Research, Development, and Technology

Turner-Fairbank Highway Research Center

6300 Georgetown Pike

McLean, VA 22101-2296

Automation in Highway Construction

Part II: Design Guidance and Guide

Specification Manual 

PUBLICATION NO. FHWA-HRT-16-031 FEBRUARY 2018
FOREWORD

The Federal Highway Administration conducted research to document gaps for implementing 

automation in highway construction and to develop guidance for State transportation 

departments to assist them in implementing and using automation to improve project delivery. 

There are two volumes of the final report. Part I presents a description of the key automation 

technology areas and the associated benefits, challenges, and solutions.(1) Part II (this volume) 

presents an overview of enabling technologies and policies for automation in highway 

construction as well as implementation strategies, design procedures, and practical guidelines to 

properly generate three-dimensional (3D) models for uses in construction and other phases of 

highway project delivery.

While 3D design practices are common in State transportation departments, automation 

technology requires added detail in 3D design models to output data in a portable and durable 

format and also requires additional organization and description of the data. This report provides 

the accuracies needed for both survey control and topographic survey. It describes how 

construction specifications can incorporate practices to manage the use of automation technology 

in a manner to adapt to project characteristics and evolving technologies. It also describes how 

consistency in 3D data and survey methods provides for automated inspection tasks, especially 

acceptance and measurement processes, can enhance transparency, make inspectors available to 

observe construction, and enhance project safety. State transportation departments interested in 

developing 3D digital design for use in automation in highway construction would benefit from 

reading this volume.

Cheryl Allen Richter, P.E., Ph.D. 

Director, Office of Infrastructure 

Research and Development

Notice

This document is disseminated under the sponsorship of the U.S. Department of Transportation

(USDOT) in the interest of information exchange. The U.S. Government assumes no liability 

for the use of the information contained in this document.

The U.S. Government does not endorse products or manufacturers. Trademarks or 

manufacturers' names appear in this report only because they are considered essential to the 

objective of the document.

Quality Assurance Statement

The Federal Highway Administration (FHWA) provides high-quality information to serve

Government, industry, and the public in a manner that promotes public understanding. Standards 

and policies are used to ensure and maximize the quality, objectivity, utility, and integrity of its 

information. FHWA periodically reviews quality issues and adjusts its programs and processes to 

ensure continuous quality improvement.
TECHNICAL REPORT DOCUMENTATION PAGE

1. Report No.

FHWA-HRT-16-031

2. Government Accession No.

N/A

3. Recipient’s Catalog No.

N/A

4. Title and Subtitle

Automation in Highway Construction Part II: Design Guidance and Guide 

Specification Manual

5. Report Date

February 2018

6. Performing Organization Code 

N/A

7. Author(s)

Francesca Maier and Dr. Jagannath Mallela of Parsons Brinckerhoff;

Helga N. Torres, J. Mauricio Ruiz, and Dr. George K. Chang of The 

Transtec Group, Inc.

8. Performing Organization Report No. 

N/A

9. Performing Organization Name and Address 

Parsons Brinckerhoff

100 S. Charles Street 

Baltimore, MD 21201

The Transtec Group, Inc. 

6111 Balcones Drive

Austin, TX 78731

10. Work Unit No. (TRAIS) 

N/A

11. Contract or Grant No. 

DTFH61-13-C-00026

12. Sponsoring Agency Name and Address 

Federal Highway Administration

Office of Infrastructure Research and Technology 

6300 Georgetown Pike

McLean, VA 22101-2296

13. Type of Report and Period Covered 

Draft Final Report; 2014–2016

14. Sponsoring Agency Code 

N/A

15. Supplementary Notes

The Contracting Officer’s Representative is Richard Duval, HRDI-20.

16. Abstract

Automation in highway construction includes an increasing number of technologies that collect, store, analyze, and 

process information to make, support, or execute an appropriate action or decision that results in enhanced 

construction outcomes. The goal of automation in highway construction is to increase speed, efficiency, and/or safety 

during the construction process. This goal is in conjunction with components, processes, and software that assist in a 

more efficient construction system.

The primary objectives of this project were to (1) address gaps identified for implementing automation in highway 

construction and (2) develop guidance for State transportation departments to assist them in implementing automation 

to improve accelerated project delivery.

There are two volumes of the final report for each of the two objectives. Part I presents a description of the 

key automation technology areas and the associated benefits, challenges, and solutions.(1) Part II (this volume) 

presents an overview of enabling technologies and policies for automation in highway construction as well as

implementation strategies. This volume also includes design procedures and practical guidelines to properly generate 

three-dimensional models for uses in construction and other phases of highway project delivery.

17. Key Words

Automation in highway construction, Intelligent 

construction, Automation, Guidelines, Guide specifications

18. Distribution Statement

No restrictions. This document is available to the 

public through the National Technical Information

Service, Springfield, VA 22161. 

http://www.ntis.gov

19. Security Classif. (of this report)

Unclassified

20. Security Classif. (of this page)

Unclassified

21. No. of Pages

130

22. Price

Form DOT F 1700.7 (8-72) Reproduction of completed page authorized.
ii

SI* (MODERN METRIC) CONVERSION FACTORS

APPROXIMATE CONVERSIONS TO SI UNITS

Symbol When You Know Multiply By To Find Symbol

LENGTH

in inches 25.4 millimeters mm

ft feet 0.305 meters m

yd yards 0.914 meters m

mi miles 1.61 kilometers km

AREA

in2 square inches 645.2 square millimeters mm2

ft2 square feet 0.093 square meters m

2

yd2 square yard 0.836 square meters m

2

ac acres 0.405 hectares ha

mi2 square miles 2.59 square kilometers km2

fl oz 

gal 

ft3

yd3

VOLUME

fluid ounces 29.57 milliliters

gallons 3.785 liters

cubic feet 0.028 cubic meters

cubic yards 0.765 cubic meters 

NOTE: volumes greater than 1000 L shall be shown in m3

mL 

L

m

3

m

3

MASS

oz ounces 28.35 grams g

lb pounds 0.454 kilograms kg

T short tons (2000 lb) 0.907 megagrams (or "metric ton") Mg (or "t")

oF

TEMPERATURE (exact degrees)

Fahrenheit 5 (F-32)/9 Celsius 

or (F-32)/1.8

oC

fc 

fl

ILLUMINATION

foot-candles 10.76 lux

foot-Lamberts 3.426 candela/m2

lx 

cd/m2

lbf 

lbf/in2

FORCE and PRESSURE or STRESS

poundforce 4.45 newtons

poundforce per square inch 6.89 kilopascals

N

kPa

APPROXIMATE CONVERSIONS FROM SI UNITS

Symbol When You Know Multiply By To Find Symbol

LENGTH

mm millimeters 0.039 inches in

m meters 3.28 feet ft

m meters 1.09 yards yd

km kilometers 0.621 miles mi

AREA

mm2 square millimeters 0.0016 square inches in2

m

2

square meters 10.764 square feet ft2

m

2

square meters 1.195 square yards yd2

ha hectares 2.47 acres ac

km2 square kilometers 0.386 square miles mi2

VOLUME

mL milliliters 0.034 fluid ounces fl oz

L liters 0.264 gallons gal

m

3

cubic meters 35.314 cubic feet ft3

m

3

cubic meters 1.307 cubic yards yd3

MASS

g grams 0.035 ounces oz

kg kilograms 2.202 pounds lb

Mg (or "t") megagrams (or "metric ton") 1.103 short tons (2000 lb) T

oC

TEMPERATURE (exact degrees)

Celsius 1.8C+32 Fahrenheit oF

lx 

cd/m2

ILLUMINATION

lux 0.0929 foot-candles

candela/m2 0.2919 foot-Lamberts

fc 

fl

N

kPa

FORCE and PRESSURE or STRESS

newtons 0.225 poundforce

kilopascals 0.145 poundforce per square inch

lbf 

lbf/in2

*SI is the symbol for the International System of Units. Appropriate rounding should be made to comply with Section 4 of ASTM E380. 

(Revised March 2003)
iii

TABLE OF CONTENTS

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

OBJECTIVE ........................................................................................................................... 2

SCOPE ..................................................................................................................................... 3

GLOSSARY OF TERMS....................................................................................................... 4

CHAPTER 2. DEVELOPMENT OF AUTOMATION TECHNOLOGY GUIDELINES..... 7

OBJECTIVES ......................................................................................................................... 7

STAKEHOLDERS ................................................................................................................. 9

POLICY AREAS .................................................................................................................. 10

CAPITAL AND HUMAN RESOURCES INVESTMENTS............................................. 11

Hardware........................................................................................................................... 11

Software ............................................................................................................................ 12

Changing Job Functions.................................................................................................... 12

Training Needs.................................................................................................................. 12

CHAPTER 3. IMPLEMENTATION STRATEGIES ............................................................. 15

FORMAL IMPLEMENTATION PLANS ......................................................................... 15

NOTABLE IMPLEMENTATION STRATEGIES ........................................................... 17

Establishing a Vision ........................................................................................................ 17

Defining a Purpose and Need ........................................................................................... 17

Identifying Known Issues................................................................................................. 17

Implementation Goals....................................................................................................... 18

Establishing an Implementation Team.............................................................................. 19

Specific Activities............................................................................................................. 19

Tracking Performance....................................................................................................... 20

IMPLEMENTATION PLANNING RESOURCES........................................................... 20

CHAPTER 4. ENABLING TECHNOLOGIES AND POLICIES ......................................... 25

IN-PLACE CAPABILITIES................................................................................................ 28

CAPABILITIES REQUIRING DEVELOPMENT........................................................... 28

Survey ............................................................................................................................... 28

Subsurface Utility Engineering (SUE).............................................................................. 29

Design ............................................................................................................................... 30

Bidding.............................................................................................................................. 30

Construction...................................................................................................................... 31

IMPLEMENTATION MATURITY ................................................................................... 31

CHAPTER 5. INTRODUCTION TO AUTOMATION TECHNOLOGY

APPLICATIONS AND GUIDELINES..................................................................................... 33

CHAPTER 6. SURVEYING...................................................................................................... 39

ESTABLISHING SITE CONTROL................................................................................... 40

Control Accuracy.............................................................................................................. 40

Situating Control............................................................................................................... 41

SURVEY METADATA........................................................................................................ 42

ACCURACY TOLERANCES FOR TOPOGRAPHIC SURVEY................................... 43

USE OF REMOTE SENSING............................................................................................. 47
iv

NON-TRADITIONAL SURVEY PRODUCTS ................................................................. 49

CHAPTER 7. SUBSURFACE UTILITY LOCATION........................................................... 51

PURPOSE OF SUE............................................................................................................... 51

DATA QUALITY LEVELS AND APPLICATIONS........................................................ 52

DATA QUALITY LEVELS AND APPLICATIONS IN PROJECT DELIVERY......... 53

USING 3D SUBSURFACE UTILITY LOCATION INFORMATION ........................... 54

CHAPTER 8. DESIGN............................................................................................................... 57

APPLICATIONS IN DESIGN DEVELOPMENT ............................................................ 58

CONSIDERATIONS FOR STANDARD DETAILS......................................................... 60

CADD DATA TYPES AND 3D MODELING APPROACHES ....................................... 60

GUIDE 3D MODEL STANDARD ...................................................................................... 63

3D Model Content............................................................................................................. 64

3D Model Density............................................................................................................. 66

3D Model Segmentation ................................................................................................... 69

GUIDE 4D AND 5D MODEL SPECIFICATION ............................................................. 70

4D and 5D Model Usage Cases........................................................................................ 70

4D and 5D Model Target Audiences ................................................................................ 71

Steps in Creating 4D and 5D Models................................................................................ 72

Viewing 4D and 5D Models............................................................................................. 73

GUIDE 3D DATA REVIEW PROTOCOLS...................................................................... 75

CONTRACT DOCUMENTS............................................................................................... 79

Contract Plans................................................................................................................... 80

Contract 3D Models.......................................................................................................... 81

CHAPTER 9. GUIDE SPECIFICATIONS.............................................................................. 85

CONTROLLING WORK: PLANS AND WORKING DRAWINGS.............................. 86

Contract Documents.......................................................................................................... 86

Hold Harmless Statements................................................................................................ 87

4D and/or 5D Models........................................................................................................ 87

3D As-Built Records......................................................................................................... 87

CONTROLLING WORK: CONFORMANCE WITH PLANS AND

SPECIFICATIONS............................................................................................................... 88

CONTROLLING WORK: CONSTRUCTION STAKES, LINES, AND GRADES ...... 89

CONTROLLING WORK: INSPECTION OF WORK .................................................... 89

CONTROLLING WORK: QUALITY CONTROL PLAN .............................................. 90

MEASUREMENT AND PAYMENT.................................................................................. 91

EARTHWORK, FINE GRADING, BASE COURSE, AND PAVING............................ 92

CHAPTER 10. CONSTRUCTION ........................................................................................... 93

CONSTRUCTION DATA MANAGEMENT .................................................................... 93

Establishing a Model of Record........................................................................................ 94

Managing Design and Field Changes ............................................................................... 95

Digital As-built Records................................................................................................... 96

LOW-ACCURACY POSITIONING .................................................................................. 96

HIGH-ACCURACY POSITIONING................................................................................. 97

AGREEING ON CONTROL AND SURVEY METHODS .............................................. 98

Source of RTK Correction for GNSS ............................................................................... 99
v

Base Station Setup .......................................................................................................... 100

AUTOMATION FOR CONSTRUCTION ENGINEERING AND INSPECTION...... 101

Use of As-Built Data for Measurement and Acceptance................................................ 101

Capturing As-Built Data with Field Survey.................................................................... 102

Capturing As-Built Data with Remote Sensing .............................................................. 105

Limitations of Real-Time Observations.......................................................................... 107

CHAPTER 11. AUTOMATION TECHNOLOGY INTEGRATION.................................. 109

CHAPTER 12. CONCLUSIONS............................................................................................. 111

ACKNOWLEDGMENTS........................................................................................................ 113

REFERENCES.......................................................................................................................... 115
vi

LIST OF FIGURES

Figure 1. Illustration. Integration of automation technology on the Southeast Freeways

project ............................................................................................................................................. 2

Figure 2. Flowchart. Developing automation technology guidelines............................................. 7

Figure 3. Flowchart. Implementation process............................................................................... 16

Figure 4. Worksheet. Initiative planning worksheet, page 1......................................................... 22

Figure 5. Worksheet. Initiative planning worksheet, page 2......................................................... 23

Figure 6. Worksheet. Initiative planning worksheet, page 3......................................................... 24

Figure 7. Flowchart. Increasing capacity with enabling technologies and policies...................... 25

Figure 8. Flowchart. Planning for automation technology integration ......................................... 33

Figure 9. Flowchart. Producing survey products to support automation in highway

construction................................................................................................................................... 39

Figure 10. Flowchart. Setting site control to support automation in highway construction ......... 40

Figure 11. Illustration. Effective control siting to support site localization for a linear project... 42

Figure 12. Illustration. Relationship between survey observations and elevations computed

for a DTM ..................................................................................................................................... 44

Figure 13. Illustration. Unfiltered point cloud .............................................................................. 49

Figure 14. Flowchart. Selecting subsurface utility locating techniques........................................ 53

Figure 15. Flowchart. Integrating 3D utility data into 3D model or project plans ....................... 54

Figure 16. Flowchart. Updating design policy documents to produce 3D data for

automation in highway construction............................................................................................. 58

Figure 17. Flowchart. Using 3D models in design development.................................................. 58

Figure 18. Illustration. CADD template representing a two-lane road with shoulders................. 61

Figure 19. Illustration. String model that uses rules to offset the baseline horizontally

and vertically................................................................................................................................. 62

Figure 20. Flowchart. Creating a standard 3D model specification.............................................. 63

Figure 21. Illustration. Approximation of curved objects in DTMs and 3D line strings.............. 67

Figure 22. Illustration. Mid-ordinate distance .............................................................................. 67

Figure 23. Flowchart. Developing a 4D/5D modeling plan.......................................................... 70

Figure 24. Illustration. Example of a 3D still image from a 4D model for a technical

audience ........................................................................................................................................ 74

Figure 25. Screenshot. Example of a construction sequence viewed in the 4D modeling 

software......................................................................................................................................... 74

Figure 26. Illustration. Roadway surface for a roundabout intersection with visually inspected

triangles with no apparent issues .................................................................................................. 77

Figure 27. Illustration. Roadway surface for a roundabout intersection with visually

inspected contours......................................................................................................................... 77

Figure 28. Illustration. Roadway surface for a roundabout intersection with color triangles

by elevation................................................................................................................................... 78

Figure 29. Illustration. Roadway surface for a roundabout intersection with color triangles

by slope ......................................................................................................................................... 78

Figure 30. Illustration. Roadway surface for a roundabout intersection with display

drainage arrows with no apparent issues....................................................................................... 79

Figure 31. Illustration. Roadway surface for a roundabout intersection using algorithms

to flag issues.................................................................................................................................. 79
vii

Figure 32. Flowchart. Producing contract documents and models............................................... 80

Figure 33. Flowchart. Providing contract models......................................................................... 81

Figure 34. Flowchart. Managing construction with automation technology................................ 93

Figure 35. Flowchart. Establishing a model of record.................................................................. 95

Figure 36. Flowchart. Managing field or design changes in model of record .............................. 96

Figure 37. Flowchart. Preparing digital as-built records .............................................................. 96

Figure 38. Screenshot. Alignment preloaded in a mobile device ................................................. 97

Figure 39. Flowchart. Establishing a plan for high-accuracy positioning .................................... 97

Figure 40. Photo. High-accuracy AMG operations...................................................................... 98

Figure 41. Photo. Horizontal and vertical errors at the control points........................................ 100

Figure 42. Flowchart. Using real-time verification in construction inspection .......................... 101

Figure 43. Photo. RTS rover being used to check grade off the back of the paver .................... 102

Figure 44. Photo. Static LiDAR being used to collect as-built data ........................................... 107
viii

LIST OF TABLES

Table 1. Stakeholders in automation in highway construction implementation ............................. 9

Table 2. Recommended modifications to manuals....................................................................... 10

Table 3. Sample RAM .................................................................................................................. 21

Table 4. Capability/maturity matrix for enabling infrastructure................................................... 26

Table 5. Capability/maturity matrix for applications of automation in highway construction..... 34

Table 6. Minimum positional accuracies for mapping control to support automation

technology..................................................................................................................................... 41

Table 7. Sample survey metadata ................................................................................................. 43

Table 8. Minimum network accuracies for different feature types............................................... 45

Table 9. Survey resolution required to support AMG operations................................................. 46

Table 10. Suitability of LiDAR methods by topographic mapping accuracy ranges ................... 48

Table 11. LiDAR method suitability for different project characteristics.................................... 48

Table 12. Project characteristics favorable for different LiDAR methods ................................... 48

Table 13. Locating technologies and resulting data for different quality levels........................... 53

Table 14. Applications of 3D models during design development............................................... 58

Table 15. CADD design methods and their uses.......................................................................... 61

Table 16. 3D Model content by CADD data type......................................................................... 63

Table 17. 3D Model content by project type and applicable AMG methods ............................... 64

Table 18. 3D Model content by design milestone ........................................................................ 66

Table 19. 3D Model density by design milestone......................................................................... 69

Table 20. Usage cases for 4D and 5D models .............................................................................. 71

Table 21. Target audiences for 4D and 5D models....................................................................... 72

Table 22. Notable practices for creating contract plans................................................................ 81

Table 23. Type, format, and metadata for bid reference files....................................................... 82

Table 24. Areas of standard specifications affected by automation implementation in

highway construction.................................................................................................................... 86

Table 25. Requirements for as-built data by intended use of data ................................................ 88

Table 26. Data types that can constitute the model of record ....................................................... 94

Table 27. Pertinent information for a contract control plan.......................................................... 99

Table 28. Inspector tool selection guidance................................................................................ 103

Table 29. Use of field surveying tools to measure payment quantities ...................................... 104
ix

LIST OF ABBREVIATIONS

2D two-dimensional

3D three-dimensional

4D four-dimensional

5D five-dimensional

AASHTO American Association of State Highway and Transportation Officials 

AMG automated machine guidance

ASCE American Society of Civil Engineers

ASCII American Standard Code for Information Interchange 

ATC alternative technical concept

BIM building information modeling

CAD computer-aided design

CADD computer-aided design and drafting 

CIM civil integrated management

CORS continuously operating reference station 

CPM critical path method

DTM digital terrain model

EDC Every Day Counts

FDOT Florida Department of Transportation 

FHWA Federal Highway Administration 

FTP File Transfer Protocol

GIS geographic information system 

GNSS Global Navigation Satellite System 

GPS Global Positioning System

Iowa DOT Iowa Department of Transportation 

KYTC Kentucky Transportation Cabinet 

LiDAR light detection and ranging

MDOT Michigan Department of Transportation 

MoDOT Missouri Department of Transportation 

NEPA National Environmental Policy Act of 1969 

NSRS National Spatial Reference System

NYSDOT New York State Department of Transportation
x

ODOT Oregon Department of Transportation 

OPUS Online Positioning User Service (OPUS) 

PDF portable document format

QL-A quality level A

QL-B quality level B

QL-C quality level C

QL-D quality level D

QTO quantity takeoff

RACI Categorical scale where R stands for responsible to complete the work, A stands 

for accountable to ensure the task is complete, C stands for consulted before 

finalizing, and I stands for informed of the results

RAM responsibility assignment matrix 

RFID radio frequency identification

ROW right of way

RTK real-time kinematic

RTN real-time network

RTS robotic total station

SHRP2 Second Strategic Highway Research Program 

SUE subsurface utility engineering

TIN triangulated irregular network

UAV unmanned aerial vehicle

UTM universal transverse mercator

WBS work breakdown structure

WisDOT Wisconsin Department of Transportation 

XML extensive markup language
1

CHAPTER 1. INTRODUCTION

While no State transportation department has fully implemented an integrated automation 

technology solution programmatically, there are several examples of mature project-level 

implementations throughout the United States that form the backdrop for the guidance developed 

in this report. There was not an attempt to capture a nationwide perspective in this report.

Instead, a collection of noteworthy practices gleaned as part of a number of in-motion parallel 

efforts were collected, including the Federal Highway Administration’s (FHWA) Every Day 

Counts (EDC) technology deployment outreach, the American Association of State Highway 

and Transportation Officials (AASHTO) Domestic Scan Program, the National Cooperative 

Highway Research Program research on automated technologies, and State and regional 

conferences.(2) Documented sources of notable practice were sought to provide illustrative 

guidance and guide specifications including survey, design and computer-aided design and 

drafting (CADD) manuals, construction specifications, special provisions and special notes, 

construction manuals, training materials, conference proceedings, and implementation 

documents.

There are examples of projects that have taken an integrated approach to leverage a shared 

three-dimensional (3D) digital dataset for automating a range of highway construction 

applications like automated machine guidance (AMG), construction layout, and real-time field

verification to accept completed work. These projects shared the cost of creating and maintaining 

the necessary data while realizing the full benefit of each individual automation application.

Figure 1, adapted from the Wisconsin Department of Transportation (WisDOT) Southeast 

Freeways civil integrated management (CIM) documentation, serves as a good example that 

illustrates how automation can be integrated into the various phases of the project for more 

efficient delivery.

(3) The vision for automation in highway construction is that the necessary 

3D engineered data can be shared among and across a multitude of automation technology uses 

that are applicable to each project. These automation technologies may include remote sensing 

survey techniques such as light detection and ranging (LiDAR), unmanned aerial vehicles

(UAVs), 3D model-based design, four-dimensional (4D) and five-dimensional (5D) construction 

simulation, subsurface utility location technologies, AMG construction, electronic construction 

documents accessed via mobile devices (a part of e-Construction), and non-destructive methods 

for measuring and accepting construction (e.g., including ground-penetrating radar, pavermounted thermal profiler, intelligent compaction, and real-time field verification with locationaware survey instruments).(4)
2

Source: ©Parve.

PI = Public involvement. 

DTM = Digital terrain model.

GIS = Geographic information system. 

CAD = Computer-aided design.

P S & E = Plans, specifications, and estimates. 

RE = Resident engineer.

GPS = Global Positioning System. 

SE = Southeast.

2D = Two-dimensional. 

6D = Six-dimensional.

RFI = Request for information. 

DINS = Design issue notices. 

CCO = Contract change order.

O & M = Operations and maintenance.

STOC = State Transportation Operations Center.

Figure 1. Illustration. Integration of automation technology on the Southeast Freeways 

project.(3)

OBJECTIVE

The objectives of this project were to address challenges and opportunities identified for 

automation in highway construction from project development through construction and to 

develop guidance for State transportation departments to assist them in determining how best to
3

use automation to improve effective and accelerated project delivery. Some automation 

applications may warrant programmatic implementation, while others may warrant use on a 

project-by-project basis. The study involved collecting, organizing, and analyzing data from 

various State transportation departments and other facility owners using automation technology.

Part I of this study relays implementation and success stories from transportation agencies on the 

use of automation.(1) This report, which is part II of this study, provides design guidance and 

accompanying guide specifications for highway agencies to successfully implement automation 

in highway construction. The guidance covers how to generate 3D digital design data for 

downstream uses in construction as well as provides information on how to manage the use of 

these data in construction.

SCOPE

The scope of this report does not imply a positive return on investment for implementing 

automation technology on all projects regardless of type, size, and range of construction 

activities. Further research is being conducted to make value judgements on where automation in 

highway construction is beneficial. This guidance is intended to be used after the decision to 

implement automation technology has been made. The scope is built on the premise that to be 

able to optimally use automation during the construction phase of a highway project, preparation 

begins during the planning, surveying, and design phases. The report is organized as follows:

• Chapter 2 describes the objectives and stakeholders involved in implementation, as well 

as affected policy areas, impacts on capital, and human resources and change instruments 

for implementing automation technology.

• Chapter 3 presents the various investments in enabling technologies and policies that a 

State transportation department needs to implement to reap the benefits of a coordinated 

approach to automation in highway construction.

• Chapter 4 presents implementation strategies used by agencies that have implemented 

mature (though not necessarily comprehensive) automation practices.

• Chapter 5 introduces the guidelines that follow in chapters 6 through 10.

• Chapter 6 describes the needs for capturing survey data prior to design.

• Chapter 7 introduces practices for subsurface utility locating.

• Chapter 8 describes design development to support the uses of 3D engineered data, 

including 4D and 5D models.

• Chapter 9 discusses guide specifications.

• Chapter 10 concludes the guidance with the use of 3D engineered data in construction by 

both the contractor and the owner.
4

• Chapter 11 discusses current successful automation technology integration and introduces 

future trends that should be planned for.

• Chapter 12 provides conclusions to the report.

GLOSSARY OF TERMS

The following glossary of terms is provided to aid in understanding the terms used in the 

following sections:

• 3D engineered model: A 3D model of a roadway or related feature that is developed to 

the appropriate engineering precision to support construction applications.

• 3D solid primitives: Solid 3D CAD objects that do not have any intelligence. They are 

based on regular 3D geometric shapes like cylinders and cubes. 3D solid primitives may 

be mathematically extracted from point clouds to represent pipes, bridge piers, bridge 

girders, utility poles, etc., in CAD objects that are easier to manipulate for clash detection 

or visualization.

• 4D model: A simulation of how a facility changes over time, usually during construction. 

A 4D model is the product of connecting a 3D model to a schedule, introducing the 

fourth dimension of time.

• 5D model: A simulation of how a facility changes over time where the related costs of 

those changes are included in the simulation. Usually, the changes involve construction, 

and the costs are incorporated in the schedule. The fifth dimension represents cost.

• Absolute accuracy: Also called “network accuracy,” the level of accuracy in relation to a 

global coordinate system. In simple terms, it is the accuracy with which something can be 

located in the world.

• AMG: Use of survey-grade position sensors and on-board computers to guide an operator 

or control the hydraulics of construction equipment.

• Classification: The process by which software sorts LiDAR data points into categories 

based on predefined rules. Predefined categories include ground, vegetation, noise, 

and water.

• Corridor model: A method of modeling linear designs in CADD. The corridor 

combines horizontal and vertical alignments, super-elevation definitions, and a 

parametric cross-section definition with a DTM surface to create a 3D approximation of 

the design concept. The corridor model can output DTMs of proposed surfaces like 

subgrade for use in AMG.

• Continuously Operating Reference Station (CORS): Continuously operating Global 

Navigation Satellite System (GNSS) receivers in a fixed location that compute and 

broadcast a position correction for use in real-time kinematic (RTK) GNSS applications.
5

• DTM: A digital topographic model of specific area of a ground surface minus objects 

such as trees, vegetation, and structures that can be manipulated through CAD programs. 

All elements of the DTM are spatially related to one another in 3D represented as a 

network of triangular or polygonal faces. DTMs for design and construction commonly 

use a triangulated irregular network (TIN).

• Geospatial data: 2D or 3D data that are spatially referenced by being projected onto a 

mapping coordinate system such as a State Plane Coordinate System.

• GNSS: A system of navigation that uses a global network of satellites to provide 

autonomous geospatial positioning. The network of satellites includes the U.S. GPS and 

Russia’s GNSS and will include China’s BeiDou and Europe’s Galileo.

• GPS: A subset of GNSS comprising the satellites owned by the United States. It is often 

used colloquially to refer to GNSS as a whole.

• LandXML: A data exchange format based on extensive markup language (XML) for 

horizontal construction data that provides support for surface, alignment, cross section, 

pipe network, and point data types.

• LiDAR: A remote sensing survey method. A sensor sends a pulse of light and measures 

the returning beam to define the position of the remote object that reflected the beam of 

light. The LiDAR sensor may be mounted on a tripod (static LiDAR), mounted on a 

vehicle and in-motion (mobile LiDAR), or mounted on an aerial vehicle such as an 

airplane or helicopter (aerial LiDAR).

• Local accuracy: Also called “relative accuracy,” the accuracy of the position of a point 

in relation to other points in the dataset. Local accuracy may exceed absolute (or 

network) accuracy for a particular dataset. Local accuracy is a consideration for 

measuring depths or lengths or areas, which are unrelated to the geospatial location of 

the features.

• Metadata: A description of the basis of the data, typically survey data, but may relate to 

any 3D data. Metadata usually includes the definition of the horizontal and vertical 

datums that relate 3D coordinate data to a physical location on the surface of the Earth.

• National Spatial Reference System (NSRS): A consistent coordinate system used 

throughout the United States. NSRS defines latitude, longitude, height, scale, gravity, and 

orientation.

• Point cloud: A collection of data points, often collected with remote sensing methods 

like LiDAR, that is so dense as to define the whole scene. Point clouds often contain 

hundreds of thousands of points and may have a point density greater than 1 point/inch.

• Point density: The number of survey data points per unit area. This may relate to field 

survey points or points within a point cloud generated by remote sensing methods such as 

LiDAR.
6

• Remote sensing: A survey method that obtains information about the position of objects 

without coming into contact with the object. LiDAR and photogrammetry are examples 

of remote sensing methods.

• Resolution: The degree of detail that is provided in a 3D dataset. For a DTM, resolution 

is a product of point density and absolute accuracy.

• Robotic total station (RTS): A total station that automatically tracks the target and is 

controlled from a distance by a remote control (usually the data collector attached to the 

target).

• RTK: A method of correcting systemic errors in a GNSS position created by atmospheric 

perturbations. An RTK unit receives both a GNSS position and a correction and applies 

both in real-time to determine position. The correction is calculated and broadcast by 

base station of known position.

• Real-time network (RTN): A similar concept to RTK, but instead of receiving the 

position correction from a defined physical station, the correction comes from a virtual 

reference station. The correction from the virtual reference station is computed using 

position corrections from a network of physical stations.

• Rover: A mobile survey instrument with a data collector that allows the operator to 

determine position in real time. The survey instrument may be an RTK GNSS receiver, a 

combination RTK GNSS receiver and laser receiver, or a target for an RTS.

• Site calibration: Also called “site localization.” A survey technique by which design grid 

coordinates are translated into coordinates on the ground with scaled distances. A site 

calibration/localization computes a rotation and scale factor for horizontal layout and 

creates a vertical datum.

• Template: A parametric CADD object that defines the cross-sectional shape of an object. 

The template is extruded along a line in 3D space to create a 3D model. In corridor 

modeling, the parametric relationships in the template are calculated at defined template 

drop locations. In corridor models, the density of template drops defines the resolution of 

the 3D model.

• TIN: A type of DTM created by applying an algorithm (usually the Delaunay 

triangulation) to connect irregularly spaced points into triangular faces. TINs are usually 

used to define elevation surfaces for CADD and AMG.
7

CHAPTER 2. DEVELOPMENT OF AUTOMATION TECHNOLOGY GUIDELINES

The rapidly evolving nature of technology advancements makes it an enormous task for 

implementing agencies to update standards, policies, and specifications and train their personnel 

to accommodate new technologies. The solution and challenge that implementing agencies must 

grapple with is to introduce agnostic, performance-based guidelines that are sufficiently flexible 

to adapt to change. This is a significant undertaking.

Developing guidelines for the specific automation technologies identified in part I requires 

making refinements to a broad range of policies, standards, and specifications as well as 

acquiring a body of knowledge that reaches far beyond any one individual or organization. There 

are significant enabling technologies and policies and staff training that must precede the use of 

automation in highway construction.

Though the magnitude has not yet been quantified by project type, delivery method, construction 

activities, duration, or other factors, it is anticipated that automation in highway construction 

provides a number of efficiency, safety, and time-saving benefits. Upfront investment may be 

large, but incremental progress should yield positive results. Ultimately, a coordinated, 

performance-based approach to agency business should provide a flexible approach to 

maintaining a highway system in an environment that supports innovation. This would allow

the selective use of automation technologies appropriate to individual project characteristics.

Figure 2 outlines the workflow for incrementally modifying guidelines to support automation.

Source: FHWA.

Figure 2. Flowchart. Developing automation technology guidelines.

OBJECTIVES

New technology is replacing less efficient technology and workflows in design as well as less 

safe and less efficient practices in construction. However, policies to manage due diligence and 

practices to equitably allocate and manage risk in the age of automation are not keeping pace 

with these new technologies. While there is strong hypothetical bias and optimism for the 

positive impact of automation in highway construction on safety, efficiency, and construction 

outcomes, there is not much documented return on investment or business case analysis to guide 

investment in any one area before another.
8

Construction documents have not materially changed over the years. Automation in highway 

construction has data needs that are not supported by paper plans or by the processes and 

methods to develop those paper plans. The breadth of policy and practice touched by automation 

implementation is broad, from detailed nuances of topographic survey accuracy thresholds, to 

retrieving as-built data from construction equipment, to processing 3D data with hardware and 

software to measure pay quantities and accept work.

The breadth of automation technology integration means that practical and actionable 

implementation requires some focus on deliberate objectives. There are some logical preemptive 

investments, identified as enabling technologies and policies, which are described in chapter 4. 

In terms of a comprehensive strategy for automation in highway construction, the first necessary 

step for an agency is to define short-, medium-, and long-term objectives for automation 

technology implementation.

As a leading State, Wisconsin began with a process to define the impact that delivering

3D digital design data to contractors would have on institutional and legal issues as well as 

determining relevant design and construction work processes. After conducting a stakeholder 

consultation, the objectives were broadened to 3D technologies in general.(5)

The Michigan Department of Transportation (MDOT) began with broad objectives for 

automation and noted anticipated benefits to using 3D engineered models and electronic data.(6) 

In its Development Guide, these benefits are noted to arise from the following:(7)

• More accuracy and data intelligence used in electronic design documents.

• More accessible visualization available during the design process.

• Enhanced ability to detect and mitigating clashes.

• Greater ease of data migration from survey to design to construction.

• Easier realization of the design intent during construction.

• Better construction quality outcomes.

• More accurate and more consumable digital as-built records.

• Digital data that are preserved in an accessible format for future use.

By contrast, Oregon Department of Transportation’s (ODOT) original implementation impetus 

had a narrower focus. ODOT’s contractors were noted to be using AMG in an effort to reduce 

construction costs. It was recognized that ODOT used software and processes that could produce 

the necessary data for AMG operations, but there was a lack of clear guidance and consistency in 

the timing and nature of 3D digital data provided to its contractors.(8)
9

STAKEHOLDERS

In order to develop practical and implementable policies and processes, agencies should consult 

with affected stakeholders with strong technical and institutional knowledge. One of the 

challenges to implementing guidelines for automation in highway construction is that the 

changes necessary to support automation technology often need to occur prior to the construction 

phase. While it can be empowering to the designers to lead the change, they need information on 

the requirements for construction or the changes will not be effective. Table 1 provides a list of 

potential stakeholders to an automation implementation and their role in the process.

Table 1. Stakeholders in automation in highway construction implementation.

Stakeholder Consultation Role

Survey Topographic survey and construction oversight

Design CADD automation, 3D model reviews, design/constructability reviews, 

contract documents, processing survey/CADD data for construction 

engineering, and inspection

Contracts Contract and bid documents

Construction Constructability reviews, field survey methods for measurement/ 

inspection, and specifications

Information 

technology

Planning and specifying of new information technology resources to 

support networked, mobile field inspection tools and new computer 

hardware, software and storage capacity for survey, and design and 

contract management

Contractors Topographic survey requirements, 3D data requirements, impact of

specifications on safety and efficiency, as-built data from AMG, and field 

survey methods for measuring and checking work

Consultants Impact of new guidelines on business and reasonable timeline for change 

and lessons learned from design-build experience

Local public agencies Impact of new guidelines on business and reasonable timeline for change

Small businesses Impact of new guidelines on business and reasonable timeline for change

Disadvantaged

business entities

Impact of new guidelines on business and reasonable timeline for change

State licensing boards Laws for digital signatures and digital seals

Contractor association advocacy has helped to identify contractor needs and make a case 

for augmenting contract documents with 3D digital design data. Many design automation

departments have made changes to the way 3D data are used in design and shared prior to bid. 

Construction specifications have been modified or special provisions have been created to allow 

optional AMG construction with reduced staking and some obligations to provide equipment and 

training. Construction engineers and inspectors are beginning to develop digital methods for 

construction oversight. Some State transportation departments have created special provisions to 

enable contractors using AMG to provide equipment and training for inspectors. This has left 

most State construction departments in a reactive position for implementing automation via 

digital 3D data-driven workflows for measurement and acceptance. With more consultation with 

construction surveyors, broader usage cases may be identified for real-time field verification 

processes for measurement and acceptance.(9)
10

There has been much focus on the 3D digital design data upon which many automation 

technologies rely, but many automation processes also rely heavily on survey equipment and 

methods. While construction surveying is typically not a licensed practice, there is a very 

important role for surveyors to play in planning and implementing automation policies and 

guidelines.(10) Contractors are important partners because they have the most experience with 

automation and have been using automation technology at risk. Consequently, many contractors 

have implemented procedures internally that optimally balance the cost of data acquisition and 

preparation with the benefits of efficient, high-yield operations.

POLICY AREAS

A number of current policies and specifications, which are unique to each State transportation 

department, can be revised to accommodate automation in highway construction. These changes 

can be managed within the current policy framework. With two notable exceptions, the changes 

are within the control of the State transportation departments. The two exceptions are laws 

governing use of digital signatures and digital seals on engineering contract documents, both of 

which are usually controlled by State licensing boards.

As the primary sources of policy for digital data, States’ survey, design, and CADD manuals 

could be modified to include provisions for creating and delivering the 3D data that automation 

technologies need. Many States have a construction manual that provides guidance to 

construction managers and inspectors in conducting their activities. Recommended modifications 

to manuals are shown in table 2.

Table 2. Recommended modifications to manuals.

Manual Type Recommended Adaptation

Survey

(see chapter 6)

• Considerations for establishing site control.

• Inclusion of metadata.

• Accuracy tolerances for topographic surveying.

• Use of remote sensing.

• Non-traditional survey products.

Design

(see chapters 7

and 8)

• Subsurface utility locating technologies.

• Potential applications of 3D models in design development.

• Possible revisions to standard details.

• Creation of a 3D model standard.

• Creation of 4D and 5D model specifications.

• Implementation of 3D data review protocols.

• Processes for creating contract documents and bid reference documents.

CADD

(see chapter 8)

• A 3D model guide specification that defines standards for creating and 

managing 3D models, in addition to standards for the outputs from 3D models.

• 3D data review protocols.

Construction 

(see chapter 10)

• Construction data management.

• Low accuracy positioning.

• High accuracy positioning.

• Automation processes for construction engineering and inspection.
11

Corridor models are an effective way to model for AMG equipment because the broad brush of a 

15-ft-long blade can be replicated digitally with a corridor template. When combining 

implementation of automation in highway construction with a desire that design data be used 

directly by contractors and inspectors, there is an opportunity to revisit standard details to 

determine if changes could provide efficiencies in modeling and construction. Specific areas that 

may be affected are introduced in the Considerations for Standard Details section in chapter 8.

As construction methods change rapidly with evolving automation technology, new document 

and data types have been introduced that do not have contract language to manage them.

Automation technology implementation provides an opportunity to review, measure, and accept 

work based on digital objective evidence.

There are guide specifications for accommodating automation in highway construction with 

modifications to the following typical sections in an agency’s standard specifications:

• Controlling Work: Plans and Working Drawings.

• Controlling Work: Conformance with Plans and Specifications.

• Controlling Work: Construction Stakes, Lines, and Grades.

• Controlling Work: Inspection of Work.

• Controlling Work: Quality Control Plan.

• Measurement and Payment.

• Earthwork, Fine Grading, Base Course, and Paving.

CAPITAL AND HUMAN RESOURCES INVESTMENTS

Automation in highway construction creates a paradigm where skilled professionals execute their 

work in a streamlined, digital environment that replaces manual tasks with automation. Some of 

the benefits of automation include fewer workers exposed to heavy equipment or less time to 

execute inspection tasks.(10) However, automation in highway construction is not perceived as an 

opportunity to reduce the construction workforce. Rather, it is an opportunity to produce better 

construction outcomes by introducing processes that allow inspectors to document as they 

inspect and spend more time observing construction. This involves investing in people to

create a highly skilled workforce that makes use of sophisticated hardware and software.

Hardware

Hardware may be needed in survey, design, or construction offices; however, it is less common 

that survey and design hardware need upgrading. Provision of equipment and training for 

construction field staff can be managed in a variety of ways. An agency may purchase or lease 

equipment, or the contractor may furnish equipment for the duration of construction.(9) The latter 

may be attractive because it takes procurement out of a capital budget. However, when 

furnishing the equipment is a line item in a bid for optional use of automation technology,
12

contractors may consider this detrimental to their ability to be competitive and may be a 

disincentive to the use of automation.

Software

Investment in software goes beyond the cost of the software licenses and support agreements. 

Most agencies have invested in software standardization and CADD automation to provide 

consistency in datasets and efficient data creation. With new software comes the cost of creating 

new standards and new automation tools. There is also a cost associated with migrating or 

accessing legacy datasets.

New software may be needed for survey, design, and construction staff to support automation in 

highway construction. Software used to manipulate and process LiDAR data is rapidly evolving. 

Many agencies are in the process of evaluating or updating their CADD software for design.

There may be a need for new CADD software licenses for construction staff to use onsite. 

Construction staff may wish to review the contractor’s AMG models, create staking data, 

evaluate potential design revisions, or process as-built survey data to measure or accept 

completed work. CADD software used by the survey and design office may fulfill these 

purposes, or construction software may be a better fit.

Changing Job Functions

Until recently, construction surveyors set the stakes and hubs that translated information on 

construction plans into a format that was interpreted on the ground in a consistent manner by the 

contractor and inspector. Automation technology is used to perform site layout in real time using 

position sensors and an on-board computer or handheld data collector. This places the site layout 

in the hands of the equipment operators and inspectors who usually are not surveyors. It also 

removes physical layout markers and separates how and when the contractor and inspector 

interpret the plans on the ground using surveying equipment. Consequently, the adoption of 

automation in highway construction requires a broader understanding of survey methods.

With automation technology, construction surveyors have a changing role, from pounding stakes 

and hubs to providing oversight. By contrast, preconstruction job functions are not materially 

affected. Surveyors have new considerations for control and topographic survey accuracy.

Designers need to add more detail, document designs in new digital formats and data types, and 

create protocols to review the digital data. Contract officers need to ensure that contract language 

and specifications adequately address the use of digital data in construction.

Training Needs

The goal of automation in highway construction is to develop new workflows that replace 

laborious manual processes. As a consequence, the training needs created by automation 

technology implementation are vast. The need for training is one of the most often cited barriers 

to implementation. There are different levels of training that are needed at different times. For 

example, webinars or short presentations can raise awareness by disseminating information, but 

they often do not advance implementation. Many agencies have found that hands-on training in 

new methods and processes can be delivered in the classroom or online to advance 

implementation of automation in highway construction.(9)
13

An integrated automation technology implementation affects surveyors and designers who 

typically are not involved in construction. Overview training of how the changes imposed upon 

them improve outcomes in construction can be beneficial. Some States have provided this 

through outreach to stakeholders at annual consultant or contractor association training 

conferences. The Florida Department of Transportation (FDOT) hosts an annual design expo 

where there have been many of such sessions; the archive of presentations is available online.(11)

Once new policies, specifications, or standards are created, they need to be implemented. Some 

changes may affect how people do their jobs. Practical hands-on training needs are greatest in 3D 

design and CADD automation, as well as in methods for performing real-time verification.(10) 

Just-in-time training has been found to be most effective for hands-on training in workflows or 

new software tools.(9) Training in survey principles and real-time verification methods can be 

provided to construction field staff through a special provision or specification. This option is 

described in the guide specifications in chapter 9.

15

CHAPTER 3. IMPLEMENTATION STRATEGIES

The culture at an implementing agency will affect the way in which automation in highway 

construction will be mainstreamed. For example, State transportation departments have different 

methods in implementing automation technology; some have adopted a formal, agency-wide 

implementation plan, while others implement it on a project-by-project basis based on resources 

and interest at the regional/local levels. Some agencies have successfully advanced the use of 

automation technologies without a formal implementation plan. The common method 

transportation agencies use to rapidly implement automation is through a small team with 

decisionmaking power and executive sponsorship.

The need to explicitly quantify the benefits of implementing 3D models and their related 

automation technology uses before any investments are made to change the traditional business 

practices would be a significant challenge. A majority of the cost overruns associated with the 

traditional project delivery processes are accrued in the construction phase in the form of errors, 

omissions, inaccurate quantities, unresolved transitions that need to be field fit, and in the 

perpetuation of construction methods and inspection protocols that could be made safer and more 

effective. However, the investments to realize the benefits of automation must be made in the 

project scoping and design phase through accurate survey and 3D model development that 

facilitates better construction. The implementation of automation in highway construction should 

be viewed in a holistic manner and should include costs and benefits spread across all project 

phases at a programmatic level to leverage the cost efficiencies associated with targeting a 

program of projects rather than a single project.

Implementing enabling technologies and policies to create 3D data during design is a necessary 

first step to achieving automation in highway construction and can be managed within a design 

or a design automation department. Putting the 3D data to work in the field (and postconstruction) takes a coordinated effort from multiple departments. Input from the range of 

stakeholders identified in the Stakeholders section in chapter 2 is important to facilitate the

implementation of automation technologies throughout the different phases of highway projects.

FORMAL IMPLEMENTATION PLANS

One recommendation to mainstream automation in highway construction is to create a formal 

implementation plan. An implementation plan recognizes the actions to consider, identifies the 

various internal and external stakeholders, and facilitates the broad collaboration required to 

achieve the end result. Writing the plan is only part of the journey; executing the plan is where 

the majority of the effort occurs. The implementation plan should provide a structured approach 

to mainstreaming automation, create a clear purpose for implementation, set goals, establish 

criteria for success, and provide input from people with multiple perspectives to identify 

opportunities for success and plan to overcome obstacles. Figure 3 is a sample flowchart for the 

implementation process.
16

Source: FHWA.

Figure 3. Flowchart. Implementation process.

As shown in figure 3, common elements of an implementation plan include the following:

• Create a vision: The vision for the future post-implementation should provide a broad 

message that unifies the organization in support of the plan.

• Form a team: Team members should be responsible and accountable. They should be 

consulted and informed of activities in the plan. Team members will do the work and will 

be affected by the consequences of implementation tasks.

• Set goals: Goals are outcomes that are intended by the implementation. They should 

align with the agency or organization’s strategic goals.

• Define the purpose and need: The purpose and need establish a logical case for why 

change is needed. This helps to secure executive sponsorship and funding for the 

implementation.

• Identify known issues: Known issues need to be identified that may provide obstacles to 

the implementation.

• Perform specific activities: These activities should describe the steps taken to 

implement the plan. Activities should be specific, measurable, achievable, realistic, and 

time-bound.

• Measure performance: Performance measures track the progress of implementation. 

When the activities are measureable and time-bound, then tracking completion of 

activities provides the data necessary for performance measures.

• Communicate progress: Reporting performance measures communicates progress and 

helps to maintain momentum and support for the implementation.(12)
17

NOTABLE IMPLEMENTATION STRATEGIES

Over the past several years, many State transportation departments have made significant 

progress in building capabilities in enabling technologies and policies and extending their 

support for automation in highway construction. Some of them have used formal implementation 

planning strategies. Notable, successful practices from those plans are described in the following 

subsections.

Establishing a Vision

Automation in highway construction is part of the greater CIM strategy that is the subject of 

ongoing consideration and much research.(13) CIM represents a global shift to digital, data-centric 

practices in developing and managing infrastructure assets. Creating a vision that places 

automation in the context of other related digital advancements is a strategy that has been used 

by a few State transportation departments, such as WisDOT and ODOT.(14,15)

For some State highway departments, the future of many automation and enabling technologies 

has been communicated under the umbrella of “engineering automation,” which is a term widely 

used by ODOT.(15) This is consistent with the philosophy of CIM. Another approach is to focus 

on seamless data flows and data lifecycles.(6,14) This uses a customer-focused view of data 

collection and creation, keeping in mind immediate data uses and potential uses in the future.

Defining a Purpose and Need

A purpose and need statement does not have to be a business case. Instead, it can be more 

persuasive if it includes objective measures of the benefits and costs involved in implementing 

automation technology. One approach is to provide a purpose and need for individual initiatives 

or activities rather than supporting the whole vision statement.(14) The purpose and need for 

implementation should be documented to define how the proposed change solves a problem or 

improves outcomes.

A common starting point for implementing automation technology has been to support AMG by 

implementing 3D design processes, as was the case in Wisconsin, Michigan, and Oregon.(16,6,8) 

These implementation documents note current practices, new developments, and a description of 

how the proposed change solves problems or improve outcomes. The purpose and need 

statements vary in length, detail, and the extent to which they cite quantitative substantiation.

Identifying Known Issues

Analyzing the current state of the practice and identifying issues that may hamper 

implementation can be instructive for setting achievable time limits on goals, identifying 

members of the implementation or stakeholder teams, and developing specific activities that

drive implementation forward. Issues should be brainstormed to craft actionable next steps that 

are achievable. Commonly known issues for different automation and enabling technologies 

include the following:
18

• Training needs.

• Need for new software or hardware.

• Need to extend, modify, or create standards or specifications.

• Policies that impede adopting new practices.

• Concerns of the impact of change on small and previously disadvantaged businesses.

• New job functions that do not fit with established job descriptions.

• A lack of clear understanding of the impact of the proposed changes.

Implementation Goals

Building on lessons learned and resources developed by other agencies significantly reduces the 

time needed to implement automation in highway construction. The original ODOT vision 

document provides a 25-year vision for implementing a variety of automation technologies.(15) 

The subsequent Construction Machine Automation Six Year Plan laid out a 6-year plan for 

implementation, but that proved too ambitious to meet all the stated goals.(17) Changing policies, 

deploying new policies, and training staff to implement new ways of working requires a 

significant, multiyear investment. ODOT successfully implemented 3D roadway design over a

3-year period.(8) That involved building on current practices, defining standards, producing a tech 

bulletin to modify policies, and introducing a 1-year implementation period before the new 

requirements for 3D roadway design became mandatory.(9)

WisDOT began exploring how to support AMG in 2007 and expanded to a broad

3D technologies implementation plan in 2009.(16,5) The original plan included 6 initiatives with a 

combined total of 26 prioritized goals between them.(5) All six initiatives were refined to reflect 

significant progress and were carried over to the 2013 update, where two more were added.(14) 

The updated plan separates goals into short-term (1–2 years) and long-term (2 or more years) 

horizons. There were an average of eight short-term goals and four long-term goals for each 

initiative.

The Utah Department of Transportation (UDOT) began their implementation planning in early 

2014 and was able to build on lessons learned and resources developed by other agencies. The 

timeline for implementing the vision for advertising and constructing projects using electronic 

plan sets utilizing 3D CAD modeling software was nearly 3 years. The UDOT implementation 

plan was divided into a short-term plan (May–December 2014), a mid-range plan (2015 calendar 

year), and a long-range plan (2016 calendar year).(18) The short-term plan focused on quick wins 

and conducting research into capturing lessons learned. The mid-range plan activities were to 

create interim policies, deliver training, and conduct outreach with stakeholders. The long-range 

plan goals were not clearly defined but rather focused on being responsive to challenges 

identified in the short-term and mid-range plan activities.(18)
19

Establishing an Implementation Team

An implementation team should include those who determine how to implement automation in 

highway construction and those who are directly affected by the change. This includes surveyors, 

designers, construction engineers, and inspectors. Responsibility assignment matrices (RAMs) 

are a useful tool to clearly define responsibilities for implementation tasks. Oregon created a 3D 

Roadway Design Committee with six primary members, five alternates, six representatives from 

other committees, and seven individuals who sponsored the committee or served as advisors.(8) 

The RAM responsibilities for each task used the RACI categories, which is defined as follows:

• R = Responsible to complete the work.

• A = Accountable to ensure the task is completed.

• C = Consulted before finalizing.

• I = Informed of the results.

It is notable that the approach by the ODOT 3D Roadway Design Committee was to place 

responsibility for defining how 3D design data would be developed and delivered in the hands of 

roadway designers. The consumers of this data (i.e., surveyors and construction personnel) were 

consulted on the process, but those affected by the change in design procedures were empowered 

to manage it.(8)

In establishing their implementation team, UDOT identified a committee chair, an assistant 

chair, and five discipline leads. The five disciplines were preconstruction, construction, survey, 

training, and technology. Two executive sponsors were identified, and external stakeholders who 

were a part of the short-term plan activities included consultant and contractor associations, 

equipment and software vendors, and contractors and consultants with experience on specific 

projects.(18) UDOT also used a RAM to assign responsibilities for implementation tasks. The 

RAM used by UDOT assigned responsibilities using the PLANS categories, which is defined as 

follows:

• P = Primary person to complete the work.

• L = Learns results of task.

• A = Accountable to ensure task is complete.

• N = Needs to be consulted.

• S = Shared completion of work.

Specific Activities

Specific activities are performed to complete the actual implementation. These are the individual 

steps taken toward meeting the goals. Specific activities should be small, focused, and readily 

completed. The more disaggregate they are, the faster they can be completed, and the greater
20

sense of momentum in the implementation. Specific activities make up the tasks in the rows of 

the RAMs (see table 3 as an example).

Usually, implementation plans are formalized after some implementation activity has been 

completed. It is an opportunity not only to document the changes that need to occur but also how 

newly implemented practices support further development. Forming a work group to undertake 

an initiative or complete the work for a set of related specific activities is a positive action that 

advances implementation and is worth of noting as a specific activity.(14) Other specific activities 

may represent larger tasks, like creating a manual or implementing a new policy.(8) Common 

specific activities for implementing automation in highway construction include the following:

• Scheduling regular meetings with stakeholder groups (e.g., contractor associations).

• Creating special notes, special provisions, or developmental specifications to pilot and 

develop new policies and procedures.

• Developing a legal disclaimer for 3D models.

• Implementing digital signatures for contract documents.

• Creating new content for design and construction manuals.

• Purchasing hardware and software for construction field offices.

• Creating training programs or procuring training from vendors.

Tracking Performance

Tracking the progress and effectiveness of an implementation plan can be daunting, but it is a 

way to maintain momentum by justifying the investments made and substantiating further 

investment. Tracking completed activities is the simplest way to track performance; it can be 

effected through the RAM or through a simple spreadsheet.(19,8)

When the specific activities include pilot projects, it is an opportunity to capture other objective 

and quantitative data to measure performance. In the Geospatial Utility Infrastructure Data 

Exchange 2014 Pilot Initiative, MDOT tracked the cost of capturing the data on seven pilot 

projects and used that data to estimate that implementation would cost between 0.75 and

2 percent of construction costs.(20) This information could be used in a cost-benefit analysis or to 

define the purpose and need of broader implementation.

IMPLEMENTATION PLANNING RESOURCES

Table 3 and figure 4 through figure 6 are example tools that can be used in creating 

implementation plans. Specifically, table 3 is a sample RAM that uses the RACI categories. It is 

set up to track performance related to completing tasks in according to the time limits established 

for the specific activities. Figure 4 through figure 6 are worksheets for creating initiatives, 

defining the purpose and need, setting multiyear goals, identifying known issues and strategies to 

manage them, and creating specific activities that are time-bound and measurable.
Table 3. Sample RAM.

Initiative Status

Task 

No. Description

Start 

Date End Date

Responsible Parties using RACI 

Scale

SponsorCommittee ChairInitiative 2 LeaderInitiative 3 LeaderStakeholder Group 1Stakeholder Group 2Survey StaffDesign StaffProcurement StaffConstruction Staff

Initiative 1 On timec1 Coordination 1/1/15 Ongoing

Coordination Completea1.1 Form an implementation team 1/1/15 2/28/15 C A R R C C I I I I

Coordination On timec1.2 Hold quarterly team meetings 3/1/15 Ongoing I A R R R R I I I I

Initiative 2 On timec2 Implementation plan 4/15/15 10/15/15

Implementation 

plan Completea 2.1 Identify known issues 4/15/15 6/15/15 I A R C C C C C C C

Implementation 

plan Completea 2.2 Create goals 4/15/15 6/15/15 I A R C C C C C C C

Implementation 

plan

Ahead of 

scheduleb

2.3 Define purpose and need 6/15/15 8/15/15 I A R C C C C C C C

Implementation

plan

Ahead of

scheduleb

2.4 Define specific activities 6/16/15 8/15/15 I A R C C C C C C C

Implementation 

plan Not startedd 2.5 Set performance measures 8/15/15 10/15/15 I A R C C C C C C C

Initiative 3 On timec3 Description Start date* End date*

Description Ahead of

scheduleb

3.1 Specific activity 1 Start date* End date* I A — R — — — — — —

Description Not startedd3.2 Specific activity 2 Start date* End date* I A — R — — — — — —

*Indicates templates/examples for agencies to define their specific activities.

—Indicates that the information is not applicable to the column headings.

Note: Status color scale is as follows: aDark green = Complete, blight green = Ahead of schedule, cyellow = On time, and dred = Not started.

21
Capability Description Purpose and Need

Responsibility Assignment Baseline and Goals

Who is Responsible to complete the work: Baseline State of Maturity

Who is Accountable to ensure the task is completed: Short-term Goal to be achieved within 12 months

Who should be Consulted before finalizing: Short-term Goal to be achieved within 24 months

Who should be Informed of the results: Medium-term Goal to be achieved within 5 years

Long-term Goal to be achieved within 10 years

Source: FHWA.

Figure 4. Worksheet. Initiative planning worksheet, page 1.(12)

22
Known Issues and/or Challenges to Implementation Strategies to Manage/Overcome Issues

Technological

Procedural

Change Management

Source: FHWA.

Figure 5. Worksheet. Initiative planning worksheet, page 2.(12)

23
Specific Activities

No. Description of Activity Responsibility Time Frame

Performance 

Measures

1

Start

Duration

Completion

2

Start

Duration

Completion

3

Start

Duration

Completion

Source: FHWA.

Figure 6. Worksheet. Initiative planning worksheet, page 3.(12)

24
CHAPTER 4. ENABLING TECHNOLOGIES AND POLICIES

Enabling technologies and policies build the framework for a coordinated approach to supporting 

automation in highway construction. Those may include hardware, software, or skills needed to 

create the 3D data upon which automation technologies depends; modifications to the 

specifications to enable the use of evolving automation technology; or guidance for 

implementing both the technology and policies. Figure 7 is a workflow for building

capacity with enabling technologies and policies to drive forward implementation of 

automation guidelines.

Source: FHWA.

Figure 7. Flowchart. Increasing capacity with enabling technologies and policies.

Table 4 lists a range of enabling technologies and policies that are needed to support automation 

in highway construction. The table presents a range of different maturity levels at which the 

technologies and policies can be implemented. Advanced maturity is not necessarily a 

prerequisite to supporting automation. Each implementing agency will need to consider the 

optimal level of maturity to support the agency’s unique goals for supporting automation in 

highway construction.

25
Table 4. Capability/maturity matrix for enabling infrastructure.(12)

Enabling 

Infrastructure

Maturity Level

1: Initial 2: Evolving 3: Defined 4: Managed 5: Enhanced

Statewide 

CORS network

Limited access to a 

CORS network

Statewide CORS 

network that is asset/ 

GIS grade only

Limited access to 

survey-grade CORS 

network

Statewide CORS 

network that is 

survey grade

Publically owned 

statewide surveygrade CORS network

RTN GNSS Single-based RTK; 

requires site 

localization

Commercial RTN 

solution; requires site 

localization

Commercial RTN 

solution; tied to the 

NSRS

Statewide CORS 

RTN solution; tied 

to the NSRS;

limited access

Statewide CORS 

RTN solution; tied to 

the NSRS with

statewide access

Coordinate 

reference 

system

State plane 

coordinate system 

used on all projects

Modified State plane 

coordinate system used 

on all projects

Some projects use 

custom coordinate 

systems

Low distortion 

projections used for 

some projects

Standardized low 

distortion projections 

used for all projects

Computer 

hardware for 

design

All staff have 

computers

All staff have 

networked computers

All staff have 

networked computers 

that are less than 3 

years old

Some staff have 

mobile tablets

All staff have access 

to desktop and 

mobile computers

Computer 

software for 

design

Email, Internet, 

portable document 

format (PDF), and

other general office 

software only

CADD design software 

for designers and 

technicians

CADD design 

software for all and 

limited access to 

design review software

All design staff have 

CADD design and 

design review 

software

Desktop and mobile 

CADD design and 

design review 

software for all staff

CADD

standard

A CADD manual 

outlines minimum 

requirements for 

2D electronic plans

CADD Manual outlines 

minimum requirements 

for 3D model used to 

generate 2D plans

Standardized 3D 

model format and 

outputs including 

standard file naming

convention

Standardized 3D 

model format and 

outputs including 

file and object

naming convention

Standardized 3D 

model with data 

density tied to 

construction

tolerance

Design review 

procedure

Plans review 

processes only

3D data are visually 

reviewed with no 

formal process

There is a formal 

process for a visual 

review of specific 

3D data

There is a formal 

process for visual 

and software review 

for 3D data

There is a rigorous, 

formal process to 

review 3D data at all 

milestones

Document 

management 

system

Files released on 

CD-ROM or

universal serial bus 

key

Files posted online on a 

File Transfer Protocol 

(FTP) site for 

unmanaged download

Files posted online on 

a secure FTP site for 

password-protected 

download

Secure, managed 

file sharing 

environment

Common data 

environment for all 

stakeholders

26
Enabling 

Infrastructure

Maturity Level

1: Initial 2: Evolving 3: Defined 4: Managed 5: Enhanced

Electronic 

signing and 

sealing

Electronic files are 

for information 

only

Digital sign and seal on 

PDF documents

Pilot initiatives to 

digitally sign 3D 

models

Digital sign and seal 

on any electronic 

documents

All deliverables are 

electronic with 

digital sign and seal

Construction 

specification

Method 

specification may 

inhibit the use of

new technology

Special provisions 

developed to facilitate 

and manage 

construction with AMG

Draft AMG 

specification 

developed and being 

piloted

AMG specification 

incorporated in 

standard 

specifications

Quality assurance 

specification enables 

use of evolving 

technology

Computer 

hardware for 

construction

Limited access to 

computers on some 

sites

Field offices have 

computers but limited 

network access

Field offices have 

computers and full 

network access

Field offices have 

networked 

computers and some

mobile tablets

Networked 

computers and 

mobile tablets on all

construction sites

Computer 

software for 

construction

Email, Internet, 

PDFs, and other 

office software only

Some access to 

construction software

Desktop computers 

have construction 

software

Desktop and mobile 

computers have 

construction 

software

All applications are 

cloud-based and can 

be accessed from 

multiple desktop and

mobile devices

Field 

equipment for 

construction 

managers and 

inspectors

Specification 

allows using the 

contractor's rovers 

and RTSs

Specification requires 

contractor to furnish 

rovers, RTSs and 

training

Limited agency-owned 

rovers and RTSs

Agency-owned 

rovers and RTSs 

available to all 

construction sites

All construction staff 

have access to rovers 

and RTS and are 

trained to use them

A construction 

manual

Provides guidance 

to implement AMG 

specification

As for level 1 plus 

provides guidance on 

AMG methods and 

equipment limitations

As for level 2 plus 

provides guidance on 

capturing independent 

field survey

observations for realtime verification

As for level 3 plus 

provides guidance 

on using CADD 

systems to measure

quantities and check 

tolerances

As for level 4 plus 

guidance on survey 

methods for site 

localization and 

verifying control

727
28

IN-PLACE CAPABILITIES

Surveyors have generally adopted new tools that enable more accurate remote sensing, rapidly 

collecting a large number of data points and more safely executing field surveys. There are 

challenges associated with managing large datasets in general and, more specifically, in 

extracting meaningful data from these datasets. Software tools are rapidly evolving to classify 

point clouds, remove noise, filter to an optimum number of data points for performing design, 

and produce the CADD graphics needed for plans development. Surveyors are able to 

consolidate datasets generated from multiple different methods of data capture to produce 

base mapping products that meet the needs of modern construction.

Geometric design computations are relatively simple. Rules-based CADD tools that compute 

3D coordinates have been in use since the late 1980s. These tools evolved to be able to display 

3D graphics, but other than 3D surface models, the 3D graphics were not widely used. Instead, 

designers used the tools with sophisticated automation to create 2D plans efficiently. This 

supported historic processes for design and constructability review that were reliant upon plans.

Continued CADD software development provided for more design automation and more 

accessible 3D graphics. Policies for design review and bidding did not change, however. 

Therefore, despite rich 3D data being available at the conclusion of design, it usually remained 

there. In the 1990s, advances in survey equipment including RTK GNSSs, mobile data 

collectors, and total stations enabled surveyors to use mobile location-aware tools. This provided 

efficiencies and safety gains in horizontal construction stake-out. In the late 1990s, AMG 

systems began to emerge, which led to contractors reverse-engineering 3D models from plans for 

use with AMG.

CAPABILITIES REQUIRING DEVELOPMENT

From a technological standpoint, the enabling infrastructure is largely in place (see table 4). The 

biggest hurdles are implementing policies, making investments in equipment and software, and 

training the workforce in using these new processes and policies. The following subsections 

describe the changes and developments that agencies need to consider in the areas of surveying, 

SUE, design, bidding, and construction.

Survey

Survey needs include construction tolerance accuracy on any tie-ins to existing hard surfaces 

(e.g., pavements, bridges, etc.) and better accuracy in general to avoid drainage issues and to 

generate accurate earthwork and materials quantity estimates.

Previously, with a paper-based delivery of design data to construction, survey computations 

remained in the hands of the construction surveyor. The construction surveyor had control of 

converting the design grid coordinates to ground stake-out coordinates. Rather than performing 

manual calculations, design data are now recreated in CADD to process computations and export 

to survey data collectors for field stake-out. These tools and survey methods form the foundation 

of AMG construction and real-time verification.
29

Subsurface Utility Engineering (SUE)

The state of the practice with regard to SUE has been evolving over the past two decades.(21) 

Since 1991, FHWA has been encouraging the use of SUE on Federal aid and Federal Lands 

Highway projects.(21) In 2009, responding to a challenge from FHWA’s administrator to identify 

ways to shorten project delivery, a joint committee representing AASHTO, the Associated 

General Contractors, and the American Road and Transportation Builders Association identified 

that improved processes for utility location and relocation is an important step in expediting the 

completion of transportation infrastructure projects.(22)

As a follow up to this recognition, FHWA’s EDC round 1 included a nationally canvassed 

initiative that highlighted existing flexibilities currently in place under Federal law and 

regulations and described techniques that foster effective utility coordination during project 

development which warrant more widespread use.(23) FHWA is currently completing a study to 

investigate issues associated with State transportation departments asserting their responsibility 

for managing utility installations within the highway right-of-way, with a focus on the use of 

3D techniques to assist in that management.(24) The Second Strategic Highway Research 

Program (SHRP2) includes several important projects that are aimed at providing additional 

guidance on utility location, data storage, mapping and conflict management. The most relevant 

studies for this work include the following:

• Technologies to Support Storage, Retrieval, and Use of 3-D Utility Location Data: This 

project developed a data storage and retrieval model to accommodate large volumes of 

utility data, interface with existing design software (e.g., CAD software), and provide a 

method for organizing the data so that it can reliably be used throughout the project 

design phase, during construction, and on future projects.(25,26) The model data store has 

provisions for including horizontal and vertical location of the utilities as well as attribute 

data that is needed to effectively coordinate with utility owners. A number of agencies 

including California, Ohio, Kentucky, and Texas are participating in proof-of-concept 

studies that are piloting the data repository.

• Utility-Locating Technology Development Using Multisensor Platforms: This project 

developed two functional automation prototypes to improve the detection and accurate 

determination of positions of buried utilities for use in detailed project design and 

construction work.(27) The specific technologies packaged in the prototypesincluded

a multichannel ground-penetrating radar system to locate utilities in one pass and a 

new multisensor platform that combines electromagnetic induction and 3D groundpenetrating radar to produce utility location data.

• Innovations to Locate Stacked or Deep Utilities: This project developed prototype 

devices that extended the locatable zone for deeply buried and stacked utilities beyond 

the surface-based detection approaches considered in utility investigation technologies.(28)

Long-range radio frequency identification (RFID) tags and active acoustic locating 

devices were selected for final prototype development and testing. Although it was 

concluded that both technologies needed further development to bring them to a 

commercially ready state, the RFID technology was judged to be closer to commercial 

readiness. The RFID prototype developed in this research overcame the traditional depth
30

limitations (approximately 6 ft) associated with this technology by incorporating an 

internal, long-life (50 years) battery on the active tag. The long-range RFID active tag 

technology has also been identified as promising utility location technology in the 

previously cited FHWA work.(24)

Finally, the American Society of Civil Engineers (ASCE) developed an important standard of 

care guideline, Standard Guideline for the Collection and Depiction of Existing Subsurface 

Utility Data.

(29) This standard is the foundational reference for much of the in-motion work 

described in this section.

Design

For roadway design, historic CADD tools have evolved to become natively 3D within the

design environment. This allows designers to interact with their designs in 3D without additional 

effort to produce 3D graphics. Perhaps the biggest leap for designers is conceptualizing the

3D graphics to be the design rather than the plans. The process of creating plans focuses effort on 

a subset of the overall project, for instance 50-ft interval cross sections. The areas between the 

cross sections may contain transitions between typical sections.

When the 3D model is conceived of as the design, there is a shift of effort to design these 

transitions rather than having them managed in the field. This results in fewer field issues, more 

accurate quantity estimates, and constructed facilities that better reflect the design intent. The 

most efficient and valuable way to communicate the design intent is to provide the 3D CADD 

data itself, which requires new policies, processes, and, in some cases, technology to be able to 

review, certify, sign, and manage the digital data contractually.

During the transition phase from designing for plans to designing 3D engineered models for 

construction, designers are hesitant to allow 3D data to supersede plans in the order of 

precedence of contract documents defined by construction specifications. While 3D data are 

beginning to flow to construction, the mechanisms that allow that data to flow currently are legal 

disclaimers and “hold harmless” agreements, which are intended to limit the agency’s liability 

for errors and omissions in the 3D data. These transfer all risk associated with the accuracy of the 

data to the contractor, which is neither equitable nor efficient risk allocation. Furthermore, it 

leaves the owner’s representative without a reliable or independent source of 3D data to use for 

real-time verification. Giving 3D data contractual standing requires revising the construction 

specification to change the precedence of 3D CADD data and contract plans and limiting 

authorized uses of the data to the specific activities for which it has suitable resolution.

Bidding

The infrastructure to transfer 3D data to a format and resolution necessary for construction 

requires the development of document management systems. Existing systems for managing 

construction contract documents provide a foundation that can be extended. Policies and 

standards are important to ensure that the 3D data are consistent in quality and presentation and 

contain all the necessary information for both the contractor and owner. This requires standards 

related to the 3D data type, the density or level of detail in that data, the format of the data, the 

horizontal and vertical coordinate datums, and authorized use of the data.
31

Construction

Most changes needed in construction are to manage 3D data and support real-time verification by 

the engineers and inspectors onsite. AMG and real-time verification take construction layout and 

surveying out of the control of the surveyor and place it into the hands of equipment operators 

and inspectors. To ensure that construction continues to be performed and measured within the 

appropriate tolerances, policies and procedures need to be implemented to provide the 

appropriate construction survey oversight to these activities.

Of paramount importance is a process and policy by which the original project control is verified 

and the method is agreed for projecting design grid coordinates into ground coordinates with 

scaled distances. If the contractor and inspector do not use consistent approaches, then 

differences in survey techniques could erroneously be interpreted as construction errors. These 

processes and policies can be built into the construction specification.

A work plan requirement can also be included in the construction specifications. The work plan 

provides notice and agreement over how the contractor will be using 3D data for layout and 

AMG as well as which AMG systems will be used for each construction activity, 3D data 

sources, and processes for keeping data current when design or field changes occur. Another 

element that can be built into a construction specification are provisions for the contractor to 

furnish equipment for the owner’s independent use.

Protocols for real-time verification need to be developed. Equipment and software are rapidly 

changing to make data capture and management more efficient. Protocols should be flexible to 

accommodate evolving technology and should focus on methods to ensure proper construction 

survey oversight while capturing the right data to measure and accept completed work with 

independence.

There are hardware, software, and training investments that are necessary to migrate to datadriven processes for construction engineering and inspection. The need extends beyond the field 

and back to the region or head office where data may need to be processed during construction 

and must be managed and archived after construction is complete.

IMPLEMENTATION MATURITY

There are various levels of implementation maturity for each of the enabling infrastructure and 

policy elements. The adoption of technology in highway construction to date has led to highly 

refined and siloed processes. Highway professionals and agencies have adopted distinct datasets, 

data formats, and software applications to meet the objectives of the individual asset lifecycle 

phase. Within phases and disciplines, technology is mature and efficient. However, single phase 

optimization is not an efficient way to manage data about highway assets throughout their 

lifecycle. Transferring data throughout the different highway project delivery phases (planning, 

surveying, design, construction, and operations and maintenance) remains largely paper-based, 

and there is often duplication of data creation and management.

The first step toward implementing paperless project delivery has been to replace a paper page 

with an electronic page. One of the limitations of using an electronic page is that the data are 

static. Database-driven systems allow data to be queried and reused, but portability beyond the
32

construction phase is enabled by a geospatial component to the database. To realize the vision for 

lifecycle highway asset data, there must be a geospatial component to the data, which references 

the 3D data to a mapping projection and geoid model. The use of geospatial data is well 

entrenched in 3D design and AMG construction. However, current procedures for construction 

engineering and inspection use project-specific linear referencing. Implementing geospatial field 

technology to perform real-time verification and capture post-construction as-built survey data is 

a significant change, but there are efficiency gains that can contribute to better safety outcomes 

by reducing the exposure of inspectors to equipment movements.(30)

While the enabling infrastructure and policies identified are wholly in the control of State 

transportation departments, the policies for digital signatures and digital seals are not. Each State 

engineering board must implement a policy before its transportation department can begin to 

digitally sign and seal contract documents. Digital signatures are an essential means of 

authenticating digital contract documents. In a digital page level of implementation, the 

technology is mature to support digitally signed PDF documents, which can be 2D or 3D 

documents. FDOT has developed software to review and digitally sign LandXML files using a 

public/private key encrypted digital signature.(11) The technology to digitally sign CADD files 

needs further development at this time. Though the FDOT software digitally signs or validates

a digital signature on any electronic file type, it is not possible to simultaneously view that file 

and validate the signature. In the interim, if 3D data are to have contractual standing, then a 

document management system is needed to protect the contractual version and provide universal 

access to it.

Regardless of whether 3D digital data can be used for construction with automation technology, 

there are considerations that should be addressed contractually.(31) The means of authenticating 

contributors, like with digital signatures or document management systems, is one consideration. 

Ownership and responsibilities for controlling the data on Web-based or other collaboration 

platforms should be identified. Responsibility for errors introduced by data exchange or using the 

data in software is another important issue to manage contractually. Finally, the extent to which 

the owner warrants the data or terms of use needs to be managed contractually. In vertical 

construction, a building information modeling (BIM) project execution plan is usually annexed 

to the contract documents that manages these issues and others associated with multidisciplinary 

coordination and collaboration.(32)
33

CHAPTER 5. INTRODUCTION TO AUTOMATION TECHNOLOGY APPLICATIONS 

AND GUIDELINES

There is a need for interdepartmental coordination between district, design, survey, and 

construction departments to determine agency-wide objectives for automation in highway 

construction. This chapter illustrates how this interdepartmental coordination supports effective 

use of automation on individual construction projects.

Effective and integrated use of automation technology starts at project scoping, as shown in

figure 8, with tailored survey mapping products. These survey products form the basis of 3D 

design data that are ready for use in construction. The 3D design models can form the necessary 

data for automation technology used in construction layout, AMG, quantity measuring, the 

capture of 3D digital as-built records, and real-time field verification to accept completed work.

Source: FHWA.

Figure 8. Flowchart. Planning for automation technology integration.

The various construction uses require open, portable, and durable data formats. Robust review 

protocols check that the design intent is preserved when 3D design data have been reformatted 

or translated. Standard specifications can accommodate the use of evolving technology by

establishing performance-based outcomes. Construction inspection manuals describe technologyneutral processes for capturing data to measure and accept work with independence.

Table 5 shows a capability/maturity matrix showing different levels of implementation of the 

processes and policies at the project or organization level to prepare and use 3D data for 

automation in highway construction. There is synergy between mature practices in some 

areas (e.g., providing 3D contract models that supersede plans and in using automation for 

construction engineering and inspection). In other areas the practices may be unrelated

(e.g., using 3D models to visualize right-of-way impacts and capturing digital as-built data).

Chapters 6–10 describe and reference workflows, business practices, standards, and 

specifications that have been adopted by State transportation departments. Note that the 

published examples referenced in the remainder of this report may not yet reflect the full 

maturity that is possible or conceivable at this time.
Table 5. Capability/maturity matrix for applications of automation in highway construction.(12)

Application of 

3D Models

Maturity Level

1: Initial 2: Evolving 3: Defined 4: Managed 5: Enhanced

Survey methods Aerial and field 

survey to create 2D 

line work and 3D 

DTMs

Aerial remote sensing 

combined with field 

survey to create 2D 

line work and highdensity 3D DTMs

Predesign survey 

deliverable from 

multiple datasets and 

survey methods

Survey manual 

identifies activities/ 

areas requiring 

enhanced vertical 

accuracy

Predesign survey 

deliverable from 

multiple datasets 

with accuracy tied 

to construction 

tolerance

Survey 

metadata

Survey metadata 

including coordinate 

system, datum, and 

projection is noted 

on the control sheet

Coordinate system, 

datum, and projection 

are shared with digital 

files and are not 

embedded

Some CADD files 

have the projection, 

datum, and coordinate 

system embedded 

digitally

CADD with spatial 

data have the 

projection, datum, 

and coordinate 

system embedded

digitally

Seed/template files 

have standard 

projection, datum, 

and coordinate 

system embedded

Visualization Occasional use for 

isolated projects and 

uses

Some projects have a 

3D model that is 

reused for multiple 

applications

Many projects use a 

3D model during 

planning for multiple 

applications

Many projects use a 

3D model for 

multiple applications 

during all phases

Need for 

visualization is 

assessed for all 

project types and

phases

Road design 3D CADD to create 

2D plans with 

manual edits.

3D models for 

information only;

inconsistent with 

plans

3D CADD to create 

2D plans. 3D models 

for information only 

but are consistent with 

plans

3D CADD to create 

2D plans. 3D models 

for information only 

but are consistent with 

plans

3D model takes legal 

precedence over 

plans for earthworks 

and paving

3D model with 

earthworks, paving, 

existing, and 

proposed utilities 

and structures

Utility design Hydraulic analysis 

output linked to 

2D plans

Hydraulic analysis 

output disconnected 

from 3D CADD for 

plans production

A single 2D CADD 

model for hydraulic 

analysis and plans 

production

A single 3D CADD 

model for hydraulic 

analysis and plans 

production

A single 3D model 

for hydraulic 

analysis, plans 

production, and 

clash detection

34
Application of 

3D Models

Maturity Level

1: Initial 2: Evolving 3: Defined 4: Managed 5: Enhanced

Bridge design Limited 3D 

structural analysis

Structural analysis 

output linked to 2D 

plans

3D structural analysis 

imports roadway 

geometrics and ground 

to spatially orient the 

model

A single 3D model 

for structural 

analysis, plans 

production, and 

constructability for 

standard bridges

A single 3D model 

for structural 

analysis, plans 

production, and 

constructability for 

all bridges

Other structural 

design

Limited 3D 

structural analysis

Structural analysis 

output linked to 2D 

plans

3D CADD model 

identifies structure 

limits, structures not 

accurately modeled

3D structural analysis 

based on a common 

data environment 

with roadway 

geometrics for 

standard structures

3D structural 

analysis based on a 

common data 

environment with 

roadway 

geometrics for all

structures

Right-of-way 

engineering 

visualization

2D diagrams created 

from the 2D CADD 

line work are used to 

consult stakeholders

2D diagrams and 

images from 3D 

visualization models 

when these are 

available

2D diagrams and 3D 

images from the 

design models are 

used on isolated 

projects

Images of the

3D design overlaid 

on an aerial image 

draped over a 3D 

surface

3D model on a 

mobile tablet to 

navigate from 

multiple angles 

with stakeholders

Right-of-way 

engineering 

data 

management

2D line work for 

proposed right-ofway limits exported 

to land information

database

Existing right-of-way 

(ROW) information 

includes links to rightof-way maps and

documents

Standard process 

updates land 

information database 

during ROW

acquisition

Existing and 

proposed ROW 

information is linked 

to the land

information database

Survey-grade land 

information 

database with map 

interface to interact

with current data

Clash detection 2D CADD files 

overlaid on a 

common spatial 

projection for

manual comparison

3D CADD files 

overlaid on a common 

spatial projection for 

manual comparison

Design review 

software used to 

perform 3D clash 

detection digitally

during design

Subsurface utility 

locations updated 

during construction 

for ongoing 3D clash

detection

Subsurface utility 

locations are 

incorporated into 

AMG models to

alert operators

Maintenance 

and protection 

of traffic

Temporary 

roadways are 

modeled in 3D 

during design to 

validate staging

Images from 3D 

model used to 

communicate MPT to 

stakeholders during 

design

3D model updated 

during construction to 

produce images for 

public outreach

Videos rendered out 

of 3D model to 

communicate MPT to 

stakeholders

4D model used to 

plan for holiday 

traffic and create 

videos for 

stakeholders

35
Application of 

3D Models

Maturity Level

1: Initial 2: Evolving 3: Defined 4: Managed 5: Enhanced

Constructability 

review

Designers review 

3D models, but 

review process is not 

documented

There is a draft design 

review process for 

surface models and 

clash detection

There is a standard 3D 

model review process 

for surface models and 

clash detection

The standard review 

process includes 3D 

clash detection and 

4D staging review

The contractor 

maintains a 3D 

model connected to 

their resourceloaded schedule 

(5D model)

Staging 2D staging plans 

with static 3D

images of each stage 

for information only

2D staging plans with 

static 3D images of

each stage as contract 

documents

High-level 4D model 

to communicate

staging for 

information only

High-level 4D model 

replaces 2D staging

plans as contract 

document

4D model used to 

resolve staging

issues across 

multiple contracts

Construction 

scheduling

3D models for 

earthworks quantity 

takeoffs (QTOs) and 

staging and locating 

borrow/spoil pits

3D models are used 

for earthworks and 

structure QTO and 

staging

3D models are used 

for 4D simulation to 

review the critical 

path

4D model with 

space/time clash 

detection is used to 

optimize the critical 

path

4D model queries a 

resource-loaded 

schedule to 

visualize cost 

and/or risk data (5D 

model)

Contract 

models

Contractors create 

3D models from 

2D plans

3D line strings and 

surfaces provided for 

information only

3D models that reflect 

the design intent 

provided for 

information only

Pilot initiatives to

provide 3D models 

that supersede 2D 

plans for some 

construction

activities

3D models 

supersede 2D plans 

for some 

construction 

activities

Construction 

via AMG

AMG systems for 

activities that 

require up to 0.1-ft 

vertical accuracy 

(e.g., rough grading)

AMG systems for 

activities that require 

up to 0.5-inch 

accuracy (e.g., fine 

grading)

AMG systems for 

activities that require 

up to 0.25-inch 

accuracy (e.g., paving)

AMG systems for a 

wide range of 

activities (e.g., 

profile milling, 

paving, and slip 

forming)

AMG systems used 

to achieve good 

material yields and 

smoothness 

regardless of 

tolerance

Construction 

layout

Agency owns site 

layout and sets 

stakes

Agency owns site 

layout and sets stakes; 

contractors perform a 

GPS/GNSS site 

localization that is not 

reviewed

Contractor's site 

localization for AMG 

operations reviewed 

by agency

Contractor and 

agency use a 

common site 

localization for 

layout with rovers

Contractor and 

agency agree on a 

common site 

localization that is 

documented in an 

automation 

technology work 

plan

36
Application of 

3D Models

Maturity Level

1: Initial 2: Evolving 3: Defined 4: Managed 5: Enhanced

Source of 

construction 3D 

data

Contractors creates 

and reviews 3D data 

used in construction

Contractor’s 3D data 

reviewed by agency 

prior to construction

Contractor and agency 

agree on a common 

set of 3D data for 

construction and

quality assurance

Agency provides 

models for 

construction, 

measurement, and

quality assurance

Agency provides 

models for 

construction, and 

contractor provides

as-built models

Quality 

assurance 

tolerance 

checks

Staff are aware of 

stakeless methods 

but lack equipment 

and training

Use contractor’s 

Rover, but no site 

localization or 3D 

model review

Contractor's site 

localization and 3D 

model are reviewed to 

use contractor's Rover 

independently

Contractor's site 

localization and 3D 

model are reviewed, 

tolerance methods 

agreed

Independent, 

3D model-based 

tolerance checks 

with survey 

equipment and 

minimal stakes

Measurement 

tools

Traditional survey 

instruments 

supplement analog 

tools

Digital levels 

supplement traditional 

survey instruments

Survey instruments 

with data collectors

and spreadsheets for 

calculating areas and 

volumes

Survey instruments 

with data collectors 

and CADD for 

calculating areas and 

volumes

Survey data 

processed with 

CADD for 

measuring and 

calculating lengths,

areas, and volumes

As-built data Paper plans are 

redlined and 

archived

PDF plans are 

redlined and archived 

electronically

CADD files are 

updated based on 

paper/PDF redlines

As-built data are 

captured and 

delivered digitally if 

requested

The format for 

capturing as-built 

data is standardized 

and required on 

projects

37

39

CHAPTER 6. SURVEYING

AMG, which is a primary mode of automation in highway construction, uses real-time survey 

instruments. This prominent role of survey equipment in construction has implications that need 

to be supported during the original control and topographic survey. A workflow for developing 

topographic and control survey products that support automation in highway construction is 

shown in figure 9.

Source: FHWA

Figure 9. Flowchart. Producing survey products to support automation in highway 

construction.

This chapter covers the following topics:

• Establishment of a site control.

• Survey metadata.

• Accuracy tolerances for topographic survey.

• Use of remote sensing.

• Non-traditional survey products.

Location, density, and durability of project survey control are important considerations to 

establish project control for successful use of automation in construction. While not an issue 

limited to construction with automation technology, consistently employing quality control 

affects the accuracy with which a project is constructed. Using the original mapping control in 

construction is the best way to build the project in accordance with the design intent.(6) 

Automation for construction engineering and inspection is most easily implemented when both 

the contractor and inspector work off the same control network and basis to translate the plans to 

build the project. Otherwise, there can be differences in observations due to different survey 

methods rather than construction errors.

Implementing automation in highway construction relies on 3D digital data that have the 

necessary accuracy to meet the tolerances in the construction specifications. This means that the 

survey information upon which the design is based must be accurate to the same tolerances.

These tolerances are documented in an agency’s construction specification. While there is no 

industry standard, there should be consistency. In many cases, the accuracies and densities
40

needed from the original topographic survey are much higher than what has been typically 

collected.

Newer survey methods like LiDAR reduce the time for capturing data with the necessary spatial 

accuracy and point density. However, they are less cost effective than traditional remote sensing 

applications. Agencies have to balance the probability of the automation technology being used 

with the cost of producing the necessary survey data. Nevertheless, existing low-accuracy ground 

survey data are a very commonly cited challenge for construction regardless of automation use. 

Contractors report checking tie-ins to existing facilities to identify any redesign that may be 

needed to fit to field conditions and spot-checking the existing ground survey during bidding to 

determine accurate quantities. While accuracy greater than 3-inch is not always needed at all 

locations, this level of accuracy can avoid earthwork change orders or redesign at tie-ins to

hard surfaces.

ESTABLISHING SITE CONTROL

The original project survey control is the source of ground truth for construction, setting the 

parameters that relate the design on the plans to locations on the ground. The original control 

accuracy can be selected to support the highest order use in design, construction, and asset 

management. The quality of the control has a direct impact on the network accuracy of as-built 

record data integrated into an asset management system. If the control is geospatially referenced 

to the NSRS, then the mapping products can be projected onto different mapping projections 

that may be needed for design, construction, and asset management. For example, design 

documents may use a State plane coordinate system, construction documents may use site 

localization, and asset management documents may use a universal transverse mercator (UTM) 

coordinate system. Figure 10 illustrates the process to successfully establish site control to 

support the use of automation processes and equipment in a project.

Source: FHWA.

Figure 10. Flowchart. Setting site control to support automation in highway construction. 

Control Accuracy

The investment in mapping control affects the network accuracy of all the data captured and 

created relative to that control. This includes the original base mapping, construction layout, and 

construction as-built surveys. Modern survey instruments make establishing control with high 

orders of accuracy more cost effective than in the past. Investing in durable, accurate control 

supports automation in highway construction and use of as-built record data for asset 

management and in future maintenance or construction activities.
41

To produce a design that ties seamlessly into existing features, the base mapping must have a 

high order of network accuracy for those features. The accuracy of the control is a limiting 

factor. Horizontal tie-ins are simpler to transition and field fit than vertical tie-ins. For design and 

construction, horizontal control can be of a lower order than vertical control. The value of higher 

accuracy horizontal control than that indicated in table 6 may materialize in asset management 

uses of the data, such as subsurface utility locations.

Table 6. Minimum positional accuracies for mapping control to support automation 

technology.

Control Type

Network Accuracy 

(ft)

Horizontal 0.10

Vertical 0.02

Situating Control

Effective site control situating practices are unchanged from long-standing practices. The 

original mapping control is what ties the ground to the projected grid upon which the design is 

developed. Durable control that has been well documented with complete metadata aids in 

preserving the design intent when mapping the design grid back onto the ground in construction.

AMG systems work effectively with site localization, which computes a rotation and scale factor 

for horizontal layout and creates a vertical datum. Using a site localization approach will result in 

tight vertical closure and good horizontal closure if the control is sited appropriately. AMG 

systems are able to replicate the surveyor’s workflow and work off a mapping projection and a 

geoid model when the base station is set up over a known point. However, this is not easy to do 

without a skilled surveyor. Many contractors prefer the site localization approach, which has 

specific control location needs.

When using site localization, RTK correction may be provided by an independent base station, a 

CORS, or an RTN. Site localization includes a map projection, a horizontal adjustment, and a 

vertical adjustment. The control is used to determine the horizontal and vertical adjustments.

The horizontal adjustment consists of a rotation, translation, and scale factor. A minimum of 

two control points are required for computing a horizontal adjustment, a minimum of

three control points are required to compute a vertical adjustment, and a minimum of five points 

are recommended for both.(33) The control needs to enclose the project area in order to produce a 

good site localization with low residuals. More than one site localization may be used on a 

project to keep the horizontal and vertical closures small.

On linear projects where the vertical control is located too close to the linear axis, the vertical 

plane computed by the site localization may result in large errors transverse to that axis, which 

increase with distance from the axis.(33) Secondary control can be placed near the alignment 

during construction. In figure 11, green circles indicate the preferred primary control distribution 

for a linear project (alignment shown in solid blue) to support a site localization. The dashed 

lines represent the control network diagrams.
42

Source: FHWA.

Figure 11. Illustration. Effective control siting to support site localization for a linear 

project.

Site localization resides in the data collector and is used with various survey instruments. Where 

total station is used for AMG operations or automated inspection, secondary control within the 

line of sight is required. The secondary control can be set during construction and tied to the 

primary control established during the original base mapping. Since the secondary control will 

not be used to establish the site localization, it can be located along the linear axis situated to aid 

in visibility and durability.

SURVEY METADATA

Given the importance of the original project control in construction, it is necessary to preserve 

the survey metadata, which describes the basis for the horizontal coordinate system projection 

and vertical datum upon which the original survey mapping is based. The metadata for control 

must be preserved so that surveyors can locate and, if necessary, replace the original survey 

control monuments during construction or for future maintenance or construction activities.

Table 7 provides a sample of survey metadata needed to reconstruct the original mapping if 

needed during construction.
43

Table 7. Sample survey metadata.

Metadata Element Example

Horizontal datum • UTM North Zone 11 referenced to North American Datum of 1983

• Adjustment: NSRS 2007

Vertical datum • North American Vertical Datum of 1988

• Geoid Model: Geoid 12A (CONUS)

Coordinate system Nevada Central 2702

Projection • Transverse mercator

• Central latitude: 34° 45' 00.00" N

• Central longitude: 116° 40' 00.00" W

• False northing: 6,000,000 ft

• False easting: 500,000 ft

• South azimuth: No

• Positive direction: North/east

Grid scale factor 0.9999912

Units of measure U.S. survey feet (ft)

In the event that the original control is disturbed prior to or during construction, the construction 

surveyor will need to establish it. It is common to include a control plan in the construction 

plans. At a minimum, the control plan should contain the metadata as well as the northing, 

easting, elevation, and description for each control point. It may be useful to include the station 

and offset of the control relative to the design baseline in the contract documents.(34) The Nevada 

Department of Transportation maintains a database of survey monuments, including construction 

control that is publicly available through a Web-based GIS.(35)

The survey report provides information to surveyors who may need to recreate the workflow, 

either to locate control or reestablish it. The report should include the metadata as described in

table 7, the list of controls, network diagrams, minimally constrained report, fully constrained 

report, means and methods of conducting the observations, and any issues or concerns arising 

from the field work.(36) The survey report does not need to be included in the contract documents, 

but it should be available if there are an issues with the control during construction.

ACCURACY TOLERANCES FOR TOPOGRAPHIC SURVEY

Traditional survey products include right-of-way and adjacent property legal descriptions, an 

existing ground DTM, CADD line work and point symbols, digital photography, control 

description, and metadata describing the map projection, vertical datum, horizontal scale factor, 

and rotation.(36) These deliverables are a streamlined set of data that are sufficient to perform 

design, right-of-way acquisition, and construction layout. These survey products are also 

sufficient for construction with automation technology.

With automation in highway construction, there is a desire that the original 3D design data be 

used in construction. For that to be possible, the topographic survey needs to provide sufficient 

accuracy so that the design data matches the field conditions at locations where the design is 

constrained by fixed features. Design issues requiring field fits in construction are usually the 

result of insufficient vertical accuracy in either the survey control or the topographic mapping.
44

The accuracy of DTM surfaces and break lines depends on two components: the accuracy of the 

data points and the distance between them. As shown in figure 12, the larger the distance 

between survey points, the greater the area of interpolation in DTM elevations.

Source: FHWA.

Figure 12. Illustration. Relationship between survey observations and elevations computed 

for a DTM.

For the data points, unnecessary network accuracy can be costly to collect, but not enough 

network accuracy of certain constraining features can lead to redesign and change orders. Tie-ins 

to hard surfaces are often constraints on the design (e.g., existing pavements, existing bridge 

structures, or existing curbs and gutters). CADD software interpolates between points. Much like 

accuracy, unnecessary point density increases cost, but too little point density can miss necessary 

details. For example, super-elevation at a tie-in may be miscalculated if the distance between 

points is greater than the lane width.

High accuracy survey is able to extend the application of automation technology into newer areas 

like full-depth recovery or asphalt resurfacing projects where there is a need for drainage 

improvements, super-elevation corrections, or profile improvements. These operations require 

survey of the existing feature with a high network accuracy to develop milling or reconstruction 

profiles that improve the roadway geometrics while optimizing material yields.

Topographic accuracy needs can be differentiated based on whether the feature is a constraint, 

a design feature, a location feature, or a planning feature. A constraint should be a fixed feature 

that the constructed facility must tie into exactly. A design feature should be a feature whose 

location or physical characteristics (e.g., slope or depth) affect design decisions, a location 

feature would be a feature that influences the design, but it can be modified or relocated

(e.g. a grass-lined ditch or a natural slope). A planning feature would be a feature that needs 

to be depicted on the plans but does not significantly influence the design (e.g. a woods line or 

wetland beyond the limits of the right-of-way). Table 8 is a guide to minimum horizontal and 

vertical accuracies for constraint, design, location, and planning features.
45

Survey instruments are constantly evolving. If a survey specification describes the outcomes of 

the topographic mapping, the surveyor can select appropriate tools to capture the necessary data 

efficiently and safely depending on the site conditions.

Table 8. Minimum network accuracies for different feature types.

Feature 

Type Description

Minimum 

Network 

Accuracy 

(ft)

Maximum 

Distance 

Between 

Points (ft) Example Features

Constraint The precise location or 

physical characteristics 

constrains the design and 

cannot be modified or

relocated cost effectively

H = 0.04

V = 0.02

5 Tie-ins to existing sewers, 

curbs, culverts, pavements, 

utility covers, and bridge 

elements

Design The location or physical 

characteristics affect 

design or constructability

H = 0.10

V = 0.04

10 Minimum grades on 

pavements or ditches, 

stream thalwegs, or existing 

pavements that will be 

modified

Location Feature can be modified 

or relocated, or its precise 

location does not affect 

design or constructability

H = 0.25

V = 0.10

25 Stream banks, tops and toes 

of slopes, ditches, natural 

ground, retaining walls, and 

storm/sanitary sewer inverts

(not tie-ins)

Planning Feature will be shown on 

plans, but location does

not affect design or 

constructability.

H = 0.50

V = 0.50

50 Utility poles, landscaping, 

woods lines, wetland limits,

fences, and features to be 

demolished.

H = Horizontal. 

V = Vertical.

Table 9 provides an example of how the features in table 8 apply to different AMG construction 

activities and includes minimum point densities for DTM surfaces.
46

Table 9. Survey resolution required to support AMG operations.

Project Type

Applicable AMG 

Methods Constraint Features Design Features

Asphalt mill and pave

with ride improvements

2D sonic averaging for

milling and paving

No survey required No survey required

Asphalt mill and pave 

with cross slope or 

drainage correction

(hard tie-ins only at 

start and end)

2D sonic averaging for 

milling and paving

No survey required No survey required

Asphalt mill and pave 

with cross slope or 

drainage correction (tie 

to hard surface or curb 

and gutter)

3D profile milling with 

constant depth or 2D 

paving. Alternately, 

constant depth milling 

and 3D paving

• Breaklines: Crown and 

edges of pavement

• DTM: Pavement 100 ft 

either side of tie-ins at start 

and end and areas with 

minimum grade

DTM: Pavement 

between constraint 

features, ditches, and 

drainage features

Concrete overlay with 

or without ride and 

drainage corrections

3D paving • Breaklines: Crown and 

edges of pavement

• DTM: Pavement 100 ft 

either side of tie-ins at start 

and end and areas with 

minimum grade

DTM: Pavement 

between constraint 

features, ditches, and 

drainage features

Reclamation Grading, fine grading, 

base, and paving

DTM: Pavement 100 ft 

either side of tie-ins at start 

and end and areas with

minimum grade

DTM: Pavement 

between constraint 

features, ditches, and

drainage features

Shoulder and side slope 

widening or 

improvements

Grading, fine grading, 

base, and paving

• Breaklines: Saw cut line

• DTM: Pavement 100 ft 

either side of tie-ins at start 

and end and areas with

minimum grade

Breaklines: Edge of 

shoulder, slope break 

points, toe of slope, 

ditches, and drainage 

features

Lane widening Grading, fine grading, 

base, and paving

• Breaklines: Saw cut line

• DTM: Pavement 100 ft 

either side of tie-ins at start 

and end and areas with

minimum grade

Breaklines: Edge of 

shoulder, slope break 

points, toe of slope, 

ditches, and drainage 

features

Reconstruction Grading, fine grading, 

base, and paving; 

possibly 3D profile

milling and excavation

DTM: Pavement 100 ft 

either side of tie-ins at start 

and end

DTM: Driveways, 

utility covers, ditches, 

and drainage features

New construction Excavation, grading, 

fine grading, base, and 

paving

DTM: Pavement 100 ft 

either side of tie-ins at start 

and end

DTM: Driveways, 

utility covers, ditches, 

and drainage features
47

Topographic mapping for the original ground DTM may merge the datasets arising from a 

variety of survey instruments.(37) It is possible to differentiate between survey shots captured 

with different methods in CADD files. Hard shots taken with total stations or GNSS rovers have 

higher accuracy than remotely sensed shots taken with aerial photogrammetry or LiDAR. DTMs 

can also be separated according to accuracy, but they would need to be consolidated for 3D 

design to target corridor model end conditions and for computing earthwork volume quantities 

in design and construction. Differentiating between sources communicates to the designer and 

contractor the confidence with which they can hold the observation and whether supplemental 

survey is needed.

USE OF REMOTE SENSING

Remote sensing has its benefits among a range of survey data acquisition tools. As a remote 

sensing application, LiDAR is vulnerable to gaps in data acquisition from shadowing and visual 

occlusions. It cannot be relied on as the sole data source for mapping data acquisition. Rather, it 

can be part of a suite of tools at the surveyor’s disposal to deliver topographic mapping products.

The four primary types of remote sensing currently in use are as follows:

• Aerial photogrammetry.

• Aerial LiDAR.

• Mobile LiDAR.

• Static LiDAR.

Aerial remote sensing is able to cover a wide area in a relatively short amount of time. However, 

processing times are long, and the network accuracy is limited to 0.25 to 0.5 ft. Mobile LiDAR 

has notable safety benefits, especially in high-volume and/or high-speed roadways, but it is 

costly to mobilize. Processing times for mobile LiDAR are long, and point density is high, 

leading to large datasets. Network accuracy from terrestrial mobile LiDAR is about 0.17 ft.

Static LiDAR has long setup times, capturing vast datasets of relatively high network accuracy, 

up to 0.02 ft close to the sensor, but eroding with distance from the sensor.(38)

Table 10 relates the different LiDAR data acquisition methods to their suitability for capturing 

data in the accuracy bands identified in table 8. Aerial LiDAR may not be able to achieve the 

higher accuracy needs. Mobile LiDAR may need extensive control to achieve higher accuracies 

and may not be able to achieve the highest accuracy category. Static LiDAR may not be cost 

effective for wider area mapping. LiDAR hardware and software continue to evolve, and the 

suitability of different methods may change. Table 10 is a guide based on current technology.

Tool selection is best left to the mapping surveyor, who is the licensed professional responsible 

for means, methods, and outcomes of the mapping survey.
48

Table 10. Suitability of LiDAR methods by topographic mapping accuracy ranges.

Feature Type Aerial LiDAR Mobile LiDAR Static LiDAR

Constraint Not appropriate Not appropriate Suitable

Design Not appropriate Consider Suitable

Location Consider Suitable Consider

Planning Suitable Suitable Consider

Certain project characteristics are predisposed toward the use of different types of LiDAR for 

data acquisition. These include the extent of the area to be mapped, the type of project, the 

terrain, and time sensitivity.(39) Other factors that may influence the choice of LiDAR method 

include traffic conditions, whether there is a need to capture roadside features in addition to 

terrain, and whether there are opportunities to consolidate data acquisition for multiple uses.

Table 11 reflects suitability of different LiDAR methods for different project characteristics.

Table 11. LiDAR method suitability for different project characteristics.

Project Characteristics Aerial LiDAR Mobile LiDAR Static LiDAR

Green fields Suitable Not appropriate Not appropriate

Existing roadway Consider Suitable Consider

Large area Suitable Suitable Not appropriate

Time sensitive Consider Consider Suitable

Variable terrain Suitable Consider Not appropriate

High traffic volumes Suitable Suitable Consider

High traffic speeds Suitable Suitable Consider

Urban area Consider Suitable Suitable

As LiDAR hardware and software technology evolves, thresholds for different methods will 

change. For example, setup speeds, effective ranges, and other limiting factors will improve, 

while data filtering and processing times will decline. Table 12 lists project characteristics 

favorable for data collection using aerial LiDAR, mobile LiDAR, and static LiDAR.(39,36) 

Individual LiDAR methods may become more broadly applicable than those shown in table 12. 

In many circumstances, field survey methods may be more efficient than LiDAR, particularly 

smaller projects. Field survey will usually be necessary for setting control, collecting subsurface 

utility locations and inverts, and collecting positions of constraint features (as defined in table 8).

Table 12. Project characteristics favorable for different LiDAR methods.

Aerial LiDAR Mobile LiDAR Static LiDAR

• Mainline lengths > 1,300 ft

• Large areas and wide 

corridors

• Large bridge replacements

• Variable terrain

• Rural reconstructions

• Areas with limited foliage

• Long, rural corridors

• High-speed corridors

• Corridors with high volumes

• Multilevel interchanges

• Resurfacing projects with crossslope or super-elevation 

corrections

• Data collection time constraints

• Mainline lengths < 1,300 ft

• Small areas

• At-grade intersections

• Low-volume and low-speed roadways

• Flat terrain

• Small bridge replacements

• Urban resurfacing projects with 

drainage or cross-slope repairs

• Interstate widening
49

Regardless of the method of collection, LiDAR acquires vast amounts of data.(2) It is prone to 

collecting “noise” (i.e., observations that are artefacts of collection or mobile obstructions like 

passing vehicles, birds, survey setups, tripods holding temporary control, and even surveyors 

themselves). The effort to perform quality control, filter, register, classify, and extract 

topographic mapping products from LiDAR data is non-trivial, as is the challenge of managing 

the large datasets. The benefits of mobile LiDAR in particular are best realized where the 

datasets are shared between many applications.(2)

In addition to topographic mapping deliverables, it is desirable that the surveyor provide detailed 

metadata, a survey narrative report that includes the quality control details, the registered point 

cloud, the raw point files in E57 format (developed by the ASTM E57.04 Data Interoperability 

Subcommittee), and, if available, digital photo mosaic files.(36,40)

NON-TRADITIONAL SURVEY PRODUCTS

New methods of survey data capture (i.e., LiDAR) enable surveyors to capture a vast collection 

of survey points in a short period. These points can be collected in such a dense collection, called 

a “point cloud,” as to depict the full scene within the sensor’s line of sight. The density of points 

is such that a full scene can often be understood and interpreted. Point clouds have been used to 

check clearances for construction equipment, plan construction activities in constrained areas, 

and view complex existing structures and features like bridges and historic buildings that would 

otherwise be challenging to model. In figure 13, the striping, traffic control barrels, and a speed 

limit sign are evident amid “noise” from scan setups and passing vehicles.

Source: FHWA.

Figure 13. Illustration. Unfiltered point cloud.

For many applications, LiDAR captures too many points, and the data need extensive filtering 

and processing to produce a workable dataset. While not useful for normal design, right-of-way, 

and construction processes, the unprocessed datasets can be useful for other functions. Software
50

tools are emerging to extract 3D solid primitives from the point cloud to better use computer 

clash detection algorithms or for 4D or 5D modeling.
51

CHAPTER 7. SUBSURFACE UTILITY LOCATION

Subsurface utility location and relocation within the right-of-way constitute leading causes for 

delays for highway and bridge construction projects. Several aspects of utility location, including 

identification of the type of utilities and the format, accuracy, and sources of their positional and 

other attribute data, are often problematic to identify from existing records and are flagged as 

project risks. Consequently, design cannot progress without expensive location identification 

investigations during construction. This chapter covers the following topics:

• Purpose of SUE.

• Data quality levels and applications.

• Data quality levels and applications in project delivery.

• How to use 3D subsurface utility location information.

At the time of mapping, it is not always clear which subsurface utilities need to be located with 

high accuracy. Traditional locating methods result in low quality data that is often only 2D. As 

the design matures, subsurface utility location information should be reviewed, and supplemental 

information of higher accuracy should be obtained where warranted.

PURPOSE OF SUE

Ownership of the utility location data is a source of risk. Even though the utilities of concern are 

located with the highway right-of-way, the data regarding the utilities are often owned and 

updated by utility companies and not coordinated with the enterprise data stores of State 

transportation departments. Predominantly, the main repository for geospatial data describing 

subsurface utilities is typically each individual utility owner’s GIS. These records often do not 

specify the spatial integrity of the data (i.e., the vertical and horizontal positional accuracy), 

making it difficult to rely on them for accurate 3D model development. Moreover, these data are 

slow to update or seldom updated when routine maintenance, repair, or rehabilitation work is 

performed on the utilities. This means that users of the data (e.g., highway designers and 

construction personnel and their contractors) must assume the lowest accuracy level associated 

with the survey data, resulting in uncertainty in decisionmaking and potential for costly 

investigations or rework. Conversely, there are many benefits to well-documented utility 

information, including the following:(41)

• Unnecessary utility relocations are avoided. Accurate utility information is available to 

the highway designers early enough in the development of a project to design around 

many potential conflicts. This significantly reduces the following:

o Costly relocations normally necessitated by highway construction projects.

o Delays to the project caused by waiting for utility work to be completed so highway 

construction can begin.
52

• Unexpected conflicts with utilities are eliminated. The exact location of virtually all 

utilities can be determined and accurately shown on the construction plans. As a result, 

the following are reduced:

o Delays caused by redesign when utility conflicts prevent construction from following 

the original design.

o Construction delays caused by cutting, damaging, or discovering unidentified 

utility lines.

o Contractor claims for delays resulting from unexpected encounters with utilities.

• Safety is enhanced. When excavation or grading work is shifted away from existing 

utilities, there is less possibility of damage to a utility that might result in personal injury, 

property damage, or release of harmful products into the environment.

DATA QUALITY LEVELS AND APPLICATIONS

The use of the ASCE 38-02 quality levels in the SUE process allows designers to certify a 

certain level of accuracy and comprehensiveness on their plans.(28,29) There are four quality levels 

described in ASCE 38-02 (levels A through D), which are described as follows:(29.41)

• Quality level A (QL-A): Also known as “locating,” QL-A is the highest level of 

accuracy presently available and involves the full use of the SUE services. It provides 

information for the precise plan and profile mapping of underground utilities through the 

nondestructive exposure of underground utilities and also provides the type, size, 

condition, material, and other characteristics of underground features.

• Quality level B (QL-B): QL-B involves the application of appropriate surface 

geophysical methods to determine the existence and horizontal position of virtually all 

utilities within the project limits. This activity is called “designating.” The information 

obtained in this manner is surveyed to project control. It addresses problems caused by 

inaccurate utility records, abandoned or unrecorded facilities, and lost references. The

proper selection and application of surface geophysical techniques for achieving QL-B 

data is critical. Information provided by QL-B can enable the accomplishment of 

preliminary engineering goals. Decisions regarding location of storm drainage systems, 

footers, foundations, and other design features can be made to successfully avoid 

conflicts with existing utilities. Slight adjustments in design can produce substantial cost 

savings by eliminating utility relocations.

• Quality level C (QL-C): QL-C is probably the most commonly used level of 

information. It involves surveying visible utility facilities (e.g., manholes, valve boxes, 

etc.) and correlating this information with existing utility records (quality level D (QL-D) 

information). When using this information, it is not unusual to find that many 

underground utilities have been either omitted or erroneously plotted. Its usefulness, 

therefore, is primarily
53

on rural projects where utilities are not prevalent or are not too expensive to repair 

or relocate.

• QL-D: QL-D is the most basic level of information for utility locations. It may provide 

an overall feel for the congestion of utilities, but it is often highly limited in terms of 

comprehensiveness and accuracy. QL-D is useful primarily for project planning and route 

selection activities.

Table 13 summarizes applicable locating technologies and the resulting data by quality level.

Table 13. Locating technologies and resulting data for different quality levels.

Quality 

Level

Applicable Locating 

Technologies Resulting Data

QL-A Vacuum excavator and potholing Precise horizontal and vertical position 

at discrete locations (discontinuous)

QL-B • Subsurface geophysics: Ground 

penetrating radar

• Electromagnetic: Inductive, 

conductive, active, and passive 

pipe and cable locators

Designated horizontal and vertical 

location

QL-C Surveying visible presence of 

utilities (e.g., valve boxes, 

manhole covers, etc.)

Positive indicator of presence of a 

utility; inferred horizontal location

QL-D Existing utility records and verbal

sources

Inferred presence of a utility

DATA QUALITY LEVELS AND APPLICATIONS IN PROJECT DELIVERY

There is a trade-off between data quality levels and project costs. While QL-A provides the 

highest data quality, the precise nature of subsurface utility location and utility attribution 

associated with it make this quality level the most expensive to achieve. Conversely, QL-D is 

less accurate and hence can be achieved at a lower cost. Therefore, data collection at a given 

quality level needs to be selected in the context of the adjacent construction activities and the 

maturity of the design. Utilities located in close proximity to excavation or foundation 

construction warrant collection of higher accuracy subsurface utility location information.

Figure 14 is a workflow for selecting appropriate subsurface utility locating technologies at each 

design milestone, from project scoping to preparation of bid documents.

Source: FHWA.

Figure 14. Flowchart. Selecting subsurface utility locating techniques.

The need for different quality levels changes through design and construction. In construction, 

QL-A information is necessary for any utilities that are near excavation activities. Often, the
54

responsibility for collecting QL-A information is left to the contractor, who bears all risk for 

utility strikes. The quality of subsurface utility records should be reevaluated at design 

milestones so that more accurate location information can be acquired where warranted.

USING 3D SUBSURFACE UTILITY LOCATION INFORMATION

While subsurface utility information is 3D in nature, using the 3D information can provide a 

false sense of security if the quality of the 3D data is not clear. As noted previously, there is 

inherent uncertainty in utility locations at all quality levels. Data with the highest level of 

accuracy (QL-A) can be useful for clash detection. QL-B data can also be used in clash detection 

if the utility location is buffered sufficiently to represent the location uncertainty. Figure 15

presents a workflow for integrating 3D subsurface utility data with CADD software to develop 

either 3D models or 2D project plans for final design and construction purposes.

Source: FHWA.

Figure 15. Flowchart. Integrating 3D utility data into 3D model or project plans.

The 3D models of subsurface utilities should be organized to distinguish the different quality 

levels for plans production and clash detection. Two effective strategies for doing so are 

separating CADD data into separate files or data layers for each quality level and using color on 

plans to distinguish between different quality levels. Separate CADD files support the seamless 

generating rules for clash detection algorithms that apply a buffer to utilities of different quality 

levels (e.g., 6 inches on QL-A and larger on other quality levels).

The most laborious and expensive part of the workflow is utility submittals and their certification 

in the content manager for design use. This workflow is recommended to be used on major 

projects where utility conflicts are identified as a substantial risk. However, it is encouraged that 

all projects using automation technology consider capturing as-built utilities for newly 

constructed, located, or relocated utility features within the right-of-way while the project is still 

under construction. If performed well, this effort has the real ability to augment and refine the 

design-level SUE mapping of the utilities and further reduce uncertainty for future projects or 

excavation in the same area. An ASCE committee is currently developing a standard for utility 

as-built records, as reported by FHWA.(42)

There is substantial long-term value in capturing accurate subsurface utility location information 

during construction as existing or new utilities are exposed during excavation, relocation, or
55

installation. When survey equipment is nearby, the cost of capturing this information is low in 

comparison to collecting the information once the utilities are buried.

57

CHAPTER 8. DESIGN

The completeness and reliability of 3D design data is within the designer’s control. Designers 

need to understand how 3D data will be used in order to create 3D design data that meets the 

needs of the specific automation technology and share it with confidence. The 3D design can be 

a dense model that depicts the design intent with sufficient accuracy to be used in construction 

for both AMG and real-time verification. Other uses of 3D design data (e.g., SUE and

4D modeling) do not usually need such high levels of detail or accuracy in the 3D models. This 

chapter covers the following topics:

• Applications in design development.

• Considerations for standard details.

• CADD data types and 3D modeling approaches.

• Guide 3D model standard.

• Guide 4D and 5D model specification.

• Guide 3D data review protocols.

• Contract documents.

Designers can adjust the level of effort invested in creating 3D design data to meet the expected 

uses of that data. There is less value in a detailed 3D model if the underlying survey data are of 

low accuracy. The designer can acquire topographic survey data at the needed accuracy, invest in 

subsurface utility mapping and subsurface utility locating, and take time to model out design 

intent in detail. At the project level, it is helpful if this flexibility is customer-focused on the 

specific automation technology needs. However, in design-bid-build delivery, it can be difficult 

to know how automation will be used in construction. Some degree of standardization is useful 

in the design process and is valuable once construction begins. During design, standardization

provides flexibility in resourcing design production and consistency in design review. During 

construction, it provides predictability and repeatability to contractors and inspectors who use 

the data.

There is more to implementing 3D design than just getting more accurate survey data and 

adding additional detail in CADD. There are opportunities to use the 3D design models to 

develop more refined designs and compute quantities more accurately or more efficiently. Some 

standard details can be modified to add design and construction efficiencies. Design model 

standardization and quality control protocols lead to consistent, reliable data for automation in 

highway construction. There may be a desire for 3D models to supersede plans for automation,

and other specification language can be modified to manage automation in highway construction.

Figure 16 is a workflow for updating design policies to produce 3D data for automation.
58

Source: FHWA.

Figure 16. Flowchart. Updating design policy documents to produce 3D data for 

automation in highway construction.

APPLICATIONS IN DESIGN DEVELOPMENT

The 3D models created during the process of developing and documenting designs can be used 

to inform the decisions made during the development of the designs. Furthermore, the design 

development process has several design review and public involvement milestones that can be 

enhanced by formal processes for using the 3D design models in those reviews. Figure 17 is a 

workflow for using 3D models during design development.

Source: FHWA.

Figure 17. Flowchart. Using 3D models in design development.

Table 14 lists potential applications of 3D models at milestones during design development.

Table 14. Applications of 3D models during design development.(12)

Design Stage 3D Design Model Elements 3D Design Model Uses

National 

Environmental 

Policy Act of 

1969 (NEPA)

(15 percent)(43)

• Existing conditions surface

• Low-density proposed surfaces

• Proposed roadway corridor models

• Proposed structures (extent, type, 

etc.)

• Existing and proposed utilities

• Quantify impacts on sensitive 

environments

• Minimize ROW impacts

• Compute preliminary quantities

• Review proof-of-concept constructability

• Minimize utility relocations (clash 

avoidance)

• Plan surface drainage systems
59

Design Stage 3D Design Model Elements 3D Design Model Uses

Preliminary 

(30 percent)

• Existing conditions surface

• Low-density proposed surfaces

• Proposed roadway corridor models

• Proposed structures (external 

faces)

• Existing and proposed utilities

• Storm drainage systems

• Check site distance

• Perform visual impact analyses

• Minimize ROW impacts

• Optimize earthwork quantities

• Coordinate interdisciplinary design

• Perform staging and constructability 

reviews

• Minimize utility relocations (clash 

avoidance)

• Create preliminary plans and estimates

Final NEPA 

(70 percent)

• Existing conditions surface

• Medium-density proposed surfaces

• Proposed roadway corridor models

• Proposed structures (external 

faces)

• Existing and proposed utilities

• Storm drainage systems

• Check site distance

• Perform visual impact analyses

• Review surface drainage

• Coordinate interdisciplinary design

• Create 3D graphics and 4D videos for 

ROW acquisition and public involvement

• Compute quantities

• Perform staging and constructability 

reviews

• Conduct maintenance of traffic 

conceptual planning

• Create ROW and utility relocation plans

Final plans 

(90 percent)

• Existing conditions surface

• High-density proposed surfaces

• Proposed roadway corridor models

• Proposed structures (major 

systems)

• Existing and proposed utilities

• Storm drainage systems

• Design validation and interdisciplinary 

review

• Create 3D graphics for public 

involvement

• Create 4D videos for public involvement

• Compute final quantities

• Perform staging and constructability 

reviews

• Conduct maintenance of traffic review

• Create contract plans and final estimate

Certify

(95 percent)

• Existing conditions surface

• Very high-density proposed 

surfaces

• Proposed roadway corridor models

• Proposed structures (major 

systems)

• Existing and proposed utilities

• Storm drainage systems

• Create bid documents

• Create 3D model reference data
60

Design Stage 3D Design Model Elements 3D Design Model Uses

Award

(100 percent)

• Existing conditions surface

• Very high-density proposed 

surfaces

• Proposed roadway corridor models

• Proposed structures (major 

systems)

• Existing and proposed utilities

• Storm drainage systems

• Create contract documents

• Create staking/layout data

• Create AMG/real-time verification 

models

CONSIDERATIONS FOR STANDARD DETAILS

If something is hard to model, it is often also hard to construct. Some standard details are historic 

and inefficient for newer construction methods. A 3D modeling implementation is an 

opportunity to review standard details and consider their relevance to construction with 

automation technology.

Some considerations for reviewing standard details include estimating quantities and 

constructability in the context of modern methods with automation in highway construction. 

Some examples include the following:

• Concrete pavements with integrated curbs: Modern pavers can pave a lane with an 

integrated curb in a single pass. Typical sections can be modified to reflect the most 

commonly supported shapes.

• Bridge abutment slopes and culvert headwall grading: AMG systems are being 

installed on a wider range of construction equipment, even as small as a skid steer. 

Modifications to the abutment and headwall standards may make these easier to model 

and easier to construct.

• Superelevation: Superelevation attainment usually happens at a constant rate, but some 

agencies allow a variable rate from one super-elevation critical station to another. These 

variations in superelevation attainment rate will be constructed as designed by precise 

AMG systems, which will create a noticeable change in the roadway.

CADD DATA TYPES AND 3D MODELING APPROACHES

CADD software provides flexible and efficient 3D modeling tools that incorporate roadway 

geometrics and rules-based layout to create the roadway in 3D. The primary tool for creating 

3D models of linear features like roadways is the corridor model. String models are growing in 

popularity, given their flexibility for modeling elements that are not parallel to the alignment. It 

is sometimes useful to manually edit features (e.g., manually grade small areas or to tidy up the

interface between corridor and/or string models). Given the differences in data types and outputs 

from these different modeling methods, it is useful for an agency to standardize methods for 

modeling different design elements.

Many State transportation departments provide the building blocks for modeling common 

roadway design elements with corridor and string models as part of their standard CADD
61

resource files. Especially for visualization, 3D solids modeling still has its place. Table 15

describes four common methods of creating 3D models and provides examples for each method.

Table 15. CADD design methods and their uses.

Design 

Method Description

Corridor 

model

Corridor models compute the parametric rules of the typical section (also 

called a “template”) at defined stations (also called “template drops”). This is 

the most common tool for modeling linear elements that are generally regular 

in shape parallel to the alignment. Standard uses of corridor models include 

roadways and ditches. Advanced uses of corridor models include retaining

walls, bridge abutments, and intersections.

String model String models use rules to offset linear features horizontally and vertically. 

This is a common tool for modeling non-linear features that follow consistent 

rules perpendicular to the base feature. Standard uses of string models are 

drainage basins and parking lots. Advanced uses include intersections and lane 

transitions.

Feature 

modeling

Features are 3D line strings. Features can be created manually or output from 

corridor or string models. This is a common tool for manually grading small 

areas like around headwalls. Features need to be added to surfaces as break

lines.

3D solid 

modeling

3D solids modeling does not follow roadway geometric rules and is usually a 

manual process. It is possible to create a library of 3D solid model elements

like standard headwalls, light standards, and sign posts.

Figure 18 shows a template for a two-lane road with shoulders and four pavement layers. The 

template consists of points that have defined locations relative to the insertion point. The 

insertion point lies on the alignment and profile in 3D space. Each point on the template has a 

point name (e.g., centerline (CL) on the crown in figure 18). Points with like names are 

connected from one template drop to another to create 3D features that are generally parallel to 

the alignment. Corridors can output 3D components that are created by extruding the enclosed 

shapes of the typical section between two template drops. Surfaces can also be produced directly 

from corridor models by triangulating points with defined names between template drops.

Source: FHWA.

Figure 18. Illustration. CADD template representing a two-lane road with shoulders.
62

As the basis of corridor models, a standard template library is an important part of a CADD 

standard. Point and feature names are needed for stake out, AMG and automation processes for 

inspection. The point and feature names are used to select data on the data collector. In figure 18, 

the finished ground surface was created by triangulating points labeled “LSHDR (left shoulder),” 

“LEP (left edge of pavement),” “CL,” “REP (right edge of pavement),” and “RSHDR (right 

shoulder).” The subgrade surface was created by triangulating points named “4LTAPER” (left 

taper), “L4EP” (left edge of pavement for layer 4/subgrade), “CL4” (centerline for layer 4/ 

subgrade), “R4EP” (right edge of pavement for layer 4/subgrade), and “R4TAPER” (right taper). 

A 3D feature for the left edge of pavement was created by connecting the LEP points.

String models also output 3D features and surfaces. String models should use the same standard 

point or feature names to provide consistent 3D line strings that are connected where corridor 

and string models interface. Figure 19 shows the rules embedded in a string model to create a 

20-ft-wide driveway connection with a 10-ft-radius curb return to the edge of lane for the 

primary road.

Source: FHWA.

Figure 19. Illustration. String model that uses rules to offset the baseline horizontally and 

vertically.

Surfaces and features are output from corridor and string models. They can be manually adjusted 

by editing the features or creating new features and writing them to the surface definition. Care 

should be taken in considering which features to include in a surface definition. In urban areas 

with curb and gutter and median islands, it should be considered what value is added by 

incorporating these features into the surface. TIN surfaces cannot include vertical faces; curbs 

and retaining walls can be challenging to incorporate into a surface model. These elements may 

be better represented as 3D solids (also called components), which can be output from the 

corridor model in addition to 3D features.

Many design elements can be modeled in different ways. For instance, intersections can be 

modeled with corridor or string models. Some site conditions may favor one tool over another, 

or one CADD software product may be stronger in one method over another. Table 16 relates
63

specific 3D model content to the CADD design methods that can generate that content and the 

CADD data format that is needed for automation in highway construction.

Table 16. 3D Model content by CADD data type.

Feature CADD Design Method CADD Data Type

Roadways Corridor model Alignment, surface, and 3D line strings

Side slopes Corridor or string model Surface and 3D line strings

Gore areas Corridor, string or feature modeling Surface and 3D line strings

Intersections Corridor or string model Alignment, surface, and 3D line strings

Interchanges Corridor or string model Alignment, surface, and 3D line strings

Sidewalks and paths Corridor or string model Surface and 3D line strings

Lane width transitions Corridor or string model Surface and 3D line strings

Culvert headwall 

grading

String model or feature modeling Surface and 3D line strings

Guardrail berm

transitions

Corridor, string, or feature modeling Surface and 3D line strings

Benching transitions Corridor, string, or feature modeling Surface and 3D line strings

Bridge abutments Corridor or string model Surface and 3D line strings

Storm water ponds String or feature modeling Surface and 3D line strings

Ditches and swales Corridor, string, or feature modeling Surface and 3D line strings

Pavement markings Corridor, string, or feature modeling 3D line strings

Curbs and gutters Corridor, string, or feature modeling 3D line string (flow line) 

3D line string (top of curb)

Retaining walls Corridor, string, or feature modeling 3D line strings

GUIDE 3D MODEL STANDARD

There are three components to defining a 3D model standard. A 3D model standard must define 

what to model and how much detail to model it in.(12) The first component is the density of the 

data in the corridor and surface models. Density in this case is a proxy for accuracy. The second 

component is a description of what features or elements to include in the model. The third 

component is the segmentation of the data.

Corridor and surface models are usually aggregate (e.g., representing the entire completed 

facility). It can be helpful to segment the data into construction stages, and it is necessary to do 

so for 4D modeling. Data segmentation can also be beneficial to the designers, allowing different 

parts of the design to progress concurrently. Figure 20 shows the workflow to create a standard 

3D model specification.

Source: FHWA.

Figure 20. Flowchart. Creating a standard 3D model specification.
64

The descriptions of content, density, and data segmentation that follow are not universally 

applicable to all project types. It can be helpful to define global inclusion or exclusion criteria for 

creating 3D models.(44,7)

3D Model Content

As shown in figure 20, automation uses provide the requirements of the 3D model in terms of 

data content, data density, and data segmentation. An implementing agency needs to consider 

which automation technology uses it is worth supporting and the impact of creating the data on 

design processes relative to the value the agency will realize from using this data. The data needs 

for construction are often simple. A 3D line string for the bottom of the trench can suffice for 

excavation. Much of the needed data is already created in the process of creating plans. The 

effort is in isolating that data and presenting it in an organized, easily consumable format.

The challenge of preempting automation in highway construction is not unique to designers; 

preempting construction uses is necessary to capture survey data with the needed resolution as 

was shown in figure 10. Table 17 uses the same project type organization and AMG methods 

provided in table 9 to present 3D model content needs. Table 17 also provides inclusion criteria 

by more specific project characteristics based on the likelihood of using the data for AMG.

Table 17. 3D Model content by project type and applicable AMG methods.

Project Type Applicable AMG Method 3D Design Data Content

Asphalt mill and pave with

ride improvements

2D sonic averaging for milling

and paving

No design data required

Asphalt mill and pave with 

cross slope or drainage 

correction (hard tie-ins only 

at start and end)

2D sonic averaging for milling 

and paving

No design data required

Asphalt mill and pave with 

cross slope or drainage 

correction (tie to hard 

surface or curb and gutter)

3D profile milling with 

constant depth or 2D paving 

Alternately: constant depth 

milling and 3D paving

• DTM: Finished grade surface

• Alignment: Primary horizontal and 

vertical geometrics and super-elevation

• 3D line strings: Crown, edges of 

pavement, grade breaks, top of curb,

and flow lines

Concrete overlay with or 

without ride and drainage 

corrections

3D paving • DTM: Finished grade surface

• Alignment: Primary horizontal and 

vertical geometrics and super-elevation

• 3D line strings: Crown, edges of

pavement, grade breaks, top of curb,

and flow lines

Reclamation Grading, fine grading, base, 

and paving

• DTM: Finished grade surface

• Alignment: Primary horizontal and 

vertical geometrics and super-elevation

• 3D line strings: Crown, edges of 

pavement, edges of shoulder, grade

breaks, and ditch flow lines
65

Shoulder and side slope 

widening or improvements

Grading, fine grading, base, 

and paving

• DTM: Finished grade surface

• Alignment: Primary horizontal and 

vertical geometrics and super-elevation

• 3D line strings: Saw cut line, edge of 

shoulder, grade breaks, and ditch flow

lines

Lane widening Grading, fine grading, base, 

and paving

• DTM: Finished grade surface

• Alignment: Primary horizontal and 

vertical geometrics and super-elevation

• 3D line strings: Saw cut line, edge of 

pavement, edge of shoulder, grade 

breaks, ditch flow lines, or top of curb 

and gutter flow line

Reconstruction Grading, fine grading, base, 

and paving; possibly 3D 

profile milling and excavation

• DTM: Finished grade and subgrade 

surfaces

• Alignment: Primary horizontal and 

vertical geometrics and super-elevation

• 3D line strings: Crown, edges of 

pavement, edges of shoulder, grade 

breaks, ditch flow lines, or top of curb

and gutter flow line

New construction Grading, fine grading, base; 

and paving; excavation

• DTM: Finished grade and subgrade 

surfaces

• Alignment: All horizontal and vertical 

geometrics and super-elevation

• 3D line strings: Crown, edges of 

pavement, edges of shoulder, grade 

breaks, ditch flow lines, or top of curb

and gutter flow lines

New AMG methods will continue to emerge or become more common. Automation for 

construction engineering and inspection may have 3D model uses regardless of what method the 

contractor employs. In addition to the AMG methods listed in table 9 and table 17, AMG is also 

used for excavation, striping, and slip forming concrete medians and curbs, among other 

activities. These methods may all be appropriate on a variety of projects. The flexibility to 

provide this data when warranted comes in establishing the CADD resource files to produce it.

The design process is iterative, and some design elements are not refined until later in the 

process when the roadway geometrics and other constraints have been determined. Table 18 lists 

the design elements needed for automation in highway construction and the optimum time to 

invest in modeling them during the design process. Table 18 is adapted from design manuals 

from Michigan, Oregon, Missouri, and Iowa. (See references 7 and 44–46.)
66

Table 18. 3D Model content by design milestone.

Features

Design Stage

Preliminary 

(30 Percent)

Final NEPA 

(70 Percent)

Final Plans 

(90 Percent)

Roadways—top surfaces Yes Yes Yes

Roadways—interim surfaces No No Yes

Roadways—subgrade surface Yes Yes Yes

Side slopes Yes Yes Yes

Gore areas Yes Yes Yes

Intersections Yes Yes Yes

Interchanges Yes Yes Yes

Medians and cross-overs No Yes Yes

Sidewalks and paths No Yes Yes

Lane width transitions Yes Yes Yes

Culvert headwall grading No No Yes

Guardrail berm transitions No No Yes

Benching transitions No Yes Yes

Bridge abutments No Yes Yes

Storm water ponds Yes Yes Yes

Ditches and swales Yes Yes Yes

Pavement markings Yes Yes Yes

Curbs and gutters Yes Yes Yes

Retaining walls Yes Yes Yes

Interim roadway surfaces noted in table 18 may include excavation below subgrade (undercut), 

subbase, and base surfaces.(47) The design elements listed in table 16 and table 18 are by no 

means exhaustive. There may be uses for other design elements either during design or 

construction. Some of these elements are relatively easy to incorporate into corridor templates 

and can aid in creating plans, visualizations, or stake-out information. These elements include 

concrete median barriers, raised median islands, and guardrails.

3D Model Density

Designers know that CADD data are incomplete and imperfect. Surface models (DTMs) and 

3D line strings are approximations. They are exact through horizontal and vertical tangents and 

other areas of constant grade. Once horizontal or vertical curvature is introduced, the DTM or 

3D line string is an approximation, as in figure 21, which shows the DTM approximation of a 

curb and gutter around a curb return.
67

Source: FHWA.

Figure 21. Illustration. Approximation of curved objects in DTMs and 3D line strings.

As figure 22 shows, the 3D line string or DTM is as accurate as the mid-ordinate distance, which 

is the distance between the chord and the true arc or between the TIN face and the curved 

surface. The mid-ordinate distance (also called the “chord height”) is proportional to the chord 

length, which is a function of the point density in the surface. The mid-ordinate distance 

represents the accuracy with which the model represents the design. Some CADD software can 

automatically densify the surface to keep the mid-ordinate distance to a maximum value.

Source: FHWA.

Figure 22. Illustration. Mid-ordinate distance.

AMG and field survey equipment measures with high accuracy relative to the model that formed 

the basis of AMG operations. This is an important distinction, because relative to the idealized 

design, the inherent error in the AMG and real-time verification hardware is compounded with 

the error within the model. However, this is immaterial to acceptable construction outcomes.

Staking accuracy and AMG tolerance are not the same. AMG and real-time verification require 

3D models with network accuracy that matches the staking tolerance. Much like for surveying,
68

increased accuracy in design increases effort and there is a limit at which more value can 

be realized.

Some AMG systems can construct to within 0.02 ft tolerance of the 3D model that is loaded in 

the onboard computer. That does not mean that the design needs a mid-ordinate distance of

0.02 ft or less. The high vertical accuracy on the AMG equipment and the inspector’s equipment 

ensures that there is consistent depth for good compaction and yields, not for ride quality or 

safety. Indeed, staking tolerance is typically lower than the nominal accuracy of AMG systems.

Corridor and string modeling methods have settings to control density. For corridor modeling, 

the setting is the template drop interval, which is set for each template or defined station range in 

the corridor. Different intervals can be established for horizontal and vertical tangents and 

curves. It is often useful to manually insert an additional template drop immediately before or 

after an abrupt change in template.(44) Template drops can be placed automatically at key stations 

that are defined by horizontal, vertical, or offset geometrics. The design manuals for the Iowa 

Department of Transportation (Iowa DOT), ODOT, and WisDOT recommend the following key 

stations:(46,44,47)

• Horizontal geometry points (e.g., begin/end points of curve and spiral).

• Vertical geometry points (e.g., high/low points and begin/end of vertical curve).

• Superelevation stations (e.g., reverse crown and begin full super-elevation).

• Offset horizontal geometry points (e.g., begin/end of lane tapers and curb return points).

• Drainage facilities (e.g., inlets and culvert inverts).

• Guardrail and barrier limits.

The density of the 3D model affects performance of the software and can take time to insert, 

particularly at the interfaces between corridor and/or string models where manual edits might be 

needed. As described previously, some design elements are not refined until later in the process 

when the roadway geometrics and other constraints have been determined. Table 19 describes 

the density recommended at each of the design milestones. The table is adapted from design 

manuals from Iowa DOT, MDOT, ODOT, and WisDOT. (See references 46, 7, 44, and 47.)
69

Table 19. 3D Model density by design milestone.

Features

Design Stage

Preliminary 

(30 Percent)

Final NEPA 

(70 Percent)

Final Plans 

(90 Percent)

Roadways 25 ft in curves; 100 ft 

in tangents

10 ft in curves; 25 ft 

in tangents

1 ft in curves; 5 ft in 

tangents

Side slopes 25 ft in curves; 100 ft

in tangents

10 ft in curves; 25 ft

in tangents

1 ft in curves; 5 ft in

tangents

Gore areas 10 ft 5 ft 1 ft

Intersections 5 ft 5 ft 1 ft

Interchanges 25 ft 10 ft 1 ft in curves; 5 ft in

tangents

Medians and

cross-overs

Not required 5 ft 1 ft in curves; 5 ft in

tangents

Sidewalks and paths Not required 10 ft in curves; 25 ft 

in tangents

1 ft in curves; 5 ft in 

tangents

Lane width transitions 25 ft 10 ft 1 ft in curves; 5 ft in

tangents

Culvert headwall 

grading

Not required 5 ft 1 ft

Guardrail berm 

transitions

Not required 5 ft 1 ft

Benching transitions Not required 5 ft 1 ft

Bridge abutments Not required 5 ft 1 ft

Storm water ponds 25 ft 10 ft 1 ft in curves; 5 ft in 

tangents

Ditches and swales 25 ft 10 ft 1 ft in curves; 5 ft in

tangents

Pavement markings 25 ft 10 ft 1 ft in curves; 5 ft in 

tangents

Curbs and gutters 25 ft 10 ft 1 ft in curves; 5 ft in

tangents

Retaining walls 25 ft 10 ft 1 ft in curves; 5 ft in 

tangents

3D Model Segmentation

Many State transportation departments already use data segmentation to manage CADD data 

during design development. There are design productivity reasons why this is helpful, including 

the following:(7)

• Limiting file size to maintain software performance.

• Allowing multiple designers to progress different portions of the design concurrently.

• Allowing different disciplines to advance the design concurrently.
70

Document management is important, especially for interdisciplinary coordination. If possible, 

geographic segments should be defined in horizontal and vertical tangents.

Contractors can segment aggregate design data for their specific phasing during construction. 

Other than the design productivity reasons noted above, there may be a need to segment design 

data for 4D modeling.

GUIDE 4D AND 5D MODEL SPECIFICATION

A 4D model results from segmenting a 3D model and connecting discrete pieces of 3D geometry 

to tasks in a critical path method (CPM) schedule. When that CPM schedule is resource-loaded 

(usually with costs for each task), then the model is called a “5D model.” How the 4D or 5D 

model is used defines the extent to which the 3D data need to be segmented and the need for 

supporting contextual models. Figure 23 is a workflow for creating a project-specific plan to use 

4D or 5D modeling.

Source: FHWA.

Figure 23. Flowchart. Developing a 4D/5D modeling plan.

4D and 5D Model Usage Cases

Contractors and State transportation departments may choose to invest in 4D modeling for a 

variety of reasons. Common usage cases for 4D modeling during design development are still 

emerging.(48) Some usage cases may be to resolve technical issues related to particular design 

complexity or constructability constraints. These may require high 3D spatial accuracy and/or 

fine detail in the schedule to resolve. Other usage cases for 4D models have involved 

communicating with the public. These 4D models frequently do not need geometric accuracy or 

detailed schedules. Some of the reasons for creating a 4D or 5D model are indicated in table 20.
71

Table 20. Usage cases for 4D and 5D models.

Type of Analysis Example Usage Case

Enhanced visualization • Analyze impacts of different alternatives

• Develop and communicate alternative technical 

concepts (ATCs)

• Evaluate constructability

• Illustrate complex traffic staging and detours

• Manage public information

Estimate and resource optimization • Optimize the critical path

• Allocate resources

• Accelerate/decelerate activities

• Plan staging and equipment movements

Risk mitigation • Accelerate bridge construction

• Communicate risky activities for safety

• Validate maintenance of traffic plans

• Manage the interface between contracts

Construction progress and payment 

tracking

• Resolve or validate claims

• Track progress

• Track impact of contracting methods

The different usage cases shown in table 20 warrant the creation of a 4D or 5D model at a 

different time in the planning-design-construction process. Enhanced visualization usages 

may be warranted in the planning phase to engage the public on alternatives being studied, 

whereas tracking construction progress does not need to be started until after the 

preconstruction meeting.

4D and 5D Model Target Audiences

Before initiating the 4D or 5D modeling process, the last consideration is the target audience for 

the analysis products. The target audience determines the extent to which visualization is needed 

in creating the outputs. Whereas technical audiences can use rudimentary graphics, construction 

workers and the public may need rendered, textured models with surrounding context to provide 

landmarks and scale. CADD models can apply textures through predetermined styles that are 

also used for automating plan production. Example usage cases and the associated target 

audiences are shown in table 21.
72

Table 21. Target audiences for 4D and 5D models.

Target Audience Example Usage Case

General public • Communicate the impacts of different alternatives

• Illustrate complex traffic staging and detours

• Communicate ongoing construction activities

• Illustrate the need for lane closures and detours

Technical professionals • Analyze the impacts of different alternatives

• Develop and communicate ATCs

• Optimize the critical path

• Plan accelerated bridge construction staging

• Allocate resources

• Evaluate constructability

• Test means and methods

• Assess the impact of accelerating/decelerating activities

• Plan staging and equipment movements

• Validate maintenance of traffic plans

• Resolve or validate claims

• Track progress

• Track financial impact of different contracting methods 

(5D model)

• Manage the interface between contracts

Construction workers • Communicate risky activities for safety.

• Communicate maintenance of traffic plans.

• Communicate staging and equipment movements.

Steps in Creating 4D and 5D Models

4D and 5D models require careful planning to ensure that there is corresponding detail and 

organization between the 3D model and the CPM schedule and that the outputs have the right 

level of visual quality to resonate with the target audience.

Once the usage case, timing for initiation, and target audience have been determined, the 

following decisions need to be taken to scope the 4D or 5D mode to provide the necessary 

information to someone who will be tasked with preparing the 3D model and the CPM schedule:

• Define the 3D model in terms of scope (i.e., whole project or a limited area), accuracy, 

detail, disaggregation, and textures.

• Define the schedule in terms of scope (i.e., whole project or a limited time period), work 

breakdown structure (WBS) organization and detail (i.e., time step and disaggregation 

of tasks).

• Identify the responsibilities for data creation and sharing.

• Identify the need for maintaining and updating the 4D or 5D model.
73

Viewing 4D and 5D Models

Technical audiences may be able to interact with the master 4D or 5D model in the model 

aggregation software. Within the software, the model can be navigated in 3D at any calendar 

date within the start and end date in the schedule. Simulations can be viewed coloring the 

existing, under construction, under demolition, and constructed elements according to a defined 

key. This key can be expanded (e.g., to include a color depicting cure times for concrete). (This 

cure period would need to be included in the WBS.)

Most 4D or 5D model authoring software is also capable of performing 3D clash detection not 

only for the overall project but also for schedule-based clashes that analyze clashes at each 

interval of the schedule time step (e.g., each week based on current existing, constructed, and 

under construction elements). Clash reports can be generated to document the identified issues 

and manage their resolution.

A range of outputs can be produced from 4D and 5D models. All of these outputs can either be 

textured (to be photorealistic) or untextured, depending on the needs of the target audience.

These outputs include the following:

• 3D still images from a range of camera angles.

• 3D model images merged with photographs (via photo editing software).

• Sequential 3D still images from a single camera angle.

• Construction simulation videos.

• Drive-through videos from any calendar date (via visualization software).

Figure 24 shows an example of a 3D still image intended for a technical audience. There is 

no context and no photorealistic textures applied to the 3D model elements. Colors depict 

constructed concrete (gray), steel (red), and elements under construction (green).
74

Source: FHWA.

Figure 24. Illustration. Example of a 3D still image from a 4D model for a technical 

audience.

Figure 25 shows a schedule simulation viewed within the 4D modeling software. On the left are 

the disaggregated 3D model selection sets representing collections of 3D geometry that match a 

task in the schedule. Below is the CPM schedule with task completion, name, planned and actual 

start and end dates, and a Gantt chart view. The blue slider between the 3D model and the Gantt 

chart allows users to select a calendar date along the construction timeline.

Source: FHWA.

Figure 25. Screenshot. Example of a construction sequence viewed in the 4D modeling 

software.
75

When detailed visualizations are needed, it is often necessary to separate the visualization 

models entirely from the design production CADD models. Rendering textured models can be 

processor-intensive, and highly detailed TIN models are inefficient. Visualization software can 

use polygon-based meshes, which are more efficient for rendering. However, polygon-based 

models are less accurate than the TIN models that are needed for AMG and real-time 

verification.

GUIDE 3D DATA REVIEW PROTOCOLS

Regardless of whether 3D data supersedes plans as the contract document or is supplemental to 

plans and subject to a hold-harmless agreement, there is a need for comprehensive review. This 

review is separate from design and constructability reviews but rather performs quality control 

on the data itself to ensure the following:

• It is consistent with plans and other contract documents.

• It accurately depicts the design intent.

• It meets the content, density, and segmentation requirements.

• It meets the needs of the intended construction uses.

Few organizations have formalized 3D data review protocols at the time this report was 

published. Some notable practices from Florida, Michigan, and Oregon include the 

following:(49,7,44)

• Performing an independent 3D model review at normal plans review milestones.

• Having a person highly experienced in 3D modeling perform the review.

• Having a person with construction survey experience perform a review.

• Consolidating comments from each milestone into a single document.

• Reimporting translated data formats into the original design software to review.

Clash detection algorithms are effective at identifying and reporting physical conflicts that are 

unintended, but they are of little benefit where consistency is the intent, as with comparing plan 

lines with surface triangles. Most methods for reviewing 3D models currently rely on visual 

inspection. As a consequence, CADD standards need to be enforced with strong document 

management. Strategies for reviewing 3D data include the following:

• Checking compliance with CADD standards.

• Checking compliance with document management protocols.

• Checking consistency between the contract documents and reference documents.
76

• Overlaying 2D lines and 3D surfaces in the XY plane with the surface set to display 

triangles.

• Overlaying 3D solids (also called “components”) with surfaces and viewing from 

multiple angles in 3D space.

• Paying careful attention to intersections and areas where the cross section changes.

• Paying careful attention to vertical elements like curbs and retaining walls.

• Using shading and thematic coloring to highlight sudden elevation and/or slope changes.

• Displaying contours at 0.1 ft or less to identify issues that may cause blade shudder 

in AMG.

• Changing the vertical scale to exaggerate triangulation issues.

• Being customer-focused: not every triangulation issue needs to be fixed, and not every 

transition needs to be smooth.

• Using the “drive-through” feature to review the roadway from the driver’s eye.

• Using software to compute the International Roughness Index.

• Using software algorithms to flag triangulation issues.

• Using clash detection algorithms with 3D solid geometry (e.g., between structural 

concrete and subsurface utilities).

Figure 26 through figure 31 provide an illustration of the results of using a selection of data 

review strategies on a roadway surface for a roundabout intersection with median islands. The 

captions state the review strategies and describe how each highlight different issues in the 

surface.
77

Source: FHWA.

Figure 26. Illustration. Roadway surface for a roundabout intersection with visually 

inspected triangles with no apparent issues. 

Figure 27 shows that there are issues with the curbs on the median islands on each approach. 

There is also a spike off the roundabout in the top center that could be an issue.

Source: FHWA.

Figure 27. Illustration. Roadway surface for a roundabout intersection with visually 

inspected contours.

In figure 28, coloration does not show unexpected spikes, but shadows identify changes in slope. 

The median island in the top right could have issues.
78

Source: FHWA.

Figure 28. Illustration. Roadway surface for a roundabout intersection with color triangles 

by elevation.

In figure 29, there are issues with the curbs on the median islands on each approach. The spike 

off the roundabout in the top center is also an issue.

Source: FHWA.

Figure 29. Illustration. Roadway surface for a roundabout intersection with color triangles 

by slope.
79

Source: FHWA.

Figure 30. Illustration. Roadway surface for a roundabout intersection with display 

drainage arrows with no apparent issues.

In figure 31, triangles are flagged on the median island in the approach at the top. The issues 

identified in visual analyses are not flagged.

Source: FHWA.

Figure 31. Illustration. Roadway surface for a roundabout intersection using algorithms to 

flag issues.

CONTRACT DOCUMENTS

This chapter does not make assumptions about the order of precedence of 3D models in the 

contract documents or whether the 3D models are contract documents at all. Rather, it describes 

notable practices for using 3D models to create plans and output 3D data that are useful for 

automation in highway construction. Figure 32 illustrates a workflow for producing contract 

plans and models that are consistent and reviewing them efficiently.
80

Source: FHWA.

Figure 32. Flowchart. Producing contract documents and models.

The Guide 3D Model Standard section in this chapter provides detail into creating the

3D models. Processes for using model outputs to create plans are well described in an array of 

design and CADD manuals, including those previously referenced. Processes for CADD 

automation are embedded in design delivery. Manual plan edits used to be a significant time 

saver, but that is not the case with newer CADD software. With newer CADD software, changes 

to the foundation alignments, profiles, templates, corridor models, string models, or surfaces 

propagate dynamically to update plan graphics and annotations. Design, constructability, and 

plans review processes are also well established. Protocols to review 3D models were previously 

introduced in the previous subsection, Guide 3D Data Review Protocols.

Contract Plans

A fundamental consideration for producing contract documents is that there must be consistency 

between 3D models and the plans. This is extremely difficult to verify if there are manual edits 

on plan sheets. Table 15 shows how manual modeling processes can be written into surface 

definitions. Writing manual edits into surface objects is critical; manual design processes are 

sometimes warranted, but CADD automation should be used to create contract plan graphics and 

annotations. Otherwise, the risk of inconsistency is hard to mitigate with laborious review 

processes, both for the owner and the contractor.

Other notable practices for the creation of contract plans from 3D models are shown in table 22. 

These practices are adapted from the design manuals from the Connecticut Department of 

Transportation, FDOT, and Iowa DOT.(50,49,46)
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Table 22. Notable practices for creating contract plans.

Consideration Description Use

Vector PDF Vector graphics are clear, can be scaled and 

measured, and do not scale when the 

document is zoomed. The vector graphics 

can be extracted by software and converted 

to CADD. The batch plotting tool in CADD 

software can be used to create vector PDFs.

• Compare 3D models and plans.

• View plans on mobile device.

Digital 

signatures

Digital signatures use a public/private key 

to authenticate the signer. They can be 

applied to any file type and validated 

independently. A digital signature is

invalidated if a file is modified.

Identify and authenticate contract 

documents.

Color graphics The simple and selective use of color on 

plans can aid in the understanding and 

interpretation of contract plans on 

computers and mobile devices. Color choice 

should consider use in the field on mobile

devices.

• Distinguish existing and proposed 

elements.

• Emphasize important elements.

Hyperlinks Hyperlinks can aid navigation through a set 

of plans by providing a shortcut from one 

sheet to another. Hyperlinks can also point 

to links external to the PDF.

• Connect plan view elements to profile 

or cross section sheets.

• Connect detail call outs to detail sheets.

• Connect quantities to quantity 

calculation sheets.

Contract 3D Models

There are a number of reasons for providing 3D models with bid documents, and many State 

transportation departments have recently implemented policies to do so, while others provide 

3D data post-award or not at all.(12) Automation implementation to date has been market-driven, 

so there is not consistency in how contractors use 3D models to prepare bids and execute 

construction. A notable practice adopted by ODOT is to provide 3D models at two milestones: a 

generic set as bid reference documents followed by a tailored package for the successful bidder 

post-award (see figure 33 ).(44) This practice is reflected in the workflow shown in figure 33, 

which defines a role for the designer post-award.

Source: FHWA.

Figure 33. Flowchart. Providing contract models.(44)
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There are a variety of software products that are used for automation in highway construction. 

Proprietary design formats are not universally supported. The challenge of using LandXML 

version 1.2 as a contract model format is that it is not consistently supported by different 

software applications, particularly for surfaces and cross-sections. At the time of writing this 

report, the most universally supported exchange format was LandXML version 1.2.(51) A newer 

schema, LandXML version 2.0, was in draft and research efforts were advancing InfraGML and 

industry foundation classes for exchanging highway data.(51) However, these newer schemas 

were not yet supported by software applications. Contract model packages should include a 

combination of 3D data in the exchange format, in the proprietary design format for those who 

have the software, and in a CAD graphics format to provide a means of checking the exchanged 

data.(12)

When producing LandXML outputs of surfaces, it is important to include both triangles and 

features in the surface definition.(46) Without the features, the software will retriangulate the 

surface, which may not match the design intent.

The data types and formats shown in table 23 are assimilated from policies implemented by 

Kentucky Transportation Cabinet (KYTC), FDOT, Iowa DOT, MDOT, Missouri Department of 

Transportation (MoDOT), ODOT, and WisDOT. (See references 52, 49, 46, 7, 45, 44, and 47.) 

Table 23 lists a set of generic outputs that can be used for bidding or construction.

Table 23. Type, format, and metadata for bid reference files.

Data Type Data Formats Metadata

Coordinate 

geometry

• CAD

• American Standard Code for 

Information Interchange

(ASCII) text

Survey metadata per table 7 embedded in CADD 

and/or in a ReadMe file in the folder

Alignment • LandXML

• ASCII text reports

• CAD super-elevation tables

• XML super-elevation report

• Survey metadata per table 7 embedded in CADD 

and LandXML and/or in a ReadMe file in the folder.

• List of file names and description of content, 

including plan sheets and related corridors and

surfaces, if applicable.

Original 

surface

• LandXML

• CADD surface format

• CAD triangle faces and 

boundary

• CADD points and break lines

Survey metadata per table 7 embedded in CADD and 

LandXML and/or in a ReadMe file in the folder.

Final 

surface

• LandXML

• CADD surface format

• CAD triangle faces and 

boundary

• CADD points and break lines

• Survey metadata per table 7 embedded in CADD 

and LandXML and/or in a ReadMe file in the folder.

• List of file names and description of content, 

including related alignments and corridors, if 

applicable.

Interim 

surface

• LandXML

• CADD surface format

• CAD triangle faces and 

boundary

• CADD points and break lines

• Survey metadata per table 7 embedded in CADD 

and LandXML and/or in a ReadMe file in the folder.

• List of file names and description of content, 

including related alignments and corridors, if 

applicable.
83

Data Type Data Formats Metadata

3D line 

strings

• LandXML (surface features)

• CAD graphics (3D line 

strings)

• Survey metadata per table 7 embedded in CADD 

and LandXML and/or in a ReadMe file in the folder.

• List of file names and description of content, 

including related alignments, corridors, and surfaces, 

if applicable.

Cross 

section

• LandXML

• CAD graphics (2D lines and 

text)

• Survey metadata per table 7 embedded in CADD 

and LandXML and/or in a ReadMe file in the folder.

• List of file names and description of content, 

including related alignments, corridors, and surfaces, 

if applicable.

Corridor 

model

• Proprietary CADD format

• CAD graphics (3D solids/ 

components)

• Survey metadata per table 7 embedded in CADD 

and/or in a “ReadMe” file in the folder.

• List of file names and description of content, 

including related alignments, surfaces, and cross 

section files, if applicable.

It can save time and remove potential data exchange errors if the designer produces a tailored set 

of outputs specific to the contractor’s and/or inspectors’ intended uses. A notable practice is to 

include a transmittal letter with the 3D data that describes the content that is provided. This 

transmittal can be a list of the files and the associated metadata, as defined in table 23. The 

transmittal can also include a list of expectations and authorized uses with automation 

technology. For instance, if the 3D data are developed only for the purpose of creating plans, it 

may not be authorized for use in AMG or to measure and accept work as it may not have 

sufficient density.

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CHAPTER 9. GUIDE SPECIFICATIONS

Many construction specifications are still methods-based, with prescriptive instructions on how 

to execute, measure, and accept work. While this leverages a deep institutional knowledge, 

methods specifications can be barriers to adopting new technology. The movement to 

performance-based specifications is certainly a broader issue than merely supporting the use of 

evolving automation in highway construction. The guide specifications are presented to avoid 

limiting the contractor or inspector to any specific methods or automation technology as well as 

to provide flexibility through describing the provision of data needed for automation technology, 

a vehicle to document agreed use of automation for construction and inspection, and flexibility to 

adapt performance measures for different approaches.

This chapter contains the following sections:

• Controlling Work: Plans and Working Drawings.

• Controlling Work: Conformance with Plans and Specifications.

• Controlling Work: Construction Stakes, Lines, and Grades.

• Controlling Work: Inspection of Work.

• Controlling Work: Quality Control Plan.

• Measurement and Payment.

• Earthwork, Fine Grading, Base Course, and Paving.

This chapter provides guide specifications that can be incorporated into specifications, special 

provisions, or special notes. The guide specifications follow the organization, format, and style 

of the AASHTO Guide Specifications for Highway Construction and are written to be 

performance-based.(53) The tolerances noted reflect current best-available practices. Each 

implementing agency needs to consider what constitutes aggressive, but achievable, tolerances 

for their current level of automation implementation and ways to provide flexibility to the 

engineer to adapt to project-specific construction activities and the capabilities, methods, and 

experience of the contractor and inspectors. This flexibility is incorporated by the provision 

for an automation technology work plan discussed in the Controlling Work: Quality Control 

Plan section.

Providing oversight to construction with automation technologies affects several chapters of the 

standard specifications.(53) These sections are identified in table 24 along with the considerations 

to support automation in highway construction for each section.

There is an evolution of special provisions to allow the incidental use of AMG and real-time 

verification. These guide specifications are adapted from special provisions, developmental 

specifications, and standard specifications from several agencies, including FDOT, Iowa DOT,
86

KYTC, New York State Department of Transportation (NYSDOT), and WisDOT. 

(See references 54–59.)

Table 24. Areas of standard specifications affected by automation implementation in 

highway construction.

Typical Standard 

Specifications Section Considerations to Support Use of Automation

Controlling Work: Plans and 

Working Drawings

Owner’s provision of 3D data, review and agreement of 

electronic plan data, including 3D digital data, requirements

for 4D/5D models, and provision of as-built records

Controlling Work: Conformance 

with Plans and Specifications

Standing of 3D data in relation to other contract documents

Controlling Work: Construction 

Stakes, Lines and Grades

Verifying control position, accuracy and usage; agreeing to a 

site localization; and staking requirements

Controlling Work: Inspection of 

Work

Provision of equipment for performing inspection and 

requirements for notification of work ready to inspect

Controlling Work: Quality 

Control Plan

Use of a work plan to agree use of automation technology in 

construction and inspection, including minimum 

requirements for equipment calibration

Measurement and Payment Means of measurement and payment

Earthwork Accuracies, tolerances, means of measurement, and payment

Base Material Accuracies, tolerances, means of measurement, and payment

Fine Grading Accuracies, tolerances, means of measurement, and payment

Asphalt Paving Accuracies, tolerances, means of measurement, and payment

Concrete Paving Accuracies, tolerances, means of measurement, and payment

CONTROLLING WORK: PLANS AND WORKING DRAWINGS

This section defines the 3D data that are provided with the plans. Refer to table 23 for a list of 

3D data and the necessary associated metadata. State transportation departments may choose to 

use digital signatures to uniquely identify and validate the individual files. Another option is to 

use descriptive information, such as a unique file storage location on a document management 

system or other descriptive information that in combination uniquely identifies the files.(56)

Contract Documents

When 3D models are used as contract documents, they should be uniquely and easily 

identifiable, accessible, and protected from modification. Sample language that can be 

incorporated into specifications, special provisions, or special notes is as follows:

The agency will furnish one set of 3D model data and one transmittal letter. The transmittal 

letter shall indicate the authorized uses of the 3D model data. The 3D model data comprises 

several individual files that in combination represent the design in such detail as necessary to 

convey the design intent sufficient to meet the authorized use(s). The transmittal letter shall list 

file names, types, content, metadata, and any other descriptive information necessary to uniquely 

identify the 3D model data.
87

Hold Harmless Statements

The implementing agency may wish to provide a liability disclaimer for the 3D model data. This 

disclaimer can be incorporated into the transmittal letter as a statement of authorized use of the 

data. Sample text that can be incorporated into specifications, special provisions, or special notes 

is as follows:

Providing the contractor with this 3D model information does not relieve the contractor from the 

responsibility of making an investigation of conditions to be encountered, including but not 

limited to site visits as well as basing the bid on information obtained from these investigations 

along with professional interpretations and judgment. The contractor assumes the risk of error if 

the information is used for any purposes for which the information was not intended.

Assumptions the contractor makes from this electronic information or manipulation of the 

electronic information are at their risk.

4D and/or 5D Models

This section defines any 4D or 5D models that are required from the contractor. The 4D or 5D 

models can be designated as working drawings or working models. The specifics of the 4D or 

5D models are described in an Automation Technology Work Plan section in this chapter.

Sample language to specify 4D or 5D model requirements is as follows:

Create working 4D and 5D models. The 3D model data shall be supplemented with 3D model 

data representing the temporary construction work necessary for the construction of the 

permanent works to the extent needed to simulate construction activities. This includes but is not 

limited to bracing, falsework, formwork, scaffolding, shoring, temporary earthworks, sheeting, 

cofferdams, and special erection equipment. The 3D model shall be segmented into discreet 

elements that are affected by each simulated task in a critical path method schedule. The 

working 4D model shall connect the discreet 3D model elements to the critical path method 

schedule tasks for the purposes of simulating the progress of construction. A 5D model shall 

connect the discreet 3D model elements to the cost-loaded critical path method schedule tasks 

for the purposes of simulating the progress of construction and tracking the costs as construction 

progresses.

3D As-Built Records

This subsection defines the as-built 3D models that are required from the contractor. The specific 

requirements for as-built 3D models depend on how the implementing agency uses the data

(i.e., either in a programmatic way or just for the individual project). Project-level uses of 

as-built data and the project-specific requirements are defined in the automation technology 

work plan referenced in the Controlling Work: Quality Control Plan section in this chapter.

As-built records can be captured directly during the normal process of executing work with some 

automation technologies like AMG. Field surveying methods or LiDAR can be used to perform 

as-built surveys using the same processes and methods as normal topographic surveying. The 

contractor needs to have the requirements for the as-built data collection, storage, and delivery 

defined. This can typically reference the agency’s survey manual. At the time this report was 

written, an ASCE committee was progressing industry standards for collecting as-built records of
88

subsurface utilities installed or located during construction. Additionally, there is currently no 

defined industry standard for the use or collection of as-built data for asset management 

purposes. As this area emerges, the requirements can be incorporated. Table 25 summarizes the 

different uses of as-built data and provides references to the requirements for the different uses.

Table 25. Requirements for as-built data by intended use of data.

As-Built 

Data Use Description Requirements Example

Acceptance Data captured to review and 

document acceptance using

real-time verification 

processes.

Staking 

tolerances

Verify earthwork, fine grading, 

subbase, base, and paving layout

by comparing as-built points to 

3D design data.

Measurement Data captured to review and 

document measurements 

using real-time verification

processes.

Measurement 

precision

Topographic survey of borrow pit 

before and after construction to 

compute volume.

Asset 

management

Data captured and stored in 

a statewide repository to 

maintain a digital inventory

of highway assets.

No current 

standard

Defined and mature uses of 3D 

data in asset management are 

emerging.

Subsurface 

utility 

location 

repository

Data captured and stored in 

a statewide repository of 

subsurface utilities in the 

right-of-way.

Standard being 

developed

Inverts, pipe sizes, and material 

for gravity systems. Tops of 

joints, pipe size, and material for 

pressure systems.

Sample language that can be incorporated into specifications, special provisions, or special notes 

is as follows:

As-built 3D models of the completed facilities shall be provided in accordance with the 

topographic survey requirements of the agency’s survey manual.

CONTROLLING WORK: CONFORMANCE WITH PLANS AND SPECIFICATIONS

This section defines the order of precedence of the 3D model data in the contract documents. 

Ideally, the plans should be created using the same 3D model data. However, as described in

figure 21, the 3D model is an approximation of the design intent in areas where there is 

horizontal or vertical curvature. The 3D model data may be used for AMG or real-time 

verification, but in the case of a discrepancy, the true curvature shown in the plans should 

govern. The following text that can be incorporated into specifications, special provisions, or 

special notes to address this topic.

If there is a discrepancy, the governing ranking is as follows: 

Dimensions:
89

• Plan.

• 3D model data.

• Calculated.

• Scaled. 

Information:

• Special provisions.

• Plans.

• 3D model data.

• Supplemental specifications.

• Standard plans.

• Information received at mandatory prebid meetings.

CONTROLLING WORK: CONSTRUCTION STAKES, LINES, AND GRADES

The current AASHTO Guide Specifications for Highway Construction use real-time layout with 

survey instruments.(53) As shown in the following paragraph, the language can be modified to be 

less specific and provide flexibility for evolving survey instruments and methods.

Furnish all stakes, templates, straight edges, and other devices necessary to check, mark, and 

maintain points, lines, and grades. Ensure that contract staking conforms to standard 

procedures used by agency engineering personnel. Use of field survey technology that provides 

equivalent control points, lines, and grades can be furnished if acceptable to the engineer.

CONTROLLING WORK: INSPECTION OF WORK

This section can be used to require the contractor to provide the necessary field inspection tool 

for automating processes to measure and verify tolerances of completed work. It is important that 

the provision of the equipment complies with State and Federal regulations. Providing equipment 

for the inspector’s autonomous control and use during the duration of the contract is a practice 

that has been used by several State transportation departments. The work plan can be used to 

document the specific instruments, training, and timing for providing the equipment. Currently, 

GNSS rovers are widely applicable and usually needed for the duration of construction.

However, total stations and other survey instruments may be needed only for limited periods 

(e.g., during bridge construction). The following text can be incorporated into specifications, 

special provisions, or special notes:

Furnish the necessary field survey technology for the engineer’s dedicated use during the 

duration of the contract.
90

This section can also provide for spot checking the contractor’s field survey and AMG systems 

to ensure that they are functioning correctly. The following text can be incorporated into 

specifications, special provisions, or special notes:

The engineer may perform spot checks of the machine control results, surveying calculations, 

records, field procedures, and actual staking.

CONTROLLING WORK: QUALITY CONTROL PLAN

There is a lot of latitude for how 3D data may be used with automation technology for 

construction and inspection. The selection of automation technologies depends on a variety of 

project-specific factors. In order to support unique project opportunities and the constant 

evolution of technology, it is a growing practice to incorporate a requirement for the contractor 

to develop an automation technology work plan, which is an addition to the overall quality 

control plan.

The automation technology work plan should document the agreement over the timing of, 

responsibility for, and methods of the following:

• Verifying control.

• Agreeing site localization or base station setup.

• Agreeing on a model of record.

• Determining low-accuracy position.

• Documenting specific uses and requirements of 4D and 5D models.

• Checking the layout.

• Verifying tolerances.

• Measuring pay quantities.

• Performing daily calibration checks on AMG systems and field survey technology.

During the early phase of implementing AMG and real-time verification, it may be helpful to 

discuss and document information on the following:

• The expertise and experience of personnel.

• Training provided to the engineer.

• Activities for which 3D data will be used.
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• Specific information about AMG systems.

• The origins of the 3D data that constitutes the “Model of Record.”

The following language can be incorporated into specifications, special provisions, or special 

notes in order to specify the requirements for an automation technology work plan:

At least 1 week prior to the preconstruction conference, submit a written automation technology 

work plan to the engineer for review, which includes the following:

• Construction activities that will use automation and the specific technologiesthat 

will be used.

• Proposed changes to the 3D model data in the model of record.

• Origins and applications of working 4D models or working 5D models.

• Proposed methods for low-accuracy positioning.

• Proposed methods and field technologies for high-accuracy positioning.

• Contract control plan.

• Description of the format, origin, network accuracy, and density of the proposed as-built 

data for the engineer’s use in acceptance.

• Description of the format, origin, network accuracy, and density of the proposed as-built 

data for the engineer’s use in measuring pay quantities.

• Proposed items and automation methods for measuring pay quantities.

• Proposed automation methods including equipment types and models to be furnished to 

the engineer for dedicated use during the duration of construction.

• Proposed timing for the provision of the specific automation technologies.

• Proposed formal training provided to the engineer and the timing of that training.

The automation technology work plan will be discussed during the preconstruction conference. 

Within 7 days of the preconstruction conference, submit to the engineer for review an updated 

written automation technology work plan which reflects any changes agreed during the 

preconstruction conference. When the engineer has accepted the automation technology work 

plan, submit a contract control plan that has been signed and sealed by a licensed surveyor.

MEASUREMENT AND PAYMENT

This section introduces methods for measuring payment quantities using field survey 

technologies in accordance with the automation processes described in the Automation for 

Construction Engineering and Inspection section in chapter 10. The primary change is to
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introduce an alternate method to measuring volumes than the average end area method. The 

following language can be incorporated into specifications, special provisions, or special notes:

Field survey technologies may be used to determine upper and lower bounding DTM surfaces for 

the purpose of calculating volumes using the surface-to-surface comparison method where 

agreed in the automation technology work plan. The DTM surfaces shall have accuracies and 

densities needed to provide sufficiently accurate volume computations.

EARTHWORK, FINE GRADING, BASE COURSE, AND PAVING

When defining positional tolerances, it is important to consider the broad range of implications 

of the defined accuracies and tolerances. Tight tolerances require line-of-sight instruments for 

positioning, which constrains productivity. However, tolerances that vary for each pavement 

material will lead to variable depths of materials. Depending on the contractor’s use of 

automation technology, it may be more efficient to place material high and trim it to grade 

immediately prior to placing the next course.

Requiring the same tolerance from fine grade up will facilitate consistent depths and good yields 

on the higher value materials. This can be particularly important when different construction 

activities are performed by different contractors. If tolerances are agreed in the preconstruction 

meeting that exceed those of the specification, they should be noted in the automation 

technology work plan.

It is recommended that tolerances for positional acceptance be set to staking tolerances for those 

construction activities. A written tolerance to allow material to be placed at grade or below might 

provide incentive to one sub-contractor to leave the finished grade low, causing overruns on the 

next material placement. Table 28 in chapter 10 provides guidance to inspectors in selecting field 

survey technologies based on staking tolerances. Tolerances for the as-built observations used to 

measure completed work for payment may need higher local accuracy to produce accurate 

volume quantities.

The next chapter provides guidance to inspectors in selecting field survey technologies based on 

measurement considerations. Sample specification language is as follows:

Construct the base to the width and section the plans show. Shape and compact the base surface 

to within 0.04 ft of the plan elevation.
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CHAPTER 10. CONSTRUCTION

This chapter covers the owner’s role of quality assurance when automation technologies do not 

require stakes or string lines. The following topics are discussed:

• Construction data management.

• Low-accuracy positioning.

• High-accuracy positioning.

• Agreeing control and site localization or mapping projection.

• Automation for construction engineering and inspection.

One of the most important considerations is how the inspectors identify their location onsite, 

which is necessary for quality assurance functions that do not change with automation, like daily 

diary entries. New functions are described for providing appropriate oversight to AMG 

operations as well as automated methods to verify construction tolerances in real time and 

measure pay quantities. The chapter briefly covers the opportunity to capture digital as-built 

records, especially as-located and as-built subsurface utility information. Figure 34 shows a 

workflow for managing construction with automation technology.

Source: FHWA.

Figure 34. Flowchart. Managing construction with automation technology.

CONSTRUCTION DATA MANAGEMENT

Automation in highway construction requires and produces a vast amount of 3D digital data. 

There is the potential to use some or all of this data in executing, measuring, and accepting 

construction as long as it is subject to good data governance. Data governance ensures that there 

is control over the quality and management of data in accordance with standards and rigorous 

processes. The following three areas need to be managed:
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• Establishing a model of record that reflects the design intent shown in the contract 

documents.

• Updating the model of record when there are design or field changes.

• Producing robust digital as-built records.

Establishing a Model of Record

The model of record is not a single file; it includes a variety of digital data, usually 3D, that 

define the design intent. This includes coordinate geometry, horizontal and vertical alignments, 

existing ground surfaces, interim ground surfaces, final ground surfaces, and 3D line strings.

Table 26 lists the data types that can constitute the model of record and the design intent 

they depict.

Table 26. Data types that can constitute the model of record.

Data Type Design Intent Depicted

Coordinate 

geometry

Control points, right-of-way corners, and geometry points on

alignments. May also include point features depicting locations for 

sign posts, piles, light standards, etc.

Alignments Baselines for layout, including primary and secondary alignments 

and interim roadways. Includes horizontal and vertical layout 

information. May include retaining walls, pipes, and other linear 

features with stationing.

Original

surfaces

Existing ground condition.

Final surfaces Final constructed condition.

Interim surfaces Subgrade surface. May also include other interim surfaces between 

top of subgrade and final ground. Can also include temporary 

roadways, excavation limits, undercut limits, and interim grading.

3D line strings Linear features, including edges of pavement, curb lines, ditch lines, 

trench excavation limits, guardrail, and shoulder break points.

The minimally sufficient information for the model of record is as follows:

• Coordinate geometry for control points.

• Primary alignments.

• Existing ground surface.

• Final ground surfaces for temporary and final roadways.

Data are needed for all construction activities that use automation technologies, but the primary 

data types for AMG and real-time verification are alignments, 3D line strings, and surfaces. The 

existing ground surface is an important component of the model of record. It can be used to 

compute earthworks volumes.
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A quality assurance survey prior to the preconstruction can be conducted to review the accuracy 

of the existing ground surface at tie-ins and other important locations. This would identify any 

potential design revisions, quantity changes, or other material changes in site topography since 

the original survey was conducted.

The model of record can be used to layout construction, execute construction with AMG, and 

inspect completed work. In order to realize all three uses, the owner and contractor must agree on 

a single set of data. Figure 35 shows a workflow for establishing the model of record.

Source: FHWA.

Figure 35. Flowchart. Establishing a model of record.

There are many sources of data for the model of record. Ideally, the model of record will be 

produced during the design phase. Frequently, the model used for layout and AMG construction 

differs from the 3D design data. The most common reason is that the 3D design data do not 

depict the design intent to the extent necessary for construction operations. This could be 

because the design was conducted before the State transportation department implemented 

rigorous 3D design practices. The survey upon which the design was based may have lacked 

sufficient accuracy in some areas or in the vertical control. Value engineering or ATCs may have 

modified the design intent.

If data are to be used to construct and inspect work, then consistency is necessary to isolate 

construction issues from data differences. Many factors may lead to differences, both large and 

small, between the original design data and the data that are ultimately used in construction. If 

the design data cannot be used as model of record, then it is possible for the contractor to provide 

the data and the engineer or designer review and agree to it. Consistency arises when the 

engineer and contractor agree on a single set of data that represent the design intent of the 

contract documents. That way, survey instruments read tolerances in real time relative to that 

data, and any issues will be real construction issues rather than differences in data sources or 

instrumentation.

Managing Design and Field Changes

Processes need to be established to manage design or field changes to the model of record. If 

AMG construction is used, then any design or field changes are necessarily incorporated into a 

3D model prior to construction. If that model is reviewed and agreed by the engineer, it may be 

accepted as an updated model of record and used by the inspector. Figure 36 shows the workflow 

for keeping the model of record current.
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Source: FHWA.

Figure 36. Flowchart. Managing field or design changes in model of record.

Digital As-built Records

As-built data can be of use during construction by both the contractor and the engineer. 

Contractors can capture as-built data during AMG operations or in quality control observations. 

Some contractors use as-built data to track productivity and quantities. Inspectors’ observations 

should also be captured and stored as independent as-built observations. These can be used

to verify the contractor’s as-built data. Figure 37 shows a workflow for preparing digital 

as-built records.

Source: FHWA.

Figure 37. Flowchart. Preparing digital as-built records.

Digital as-built data provide a robust digital record of construction. These data can be used to 

measure pay quantities and verify tolerances. The Automation for Construction Engineering and 

Inspection section in this chapter explains how as-built data can be used by the inspector to

automate measurement and acceptance processes. There may be uses for the data to substantiate 

claims, resolve disputed quantities, or plan future operations or after the facility has been 

commissioned. The ability to share auditable data with the contractor increases transparency 

and trust between the contractor and the engineer.

LOW-ACCURACY POSITIONING

Not all construction observations require the precise positioning realized by survey-grade 

equipment. One option is to use stakes or paint to mark stations at an agreed interval. Positioning 

from mobile devices like smart phones and mobile tablets may be sufficiently accurate for 

recording locations for daily diary entries and permit compliance observations (e.g., for storm 

water pollution prevention). To use low-accuracy horizontal positioning with mobile devices, 

the inspector needs software that has the primary alignments preloaded. Figure 38 shows a 

screenshot from a mobile device where the alignment information has been preloaded.
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Source: FHWA.

Figure 38. Screenshot. Alignment preloaded in a mobile device.

Inspectors can use mobile devices in this way to overcome their reliance on stakes for lowaccuracy location awareness onsite. Mobile devices can also enhance inspectors’ productivity by 

using voice recognition to dictate notes, capturing photos and videos to document site conditions, 

and using video conferencing to discuss and show issues in real time with remote participants.

HIGH-ACCURACY POSITIONING

High-accuracy positioning, or survey-grade positioning, is a requirement for AMG construction 

for measuring pay quantities, such as earthwork, and for accepting work for many activities, such 

as paving and bridge construction. Some of these activities, like bridge construction, require

high-accuracy positioning because of the tolerance required by the specifications. Other 

activities, like seeding areas, require high-accuracy positioning in order to measure quantities 

with sufficient precision. Many activities, like earthwork and fine grading, require survey-grade 

positioning for measuring both tolerances and quantities. Figure 39 shows a workflow for 

establishing a plan for high-accuracy positioning onsite.

Source: FHWA.

Figure 39. Flowchart. Establishing a plan for high-accuracy positioning.

Regardless of whether the contractor uses AMG at all, inspectors can make use of automation 

processes to measure and accept completed work. When the contractor and engineer use a 

common model of record and a common site localization or mapping projection, any issues
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identified by real-time verification will be true construction issues and not discrepancies arising 

from differences in dataset or site localization. Consistency between 3D data and survey methods 

is particularly important when verifying construction within tolerances as tight as 0.02 ft.

Generally, there is synergy when the contractor uses AMG and the inspector uses automation 

processes to measure and accept completed work.

AGREEING ON CONTROL AND SURVEY METHODS

As described in the Establishing Site Control section in chapter 6, the original mapping control 

is important for constructing the project in accordance with the design intent in the contract 

documents. One of the first steps of site mobilization is to recover the original control, identify 

any control that is missing or has been disturbed, and determine if the control is still within its 

prescribed tolerance.

As noted previously in table 6, construction control requirements in the vertical may exceed the 

requirements for cadastral surveying. Vertical control is extremely important for high-accuracy 

AMG operations, particularly those using total station control, as shown in figure 40. Low 

vertical accuracy resulting in inconsistency in control will be felt in the ride where the RTSbased machine control switches from one setup to the next. There may be a need to improve the 

accuracy of the vertical control, and, as indicated in figure 11, there may be a need to set 

additional vertical control to ensure a robust site localization.

Source: FHWA.

Figure 40. Photo. High-accuracy AMG operations.

There are two options for data collector setup: using site localization or using a horizontal 

mapping projection and a geoid model for elevation. The choice of site localization or mapping 

projection and geoid model resides within the data collector. It is independent of the source of 

RTK correction for GNSS positioning and is equally applicable to line-of-sight based positioning 

methods like total stations or laser-augmented GNSS.
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AMG systems work effectively with a site localization, often achieving tighter vertical closure 

than with a mapping projection and geoid model. It is a simpler setup than the mapping 

projection and is commonly used by contractors; however, it is not as easy to reproject to a 

geospatial coordinate system.

In order for observations to be comparable, it is important that the contractor and inspector use 

the same data collector setup. Observations taken with different data collector setups will almost 

certainly be different and can be significantly different when following some of the tighter 

required tolerances for inspection. It can be helpful to have a standard form for agreeing on the 

construction control and mapping projection or site localization.(12) Table 27 indicates the 

pertinent information for a surveyor to review and accept the construction control plan to be used 

by the contractor and engineer.

Table 27. Pertinent information for a contract control plan.(58)

Element Description

Original mapping control Unrecovered horizontal and/or vertical control points; disturbed 

control or control that is out of tolerance of original position.

Survey network diagrams Control should be used for construction.

Coordinate differences If any control has been disturbed, note methods used to check 

existing points and the northing, easting, and elevation of the 

new location

New control Note methods used to establish the new control and the 

description, northing, easting, and elevation. Note intended uses

for the new control.

Mapping projection and 

datum

Note the full metadata for the mapping projection and datum per 

table 7.

Method of RTK correction The method of RTK correction should be defined (base station,

CORS, RTN, etc.).

Site localization If used, note computations for horizontal and vertical transform 

parameters.

Surveyor’s seal Seal and signature of a licensed surveyor should be used.

Source of RTK Correction for GNSS

Frequently, the contractor uses a base station for RTK correction for GNSS operations. 

Inspectors should use the same site localization or mapping projection as the contractor 

regardless of whether they use the contractor’s base station, a CORS network, or an RTN. When 

the inspectors do not use the same source of RTK correction as the contractor, it is important to 

understand the potential differences in RTK correction that can occur between the two sources.

RTK corrects a number of sources of positioning errors. Some of these, like multipath errors, 

may not be consistent between the contractor’s base station and the station(s) upon which a 

CORS or RTN solution is based. A networked solution like CORS or RTN provides better 

correction of atmospheric distortions. It is important that field observations are properly overseen 

by a surveyor, especially if the inspector and contractor use different sources of RTK correction.
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Base Station Setup

Using a base station with GNSS rovers and a mapping projection and geoid model requires that 

the location of the base station is a known geospatial position tied to the NSRS. This is not 

necessary for a site localization. However, data collector software can interchange between using 

a site localization and a mapping projection and geoid model if the base station is set up over a 

known point. There may be a need to collect as-built data on a different mapping projection, 

which is more easily achieved if the data collector switches to that mapping projection when 

collecting that data. Figure 41 shows the horizontal and vertical errors at the control points used 

to compute the site localization. A minimum of five control points are needed to compute a site 

localization.

Source: FHWA.

Figure 41. Photo. Horizontal and vertical errors at the control points.

To determine the base station location with high accuracy, the base station should occupy the 

position for at least 2 h. A longer occupation results in a more accurate position (24 h is 

preferable). The collected data can then be uploaded to the National Geodetic Survey’s Online 

Positioning User Service (OPUS), which provides a corrected position that is tied to NSRS.(60) 

The elevation from OPUS can be verified by using a high-accuracy vertical surveying method 

such as leveling or a total station. The data collector can then be set up with the original mapping 

projection from the control plan. Geoid definitions change frequently, and the differences in 

elevation can be significant in some areas. If a newer geoid definition is used, there may be 

serious errors when checking into control and at tie-ins.
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AUTOMATION FOR CONSTRUCTION ENGINEERING AND INSPECTION

Methods for inspecting work should verify performance-based construction outcomes and not be 

method-driven. A range of as-built data are available from automation technologies like AMG, 

intelligent compaction, and real-time smoothness profilers. Non-destructive testing equipment 

like ground-penetrating radar and infrared thermal profilers also produce digital as-built data.

These data can be spot-checked by the inspector to independently verify the accuracy and 

confidence in the data. These as-built data can then be used as a resource for verifying 

compliance with specifications or measuring completed work. Figure 42 shows a workflow for 

using real-time verification in construction inspection.

Source: FHWA.

Figure 42. Flowchart. Using real-time verification in construction inspection.

Use of As-Built Data for Measurement and Acceptance

Using these as-built data can greatly enhance the efficiency and safety of inspectors onsite, 

reduce interruptions to the contractor performing operations, and provide a robust record of 

construction that can increase transparency in pay quantity measurements or equitably resolve 

claims. However, implementing these data-dependent processes requires creating resources and 

skillsets that traditionally are absent from the owner’s role in construction. Using the contractor’s 

as-built data requires skill, understanding, and the use of methods to independently verify the 

quality of the data.

An important consideration when developing methods for automating inspection processes is 

the difference between local accuracy and network accuracy. Inspectors need to understand the 

difference between local accuracy and network accuracy and how it relates to measuring 

quantities and checking tolerances. Local accuracy refers to the position of one element in 

relation to another (e.g., the distance between the final wearing course and the base course). A 

very high local accuracy is needed to ensure smoothness, consistent depths, and high material
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yields. For this reason, contractors select a high accuracy method for AMG construction. 

However, the network accuracy, which is the location of the constructed facility in the world, 

only needs to be within 0.25-inch accuracy where that facility must tie into an existing facility 

like a bridge or an existing roadway.

Capturing As-Built Data with Field Survey

Using AMG as-built data for measurement and inspection relies on the contractor performing 

work with AMG systems that meet the tolerance necessary for measurements with the 

appropriate network and local accuracies. Where this is not the case, inspectors may use field 

survey methods to create the necessary data. The range of field survey tools available to 

inspectors for field surveying includes total stations, GNSS rovers, digital levels, and

laser-augmented GNSS rovers. These tools have a range of accuracy thresholds; as such, it is 

important for the inspector to choose the right survey tool for the job. Tool selection is based on 

the tolerances required by the construction specification. Each instrument needs to be calibrated 

and serviced regularly. Inspectors should check into control before, during, and after performing 

observations to verify that the instrument is functioning correctly. It is anticipated that UAVs 

with photogrammetry will soon be an additional resource for data collection. Current remote 

sensing tools are discussed later in the following section: Capturing As-Built Data with Remote 

Sensing.

Figure 43 shows an RTS rover being used to check grade off the back of the paver. Any 

tolerance issues would be caught immediately. Grade checks are most important when switching 

from one total station setup to another. The grade checker can store a data point for each grade 

check, capturing a digital as-built with no additional effort beyond pressing a button.

Source: FHWA.

Figure 43. Photo. RTS rover being used to check grade off the back of the paver.
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Table 28 summarizes the appropriate tools for capturing field survey observations to check work. 

The table is organized by the tolerance required by the specification. Total stations are versatile 

tools because of their high accuracy, but they require line-of-sight to control and the area to be 

surveyed. GNSS is the most efficient tool because it is not limited by line-of-sight, but the 

vertical accuracy is insufficient for some activities. Levels provide accurate vertical positioning. 

In some cases, it may be optimal to check the horizontal tolerance with GNSS and the vertical 

tolerance separately with a level. In other cases, using a total station to check horizontal and 

vertical tolerances at once may be more efficient. Laser-augmented GNSS has line-of-sight 

limitations to the laser that provides the vertical accuracy.

Table 28. Inspector tool selection guidance.(61)

Horizontal 

Tolerance 

(ft)

Vertical 

Tolerance 

(ft) Example Activities

Total 

Station GNSS

GNSS

and 

Laser Level

0.50 0.16 Rough grading H and V H and V — —

0.16 0.10 Subgrade, street lights, and 

utility poles

H and V H and V — —

0.16 0.07 Waterlines H and V H only H and V V only

0.16 0.03 Finished grade, base, 

paving, sewers, and drainage 

structures

H and V H only H and V V only

0.03 0.02 Curbs, bridge bearing seats, 

bridge beams, and structural 

concrete

H and V — — V only

—Indicates that the technology is not sufficient/recommended for the outlined tolerances/activities. 

H = Horizontal.

V = Vertical.

When using the tools in table 28 to capture as-built data, it is important for the inspector to 

understand the accuracy limitations of the tool and the necessary accuracy to verify tolerances 

and measure pay quantities in accordance with the specification. Positional tolerances relative to 

a geospatial datum are indicated by the staking accuracy for each work item. Positional 

tolerances required by the specification may be lower than the lowest tolerance in table 28.

Generally, an inspector should choose a tool that can achieve the needed local accuracy so data 

only need to be captured once. Table 29 shows methods and tools for using as-built data to 

compute measurements. The survey tool for capturing the as-built records should support the 

needed accuracy on the measurement. For instance, a total station should be used to measure 

structural concrete volumes, whereas GNSS is appropriate for computing borrow pit excavation 

quantities.
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Table 29. Use of field surveying tools to measure payment quantities.

Quantity Example Tools Method

Volume Earthworks 

excavation and 

rock 

excavation

GNSS and 

CADD

• Conduct topographic survey of top and bottom 

surfaces (e.g., original and final ground).

• Compute DTM surfaces for top and bottom in 

CADD.

• Perform surface-to-surface volume calculation 

in CADD.

• Produce exhibit and calculation sheet.

Volume Pavement 

materials

Total 

station and 

CADD

• Conduct topographic survey of top and bottom 

surfaces.

• Compute DTM surfaces for top and bottom in 

CADD.

• Perform surface-to-surface volume calculation 

in CADD.

• Produce exhibit and calculation sheet.

Volume Structural 

concrete

Total 

station and 

CADD

• Collect as-built points.

• Create faces and solids in CADD.

• Compute solid volumes in CADD.

• Produce exhibit and calculation sheet.

Volume Concrete curb GNSS,

CADD, and 

spreadsheet

• Collect flowline as-built points.

• Compute length in CADD.

• Multiply length by cross-sectional area in 

spreadsheet.

• Produce exhibit and calculation sheet.

Area Seeding 

clearing and 

grubbing

GNSS and 

CADD

• Collect points on the perimeter.

• Create boundary in CADD.

• Compute area in CADD.

• Produce exhibit and calculation sheet.

Length Culvert and 

water line

GNSS and 

CADD

• Collect as-built inverts/pipe joints with field 

codes.

• Produce flow lines in CADD.

• Compute lengths in CADD.

• Produce exhibit and calculation sheet.

Length Curb, striping, 

and silt fence

GNSS and 

CADD

• Collect as-built points with field codes.

• Create line work in CADD.

• Compute lengths in CADD.

• Produce exhibit and calculation sheet.

Unit Bridge piles 

and traffic 

control devices

GNSS and 

spreadsheet

• Collect as-built points with field codes.

• Sort points by field code and count in 

spreadsheet.

• Produce calculation sheet.
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In some cases, it may be optimal to check the horizontal tolerance with GNSS and the vertical 

tolerance separately with a level. In other cases, using a total station to check horizontal and 

vertical tolerances at once may be more efficient. Laser-augmented GNSS has line-of-sight 

limitations to the laser that provides the vertical accuracy.

Capturing As-Built Data with Remote Sensing

Table 28 and table 29 are not the only tools available to capture independent survey data to 

verify and measure construction outcomes. In some cases, remote sensing applications are viable 

alternatives to capture the data. In certain conditions, aerial remote sensing can be an efficient 

method to capture the data necessary for computing earthwork volumes.(62) It is also possible to 

use tripod-mounted LiDAR to collect data to verify and measure earthwork construction.(63)

Aerial photogrammetry can capture a wide area in a short period but requires more intensive data 

processing than does field survey data. Clearing and grubbing must be complete prior to 

capturing the aerial photography to prevent missing data in occluded areas. Aerial 

photogrammetry results in a DTM and may be used to capture either or both the original and 

final ground conditions. The DTMs can then be used to cut cross sections or for surface-tosurface volume computations. The latter is more accurate than average end area method 

computations from cross sections.

There are several factors that determine whether aerial photogrammetry is practical or 

economical, including the following:(62)

• Safety considerations that make field survey more risky.

• Volume of unclassified excavation (100,000 yd3 is a threshold).

• There is a 20-acre threshold for the area to be surveyed.

• Considerations that require multiple flights to capture the data.

• Visual occlusions like water bodies or areas that cannot be cleared.

• Availability of individuals to perform field survey or photogrammetry.

• Turn-around time available for processing the data.

• Ability to reuse the data for other purposes or to consolidate data acquisition.

It is anticipated that UAVs will make photogrammetry more viable and cost effective for 

capturing DTMs due to enhanced accuracy and lower costs compared to normal methods. It is 

also feasible to use static, tripod-mounted LiDAR for capturing the data needed to measure 

earthwork quantities for payment.(63) Productivity rates affect the economic feasibility of using 

static LiDAR. Setup time, scanning time, and the minimum distance between setups required to 

achieve sufficient accuracy affect whether static LiDAR is more or less cost effective than other 

survey data acquisition methods like GNSS rovers and RTSs.
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The workflow for using static LiDAR to collect data for earthwork computations is as follows:

1. Enforce control every 800–1,000 ft along the highway alignment.

2. Establish secondary temporary control to supplement the primary control to identify and 

eliminate sources of systemic error in data collection. These should be established to provide 

full radial coverage within the effective radius of the scan.

3. Establish the coordinates of the scanner and instrument height at each setup.

4. Select the density of point acquisition taking into account (e.g., scanning time, accuracy, and 

data storage, transfer, and manipulation).

5. Migrate the point cloud data to a workstation.

6. Register scans to each other to provide a contiguous dataset.

7. Filter and classify points to extract finished ground points.

8. Perform quality control procedures on the dataset.

9. Create a DTM from finished ground points.

10. Use surface-to-surface comparison to calculate the earthwork volumes.

In a 2010 study with data captured with an older static LiDAR system (a Trimble® GS200 

scanner), productivity rates of 18 h/mi for finished ground surface were achieved as compared 

to 30 h/mi for capturing the necessary data with a total station and a two-man crew.(63) Newer 

systems, like the one shown in figure 44, can achieve the necessary accuracy with a larger

interval between setups and can achieve a wider vertical coverage angle; however, scan planning 

is important, especially where there are visual occlusions.
107

Source: FHWA.

Figure 44. Photo. Static LiDAR being used to collect as-built data.

GNSS rovers are able to achieve the same 0.1-ft vertical accuracy without line-of-sight 

limitations, allowing much faster data acquisition for the limited purpose of earthworks 

computations. A GNSS rover may be mounted onto an all-terrain vehicle and set to capture a 

data point every 10 ft. This is a fast and efficient way to capture the information necessary to 

create a DTM. The processing time is much shorter than for LiDAR data; the points can be 

downloaded directly into CADD to produce a DTM within hours.

Limitations of Real-Time Observations

Data collectors can display the tolerance achieved relative to a design surface in real time and 

can perform real-time distance and volume computations. However, the survey observations 

need to be conducted with the proper oversight of a qualified individual. The data then need to be 

manipulated by a qualified CADD operator to produce transparent supporting materials for the 

quantity computations.

One of the benefits of using these inspection protocols is that they free up the inspector’s time 

to observe construction activities, resulting in a better quality product. Inspectors can quickly 

capture data to measure and verify work with GNSS rovers and RTSs. The process of capturing 

the data for measurement and inspection can be close to real time behind the equipment.

However, surveying and CADD skills are not necessarily appropriate for inspectors to develop
108

and maintain. It may be more efficient to have dedicated construction surveyors and CADD 

operators who are trained to review and manipulate the data to measure quantities and produce 

exhibits and reports for the inspectors. CADD skills are useful onsite to prepare or review the 

data for field changes prior to execution.

Migration of data between the field and the office is expedited with network accessible sites. 

Commercial solutions use cloud-based data storage and cellphone or wireless Internet 

connectivity to migrate data from the data collectors in the field. Data can be manually 

transferred from the construction office using document management systems and network 

connectivity. While not real time, the turn-around time can be sufficiently short to flag any 

potential issues early and resolve any quantity discrepancies in the field while the field 

observations can be revisited.
109

CHAPTER 11. AUTOMATION TECHNOLOGY INTEGRATION

3D data can enhance decisionmaking and the functions of all phases of the highway asset 

lifecycle. Indeed, 3D data frequently integrate automation technologies. However, there is a 

perception, borrowed from the implementation of BIM in vertical construction, that automation 

technology integration culminates in a common repository of 3D data that is used throughout 

the asset lifecycle. Most building assets like windows; doors; heating, ventilating, and air 

conditioning systems; or walls are discrete objects that do not change in physical character 

between planning, design, construction, operation, and maintenance. This is a fundamental 

difference between buildings and highways and affects the way that asset management systems 

create, maintain, and use 3D data.

Highway assets are formed on and, in many cases, with the environment in which they reside. 

Furthermore, the character of the constituent parts changes as facilities are constructed, used, and 

maintained. Frequently, substantial effort and resources are invested in extensive temporary 

works. Settlement occurs, bridges may be struck, concrete may spall, and pavements may rut.

These physical changes have a measurable impact on structural integrity and other performance 

measures. This means that as highway assets progress through their lifecycles, the existing

3D data about the assets are rendered obsolete. That does not dispel the notion of automation 

technology integration across lifecycle phases, but caution and careful planning are important.

One of the greatest challenges to a central repository of 3D digital data at the statewide level is 

the ability to maintain high orders of network accuracy. This is a challenge that the industry has 

yet to resolve. The value of such a system is proportional to the confidence users have in the 

spatial accuracy of the 3D data. For GIS systems, especially for subsurface utility data, 

confidence is currently low.

As noted in chapter 6, investment in mapping control has a long-term impact on the value of data 

captured using that control. Verifying the currency, quality, and integrity of the existing data is 

of the utmost importance, especially for subsurface utilities and the tie-in points on existing 

features. There is a need for frequent data capture, especially during construction. When 

automation technology is used, this data capture serves multiple purposes, including executing 

construction with AMG, tracking productivity, and verifying and measuring completed work.

Currently, automation technology integration occurs in an ad hoc fashion. Agencies have not yet 

created policies to require automation technologies in a broad or integrated manner, and much of 

the contractor’s use of automation is market-driven. Standards are emerging for requiring 3D 

engineered design programmatically for many project types, typically those with cross sections 

or significant earthwork quantities. Significant strides have been made in recent years to passthis 

data on from design to the construction phase, increasingly as the contract document. The 

owner’s use of automation in inspection is most often linked to the contractor’s use of AMG.(10)

Many agencies have special provisions or alternate specifications for intelligent compaction 

and AMG.

The most common uses of automation in highway construction are using 3D data for estimating 

and planning construction, executing grading and excavation with AMG, growing the
110

usage of AMG for paving and emerging the usage for milling, and growing the usage for 

inspection.(9) Using 3D data for planning crane mobilization and lifts, as well as for 4D and 

5D modeling, is growing at the project level.(12) Use is still typically for large, multiyear,

multicontract projects, especially those involving complex bridge or interchange reconstruction. 

Projects such as the Southeast Freeways, the San Francisco-Oakland Bay Bridge, the New Haven 

Harbor Crossing, Presidio Parkway, Sellwood Bridge, Dallas-Fort Worth Connector, and 

Horseshoe Interchange have made extensive and integrated use of automation. (See references 3 

and 64–69.) Contractors act as sophisticated creators and consumers of 3D models to support 

automation.(12) Automation technology integration may also occur on smaller projects, but these 

are more difficult to identify, especially where contractors see the use of automation as a market 

differentiator.

Changes in how highway assets are managed emanate from the Moving Ahead for Progress

in the 21st Century Act.

(70) The act changed the focus from construction to system preservation 

and performance, implementing requirements for data-driven, performance-based strategies 

for maintenance and replacement of highway assets. Capitalizing on mobile technology,

e-Construction, which is a paperless approach to construction management, is rapidly emerging. 

The current trend for e-Construction is to utilize a digital page, but in the future, as the use of

3D data by inspectors proliferates, e-Construction may evolve to make more extensive and direct 

use of 3D data from other automation technology applications.

The highway industry is steadily improving the flow of data from one phase of project 

development to another. As was noted in the Notable Implementation Strategies section in 

chapter 3, this was a central part of the automation technology implementation vision for some 

agencies. There are project examples where there has been a concerted effort to improve the data 

flow between phases and automation applications. The most significant challenges identified 

during EDC round 2 webinars were a lack of guidelines and best practices, a lack of expertise 

and training, and the ability to learn new methods while responding to accelerated deadlines

for design.(9)
111

CHAPTER 12. CONCLUSIONS

The coordinated planning for and use of automation in highway construction from project 

scoping through construction acceptance has the potential to add significant value across project 

delivery but especially in construction and beyond. While clear benefit/cost analysis is not

yet available to prioritize investment in automation technology implementation, digital data 

migration into and out of the construction phase is one limiting factor to fully exploiting the 

potential benefits. The challenge of digital data management is optimizing the collection and 

creation of data such that they are available in the right resolution when they are needed, but 

those needs vary across the project delivery—or asset—lifecycle.

This report describes a snapshot in time of automation technology implementation, which is an 

ongoing process in almost every State transportation department across the United States. Much 

as the in-place capabilities nationally will continue to advance, so too will the opportunities 

presented by automation. Ongoing research activities seek to quantify the benefits and costs

of, or explore the potential of, a variety of automation technologies that will bring with them 

changing data needs and products. At the same time, outreach initiatives are currently deploying 

some of the more mature automation technology uses, such as post-construction survey,

e-Construction, new data sources for asset management decisionmaking, and the incorporation of 

schedule and cost information into 3D models. The products of these efforts will likely provide 

information that helps implementing agencies to focus their investments and efforts for 

supporting automation in highway construction.

113

ACKNOWLEDGMENTS

This report represents the results of research conducted by the authors and does not necessarily 

represent the views or policies of the State transportation departments whose policies and 

practices have been referenced. This project is possible due to the funding from FHWA and the 

assistance from State transportation departments leading efforts to implement automation in 

highway construction.

115

REFERENCES

1. Torres, H.N., Ruiz, J.M., Chang, G.K., Rutledge, J.L., and Garber, S. (In Press). Automation 

in Highway Construction: Final Report—Part I, Report No. FHWA-HRT-16-030, Federal 

Highway Administration, Washington, DC.

2. Olsen, M.J., Roe, G.V., Glennie, C., Persi, F., Reedy, M., Hurwitz, D., Williams, K., Tuss, 

H., Squellati, A., and Knodler. (2013). Guidelines for the Use of Mobile LIDAR in 

Transportation Applications, NCHRP Report 748, National Cooperative Highway Research 

Program, Transportation Research Board, Washington, DC.

3. Parve, L. (2015). 3D Model Data-Final Specifications. Southeast Freeways Design Manual, 

Wisconsin Department of Transportation, Southeast Region, Waukesha, WI.

4. Federal Highway Administration. E-Construction, Federal Highway Administration, 

Washington, DC. Obtained from: http://www.fhwa.dot.gov/innovation/everydaycounts/edc3/econstruction.cfm. Site last accessed April 22, 2016.

5. Vonderohe, A. (2009). Status and Plans for Implementing 3D Technologies for Design and 

Construction in WisDOT, University of Wisconsin–Madison, Madison, WI.

6. Lobbestael, J., VanDeventer, R., and Bogren, T. (2012). Moving Towards Electronic Model 

Data—Cradle to Grave, Michigan Department of Transportation, Lansing, MI.

7. Michigan Department of Transportation. (2014). Development Guide, Michigan Department 

of Transportation, Lansing, MI. Obtained from: http://mdotwiki.state.mi.us/design/index.

php/Main_Page. Site last accessed May 25, 2016.

8. Mosier, D. (2012). 3-Dimensional (3D) Roadway Design: Developing ODOT’s Roadway 

Design Crews to Deliver 3D Digital Buildable Design Files, Oregon Department of 

Transportation, Salem, OR.

9. Struthers, J.Q., Maier, F., and Darter, S. (2015). Webinar Series Summary, Federal Highway 

Administration, Washington, DC. Obtained from: https://www.fhwa.dot.gov/construction/3d/

webinars/summary.pdf. Site last accessed March 24, 2017.

10. Darter, S., Maier, F., and Struthers, J.Q. (2015). Final Report: Webinars and Workshops for 

3D Engineered Models for Construction, Federal Highway Administration, Washington, DC.

11. Florida Department of Transportation. (2015). FDOT Design Training Expo June 9–11, 

2015, Florida Department of Transportation, Tallahassee, FL. Obtained from: 

http://www.dot.state.fl.us/officeofdesign/Training/DesignExpo/2015. Site last accessed 

April 22, 2016.

12. Maier, F., Struthers, J.Q., and Darter, S. (2013). 3D Engineered Models forConstruction 

Workshop Instructor Guide, Federal Highway Administration, Washington, DC.
116

13. Jahren, C. (2014). Scan 13-02 Advances in Civil Integrated Management (CIM), 

International Highway Engineering Exchange Program, New Orleans, LA. Obtained from: 

http://www.heep.org/conference/archive/2014/files/presentations/advances_in_cim.pdf. Site 

last accessed April 22, 2016.

14. Vonderohe, A. (2013). Wisconsin Department of Transportation 3D Technologies 

Implementation Plan, University of Wisconsin–Madison, Madison, WI.

15. Singh, R. (2008). Engineering Automation: Key Concepts for a 25-Year Time Horizon,

Oregon Department of Transportation, Salem, OR.

16. Vonderohe, A. (2007). Final Report: Implementation of GPS Controlled Highway 

Construction Equipment, University of Wisconsin–Madison, Madison, WI. Obtained from: 

http://cmsc.engr.wisc.edu/Vonderohe2007Apr01.pdf. Site last accessed April 22, 2016.

17. Singh, R., Holeman, G., Brinton, D., Cantrell, E., Thwaits, R., Ohmer, S., Fosgard, E., and 

Maley, M. (2010). Construction Machine Automation Six Year Plan, Oregon Department of 

Transporation, Salem, OR.

18. Lukes, G. and Page, M. (2014). 3D Engineered Models for Construction Implementation 

Plan, Utah Department of Transportation, Salt Lake City, UT.

19. Cassar, C. (2015). Implementation Plans & Efforts, Successes & Lessons Learned, Michigan 

Department of Transporation, Lansing, MI.

20. Barden, E. (2015). Geospatial Utility Infrastructure Data Exchange 2014 Pilot Initiative, 

Michigan Utility Coordination Committee, Lansing, MI.

21. Federal Highway Administration. Subsurface Utility Engineering, U.S. Department of 

Transportation, Washington, DC. Obtained from: https://www.fhwa.dot.gov/programadmin/

sueindex.cfm. Site last accessed March 23, 2017.

22. McAbee, W. (2012). “Every Day Counts,” Public Roads, 75(4). Obtained from: 

https://www.fhwa.dot.gov/publications/publicroads/12janfeb/01.cfm. Site last accessed 

March 23, 2017.

23. Center for Accelerating Innovation. EDC-1 Innovations (2011–2012), Federal Highway 

Administration, Washington, DC. Obtained from: https://www.fhwa.dot.gov/innovation/

everydaycounts/edc-1.cfm. Site last accessed March 23, 2017.

24. Quiroga, C., Anspach, M., Scott, P., and Kraus, E. (2015). Feasibility of Mapping and 

Marking Underground Utilities by State Highway Agencies, Report No. FHWA-HRT-16-

019, Federal Highway Administration, Washington, DC.

25. Hammerschmidt, A. and Gale, W. (2015). Technologies to Support Storage, Retrieval, and 

Use of 3-D Utility Location Data, Report No. S2-R01A-RW-1, Transportation Research 

Board, Washington, DC. Obtained from: http://onlinepubs.trb.org/onlinepubs/shrp2/

SHRP2_S2-R01A-RW-1.pdf. Site last accessed April 22, 2016.
117

26. Gale, W. (2013). Technologies to Support Storage, Retrieval, and Utilization of 3-D Utility 

Location Data, Project No. SHRP 2 R01(A), Second Strategic Highway Research Program, 

Transportation Research Board, Washington, DC.

27. Young, G.N. and Kennedy, C.M. (2015). Utility-Locating Technology Development Using 

Multisensor Platforms, Report No. S2-R01B-RW-1, Transportation Research Board, 

Washington, DC. Obtained from: http://onlinepubs.trb.org/onlinepubs/shrp2/SHRP2_S2-

R01B-RW-1.pdf. Site last accessed April 22, 2016.

28. Hammerschmidt A., Ziolkowski, C., Huebler, J., Givens, M., and McCarty, J. (2015). 

Innovations to Locate Stacked or Deep Utilities, Report No. S2-R01C-RW-1, Second 

Strategic Highway Research Program, Transportation Research Board, Washington, DC.

29. American Society of Civil Engineers. (2002). Standard Guideline for the Collection and 

Depiction of Existing Subsurface Utility Data, ASCE 38-02, American Society of Civil 

Engineers, Reston, VA.

30. Dean, B. (2014). Parksville Bypass CADD/Survey Tasks Performed, New York State 

Department of Transportation, Albany, NY.

31. Thomas, L.W. and McDaniel, J.B. (2013). “Legal Issues Surrounding the Use of Digital 

Intellectual Property,” Legal Research Digest, 58, National Cooperative Highway Research 

Program, Transportation Research Board, Washington, DC.

32. Computer Integrated Construction Research Program. (2010). BIM Project Execution 

Planning Guide—Version 2.0, The Pennsylvania State University, University Park, PA.

33. Trimble. (2007). Using Trimble Business Center—HCE to Manage Site Calibrations, 

Trimble, Las Vegas, NV.

34. Nevada Department of Transportation. (2012). Construction Survey Manual, Nevada 

Department of Transportation, Carson City, NV.

35. Nevada Department of Transportation. NDOT Survey Monuments, Nevada Department of 

Transportation, Carson City, NV. Obtained from: http://maps.nevadadot.com/Lois/. Site last 

accessed March 23, 2017.

36. Nevada Department of Transportation. (2015). Special Instructions for Location Consultants, 

Nevada Department of Transportation, Carson City, NV.

37. Iowa Department of Transportation. (2004). Preliminary Survey Procedure, Iowa 

Department of Transportation, Ames, IA.

38. Parve, L. (2011). Integrated LiDAR Scanning, Mapping & Modeling for WisDOT SE 

Freeways Zoo IC-Corridor Transportation MegaProject, Transportation Research Board, 

Washington, DC.
118

39. Missouri Department of Transportation. (2014). 238.1 Aerial Mapping and LiDAR Surveys, 

Missouri Department of Transportation, Jefferson City, MO. Obtained from: http://epg.

modot.mo.gov/index.php?title=238.1_Aerial_Mapping_and_LiDAR_Surveys. Site last 

accessed May 25, 2016.

40. ASTM E2807-11. (2011). “Standard Specification for 3D Imaging Data Exchange, Version 

1.0,” Book of Standards Volume 10.04, ASTM International, West Conshohocken, PA.

41. Leuderalbert, K. (2014). Subsurface Utility Engineering, Federal Highway Administration, 

Washington, DC. Obtained from: http://www.fhwa.dot.gov/programadmin/sueindex.

cfm#s03. Site last accessed May 21, 2015.

42. Federal Highway Administration. (2016). Guide for Efficient and Effective Utility Asset Data 

Collection Using Geospatial 3D Techniques, Report No. FHWA-HIF-16-019, Federal 

Highway Administration, Washington, DC. Obtained from: http://www.fhwa.dot.gov/

construction/3d/hif16019.pdf. Site last accessed June 15, 2016.

43. U.S. EPA. National Environmental Policy Act, U.S Environmental Protection Agency, 

Washington, DC. Obtained from: https://www.epa.gov/nepa. Site last accessed June 2, 2017.

44. Oregon Department of Transportation. (2012). 2012 ODOT Highway Design Manual, 

Oregon Department of Transportation, Salem, OR.

45. Missouri Department of Transportation. (2015). 237.14 Electronic Design Data Delivery, 

Missouri Department of Transportation, Jefferson City, MO. Obtained from: http://epg.

modot.org/index.php?title=237.14_Electronic_Design_Data_Delivery. Site last accessed 

May 17, 2015.

46. Iowa Department of Transportation. (2014). Design Manual, Iowa Department of 

Transportation, Ames, IA.

47. Wisconsin Department of Transportation. (2014). Facilities Development Manual,Wisconsin 

Department of Transportation, Madison, WI. Obtained from: http://wisconsindot.gov/

rdwy/fdm/fd-15-05.pdf. Site last accessed April 22, 2016.

48. Maier, F., Mallela, J., and Struthers, J. (2015). 3D Engineered Models: Schedule, Cost and 

Post-Construction Implementation Plan, Federal Highway Administration, Washington, DC.

49. Florida Department of Transportation. (2015). CADD Manual, Florida Department of 

Transportation, Tallahassee, FL.

50. Connecticut Department of Transportation. (2014). Digital Project Development Manual,

Connecticut Department of Transportation, Newington, CT.

51. Carlson, B. and Crews, N. (2014). “LandXML 2.0: New Update to Data Exchange

Standard,” Machine Control Online, Spatial Media, LLC, Frederick, MD. Obtained from:

http://www.machinecontrolonline.com/software-b/5334-landxml-2-0-new-update-to-dataexchange-standard. Site last accessed May 25, 2016.
119

52. Kentucky Transporation Cabinet Division of Highway Design. (2009). Electronic Files 

Submittal, Kentucky Transportation Cabinet, Frankfort, KY.

53. American Association of State Highway and Transportation Officials. (2008). Guide 

Specifications for Highway Construction, American Association of State Highway and 

Transportation Officials, Washington, DC.

54. Florida Department of Transportation. (2015). Standard Specifications for Road and Bridge 

Construction, Florida Department of Transportation, Tallahassee, FL.

55. Iowa Department of Transportation. (2015). Section 1105. Control of Work, Iowa 

Department of Transportation, Ames, IA. Obtained from: http://www.iowadot.gov/erl/

current/GS/content/1105.htm. Site last accesed March 26, 2015.

56. Iowa Department of Transportation. (2015). Special Provisions for Conformity with and 

Coordination of the Contract Documents, Iowa Department of Transportation, Ames, IA.

57. Jasper, J. (2013). KYTC's Electronic Data and 3D Models, Division of Highway Design, 

Kentucky Transportation Cabinet, Frankfort, KY. Obtained from: http://design.

transportation.org/Documents/SCOD%202013%20Meeting/KYTC%27s%20Electronic%20 

Data%20and%203D%20Modeling-Jeff%20Jasper%20(session2).pdf. Site last accessed 

April 22, 1016.

58. New York State. (2014). Standard Specifications (USC), New York State Department of 

Transportation, Albany, NY.

59. Wisconsin Department of Transportation. (2015). Standard Specifications for Highway 

and Structure Construction, 2016 Edition, Wisconsin Department of Transportation, 

Madison, WI.

60. National Geodetic Survey. OPUS: Online Positioning User Service, Silver Spring, MD. 

Obtained from: http://www.ngs.noaa.gov/OPUS. Site last accessed April 22, 2016.

61. Lobbestael, J. (2015). Construction Tolerances and Inspector Tool Selection, Michigan 

Department of Transportation, Lansing, MI.

62. North Carolina Department of Transportation. (2014). Construction Manual Engineering 

Control 2014, North Carolina Department of Transportation, Raleigh, NC.

63. Slattery, K.T. and Slattery, D.K. (2010). Evaluation of 3-D Laser Scanning for Construction 

Application, Report No. FHWA-ICT-10-068, Illinois Department of Transportation, 

Springfield, IL. Obtained from: https://www.ideals.illinois.edu/bitstream/handle/

2142/45889/FHWA-ICT-10-068.pdf. Site last accessed April 22, 2016.

64. Fluor®. Caltrans San Francisco-Oakland Bay Bridge Construction, Fluor®, Irving, TX. 

Obtained from: http://www.fluor.com/projects/san-francisco-oakland-bridge-construction.

Site last accessed Marcy 23, 2017.
120

65. Federal Highway Administration Office of Innovative Program Delivery Project Delivery 

Team. (2015). Joint DOT/FHWA Major Project Webinar, Federal Highway Administration, 

Washington, DC. Obtained from: https://www.fhwa.dot.gov/majorprojects/training/

150505presentation.pdf. Site last accessed March 23, 2017.

66. Federal Highway Administration. Project Profiles: Presidio Parkway, U.S. Department of 

Transportation, Washington, DC. Obtained from: https://www.fhwa.dot.gov/ipd/project_

profiles/ca_presidio.aspx. Site last accessed March 23, 2017.

67. Multnomah County. SellwoodBridge.org: A Project of Multnomah County, Oregon, Portland, 

OR. Obtained from: http://www.sellwoodbridge.org/. Site last accessed March 23, 2017.

68. DFW Connector. DFW Connector Homepage, Texas Department of Transportation, Austin, 

TX. Obtained from: http://www.dfwconnector.com/. Site last accessed March 23, 2017.

69. Dallas Horseshoe Project. The Horseshoe: Fixin’ the Mix, Dallas, TX. Obtained from: 

http://dallashorseshoe.com/. Site last accessed March 23, 2017.

70. Government Printing Office. (2012). Moving Ahead for Progress in the 21st Century Act, 

Public Law 112-141, Washington, DC. Obtained from: https://www.gpo.gov/fdsys/pkg/

PLAW-112publ141/pdf/PLAW-112publ141.pdf. Site last accessed April 22, 2016.

HRDI-20/02-18(100)E