fluctuating air pressure to that of a standardized reference air pressure of 20 

micro-pascals (i.e. dB re: 20 μPa). For this reason the noise levels that humans hear are 

called sound pressure levels. Noise is expressed as a logarithmic quantity because 

humans are sensitive to relative changes in noise levels. To illustrate, humans can just 

barely perceive a change in noise levels of +/- 3 dB, can easily perceive a change of +/- 5 

dB, and will generally perceive a change of +/- 10 dB as a doubling or halving in noise 

levels. 

With respect to tonal qualities (frequency), a frequency weighting adjustment has been 

standardized to account for human auditory response over the audible frequency range of 

approximately 20 Hz to 20,000 Hz. Humans respond less sensitively to low frequency 

noise ranges, exhibiting a maximum sensitivity to tones in mid-frequency ranges, and being 

somewhat less sensitive at higher frequency ranges. This frequency weighted adjustment 

is referred to as "A-weighting", with results expressed as A-weighted decibels, or dBA. 

The A-weighted noise level is the basic descriptor for environmental noise. Typical Aweighted noise levels are illustrated in Figure 1. 

Figure 1: Typical A-weighted Noise Levels 

Numerous different indices have been developed to quantify the temporal characteristics 

(changes over time) of environmental noise. The following noise metrics are used in this 

assessment: 
3 

Leq(h), or Hourly Equivalent Sound Level, is the energy-averaged single noise level 

that represents the same (equivalent) energy that was contained in the fluctuating 

noise level over a period of an hour. The Leq(h) is useful for describing the "average" 

noise level over time, and is expressed in dBA. 

Ln, or Percentile Level, is a statistical representation of changing noise levels indicating 

that over some time period, the fluctuating noise level was equal to, or greater than, the 

stated level for "n" percent of the time. For example, the L10, L33, L50, and L90 

represent the noise levels exceeded 10, 33, 50, and 90 percent of the time. The L10 is 

often used to identify impacts of transportation or construction noise sources, while the 

L90 is considered to represent steady ambient background noise levels. Ln percentile 

levels are expressed in dBA. 

Ldn, or Day-Night Sound Level, represents an average noise level evaluated over 24 

hours in which a 10 dBA "penalty" is added to the Leq(h) noise level for each of the nine 

nighttime hours (10 PM to 7 AM). The penalty is applied to account for both increased 

human sensitivity to nighttime noise intrusions during quiet activities (such as 

sleeping) and the reduction in ambient noise levels during the nighttime hours which 

may allow offending noise sources to be more noticeable. The Ldn is expressed in dBA. 

Acoustical data can also be described in terms of the amount of sound power that is 

emitted by a source. Sound power levels are also expressed in decibels, however being a 

measure of power, they are derived relative to a reference level of 1 Pico-Watt (i.e. dB re: 1 

pW). Humans do not hear sound power levels; rather they are useful to use in computer 

modeling of noise levels because they are a property of the source itself and as such are 

independent of environmental effects or distance. Sound power levels, abbreviated Lw or 

PWL, can be computed using the A-weighting adjustment to yield a broadband level or in 

discrete frequency-selective regions known as octave or third-octave bands. 

3. Noise Criteria 

3.1 FRA/FTA 

FRA and FTA use the same criteria for assessment of noise impacts from rail projects. The 

criteria limits incorporate both absolute criteria, which consider activity interference 

caused by the transit project alone, and relative criteria, which consider annoyance due to 

the change in the noise environment caused by the project. 

Thresholds for two degrees of impact, moderate and severe, are specified. Both thresholds 

are dependent on the existing noise level and the land-use of the receptor. The noise 

criterion for moderate impact is the threshold at which the percentage of people highly 
4 

annoyed by the change in cumulative noise level as a result of the project starts to become 

measurable. The corresponding criterion for severe impact is determined by a higher, more 

significant percentage of people highly annoyed. 

FRA/FTA noise impact criteria are typically expressed in the form of project noise limits 

and the impact assessment involves comparing the predicted future noise levels from the 

project to the appropriate noise impact criteria. The FRA/FTA project noise impact criteria 

are shown graphically in Figure 2. 

Figure 2: FRA/FTA Project Noise Impact Criteria 

Noise impact criteria are also dependent on the land-use category of the receptor. Category 

1 land-use includes tracts of land where quiet is an essential element in their intended 

purpose, such as outdoor concert pavilions, recording studios, concert halls, and historical 

sites with significant outdoor land-use. Category 2 land-use includes residences and 

buildings where people normally sleep. This category includes homes, hospitals, and hotels 

where nighttime sensitivity to noise is assumed to be of utmost importance. Category 3 

land-use includes institutional land-uses with primarily daytime and evening use, such as 

medical offices, churches, schools, libraries, and theaters. Places with meditation or study 

associated with cemeteries, museums, monuments, and recreational facilities are also 

included in this category. Most general purpose commercial buildings are not included in 

any category. 
5 

The relevant noise metric when evaluating Category 2 receptors is the Ldn, due to the 

receptor's sensitivity to nighttime noise intrusion. Category 1 and 3 receptors are analyzed 

using the Leq for the loudest hour of transit-related activity, or Leq(h), during hours of 

noise sensitivity. All noise levels measured or predicted using the FRA/FTA procedure are 

expressed in A-weighted decibels (dBA) and are evaluated on the exterior of the receptor at 

a position closest to or facing the project. 

3.2 Maine DEP and Brunswick Ordinance 

It is important to note that this project is not subject to compliance with either the Maine DEP 

Noise Regulation or the Town of Brunswick Noise Ordinance per federal laws concerning 

interstate commerce and primacy of federal regulations relating to railroads. Comparisons of 

potential noise levels generated by this project relative to these two guidelines have been 

included in this report; however, these are provided for information only and not for the 

evaluation of mandatory compliance with regulatory requirements. 

Maine Department of Environmental Protection’s (Maine DEP) noise regulation can be 

found in Regulation 06-096, Chapter 375, Section 10, Control of Noise. The regulation 

provides noise criteria limits and definitions for, amongst other things, Routine Operation 

of Developments. However, railroad equipment (train sets) are explicitly exempted per 

paragraph C.(5)(a). 

The Maine DEP regulations also specify that the noise limits contained in a local noise 

ordinance, if one exists, shall apply. In this case, the Town of Brunswick Zoning Ordinance

includes Section 109.4 Noise. In paragraph A the ordinance states that property line noise 

levels cannot exceed the following limits: 

· For Residential Districts: 55 dBA Leq(h) daytime (6 AM to 8 PM) and 45 dBA Leq(h) 

nighttime (8 PM to 6 AM). 

· For Mixed Use Districts: 60 dBA Leq(h) daytime (6 AM to 8 PM) and 50 dBA Leq(h) 

nighttime (8 PM to 6 AM). 

The Maine DEP Noise Regulations specify a different set of criteria. Per paragraph C.(1)(a) 

the operational noise limits at the property lines of Protected Locations would be: 

· At the property line of the layover facility site: 75 dBA Leq(h) for any time of day. 

· For residential locations: 60 dBA Leq(h) daytime (7 AM to 7 PM) and 50 dBA Leq(h) 

nighttime (7 PM to 7 AM). 

· For commercial locations: 70 dBA Leq(h) daytime (7 AM to 7 PM) and 60 dBA 

Leq(h) nighttime (7 PM to 7 AM). 
6 

Site 3 

Site 1 

Site 2 

The regulation also describes alternative noise limits for areas of exceptionally quiet or 

exceptionally loud ambient conditions, but these do not apply in this case. Similarly, the 

regulation provides for noise limit adjustments for pure tones or short duration impulsive 

noise, however the conditions required to trigger these adjustments are not expected in 

this case. 

4. Community Receptor Sites 

The suburban area in the vicinity of the project has an existing rail line with daily Amtrak 

Downeaster service and occasional freight activities. The neighborhoods surrounding the 

proposed layover facility site consist of mixed commercial and residential land-uses along 

Route 1 north of the tracks, and residential dwellings along Bouchard Drive south of the 

tracks. The Church Road crossing is located to the west, and the Stanwood Street crossing 

is located to the east of the project site. 

Three noise and vibration sensitive receptors were selected for evaluation purposes in this 

study as shown in Figure 3. The receptors were selected in order to represent the closest 

noise-sensitive abutters surrounding the proposed project. The receptors’ locations, 

addresses, and further details are summarized in Table 1. 

Figure 3. Aerial of Community Receptor Sites 
7 

Table 1. Community Receptor Site Details 

Site 

No. Address 

FRA/FTA 

Land-Use 

Category 

Site Description 

1 

Knights Inn at 133 

Pleasant Street, 

Apartment H8 

2 

This residential receptor is located directly north of the 

proposed layover facility site and is the closest abutter to the 

project north of the tracks. The Inn has a separate residence, 

Apt. H8, located behind the Inn’s main building. 

2 Residence at 22 

Bouchard Drive 2 

This residential receptor is located southeast of the proposed 

layover facility site and is the closest residential abutter south 

of the tracks. This receptor is representative of other 

residences along Bouchard Drive. 

3 

Resource Systems 

Engineering at 30 

Parkers Way 

2 

This receptor is occupied by Resource Systems Engineering 

(RSE), an acoustical consulting firm, and is located southwest 

of the proposed layover facility site south of the tracks. The 

property is zoned for mixed use, so it has been considered to 

be a potential residential receptor. 

5. Existing Ambient Noise Measurements 

In order to establish existing noise levels in accordance with FRA/FTA requirements, 

ambient noise levels were measured at each of the three receptor locations from 2/13/13 

to 2/20/13. Details on the noise measurement instrumentation are summarized below in 

Table 2. 

Larson Davis Model 720 (LD 720) Environmental Noise Monitors (ANSI Standard S1.4 Type 

2) were deployed at each receptor location by hanging them approximately 10 feet above 

the ground in trees or on porch structures in close proximity to the subject buildings. The 

monitors’ microphones were protected by 3-inch windscreens. The monitors were 

programmed to measure and digitally store relevant ambient noise data in hourly intervals 

such as the Leq, L1, L10, L50, L90, Lmax and Lmin levels in A-weighted decibels (dBA). The 

response time of the noise monitors was set to RMS ‘slow’. The calibration of the monitors 

was checked before and after use with a Bruel & Kjaer Model 4231 Portable Acoustical 

Calibrator (ANSI Standard S1.4 Type 1.) 
8 

Table 2. Noise Monitoring Instrumentation 

Site Manufacturer Model Description Serial No. 

1 Larson Davis 720 Environmental Noise Monitor 0301 

2 Larson Davis 720 Environmental Noise Monitor 0303 

3 Larson Davis 720 Environmental Noise Monitor 0297 

All Bruel & Kjaer 4231 Acoustic Calibrator 2099917 

Typical ambient noise sources noted during the measurements included passing 

Downeaster trains, traffic from Route 1, local traffic, birds, and aircraft overpasses. 

Monitoring during the winter ensured that insect noise and foliage noise from wind 

blowing through trees, which could otherwise increase the ambient levels, would not be 

included in the measurements. 

During the monitoring period, meteorological data was collected from the weather station 

at Wiscasset Airport. Weather conditions were generally fair to overcast with 

temperatures in the range of 20 – 40°F over the week, but there was also snow, rain, 

and/or strong winds on several days. Only noise data measured during periods of 

acceptable meteorological conditions (i.e. no snow, rain, or strong winds) were included in 

the results. The data was then reduced to average noise levels for each of the 24 hours. 

The results of the ambient noise measurements can be seen in Figures 4, 5 and 6 for 

receptor Sites 1, 2 and 3, respectively. 
9 

Figure 4. Ambient Noise Monitoring Data from Site 1 
10 

Figure 5. Ambient Noise Monitoring Data from Site 2 

Figure 6. Ambient Noise Monitoring Data from Site 3
11 

While considerable amounts of ambient noise data were collected, the only noise metric of 

interest in performing a noise assessment in accordance with FRA/FTA guidelines is the 

Day-Night Sound Level (Ldn) for Category 2 land-use residential receptors. Table 3

summarizes the Ldn noise levels resulting from the ambient noise measurements.

Downeaster service was fully operational during the noise monitoring period, so noise 

from the existing Downeaster service is part of the measured ambient noise levels. The 

existing Downeaster service includes four scheduled Downeaster trips and two nonrevenue (deadhead) trips between Portland and Brunswick daily. Five of the train trips 

occur during daytime hours (7 AM to 10 PM) and one occurs during the nighttime period 

(10 PM to 7 AM), with each passing train sounding its horn at both the Stanwood Street and 

Church Road at-grade crossings. A typical Downeaster train set consists of a diesel-electric 

locomotive with five railcars. 

While a Downeaster train may idle in Brunswick yard during the mid-day period, this may 

not occur on a consistent basis. The noise monitoring data included days where the train 

both was and was not idling in Brunswick yard. To be conservative, the Ldn noise levels 

shown in Table 3 intentionally do not include noise from the idling train because higher 

existing noise levels generally lead to higher noise impact criteria. 

Table 3. Measured Ambient Ldn Noise Levels 

Site No. Address FRA/FTA 

Land-Use Category 

Measured Ambient 

Noise Level 

(Ldn, dBA) 

1 Knights Inn at 133 Pleasant Street, Apartment H8 2 53

2 Residence at 22 Bouchard Drive 2 53

3 Resource Systems Engineering, 30 Parkers Way 2 54
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6. Downeaster Train Set Noise Emission Measurements 

Noise emission measurements of 

Amtrak Downeaster train set 

locomotive No. 157 were made on 

2/13/13 while the train was idling in 

Brunswick yard. Measurements were 

taken at a distance of 50-feet wayside 

of the idling locomotive using a CEL 

593 noise analyzer which complies 

with ANSI Standard S1.4 for Type 1 

accuracy. The measurements captured 

steady-state idling locomotive noise as 

well as intermittent noise from pressure releases and compressor cycles. The results of the 

measurements are shown in Table 4. This noise emission data was later used to model 

noise from the train idling inside the proposed layover facility.

Table 4. Measured Noise Emission Level of Idling Downeaster Train Set at 50 feet 

Broadband Leq Sound Level Octave Band Leq Sound Level (dB) 

Linear

 (dB) 

A-Weighted 

(dBA) 16 32 63 125 250 500 1000 2000 4000 8000 16000

92 73 76 83 91 77 69 65 69 62 59 59 60 

7. Noise Assessment Approach

The FRA/FTA’s “detailed” noise assessment procedure was followed in order to predict 

noise levels associated with the operation of the proposed layover facility at the three 

community receptor sites. Noise assessments were completed for two different 

Downeaster service level scenarios: (1) Existing Service Levels, and (2) Future Service 

Levels. 

The Existing Service Levels scenario represents current track usage agreements and 

capacity constraints, which limit the number of Downeaster trains that can operate 

between Portland and Brunswick to six daily train trips (i.e. three round trips). The 

Downeaster service was operating at this service level when ambient noise measurements 

were made, so noise from the existing service is accounted for in the measured ambient 

noise levels. 
13 

This assessment intentionally does not evaluate noise or vibration impacts associated with 

the running of Downeaster trains on the mainline tracks, as that project, the Portland North 

Expansion Project (2008), was previously analyzed and approved by others. To assess 

potential impacts of this project, noise associated with the addition of the proposed layover 

facility itself was predicted and evaluated relative to appropriate FRA/FTA impact criteria. 

The Future Service Levels scenario represents the potential for extending all ten scheduled 

Downeaster trips (i.e. five round trips) to operate between Portland and Brunswick. For 

this to occur, physical track improvements unrelated to this layover facility project would 

need to be made. Thus, the expansion of the Downeaster service to ten daily trips is not 

part of the proposed action. However, to be conservative and assess potential impacts for 

the two scenarios in a consistent manner, both layover facility noise as well as noise from 

the expanded Downeaster service traveling through the project area was considered for the 

Future Service Levels scenario. This approach allows the same impact criteria to be used 

for both service level scenarios while accounting for all noise sources. To assess potential 

impacts, the combined noise level from the two activities (increase in Downeaster service 

and the layover facility) was predicted and evaluated relative to appropriate FRA/FTA 

noise impact criteria. 

For each of these scenarios, an associated No-Build scenario is also discussed qualitatively. 

The No-Build scenario represents future conditions that could potentially occur if this 

project (the layover facility) is not built. 

The noise impact criteria used for the assessments are shown in Table 5. In accordance 

with FRA/FTA methods, the impact criteria levels were determined by using the chart 

shown in Figure 2 to identify the thresholds for moderate and severe impact based on the 

existing measured ambient noise level and the land-use category of each receptor site. 

Table 5. FRA/FTA Receptor Noise Impact Criteria 

Site 

No. Address 

FRA/FTA 

Land-Use 

Category 

Existing 

Noise Level 

(Ldn, dBA) 

FRA/FTA Project-Generated 

Noise Impact Criteria 

(Ldn, dBA) 

Moderate Severe 

1 Knights Inn at 133 Pleasant Street, 

Apartment H8 2 53 54 60 

2 Residence at 22 Bouchard Drive 2 53 54 60 

3 Resource Systems Engineering, 

30 Parkers Way 2 54 55 61 
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7.1 Noise Modeling 

The Cadna-A® noise model, developed by Datakustik GmbH, was used for all noise 

predictions. In this manner the noise contributions of train movements, staff and service 

vehicles, and other noise sources such as forklifts, rail switches, train horns, and rooftop 

ventilation fans could all be included in the same model. The Cadna-A model implements 

accepted methods for the propagation and prediction of outdoor noise levels in accordance 

with ISO Standard 9613. 

A design file of the proposed layover facility overlaid on a GoogleEarth® base map of the 

area provided the starting point for the model. The locations of noise sources and 

community receptors were then added. Because the ground in the area is almost all lawn 

and/or wooded areas, it was modeled as being acoustically absorptive. However, to be 

conservative no additional shielding or absorption was assumed for leaf bearing trees. 

The Cadna-A model features an FRA/FTA rail noise module that implements standard rail 

vehicle source emission levels and sound propagation equations in order to facilitate 

predictions that are consistent with FRA/FTA guidelines. The FRA/FTA’s noise prediction 

model takes into account the number of locomotives and railcars per train set, the number 

of train passby events per day (7 AM to 10 PM) and night (10 PM to 7 AM), the throttle 

setting and speed of the trains, the distance the receptors are located from the tracks, and 

the intervening acoustical ground conditions. The relatively limited number of staff and 

service vehicles accessing the facility were also included in the model using Cadna-A’s TNM 

module which implements FHWA’s standard automotive and truck vehicle noise emission 

levels and propagation equations. 

For other noise sources associated with the facility, the sources were modeled by inputting 

their respective sound power emission levels in octave band format and assembling point-, 

line-, or area-source components as appropriate. Sources that would be operating inside 

the layover facility were modeled assuming the building shell (exterior walls and roof) 

were made of material with a composite sound transmission class (STC) of 21. 

Noise sources assumed to be operating inside the layover facility included small forklift 

type vehicles, use of hand tools with air compressors, up to three idling trains, and brief 

safety testing of train horns (toots) prior to departure from the building. Physical 

structures, such as the proposed layover facility itself, were also entered in the Cadna-A 

model in their three-dimensional sizes to account for the propagation of sound around and 

over such obstacles. Noise sources outside the layover facility included up to four roof top 

fans for ventilation, rolling service doors, employee and delivery truck vehicles, trains 

moving slowly (10 mph) in/out of the building, rail switch noise as trains roll over them, 
15 

and train horn soundings at Church Road and Stanwood Street, as applicable. Detailed 

printouts of the Cadna-A model’s input data tables and results tables are included in 

Appendix A. 

8. Existing Service Levels Noise Assessment 

The first noise analysis scenario assesses noise from the layover facility with existing 

Downeaster service levels, i.e. the three round trip scenario. 

8.1 No-Build Scenario 

Without a layover facility, the No-Build scenario would include the existing Downeaster 

service levels along with a single train idling in Brunswick yard from approximately 12:00 

noon to 5:00 PM daily. The train set would return to Brunswick yard after unloading 

passengers at Brunswick Station and remain in the yard until the next southbound trip. 

The locomotive will need to idle to prevent freezing during colder months of the year. 

The noise emission levels of the idling Downeaster train set were measured and are 

presented in Sections 4. Ambient noise measurements performed in February 2013 as 

described in Section 5 included days when the Downeaster was, and was not, idling in the 

Brunswick yard. A comparison of the two conditions revealed that noise levels at the three 

receptor locations were elevated by an average of 2 to 7 dBA while the train was idling in 

Brunswick yard. Not surprisingly, discussions with affected neighbors revealed their 

dislike of the noise when the Downeaster train set was idling outdoors. However, it should 

be noted that the same service level scenario with a layover facility would allow the train to 

move indoors year-round and remain shut down while inside the facility, thus providing a 

substantial degree of noise reduction for the affected community by rendering the idling 

trains essentially inaudible. 

8.2 Project-Generated Noise Assumptions 

The layover facility is expected to generate minimal sound of its own. No heavy equipment, 

major maintenance, or cleaning activities will be conducted at the facility. The trains and 

any light housecleaning equipment will be housed inside the facility building. It is assumed 

that two forklifts, two air compressors, and up to two pneumatic tools may be used inside 

the facility for a couple hours per day. At most, 70 staff and 8 service vehicles (trucks) may 

visit the facility in a single day. Parking will be located on the north side of the building 

with access from Church Road. 

The assumptions for project-generated noise sources in accordance with FRA/FTA 

requirements are summarized below in Table 6. To compare predictions with the Maine 
16 

DEP and Town of Brunswick noise limits, both of which use the hourly equivalent sound 

level (Leq(h)) noise metric, the operations that would occur during a potential worst-case 

hour were identified. These assumptions are also included in Table 6. 

Downeaster train sets will make six daily trips between Brunswick Station and the facility. 

All trains will enter and exit on the east side of the facility, so the project will cause no 

additional horn blows at the Church Road crossing. All trains will be traveling at 10 mph 

within Brunswick yard. Four train movements between Brunswick station and the facility 

will occur during the daytime (7 AM to 10 PM) and two will occur at night (10 PM to 7 AM), 

each with an associated horn sounding at the Stanwood Street crossing. 

Up to three trains at a time may be housed inside the layover facility. They will remain 

shut-off during the night and then be powered up to allow for about a half-hour warm up 

period in the mornings. Train horns will then be tested briefly with a “short toot” inside 

the facility before exiting. The facility’s walls have been specified to provide for a sound 

transmission class of at least STC 21. The building’s roll-up doors will remain closed except 

to allow trains to enter and exit. 

It is assumed that four rooftop mounted ventilation fans will be required to provide 

adequate airflow inside the facility building. It has been specified that these rooftop fans be 

of the low-noise emission variety, which are typically about 10 decibels quieter than 

standard fans. 
17 

Table 6. Project-Generated Noise Assumptions – Existing Service Levels 

Source 

Daytime Nighttime Worst 

Hour*

(7 AM - 10 PM) (10 PM - 7 AM) 

E

XT

E

RIO

R

Downeaster train passbys at 30 mph 0 0 0 

Horn blows at Church Rd. crossing 0 0 0 

Horn blows at Stanwood St. crossing 4 2 1 

Trains entering or exiting Brunswick 

yard from Brunswick Station at 10 mph 4 2 1 

No. of rail switch events in Brunswick 

yard 8 4 2 

No. of fans operating continuously on 

roof of layover facility 4 4 4 

No. of automobiles entering or exiting 

layover facility 50 20 5 

No. of trucks entering or exiting 

layover facility 6 2 1 

IN

T

E

RIO

R

Duration of trains idling inside layover 

facility (min) 70 30 30 

No. of train horn soundings inside 

layover facility 2 1 1 

Duration of 2 forklifts operating inside 

layover facility (min) 120 60 60 

Duration of 2 air impact tools 

operating inside layover facility (min) 60 60 60 

Duration of 2 air compressors 

operating inside layover facility (min) 60 60 60 

Duration of rolling service doors 

operating (min) 10 5 5 

 

*

 Worst-hour assumptions are for comparison relative to Maine DEP and Brunswick Ordinance criteria. 

Assumptions only include project-generated noise associated with the introduction of the layover facility. 
18 

8.3 FRA/FTA Noise Predictions and Impact Assessment 

Table 7 summarizes the predicted noise levels and noise impact assessment for Existing 

Downeaster Service Levels relative to FRA/FTA criteria. The predictions are also shown 

graphically in Figure 7. 

The predicted project-generated noise level at Site 1 is 49 dBA Ldn where the FRA/FTA 

noise limits are 54 and 60 dBA Ldn for moderate and severe impact, respectively. 

Similarly, the project is expected to generate a noise level of 48 dBA Ldn at Site 2 where the 

FRA/FTA noise limits are also 54 and 60 dBA Ldn for moderate and severe impact, 

respectively. And due to its farther distance from trains moving in the yard, the predicted 

project-generated noise level at Site 3 is expected to be only 43 dBA Ldn, well below its 

FRA/FTA noise limits of 55 dBA Ldn and 61 dBA Ldn for moderate and severe impact, 

respectively. 

The results show that project-generated noise levels are not predicted to exceed FRA/FTA 

noise criteria limits at any receptor site. The predicted noise levels are highest at Sites 1 

and 2, which is primarily a result of train movements in Brunswick yard. Nevertheless, the 

predicted project noise levels are still five decibels or more below the threshold for 

moderate impact at all receptor sites. 

8.4 Maine DEP and Brunswick Ordinance Noise Predictions 

Table 8 compares the predicted project noise levels for Existing Downeaster Service 

relative to Maine DEP and Town of Brunswick Ordinance noise limits. The predictions are 

also shown graphically in Figure 8. Worst hour Leq(h) noise levels were calculated at both 

the facade and at the property lines for each receptor site. 

It is important to note again that this project is not subject to compliance with either the 

Maine DEP Noise Regulation or the Town of Brunswick Noise Ordinance. Comparisons 

relative to these two guidelines have been included for information only and not for the 

evaluation of mandatory compliance with regulatory requirements.

As can be seen, project noise levels are predicted to comply with Maine DEP noise limits at 

all receptor sites during the daytime and at Sites 1 and 3 during the nighttime. The 

predicted noise levels exceed the Maine DEP nighttime limits at the property line of Site 2 

by three decibels. 
19 

Project noise levels are predicted to comply with Brunswick Ordinance noise limits at all 

receptor sites during the daytime and at Site 1 during the nighttime. Project noise levels 

are predicted to exceed the nighttime noise limits at Sites 1 and 2. The nighttime 

exceedance at the Site 1 property line is primarily due to its close proximity to the layover 

facility facade. The predicted project-generated noise level at the Site 1 property line is 57 

dBA Leq(h), which exceeds the Brunswick ordinance limit by seven decibels. A nighttime 

exceedance is not expected at the Site 2 receptor facade. 

The nighttime noise exceedance at Site 2 is primarily due to a single train movement in 

Brunswick yard. The predicted project-generated noise level at the Site 2 receptor facade 

is 48 dBA Leq(h), which exceeds the Brunswick ordinance limit by three decibels. The 

predicted noise level at the receptor’s property line is 53 dBA Leq(h), which would exceed 

the guideline by eight decibels. 

However, it should be noted that people would generally not be using the property line 

location in the middle of the night, so these predicted exceedances need to be viewed in 

that context. The ambient noise measurements shown in Figures 4 – 6 also illustrate that 

existing noise levels during several nighttime hours are already higher than the worst-case 

noise levels the project is expected to generate. 
20 

Table 7. Summary of Predicted Noise Levels and FRA/FTA Impact Assessment for Existing Se

Measured 

Ambient 

Noise Level 

FRA/FTA Project Noise Impact 

Criteria 

Pre

P

Noi

Moderate Severe 

Site No. Receptor Address Land-Use Ldn, dBA Ldn, dBA Ldn, dBA Ld

1 

Knights Inn, 133 Pleasant Street, 

Apt. H8 

Category 2 53 54 60 

2 Residence, 22 Bouchard Drive Category 2 53 54 60 

3 

Resource Systems Eng., 30 Parkers 

Way 

Category 2 54 55 61 

Table 8. Summary of Predicted Noise Levels and Maine DEP/Brunswick Ordinance Limits for Exis

Applicable Noise Criteria 

Maine DEP Brunswick Ordinance

Proj

Noise 

Site 

No. 

Receptor Address Land-Use Daytime Nighttime Daytime Nighttime 

Leq

dB

1 Knights Inn, 133 Pleasant Street, Apt. H8 Mixed 70 60 60 50 5

1 Site 1 Property Line Mixed 70 60 60 50 5

2 Residence, 22 Bouchard Drive Residential 60 50 55 45 4

2 Site 2 Property Line Residential 60 50 55 45 5

3 Resource Systems Eng., 30 Parkers Way Mixed 70 60 60 50 4

3 Site 3 Property Line Mixed 70 60 60 50 4
21 

Figure 7. Predicted Project Ldn Noise Levels – Existing Service Levels 

Figure 8. Predicted Project Worst-Hour Leq(h) Noise Levels – Existing Service Levels 

9. Future Service Levels Noise Assessment 

The second noise analysis scenario assesses noise from the layover facility with future 

Downeaster service levels, i.e. the five round trip scenario. 

9.1 No-Build Scenario 

Without a layover facility, the No-Build scenario with future Downeaster service levels 

would include sixteen daily Downeaster trips between Portland and Brunswick. Eleven of 

these trips would occur during the daytime and five would occur at night. Each passing 
22 

train would be traveling at full speed and sound its horn at both the Stanwood Street and 

Church Road at-grade crossings. Ten of these trips (8 day, 2 night) would be scheduled 

Downeaster service, while the remaining six trips (3 day, 3 night) would be non-revenue 

(deadhead) trips. The deadhead trips would be necessary so that trains could layover in 

Portland at night and return to Brunswick in the morning to begin the trip south towards 

Boston. 

By comparison, building the layover facility would eliminate the need for all six of the 

deadhead trips, as trains would be stored in Brunswick overnight. Six horn soundings at 

the Church Road crossing also would not occur if the layover facility were built. 

9.2 Project-Generated Noise Assumptions 

The project-generated noise assumptions for the Future Service Levels scenario are shown 

in Table 9. The assumptions include noise associated with the expanded Downeaster 

service, the layover facility itself, and any trains accessing it. As discussed in Section 7, 

while expansion of Downeaster service is not a part of the proposed action, noise associated 

with the expanded service has been included in the project-generated noise predictions to 

be conservative and allow for direct comparison to the existing service levels scenario. 

The Future Service Levels scenario assumes ten daily Downeaster trips between Portland 

and Brunswick. A typical Downeaster train set consists of a diesel-electric locomotive with 

five railcars. Eight of the train trips will occur during daytime hours and two will occur 

during the nighttime period with trains assumed to be traveling at 30 mph. Each passing 

train will sound its horn at both the Stanwood Street and Church Road at-grade crossings. 

Noise from the existing Downeaster service (6 daily trips) is already accounted for in the 

ambient noise measurements and factored into the noise impact criteria. The increase in 

operations associated with further expanding the Downeaster service to 10 daily trips 

would be three daytime passbys and one nighttime passby, each with an associated horn 

sounding at the Stanwood Street and Church Road at-grade crossings. 

Downeaster train sets will make ten trips between Brunswick Station and the facility daily. 

Seven trips will occur during the daytime (7 AM to 10 PM) and three will occur at night (10 

PM to 7 AM), each with an associated horn sounding at the Stanwood Street crossing. All 

trains will enter and exit on the east side of the facility and travel at 10 mph within 

Brunswick yard. 

The layover facility is expected to generate minimal sound of its own. No heavy equipment, 

major maintenance, or cleaning activities will be conducted at the facility. The trains and 

any light housecleaning equipment will be housed inside the facility building. It is assumed 
23 

that two forklifts, two air compressors, and up to two pneumatic tools may be used inside 

the facility for a couple hours per day. At most, 70 staff and 8 service vehicles (trucks) may 

visit the facility in a single day. Parking will be located on the north side of the building 

with access from Church Road. 

Up to three trains at a time may be housed inside the layover facility. They will remain 

shut-off during the night and then be powered up to allow for about a half-hour warm up 

period in the mornings. Train horns will then be tested briefly with a “short toot” inside 

the facility before exiting. The facility’s walls have been specified to provide for a sound 

transmission class of at least STC 21. The building’s roll-up doors will remain closed except 

to allow trains to enter and exit. 

It is assumed that four rooftop mounted ventilation fans will be required to provide 

adequate airflow inside the facility building. It has been specified that these rooftop fans be 

of the low-noise emission variety, which are typically about 10 decibels quieter than 

standard fans. 

To evaluate compliance with the Maine DEP and Town of Brunswick noise limits, both of 

which use the hourly equivalent sound level (Leq(h)) noise metric, the operations that 

would occur during a potential worst-case hour were identified. To be consistent with the 

regulations, only noise associated with the introduction of the layover facility was 

predicted. These assumptions are also listed in Table 9. 
24 

Table 9. Project-Generated Noise Assumptions – Future Service Levels 

Source 

Daytime Nighttime Worst 

Hour*

(7 AM - 10 PM) (10 PM - 7 AM) 

E

XT

E

RIO

R

Downeaster train passbys at 30 mph 3 1 0 

Horn blows at Church Rd. crossing 3 1 0 

Horn blows at Stanwood St. crossing 10 4 1 

Trains entering or exiting Brunswick 

yard from Brunswick Station at 10 mph 7 3 1 

No. of rail switch events in Brunswick 

yard 14 6 2 

No. of fans operating continuously on 

roof of layover facility 4 4 4 

No. of automobiles entering or exiting 

layover facility 50 20 5 

No. of trucks entering or exiting 

layover facility 6 2 1 

IN

T

E

RIO

R

Duration of trains idling inside layover 

facility (min) 70 120 30 

No. of train horn soundings (1 sec 

duration) inside layover facility 1 2 1 

Duration of 2 forklifts operating inside 

layover facility (min) 120 60 60 

Duration of 2 air impact tools 

operating inside layover facility (min) 60 60 60 

Duration of 2 air compressors 

operating inside layover facility (min) 60 60 60 

Duration of rolling service doors 

operating (min) 10 5 5 

9.3 FRA/FTA Noise Predictions and Impact Assessment 

Table 10 summarizes the predicted noise levels and noise impact assessment for future 

Downeaster service levels relative to FRA/FTA criteria. The predictions are also shown 

graphically in Figure 9.

 

*

 Worst-hour assumptions are for comparison relative to Maine DEP and Brunswick Ordinance criteria. 

Assumptions only include project-generated noise associated with the introduction of the layover facility. 
25 

The predicted project-generated noise level is 51 dBA Ldn at Site 1 where the FRA/FTA 

noise limits are 54 and 60 dBA Ldn for moderate and severe impact, respectively. 

Similarly, the project-generated noise level is expected to be 51 dBA Ldn at Site 2 where the 

FRA/FTA noise limits are also 54 and 60 dBA Ldn for moderate and severe impact, 

respectively. The predicted project-generated noise level at Site 3 is expected to be 50 dBA 

Ldn where the FRA/FTA noise limits are 55 and 61 dBA Ldn for moderate and severe 

impact, respectively. 

The results show that project-generated noise levels are not predicted to exceed FRA/FTA 

noise criteria limits at any receptor site. The predicted noise levels are highest at Sites 1 

and 2, which is primarily a result of train movements in Brunswick yard. Nevertheless, the 

predicted noise levels are still three decibels or more below the threshold for moderate 

impact at all receptor sites. 

9.4 Maine DEP and Brunswick Ordinance Noise Predictions 

Table 11 compares the predicted project noise levels for Future Downeaster Service 

relative to Maine DEP and Brunswick Ordinance noise limits. The predictions are also 

shown graphically in Figure 10. Worst hour Leq(h) noise levels were calculated at both 

the facade and at the property lines for each receptor site. 

It is important to note again that this project is not subject to compliance with either the 

Maine DEP Noise Regulation or the Brunswick Noise Ordinance. Comparisons relative to 

these two guidelines have been included for information only and not for the evaluation of 

mandatory compliance with regulatory requirements.

As can be seen, project noise levels are predicted to comply with Maine DEP noise limits at 

all receptor sites during the daytime and at Sites 1 and 3 during the nighttime. The 

predicted noise levels exceed the Maine DEP nighttime limits at the property line of Site 2 

by three decibels. 

Project noise levels are predicted to comply with Brunswick Ordinance noise limits at all 

receptor sites during the daytime and at Site 1 during the nighttime. Project noise levels 

are predicted to exceed the nighttime noise limits at Sites 1 and 2. The nighttime 

exceedance at the Site 1 property line is primarily due to its close proximity to the layover 

facility facade. The predicted project-generated noise level at the Site 1 property line is 57 

dBA Leq(h), which exceeds the Brunswick ordinance limit by seven decibels. A nighttime 

exceedance is not expected at the Site 2 receptor façade. 

The nighttime noise exceedance at Site 2 is primarily due to a single train movement in 

Brunswick yard. The predicted project-generated noise level at the Site 2 receptor facade 
26 

is 48 dBA Leq(h), which exceeds the Brunswick ordinance limit by three decibels. The 

predicted noise level at the receptor’s property line is 53 dBA Leq(h), which would exceed 

the guideline by eight decibels. 

However, it should be noted that people would generally not be using the property line 

location in the middle of the night, so these predicted exceedances need to be viewed in 

that context. The ambient noise measurements previously shown in Figures 4, 5 and 6

also illustrate that existing noise levels during several nighttime hours are already higher 

than the worst-case noise levels the project is expected to generate. 
27 

Table 10. Summary of Predicted Noise Levels and FRA/FTA Impact Assessment for Future Se

Measured 

Ambient 

Noise Level 

FRA/FTA Project Noise Impact 

Criteria 

Pre

P

Noi

Moderate Severe 

Site No. Receptor Address Land-Use Ldn, dBA Ldn, dBA Ldn, dBA Ld

1 

Knights Inn, 133 Pleasant Street, 

Apt. H8 

Category 2 53 54 60 

2 Residence, 22 Bouchard Drive Category 2 53 54 60 

3 

Resource Systems Eng., 30 Parkers 

Way 

Category 2 54 55 61 

Table 11. Summary of Predicted Noise Levels and Maine DEP/Brunswick Ordinance Limits for Fut

Applicable Noise Criteria 

Maine DEP Brunswick Ordinance

Proj

Noise 

Site 

No. 

Receptor Address Land-Use Daytime Nighttime Daytime Nighttime 

Leq

dB

1 Knights Inn, 133 Pleasant Street, Apt. H8 Mixed 70 60 60 50 5

1 Site 1 Property Line Mixed 70 60 60 50 5

2 Residence, 22 Bouchard Drive Residential 60 50 55 45 4

2 Site 2 Property Line Residential 60 50 55 45 5

3 Resource Systems Eng., 30 Parkers Way Mixed 70 60 60 50 4

3 Site 3 Property Line Mixed 70 60 60 50 4
28 

Figure 9. Predicted Project-Generated Ldn Noise Levels – Future Service Levels 

Figure 10. Predicted Project Worst-Hour Leq(h) Noise Levels – Future Service Levels
29 

10. Train Horn Noise 

Horns are a necessary and proveneffective warning device used on trains 

of all types in service in the United 

States. For Downeaster trains, Amtrak 

uses a Nathan 5 Air Chime K5LA horn 

mounted on the top middle of the 

locomotive. All five “bells” face forward 

and produce a B major 6th chord (220 to 

554 Hertz) measuring 104 dBA at a 

reference distance of 100 feet. The 

K5LA five-chime assembly’s musical 

chord helps the horn to be heard and 

lessens complaints. However, to serve its intended purpose the horn must be loud relative 

to its surrounding background noise condition. 

The use and loudness of train horns are dictated in the United States by 49 CFR Parts 222 

and 229, as administered by the FRA. Train horns must produce a minimum of 96 dBA at a 

distance of 100 feet, but should not exceed 110 dBA at 100 feet. Train horns are required 

to be sounded 1⁄4 mile ahead of a street crossing as the train is approaching. The approach 

distance can be even greater if the train is moving at higher speeds. The warning should 

consist of two-long – one-short – one-long horn blows. The horn is also used at the 

engineer’s discretion and judgment in the event of pedestrians, vehicles or obstacles on the 

tracks. 

Of particular significance to this project, per FRA regulations the horn does not need to 

sound as the train moves around the yard or in and out of the layover facility to merge with 

the mainline track. Thus, the only location associated with this project where trains would 

need to sound their horn would be at the Stanwood Street crossing as trains move to and 

from Brunswick Station and the layover facility. 

Train horn noise was assessed for this project in the same manner as other facility and rail 

noise sources through use of the Cadna-A model. The model’s FRA/FTA module has train 

horn noise emissions in its database. Horn soundings at Stanwood Street and Church Road 

were included as point sources in the model; however, there are no train horn soundings 

expected at Church Road attributable to this project. The noise prediction results, as 

shown in Tables 7 and 10 for the Existing and Future Downeaster Service Levels scenarios, 

respectively, confirm that compliance with FRA/FTA noise limits is easily demonstrated 

even with the effects of trains horns included in the predicted levels. 
30 

10.1 Horn Noise Mitigation 

If reduction of from train horn noise were to be desired then noise barriers are generally 

not feasible at street crossings due to driver visibility. Residential soundproofing only 

addresses interior noise levels and is also fraught with issues involving access and liability 

on private property. Therefore, the only horn noise mitigation measure approved by 

FRA/FTA would be the establishment of a Quiet Zone. 

By adopting approved Supplemental Safety Measures (SSM) at each public grade crossing, a 

Quiet Zone of at least a half-mile long can be established. These measures are in addition to 

the standard safety devices required at most public grade crossings (e.g. stop signs, 

reflective cross bucks, flashing lights with gates that do not completely block travel over 

the tracks). Below are six SSM’s which have been predetermined by the FRA to fully or in 

tandem compensate for the lack of a locomotive horn: 

· Reconstruct the street crossing into an under-over pass. This measure, while expensive, 

would completely eliminate the need for a train to sound its horn. 

· Temporary closure of a public highway-rail grade crossing. This measure requires 

closure of the grade crossing one period for each 24 hours, and must be closed the 

same time each day. 

· Four-quadrant gate system. This measure involves the installation of at least one gate 

for each direction of traffic to fully block vehicles from entering the crossing. 

· Gates with medians or channelization devices. This measure keeps traffic in the proper 

travel lanes as it approaches the crossing. This denies the driver the option of 

circumventing the gates by traveling in the opposing lane. 

· One-way street with gates. This measure consists of one-way streets with gates 

installed so that all approaching travel lanes are completely blocked. 

· Pole-mounted wayside warning horns. This measure places warning horns on signal 

poles directly at the street crossing in question. The wayside horns are still relatively 

loud (92 dBA at 100 feet) but can be effectively aimed directly down the affected 

street to minimize disturbance to adjacent neighborhoods. 

The lead agency in designating a Quiet Zone is the local public authority responsible for 

traffic control and law enforcement on the roads crossing the tracks. In order to satisfy the 

FRA regulatory requirements, the public transit agency must work closely with the 
31 

highway/traffic agency while also coordinating with any freight or passenger railroad 

operator sharing the right-of-way. 

Renovating a street crossing in accordance with the SSM’s above can be expensive. It could 

easily cost $250,000 per crossing to complete all the necessary modifications to keep the 

street crossing at grade, and reconstructing the crossing into an under-over pass would 

cost millions of dollars. 

11. Vibration Assessment 

11.1 Vibration Fundamentals 

Environmental vibration can be generated by transportation systems such as trains, 

subways, trucks, automobiles; construction activities such as heavy earth moving 

equipment, blasting, pile driving; power generation or other large mechanical systems; or 

by actual seismic motion. While vibratory motion can be generated in all directions, only 

the vertical component is addressed in environmental studies. Vertical vibration typically 

contains more energy than either the longitudinal or latitudinal directions. 

Due to human perception of vibration, ease of quantifiable measurement, and predictability 

within the low frequencies of interest (1 Hz to 100 Hz), vibration velocity has been 

standardized as the metric for evaluating environmental vibration impacts. As such, 

vibration results can be expressed in linear units of inches per second. However, due to the 

very large velocity range over which vibration energy can be found (.0001 to 1.0 inch/sec), 

a more convenient decibel scale has also been adopted. The Vibration Velocity Level, or 

VdB, expressed in decibels relative to 1 micro-inch/sec, allows for the compression of this 

large velocity range into a more practical scale of about 40 to 120 VdB. 

According to FRA/FTA guidelines, the frequency range over which to examine human 

annoyance from vibration ranges from about 1 Hz to 100 Hz. The broadband VdB level is 

typically summed over this frequency range. However, the frequency spectrum range over 

which vibration levels are measured can be filtered to examine the amount of vibration 

energy within a finite bandwidth. Octave band and third-octave band filters serve this 

purpose. 

Vibration magnitude can be described using various quantities depending on the intent of 

the analysis and type of sensitive receptor being evaluated. In accordance with FRA/FTA 

procedures, all vibration measurements and predictions in this study are in the form of 

energy-averaged Root Mean Square (RMS) levels. RMS represents a mathematically 

averaged level which is more proportional to the energy-of-motion generated by a 
32 

vibrating surface. The RMS vibration velocity level has been shown to correlate better with 

the human body's sensitivity to vibration when computed with a one-second response time 

(i.e. RMS ‘slow’). Train passby vibration events are typically expressed in VdB levels using 

the maximum RMS levels within each frequency band in order to evaluate worst-case 

potential consequences. 

A related vibration metric would be the Peak Particle Velocity (PPV) which is a measure of 

the vibration signal’s absolute highest instantaneous magnitude. Being a measure of 

vibration velocity, the PPV is also expressed in linear units of inches/second. Human 

annoyance is generally not a function of instantaneous PPV levels, however potential 

damage to buildings and structures can be, so an analysis of PPV levels is only used to 

assess potential cosmetic or major damages to structures. For example, PPV levels are 

used to describe potential building damages from impact sources such as construction. 

11.2 Vibration Criteria 

As shown in Figure 11, FRA/FTA’s vibration criteria are intended to avoid human 

annoyance and are based on root-mean-squared (RMS) vertical vibration velocity levels 

expressed in decibel units of VdB relative to one micro-inch per second (VdB re: 1 microinch/second). The vibration criteria limits are absolute levels, not relative increases above 

existing conditions, and thus do not require ambient vibration levels to be established. 

The FRA/FTA’s vibration limits vary based on a receptor’s categorized land-use and 

frequency of vibration events (i.e. train passbys). Residential receptors are considered as 

Category 2 receptors, while institutional land-uses are placed in Category 3. Most general 

purpose commercial buildings are not included in any category. "Frequent" events are 

defined as more than 70 vibration events per day, “Occasional” events range from 30 to 70 

per day, and "Infrequent" events are defined as fewer than 30 per day. Most commuter and 

inter-city rail systems fall into this latter category. 

In addition, vibration criteria for special buildings such as concert halls, TV and recording 

studios, auditoriums and theaters have been established, as have criteria limits for groundborne vibration-induced interior noise levels, although these criteria are only applied in 

special cases involving particularly sensitive receptors and are not expected in the current 

study. 

For the current project, the three receptors were considered to be Category 2 or Category 3 

receptors, as appropriate, exposed to “infrequent” events (i.e. less than 30 per day). This 

will be the case for the both the Existing and Future Downeaster Service Levels scenarios 

being evaluated in this study. 
33 

Therefore, based on the relatively limited number of future vibration events per day 

associated with the subject layover facility, the vibration impact limits for this project per 

FRA/FTA’s criteria approach are shown in Table 12 for the three receptor locations.

Figure 11. FRA/FTA Criteria for Ground-Borne Vibration Impact 

Table 12. FRA/FTA Criteria Limits for Vibration Impact 

Site 

No. Receptor Address Land-Use(FRA/FTA Category) 

Vibration Velocity Limit

for Infrequent Events (VdB) 

1 Knights Inn, Apt. H8, 

133 Pleasant Street 

Residential 

(Category 2) 80 

2 Residence, 

22 Bouchard Drive 

Residential 

(Category 2) 80 

3 Commercial Business, 

30 Parkers Way 

Commercial 

(Category 3) 83 
34 

11.3 Ambient Vibration Measurements 

Even though ambient vibration measurements are not required in accordance with 

FRA/FTA procedures, ambient vibration levels were measured in September 2011 with no 

train activity, and again in February 2013 to document the levels with Downeaster train 

service on the mainline. Both of these conditions are considered to represent ambient or 

existing vibration conditions as they are not generated by the current project. 

Measurements were conducted at the three receptor locations identified in Section 4 in 

order to provide a better frame of reference for understanding vibration levels and relative 

differences with and without the project. The vibration monitoring instrumentation used 

in this study is listed in Table 13. 

A highly sensitive (10 V/g) PCB 393B05 Accelerometer was used on a 35 pound mounting 

mass to measure vibration levels in the vertical direction a few inches outside the 

foundation at each receptor building. The accelerometer’s signal was passed through a PCB 

480E09 Power Supply Amplifier and into a CEL Instruments 593 Analyzer via a Bruel & 

Kjaer ZR0020 Input Adaptor. The CEL 593 allowed for optimization of the signal’s dynamic 

range prior to its being output and permanently stored as a digital wav file in a Marantz 

PMD670 Recorder. The digital wav file was later analyzed using SpectraPLUS computerbased FFT software to allow analysis of the low frequency third-octave band range of 1Hz 

to 100 Hz using an RMS ‘slow’ response. The resulting acceleration spectra were then 

exported to Excel spreadsheets in order to convert and calculate the resulting measured 

RMS vertical vibration velocity level into decibel units of VdB re: 1 micro-inch/second. 

The PCB 393B05 accelerometer is too sensitive to be calibrated by a typical hand-held field 

calibrator. Therefore, its published sensitivity was used in a comparison calibration 

method with the results obtained from a less-sensitive Endevco 7703A-1000 accelerometer 

mounted on a PCB 394C06 vibration calibrator which produces 1 g RMS. This method 

allowed for proper calibration of the entire vibration data collection and analysis system. 

Table 13. Vibration Monitoring Instrumentation 

Manufacturer Model Description 

CEL Instruments CEL593.C1T/2M Noise and Vibration Analyzer, ANSI Type 1 

Bruel & Kjaer ZR0020 Accelerometer Input Adaptor for SLM 

PCB Piezotronics 394C06 Vibration Calibrator, 1.0 g at 159.2 Hz 

PCB Piezotronics 480E09 Signal Conditioner, x1, x10, x100 gain 
35 

PCB Piezotronics 422E13 Charge Amplifier Converter, 1pC to 1mV 

PCB Piezotronics 393B05 Accelerometer, 9870 mV/g 

Endevco 7703A-1000 Accelerometer, 981.3 pC/g, 981.3 mV/g 

Marantz PMD670 Solid State Data Recorder (wav files) 

Pioneer Hill Software SpectraPLUS 5.0 FFT & RTA Spectral Analysis PC Software 

The results of the ambient vibration monitoring exercises are shown in Figures 12, 13 and 

14 for receptor Sites 1, 2 and 3, respectively. As shown, vibration levels exterior to the 

buildings ranges from 44 to 48 VdB during non-event time periods, and can be as high as 

63 to 65 VdB during passbys of the Downeaster train. The speeds at which the Downeaster 

passed the receptors during the vibration measurements ranged from 10 to 50 mph as 

measured with a radar gun. These ambient vibration results are also summarized in Table 

14 as they relate to predicted future project-generated vibration levels and FRA/FTA 

vibration criteria limits.

Figure 12. Ambient Vibration Levels at Site 1 
36 

Figure 13. Ambient Vibration Levels at Site 2 

Figure 14. Ambient Vibration Levels at Site 3 
37 

11.4 Project-Generated Vibration Levels 

The subject layover facility is expected to generate negligible vibration of its own. No 

heavy earth-moving equipment will be used at the facility, nor will any drilling, blasting or 

impact-type work be performed. As such the only notable potential vibration generating 

source to consider is the movement of Amtrak Downeaster trains in/out of the layover 

facility’s eastern end moving at a very slow speed. 

In this case the FRA/FTA’s “general method” ground-borne vibration model was used to 

predict train movement vibration levels potentially affecting the three receptor locations. 

The model predicts vibration velocity levels in units of VdB based on a train’s speed, 

distance to the receptor (i.e. from the center of the future layover facility area, not from the 

closest point at which the mainline tracks pass the receptors), number of events per day, 

coupling efficiency of the receptor’s foundation to the ground, and any special track or 

ground conditions that may accentuate or diminish vibration. 

It was assumed that future tracks will be continuous welded rail (CWR), and that the trains 

would be moving as fast as 10 mph in and out of the eastern end of the layover facility. 

Once trains merge back onto the mainline tracks they are no longer considered part of this 

project for either the Existing Service Level or the Future Service Level. The applicable 

vibration adjustment of +10 VdB was selected in the model for trains moving over switches 

in the yard. 

To estimate the vibration levels inside each receptor building per FRA/FTA procedures, a 

foundation coupling efficiency adjustment of -5 VdB for wooden framed structures was 

assumed for all three receptors. In contrast, the ambient vibration level measurements 

were performed outside of each receptor's building. Vibration levels inside a building will 

always be less than those measured outside the building. And based on a report that there 

may be a high water table in the area, a penalty of +10 VdB was applied in the model to 

account for potentially more effective vibration transmission through soil. These 

assumptions and adjustments were applied in order to yield conservative or worst-case 

vibration predictions at the receptors’ locations. 

The results of the train movement-induced ground-borne vibration velocity level 

predictions can be seen in Table 14 for each receptor location. As can be seen, even with 

the relatively conservative assumptions for efficient vibration generation and propagation, 

the results are expected to be orders of magnitude below applicable FRA/FTA vibration 

criteria limits. It can therefore easily be concluded that this project represents no groundborne vibration-related impacts of any kind for any of the receptors. 
38 

Table 14. Ambient and Predicted Vibration Levels 

Site 

No. Receptor Address 

Land-Use 

(FRA/FTA 

Category) 

Modeled 

Distance 

from 

Train to 

Receptor 

(feet) 

Measured

Exterior 

Ambient 

Vibration 

Level 

Non-Event/ 

Downeaster

(VdB) 

Predicted 

Interior 

Train 

Movement 

Vibration 

Level 

(VdB) 

FRA/FTA 

Vibration 

Criteria 

(VdB) 

1 Knights Inn, Apt. H8, 

133 Pleasant Street 

Residential 

(Category 2) 200 48 / 64 73 80 

2 Residence, 

22 Bouchard Drive 

Residential 

(Category 2) 490 44 / 65 66 80 

3 Commercial Business, 

30 Parkers Way 

Commercial 

(Category 3) 870 47 / 63 61 83 

12. Conclusions 

A comprehensive noise and vibration assessment was performed for the Brunswick 

Layover Facility project. Two scenarios with differing levels of Downeaster train service 

were evaluated: (1) Existing Service Levels, and (2) Future Service Levels. For each 

scenario, predicted noise and vibration levels were evaluated at three community receptor 

locations in accordance with Federal Railroad Administration and Federal Transit 

Administration guidelines. Project-generated noise levels were also assessed for 

information only relative to Maine Department of Environmental Protection and Town of 

Brunswick Ordinance noise guidelines. 

The results conclude that the project will easily comply with all relevant FRA/FTA noise 

and vibration impact criteria. Additional noise and vibration mitigation measures beyond 

those assumed in this study will not be required for this project. 

Moreover, the construction of an indoor layover facility in the Brunswick yard will provide 

a notable reduction in community noise level relative to the No-Build scenario in which a 

Downeaster train set is allowed to idle outdoors during the afternoon hours.