Road Safety Audit Case Studies:

Using Three-Dimensional Design Visualizatio

in the Road Safety Audi

U.S. Department of Transportation

Federal Highway Administration FHWA-SA-14-003
Notice

This document is disseminated under the sponsorship of 

the U.S. Department of Transportation in the interest of 

information exchange. The U.S. Government assumes no 

liability for the use of the information contained in this 

document. This report does not constitute a standard, 

specification, or regulation. 

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 

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i

Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

Technical Documentation Page

1. Report No.

FHWA-SA-14-003

2. Government Accession No. 3. Recipient’s Catalog No.

4. Title and Subtitle

Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization 

in the Road Safety Audit Process

5. Report Date

July 2013

6. Performing Organization Code

7. Author(s)

Dan Nabors, Jon Soika

8. Performing Organization Report No.

9. Performing Organization Name and Address

Vanasse Hangen Brustlin, Inc.

8300 Boone Boulevard, Suite 700

Vienna, VA 22182-2626

10. Work Unit No. (TRAIS)

11. Contract or Grant No.

12. Sponsoring Agency Name and Address

Federal Highway Administration

Office of Safety

1200 New Jersey Ave. S.E. 

Washington, DC 20590

13. Type of Report and Period Covered

Final Report

July 2013 

14. Sponsoring Agency Code

15. 1 Supplementary Notes

The Federal highway Administration Office of Safety sponsored the study of the Road Safety Audits reported in this 

document. The Task Manager for this report was Rebecca Crowe (FHWA Office of Safety). The three-dimensional 

visualization work was completed by Chris Dubois and graphic design was provided by Jorge Quinones.

16. Abstract

Road Safety Audits (RSAs) are a formal safety performance examination of an existing or future roadway or off-road 

facility and are conducted by an independent, experienced, multidisciplinary team. The purpose of the Road Safety 

Audit Case Studies: Using Three-Dimensional Visualization in the Road Safety Audit Process is to help Federal, State, 

local, and Tribal agencies understand the benefits of utilizing interactive three-dimensional (3-D) visualization to assist 

an RSA team in assessing the safety effects of potential roadway designs. This case study document provides a review 

of the RSA process, a 3-D visualization overview, and four case study examples of planning and design-stage RSAs 

where 3-D visualization was used. The case studies include photographs, a project background, key RSA findings and 

suggestions, and the benefits of the 3-D visualization. These case studies will help jurisdictions integrate this innovative technology into their RSA process.

17. Key Words

Road safety audit, 3-D visualization, 3-D model, design 

visualization, innovative technologies, roadway design

18. Distribution Statement

No restrictions. This document is available to the public through the National Technical Information Service, 

Springfield, Virginia 22161.

19. Security Classif. 

(of this report)

Unclassified

20. Security Classif. 

(of this page)

Unclassified

21. No. of Pages

62

22. Price

Form DOT F 1700.7 (8-72) Reproduction of form and completed page is authorized
Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

ii

Ack

Information obtained for this document involved transportation agencies at the Federal, State, 

and local levels. The Federal Highway Administration (FHWA) and the authors greatly appreciate 

the cooperation of the Rhode Island Department of Transportation, The Aquidneck Island Planning 

Commission, the Montana Department of Transportation, the Prince William County Department 

of Transportation, the Virginia Department of Transportation, the Riverside County Transportation 

Commission, and the California Department of Transportation. 
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Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

Table of Conten

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

Background............................................................................................................................................................................................................................................................................................ 3

Eight Steps of an RSA................................................................................................................................................................................................................................................................. 4

RSAs: Benefits and Costs....................................................................................................................................................................................................................................................... 6

Purpose...................................................................................................................................................................................................................................................................................................... 7

3–D Visualization Overview.............................................................................................................................................................................................................................................. 8

Cases in which RSAs May Benefit from 3-D Visualization........................................................................................................................................................ 10

Benefits of 3-D Visualization........................................................................................................................................................................................................................................ 10

Visualization Development Efforts....................................................................................................................................................................................................................... 14

Conclusions and Recommendations.................................................................................................................................................................................................................. 15

Appendix A: Cas

Defense Highway/Burma Road Corridor, Middletown, Rhode Island............................................................................................................................................................18

RSA No. 1—Defense Highway/Burma Road Corridor, Middletown, Rhode Island ................................................................................... 19

Project Background..................................................................................................................................................................................................................................................... 19

Key RSA Findings and Suggestions............................................................................................................................................................................................................ 2

Selected Issues beyond the 3-D Model .............................................................................................................................................................................................. 23

Benefits of the 3-D Visualization................................................................................................................................................................................................................. 24

RSA No. 2—Road Safety Audit of I-90 Interchanges....................................................................................................................................................................... 29

Project Background..................................................................................................................................................................................................................................................... 29

Key RSA Findings and Suggestions............................................................................................................................................................................................................ 3

Benefits of the 3-D Visualization................................................................................................................................................................................................................. 34

RSA No. 3—Road Safety Audit of Purcell Road (Route 643)................................................................................................................................................. 38

Project Background..................................................................................................................................................................................................................................................... 38

Key RSA Findings and Suggestions............................................................................................................................................................................................................ 4

Benefits of the 3-D Visualization................................................................................................................................................................................................................. 41

RSA No. 4—Western Terminus of Proposed Mid County Parkway, Riverside County, California ........................................... 44

Project Background..................................................................................................................................................................................................................................................... 44

Key RSA Findings and Suggestions............................................................................................................................................................................................................ 4

Benefits of the 3-D Visualization................................................................................................................................................................................................................. 47

Appendix B: Creation 
Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

iv

List of Fi

Figure 1: Typical eight-step RSA process ...................................................................................................................................................................................................4

Figure 2: Three-dimensional visualization enables an RSA team to drive through a project 

in the design stage .................................................................................................................................................................................................................................... 8

Figure 3: RSA team reviewing a 3-D model ...........................................................................................................................................................................................9

Figure 4: Graphic showing primary routes in Aquidneck Island Transportation Study ............................................................... 19

Figure 5: Limits of the entire study area for the RI RSA, including NAVSTA gates 10, 11, 17, 23, and 3  ............

Figure 6: Plan view of area modeled as part of the RI RSA (roundabout alternative) ................................................................. 21

Figure 7: Images from both 3-D models comparing the signalized intersection and roundabout 

alternatives at Coddington Highway and the proposed connector road (Burma Road South) .............21

Figure 8: Proposed crosswalk and sidewalk accommodations along Burma Rd South, looking north from 

Coddington Hwy (left) and south from Gate 17 Access Rd (right) ............................................................................................. 23

Figure 9: Driver’s-eye view approaching roundabout along Coddington Highway ......................................................................... 25

Figure 11: Early morning sun-glare as seen from eastbound Gate 17 Access Rd .................................................................................. 25

Figure 10: Image from model showing proximity of Sherman Lane to proposed roundabout ............................................ 2

Figure 12: Schematic diagram of the “dog-bone” concept ............................................................................................................................................... 26

Figure 13: Recently implemented road diet on Coddington Hwy, Newport per RSA team 

recommendations .................................................................................................................................................................................................................................. 26

Figure 14: Existing and proposed cross sections for Coddington Hwy developed by the RSA team ............................. 27

Figure 15: General project study area ......................................................................................................................................................................................................... 29

Figure 16: Significant traffic congestion on eastbound Amsterdam Road during weekday morning peak .........30

Figure 17: 3-D model plan view of RSA study area with closeups of proposed right-turn 

at Jackrabbit Lane and proposed on-ramp from Amsterdam Road ......................................................................................... 30

Figure 18: Southbound right turn at the intersection of Jackrabbit Lane /Amsterdam Road –

Existing (L) and Modeled (R) Views Significant right-turn traffic volume obstructs view

of approaching through vehicles ......................................................................................................................................................................................... 31

Figure 19: Modeled view of the existing (L) and proposed (R) design at Amsterdam Road and the

I-90E on/off-ramp ................................................................................................................................................................................................................................... 33

Figure 20: Conceptual illustration of the East Belgrade interchange .................................................................................................................... 34

Figure 21: General project study area ......................................................................................................................................................................................................... 38

Figure 22: 3-D model plan view of RSA study area on Purcell Road ...................................................................................................................... 39

Figure 23: Shoulder with edge drop-off before (L) and after (R) RSA was conducted The edge drop-off

was immediately corrected following the RSA workshop .................................................................................................................... 41

Figure 24: Bird’s-eye view of the convenience store and the neighborhood in the background 

as seen from west of Dumfries Road ............................................................................................................................................................................. 41

Figure 25: Bird’s-eye view of realigned section of road at the west end of the project ............................................................... 42
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Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

Figure 26: View along westbound Purcell Road approaching convenience store and Dumfries Road ........................42

Figure 27: Study area for Mid County Parkway RSA ....................................................................................................................................................................44

Figure 28: Preferred alignment (Alternative 9) for the western terminus of Mid County Parkway ................................45

Figure 29: Illustration of proposed lane configurations and key 2040 AM peak hour volumes for NB I-215 ......47

Figure 30: Image from 3-D model showing proximity of northbound I-215 entrance ramps from 

Placentia Ave and Mid County Pkwy ...............................................................................................................................................................................48

Figure 31: Mock up of freeway guide signs on Mid-County Parkway ...................................................................................................................48

Figure 32: Mock up of exit sign along I-215 ...........................................................................................................................................................................................48

Figure 33: Photo of existing freeway guide sign in use along I-215 .........................................................................................................................49

Figure 35: Vantage of NB driver on frontage road as seen in plan view ............................................................................................................49

Figure 36: 3-D Image from 3-D model showing vantage of NB driver on frontage road ...............................................................49

Figure 34: 3-D image showing wide cross section of I-215 and distance from left lanes to the 

right edge of the roadway ............................................................................................................................................................................................................49

Figure 37: Image from 3-D model showing proximity of bridge structure to ramp terminus ................................................51

Figure 38: Image from 3-D model showing potential for overpass structure to obstruct sight 

distance of drivers at SB exit ramp ....................................................................................................................................................................................51

Figure 39: Image from 3-D model showing closeness of interchange ramps and multilane cross section ............51

List of Ta

Table 1: Pre-construction Stage RSAs Conducted Using 3–D Visualization .....................................................................................................1

Table 2: Pre-construction stage RSAs conducted using 3–D visualization ........................................................................................................9

Table 3: Selected safety issues and suggested mitigating actions on modeled section of roadway ........................... 22

Table 4: Suggestions on preliminary concept designs for proposed Burma Road South .......................................................... 23

Table 5: Selected safety issues and suggested actions for areas beyond the 3-D model .......................................................... 24

Table 6: Comparison of the various design alternatives considered by the RSA team .................................................................. 32

Table 7: Key safety issues and suggested mitigating actions ........................................................................................................................................ 

Table 8: Summary of select safety issues and suggested actions ........................................................................................................................... 46
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Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

Executive Summar

The purpose of this document is to help Federal, State, Tribal, and local agencies understand the 

benefits of utilizing interactive, three-dimensional (3-D) visualization to assist a road safety audit 

(RSA) team in performing a safety performance examination of potential roadway designs. This 

effort included performing four pre-construction stage RSAs in four different regions of the country 

that incorporated 3-D visualization in the standard eight-step RSA process (see Table 1).

Table 1: Pre-construction Stage RSAs Conducted Using 3–D Visualization 

Location and Host Agencies RSA Design Stage Facility Type Foc

Middletown, RI; Rhode Island: Rhode Island Department 

of Transportation (RIDOT), Aquidneck Island Planning 

Commission, US Navy

Preliminary 

Concept

(0 – 1%)

Two-lane 

limited access 

connector road

New roadway 

and alternative 

intersection designs.

Belgrade, MT; Montana Department of Transportation 

(MDT)

Conceptual

(1 – 25%)

Expressway 

interchanges

New Interstate 

highway access.

Prince William County, VA; Prince William County 

Department of Transportation, Virginia Department of 

Transportation (VDOT)

Advanced

(90%)

Two-lane road 

widened to four 

lanes

Roadway widening 

and curve flattening 

and realignment.

Perris, CA; Riverside County Transportation Commission 

(RCTC), California Department of Transportation 

(Caltrans)

Preliminary

(40 – 80%)

Expressway 

interchanges; 

multilane 

arterial

New complex 

interchange design.

Three-dimensional models of the proposed concepts and designs were developed using digital 

terrain models, design surface models, associated 2-D or 3-D computer-aided design (CAD) files, and 

other information necessary to create a detailed rendering of the proposed roadway and surrounding environment. This included traffic control signs, pavement markings, lane configurations, major 

landscaping, roadside appurtenances, traffic signals, and other items within the right-of-way to 

render a realistic visualization of the roadway and its environment. The 3-D models were exported to 

a 3-D PDF format that allowed them to be viewed using Adobe software that is both free and readily 

available to the general public. Furthermore, the 3-D PDF controls were easy to use for someone 

with basic computer skills. The user could easily rotate 360 degrees while virtually “walking” or 

“driving” through stations spaced 100 feet apart along the proposed alignment. Using the technique 

of creating the model in the 3-D PDF format enabled the RSA team and roadway owner to share and 

review the 3-D models to ensure their accuracy.

The use of this tool during the RSA allowed team members to visualize the project designs and 

identify elements that may pose a safety concern to future road users. These elements can then be 

further discussed and evaluated during design phases, allowing changes to be more easily made to 

plans rather than after the roadway has been constructed.

Three-dimensional visualization can be a useful tool in assisting RSA teams to make a more thorough 

assessment of safety. When used effectively, the 3-D model is a tool that will save the RSA team 

time and yield a heightened awareness of safety issues related to the design project. In general, the 

benefits associated with 3-D visualization include the following:
Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

2

• Enabling persons who are not proficient at reading roadway design plans to comprehend the 

proposed improvements This is particularly important for large, complex projects, innovative 

designs, significant differences in elevation and/or grade, unusual designs, and understanding 

key engineering concepts.

• Illustrating how proposed features (e g , signs, structures, and traffic signals) will affect the 

roadway environment.

• Allowing users to view the proposed conditions from a countless number of vantage points 

which may reveal issues not otherwise obvious from a review of standard 2-D plans.

• Providing visual support of the RSA team’s findings and recommendations to the project 

owners, stakeholders, and others.

• Helping to maximize the effective time of the RSA team members.

• Understanding and visualizing inaccessible locations (due to weather, terrain, security 

restrictions, etc).

• Identifying potentially significant impacts to community, cultural, or historic interests and other 

sensitive areas.

• Providing another set of collective eyes to review the project designs and engineering studies.

• Promoting a holistic design process, ensuring that, if done early, potential design issues are 

identified and can be addressed in a timely manner, rather than late in the design process when 

changes can be timely and costly. 

Moving forward, techniques are continually advancing the ability to utilize 3-D visualization. Future 

tools will be more efficient and graphic capabilities more advanced, which will allow the further 

integration of 3-D visualization in the RSA and other safety processes. It is recommended that 3-D 

visualization continue to be incorporated within RSAs of future/potential construction projects.
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Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

Background

Road Safety Audits (RSAs) are an effective tool for proactively improving roadway safety. The Federal 

Highway Administration (FHWA) defines an RSA as a “formal safety performance examination of 

an existing or future road or intersection by an independent, multidisciplinary team.” The primary 

focus of an RSA is safety, while working within the context of other aspects, such as mobility, access, 

surrounding land use, and aesthetics. By using an independent and multidisciplinary team to perform a comprehensive review and an evaluation of physical, operational, and human-factors-related 

safety issues for a given study area, promote an holistic approach to evaluating roadway safety. The 

RSA team is typically composed of at least three members having expertise in road safety, traffic 

operations, and road design. Other potential team members may have a background in (but not 

limited to) enforcement, emergency medical services, maintenance, human factors analysis, transportation planning, pedestrian safety, and bicyclist safety.

RSAs can be done at any stage in a project’s life:

• A Pre-Construction RSA (planning and design stages) examines a road before it is built. This could 

occur at the system or project planning, feasibility, or project development stage or could occur 

during the design state beginning with preliminary design stage and ending with final design stage. 

An RSA at this stage identifies potential safety issues before crashes occur. The earlier a preconstruction RSA is conducted, the more potential it has to effectively remedy possible safety concerns. For example, a planning stage RSA can examine a system of roads before a specific project 

has been identified for project development, design, and construction. The transportation system 

is assessed at this earliest point to identify, assess, prioritize, and program projects and activities 

that would considerably enhance traveler safety, in the context of and in collaboration with other 

multi-modal transportation investments.

• Construction RSAs (work zone, changes in design during construction, and preopening) examine 

temporary traffic management plans associated with construction or other roadwork and changes 

in design during construction. RSAs at this stage can also be conducted when construction is completed, but before the roadway is opened to traffic.

• A Post-Construction or Operational RSA (existing road) examines a road that is operating and is 

usually conducted to address a demonstrated crash problem.
Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

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Figure 1: Typical eight-step RSA process

Eight Steps of an RS

The eight steps of an RSA are shown in Figure 1 and follow the procedures outlined in the FHWA 

Road Safety Audit Guidelines document (Publication Number FHWA-SA-06-06).

The RSA Projects were pre-selected for this case studies document and the RSA teams were interdisciplinary, typically including engineering, planning, enforcement staff (Steps 1 and 2) from various 

levels of government to include Federal, State, municipal, and metropolitan planning organizations (MPO).

All meetings and site visits for the RSAs in the case studies document were conducted over two or 

three day periods. The RSAs typically began with a start-up meeting (Step 3) attended by the Project 

Owner and/or Design Team (hereafter referred to as the Owner), and the RSA team:

• The Owner described concerns regarding the roads and intersections to be assessed, why the 

sites had been chosen for an RSA, and any constraints or limitations Typically, the reasons for 

the RSA site selection centered on high-profile crashes or public safety concerns 

• The multidisciplinary RSA Team then described the RSA process This included an overview of 

the RSA process with examples of safety issues that are typically encountered and mitigation 

measures to address them 

• Additional issues, such as planned roadway improvements, can be discussed during this step 
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Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

Following the start-up meeting and a preliminary review of the design or site documentation, the 

RSA Team conducted a field review (Step 4). The purpose of the field review was to observe the 

ambient conditions in which the proposed design would operate (for the planning-stage RSA), or to 

observe geometric and operating conditions (for the RSAs of existing roads). The RSA Team observed 

site characteristics (such as road geometry, sight distances, clear zones, drainage, signing, lighting, 

and barriers), traffic characteristics (such as typical speeds and traffic mix), surrounding land uses 

(including traffic and pedestrian generators), and link points to the adjacent transportation network. 

Human factors issues were also considered by the RSA team, including road and intersection “readability,” sign location and sequencing, and older-driver limitations. Field reviews were conducted 

by the RSA Team under a variety of environmental conditions (such as daytime and night-time) and 

operational conditions (such as peak and off-peak times).

The team conducted the RSA analysis (Step 5) in a setting in which all team members reviewed available background information (such as traffic volumes and collision data) in light of the observations 

made in the field. On the basis of this review, the RSA Team identified and prioritized safety issues, 

including features that could contribute to a higher frequency and/or severity of crashes. For each 

safety issue, the RSA Team generated a list of possible measure to mitigate the crash potential and/

or severity of a potential crash.

At the end of the analysis session, the Owner and the RSA Team reconvened for a preliminary findings meeting (Step 6). Presenting the preliminary findings verbally in a meeting gave the Owner the 

opportunity to ask questions and seek clarification on the RSA findings, and also provided a useful 

forum for the Owner to suggest additional or alternative mitigation measures in conjunction with 

the RSA team. The discussion provided practical information that was subsequently used to write 

the RSA report.

In the weeks following the on-site portion for the RSA, the RSA Team wrote and issued the RSA 

report (also part of Step 6) to the Owner documenting the results of the RSA. The main content of 

the RSA report was a prioritized listing and description of the safety issues identified (illustrated 

using photographs taken during the site visit), with suggestions for improvements.

The Owner was encouraged to write a brief response letter (Step 7) containing a point-by-point 

response to each of the safety issues identified in the RSA report. The response letter identifies the 

action(s) to be taken, or explains why no action would have been taken. The formal response letter is 

an important “closure” document for the RSA. As a final step, the Owner was encouraged to use the 

RSA findings to identify and implement safety improvements when policy, manpower, and funding 

permit (Step 8).
Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

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RSAs: Benefits and Costs

RSA Benefits

The primary benefits of RSAs are the reduction of crashes and associated crash costs as road 

safety is improved. The costs of automotive crashes are estimated by the US Department of 

Transportation as:

• $9,197,370 for a traffic fatality (category K)

• $5,454,040 for a critical injury (category A1) 

• $2,446,500 for a severe injury (category A2) 

• $965,724 for a serious injury (category B1) 

• $432,276 for a moderate injury (category B2) 

• $27,592 for a minor injury (category C) 

• $6,500 for property damage only (PDO) 

Other benefits of RSAs include reduced life-cycle project costs as crashes are reduced, and the development of good safety engineering and design practices, including consideration of the surrounding 

land use and development in combination with the potential multimodal safety issues and integrating human factors issues in the design, operations, and maintenance of roads. Additional benefits 

may include enhanced traveler experience and access management, reduced travel delay and travel 

time, and improved travel reliability.

 FHWA sponsored a study of nine RSA programs and five RSA projects, and results are published 

in the FHWA report Road Safety Audits: An Evaluation of RSA Programs and Projects (FHWASA-12-037). The evaluation documented key strategies underpinning the success of the nine RSA 

programs as well as the quantitative safety benefits of specific improvements implemented as a 

result of the five specific RSA projects. Other local and regional studies have been completed to 

quantify the benefits of RSAs; practitioners are encouraged to consult partnering agencies with 

regard to the success in implementing RSAs.

RSA Costs

Three main factors contribute to the cost of an RSA:

• RSA Team costs 

• Design team and Owner costs 

• Costs of design changes or enhancements 

The RSA Team costs reflect the size of the team and the time required for the RSA, which in turn are 

dependent on the complexity of the RSA project.
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Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

RSA teams are typically composed of three to four persons although they can be larger when multiple owners are involved.

Opening and closing meetings, site visits, and RSA analysis sessions are typically conducted in a 

two – or three-day period for each RSA. Prior to and following the on-site portion of the RSA, time is 

required for analysis (such as analysis of collision records, and research on applicable design standards or mitigation measures) along with writing the RSA report.

The design team and owner costs reflect the time required for staff to attend the start-up and 

preliminary findings meetings, and to subsequently read the RSA report and respond to its findings. 

In addition, staff time is required to compile project or site materials for the RSA team.

The final cost component is that resulting from design changes or enhancements, which reflect the 

number and complexity of the issues identified during the RSA.

Purpose

The purpose of this document is to help Federal, State, 

Tribal, and local (such as municipal and county) agencies 

understand the benefits of utilizing interactive threedimensional (3-D) visualization to assist an RSA team in 

assessing the safety effects of potential roadway designs.

Innovative technologies and methods, such as those presented in this document, are supported 

by the Federal transportation bill, Moving Ahead for Progress in the 21st Century Act (MAP-21). 

Section 1304 of the bill specifically addresses the use of innovative technologies and states that it is, 

“in the national interest to promote the use of innovative technologies and practices that increase 

the efficiency of construction of, improve the safety of, and extend the service life of highways and 

bridges.”1 An example of an innovative technology includes the use of 3-D visualization technologies.

Section 1503 states that transportation projects that receive Federal funding are encouraged to 

use advanced visualization technologies during environmental, planning, financial management, 

design, simulation, and construction process. These advanced visualization technologies include 3-D 

modeling that can enhance the detail and accuracy of project designs, increase safety, accelerate 

construction and reduce construction costs, or otherwise expedite project delivery with respect to 

transportation projects that receive Federal funding.

FHWA further supports the use of 3-D modeling through the second Every Day Counts (EDC-2) initiative and the second Strategic Highway Research Program (SHRP 2). EDC-2 initiatives are aimed at the 

use of new technologies and innovative processes that can shorten the completion time of highway 

1  Moving Ahead for Progress in the 21st Century Act (MAP-21). Available: 

http://www.gpo.gov/fdsys/pkg/PLAW-112publ141/html/PLAW-112publ141.h

The Federal Highway Administration 

defines 3-D visualization - also known as 

design visualization (DV) - as the simulated 

representation of a design concept and its 

contextual impacts or improvements.
Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

8

projects and a 2012 initiative included the use of 3-D modeling.2 The goal of the SHRP 2 program is 

to research methods of expediting highway work with minimal disruption to the community.3

3–D Visualization Overview

There were three primary goals for the four RSAs conducted for this project:

1. To evaluate whether existing issues contributing to crashes were addressed through 

proposed designs.

2. To identify design elements that may be modified or included to further enhance safety.

3. To address potential safety concerns associated with existing alignments beyond the proposed 

design projects.

To aid in achieving these goals, the RSA team utilized 3-D visualization techniques to model the 

proposed designs (see Figure 2).

Three-dimensional models of the proposed concepts and designs were developed using digital 

terrain models, design surface models, associated 2-D or 3-D computer-aided design (CAD) 

files, and other information necessary to create a detailed rendering of the proposed roadway 

and surrounding environment. This included traffic control signs, pavement markings, lane 

configurations, major landscaping, roadside appurtenances, traffic signals, and other relevant 

2  FHWA’s Every Day Counts Initiative. Available: http://www.fhwa.dot.gov/everydaycounts/edctwo/index.cfm

3  FHWA’s FOCUS, SHRP 2: Accelerating Utilities Innovations. Available: http://www.fhwa.dot.gov/publications/focus/10mar/05.cfm

Figure 2: Three-dimensional visualization enables an RSA team to drive through a project in the design stage
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Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

items within the right-of-way to render a realistic view of the roadway. The model was created in 

PDF format so that it could be used by nearly anyone with access to a computer, since Adobe PDF 

software can be downloaded for free; in other words, team members did not have to purchase 

specialized design software to view the 3-D models. Furthermore, the controls were easy to use for 

someone with basic computer skills. The user could easily rotate 360 degrees while “walking” or 

“driving” through stations spaced 100 feet apart along the proposed alignment. The use of this tool 

during the RSA allowed team members to visualize the project designs and identify elements that 

may pose a safety concern to future road users. These elements can then be further discussed and 

evaluated during design phases, allowing changes to be more easily made to plans rather than after 

the roadway has been constructed. The methodology used for creating the 3-D models utilized in 

this effort is described in Appendix B.

The 3-D model was reviewed by the RSA team during the start-up meeting (Step 3 in the RSA process) and during the RSA analysis workshop (Step 5 in the RSA process). During the start-up meeting, 

one person familiar with navigating the controls 

of the 3-D model virtually “drove” through the 

project and pointed out some basic design 

features and area landmarks to familiarize the 

RSA team with the design. Later, during the RSA

analysis workshop, a more detailed virtual 

“drive-through” was conducted using the model 

(see Figure 3). The objective of this review was 

to more thoroughly analyze and discuss the 

various aspects of the design.

These RSA projects for this effort are summarized in Table 2; detailed information about each RSA 

project is included in Appendix A.

Table 2: Pre-construction stage RSAs conducted using 3–D visualization 

Location and Host Agencies Design Stage Facility Type Foc

Middletown, RI; Rhode Island Department of 

Transportation (RIDOT), Aquidneck Island Planning 

Commission, US Navy

Preliminary 

Concept

(0 – 1%)

Two-lane limited 

access connector road

New roadway concept 

and potential alternative 

intersection designs.

Belgrade, MT; Montana Department of 

Transportation (MDT)

Conceptual

(1 – 25%)

Expressway 

interchanges

New Interstate highway 

access.

Prince William County, VA; Prince William County 

Department of Transportation, Virginia Department 

of Transportation (VDOT)

Advanced

(90%)

Two-lane road 

widened to four lanes

Roadway widening and 

curve flattening and 

realignment.

Perris, CA; Riverside County Transportation 

Commission (RCTC), California Department of 

Transportation (Caltrans)

Preliminary 

(40 – 80%)

Expressway 

interchanges; multilane arterial

New complex 

interchange design.

Figure 3: RSA team reviewing a 3-D model
Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

10

Three-dimensional visualization should not be confused with microsimulation or advanced computer traffic simulation techniques that are performed by traffic microsimulation programs, such as 

Synchro, CORSIM, or VISSIM. Microsimulation is used to assess the impact of traffic flow and determine vehicular delay results. These programs also enable the user to visualize traffic operations on 

the roadway network but are not designed for detailed assessments of designs.

Cases in which RSAs May Benefit from 3-D Visualization

Three-dimensional models may require significant time and effort to create and, therefore, may not 

be cost-effective on all types of projects. Specific characteristics of projects that may benefit from 

3-D visualization as a cost-effective tool to improve safety are as follows:

• Large or complex projects

• Innovative or unusual designs 

• Significant differences in elevation and/or grade 

• Inaccessible locations 

• Vital public involvement 

Benefits of 3-D Visualization

Generally speaking, the incorporation of 3-D visualization into the RSA process offers a number of 

tangible benefits:

• The 3-D model enables members of the RSA team who are not proficient at reading and interpreting roadway design plans to grasp the proposed improvements. A typical roadway plan sheet 

includes a variety of information types, including existing topographic features; existing right-ofway and easements; existing drainage facilities and utilities; property lines; construction baselines; 

proposed roadway improvements; proposed right-of-way and easements; proposed drainage facilities and utilities; etc. Linework will vary in type, thickness, and color to represent specific components of the roadway environment, and there are various textual and numerical details presented

on the sheet. To unfamiliar eyes, a roadway plan sheet may represent little more than “information overload,” as the reviewers may not be able to directly decipher the material before them. 

Because 3-D visualization strives to replicate real-world conditions, it is more easily comprehended 

by persons of limited roadway design experience.
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Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

• The 3-D model can be used to illustrate exactly how the roadway environment will be affected by 

signs, structures, guardrail, and other key features that are supplemental to the roadway itself.

While the characteristics of a roadway’s horizontal geometry may be effectively conveyed through 

a roadway plan sheet, the vertical components of other features may be lost in this traditional 

2-D vantage. The 3-D model conveys not only the vertical qualities of the roadway itself—namely 

its superelevation and the incidence of crest and sag vertical curves—it can also illustrate the 3-D 

characteristics of other features of the existing or proposed environments. These features may 

include trees, fence lines, guardrail, and concrete barrier. Furthermore, the accurate incorporation 

of proposed or existing signs can also be invaluable in allowing the reviewer to observe how the 

positioning and size of the signs may affect their perceptibility (and, ultimately, their effectiveness) 

with regard to approaching drivers.

• The 3-D model allows users to view the proposed conditions from any number of vantage points, 

which may reveal issues not otherwise obvious from a review of standard 2-D plans. A traditional 

2-D rendering could be developed to capture the perspective of a driver at a specific location 

looking at a specific point or in a specific direction, and such a rendering may prove useful to a 

reviewer. However, if the reviewer then wanted to observe a slightly different vantage (e.g., for a 

driver positioned 20 ft. to the west or pivoting 15 degrees to the left), then a brand new rendering 

must be created to accurately recreate that perspective. The development of a series of similar 

renderings would require significant time and effort. Conversely, the models created here are truly 

3-D and allow the user to turn 360 degrees and move about throughout the virtual environment; 

as such, the models provide the users with essentially every possible vantage that they may desire. 

This array of available perspectives ranges from an on-the-ground street view to an overhead 

view and includes every vantage in between. By capturing screen images of various perspectives, 

users can create a vast collection of viewpoints of the proposed or existing conditions to use for a 

number of purposes.

• The 3-D model can be used by the RSA team to provide visual support of its findings and recommendations to the project owners, stakeholders, and others. Regardless of whether a recommendation of the team was based on a review of the 3-D model, field observation, or another exercise, 

3-D visualization often serves as an effective tool to explain and support that recommendation to 

the project stakeholders. The unrestricted movement allowed within the parameters of the model 

affords the team the opportunity to “bring” the stakeholders to the location and vantage in question. One need not rely on the audience members’ ability to visualize the roadway environment 

within their own minds, as that very roadway environment can be explored collectively using 

3-D visualization.
Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

12

• The 3-D model can help to maximize the effective time of the RSA team members. A typical RSA 

is conducted over two to three consecutive days, with its beginning and ending proceedings—the 

kickoff and preliminary findings meetings, respectively—scheduled well in advance. These meetings serve as bookends to the multi-day process and establish a finite time frame in which all 

group activities must transpire. It is, therefore, essential that each group activity is completed in 

as efficient a manner as possible to maximize the reach of the team in its short time together. By 

streamlining the process of familiarizing itself with the roadway environment through the review 

of the 3-D model, the team spends less time comprehending the conditions and more time pondering the potential safety concerns and associated mitigating actions related to those conditions, 

which, of course, is the overarching goal of any RSA.

• The 3-D model affords the RSA team the opportunity to provide another set of collective eyes in 

reviewing the project designs and engineering studies. The main purpose of the 3-D visualization 

is to bring a static design to life for its audience. The RSA team is able to evaluate and validate the 

appropriateness of many of the design and engineering components because the model brings 

multiple portions of the design together in an easily comprehensible format. First, it allows the 

coordinated review of the horizontal and vertical alignments because it presents both simultaneously. Second, because the 3-D model is analyzed in light of other key engineering components 

beyond the geometric design, it can also bring those pieces to life. For instance, reviewing a traffic 

impact assessment while simultaneously driving the corridor via the model will assist the RSA 

team in giving more thoughtful consideration of the projected traffic demands than if that document were viewed independently of the visualization.

There were also several specific benefits realized for the particular projects analyzed here:

• In Rhode Island, the 3-D model helped the team to visualize and understand key engineering 

concepts. One of the potential benefits of a modern roundabout is a traffic calming effect on 

vehicular speeds at the intersection. While the departure legs are designed to allow vehicles to 

exit the circle efficiently, an element of horizontal deflection is incorporated into the design of the 

approach legs such that drivers are obliged to reduce their speeds in order to navigate the geometry ahead. Excessive speed was a major concern on an urban four-lane arterial considered during 

the Rhode Island RSA. Posted at 25 mph, this roadway was characterized by exceptionally wide 

travel lanes (i.e., 15-18 ft) and commonly-observed speeds greater than 40 mph. During the team’s 

comparison between a roundabout and traffic signal along this corridor, 3-D visualization was 

invaluable in illustrating how the geometric deflection applied to each approach of the roundabout 

would in essence slow every vehicle that traversed this intersection. The team “drove” in a virtual 

sense along each approach and observed directly how the horizontal deflection would combine to 

command deceleration and a heightened awareness of the impending intersection.
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Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

• In California, the 3-D model promoted a holistic design approach. Traditionally, the early stages 

of roadway design focused primarily on establishing “line and grade” (i.e., horizontal and vertical alignments). Oftentimes, little attention was paid to other vital components of the roadway 

environment (e.g., signs, pavement markings, roadside barriers, etc.) until much later in the design process. At the heart of the California RSA was a complex interchange between an existing 

Interstate highway and a proposed high-speed multi-lane facility. The 3-D model enabled the RSA 

team to virtually “drive” along several of the paths within the study area, including the Interstate 

mainline, several of the interchange ramps, the crossing streets, and a frontage road paralleling 

the Interstate. Reviewing the model highlighted just how critical the pavement markings and overhead guide signs would be to the safe and efficient operation of the proposed intricate roadway 

system. As a result, the RSA team recommended that the design team make it a priority to progress the overhead signing plan from a conceptual level to a more advanced state to ensure that 

critical wayfinding measures can be provided. Additionally, the team discussed the impact of sign 

structure locations and grading practices on the extent and type of roadside barrier that would 

be required throughout the project limits. In summary, because it combined all elements of the 

proposed design, 3-D visualization for California highlighted the importance of a holistic approach 

to design by simultaneously considering all design features that affect roadway safety—pavement 

markings, signing (and supporting structures), roadside barriers, etc.

• In Montana, the value of the 3-D model was fully realized when the RSA team considered two 

separate interchange designs—one of which was modeled while the other was not. Across the 

four RSAs that comprised this effort, there was a sense that the 3-D visualization offered a real 

benefit to the RSA team. There was no clearer case presented for this sentiment than the Montana 

RSA that involved two separate interchange designs. The scope of the visualization effort allowed 

only one of the alternatives to be modeled; thus, the RSA team had one modeled design and 

unmodeled design at their disposal. The team was able to conduct a more thorough review and 

generate a series of detailed recommendations for the interchange design that was modeled. Conversely, for the design alternative not modeled, the team conducted a more basic assessment and 

was more limited in the overall project visualization and associated depth of potential improvements. The RSA team concluded that the modeling of the second alternative would have enabled 

it to complete a much more thorough evaluation of the two designs.

• In Rhode Island, the 3-D model allowed for the review of locations that were not readily accessible to the RSA team. A bypass corridor was being considered as a way to alleviate congestion on 

Aquidneck Island, and the conceptual alignment of this new roadway bisected the secured Naval 

Station Newport (NAVSTA). Because some sections of the alignment were well within the security 

fencing at NAVSTA, the RSA team was unable to walk the entire path of the bypass route. However, 

the 3-D model allowed the team to virtually “drive” the whole corridor and get a general sense of 

the future roadway environment.
Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

14

• In Virginia, the 3-D model helped clearly visualize impacts of proposed designs in sensitive areas.

The 3-D model was an important element in demonstrating the proposed changes to the public. 

Since the project passed directly behind houses and a neighboring community, it was important 

to be able to show the impacts on homeowners and the adjacent community. The extents of the 

proposed roadway widening and realignment as well as landscaping and fencing placement were 

all critical to demonstrating the overall project impact. Furthermore, realistically depicting existing 

features, such as a highly-recognizable convenience store, was key to building confidence in the accuracy of the model. Ultimately, the model was utilized in a public meeting to illustrate the project 

to all stakeholders.

Visualization Development Effort

The models developed for these four RSAs were created using Microstation V8 and V8i and then 

exported to a 3-D PDF format. This technique was used because the 3-D PDF format is easily accessible. The PDF platform is commonly used by many people and can be downloaded for free. During 

the course of this project the RSA team and roadway owner were able to share and review the 

3-D models to ensure their accuracy. In no way is this an endorsement of this or any of the design 

tools used to create these models. There are many other design visualization design tools and 

methods that can be used to create a 3-D model. The FHWA Office of Federal Lands Highway Design

Visualization Guide provides information on other design visualization techniques and procedures. 

Detailed information on the techniques used for this project is in Appendix B. A basic review of this 

process and effort is provided as follows:

• The effort expended in the development of the 3-D models for the four RSAs varied from 100 

to 200 person-hours The same individual developed the visualization models for each RSA and 

estimated his efficiency increased by as much as 40 percent from the first to the last 

• Trimble 3-D warehouse was used to secure some of the supplemental elements, such as 

light poles 

• Information requested from the project design team included a variety of files:

> Proposed CAD linework (both 2-D and 3-D, if available) for all improvements, including 

pavement markings.

> Existing and proposed digital terrain models (DTMs) or triangulated irregular networks (TINs).

> Supplemental files, such as pavement marking plans and typical sections for bridge designs.

> PDF of the entire plan set.

• For the RSA conducted in Rhode Island, DTMs were not provided Rough elevation information 

was pulled from an on-line mapping resource, which increased the overall level of effort needed to create the 3-D model 
15

Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

• For the RSA conducted in Montana the proposed on ramp design was not provided in CAD 

and therefore had to be created in the 3-D model, thereby increasing the overall level of effort 

needed 

Conclusions and Recommendations

The purpose of this document is to help Federal, State, Tribal, and local agencies understand the 

benefits of utilizing interactive 3-D visualization to assist an RSA team in assessing the safety effects 

of potential roadway designs. This effort comprised a series of four RSAs in four different regions of 

the country that incorporated 3-D visualization into the standard eight-step RSA process. Developed 

from various electronic files provided by the designers of each roadway project, the 3-D models 

were based in a common PDF format that allowed them to be viewed using Adobe software that is 

both free and readily available to the general public. A minimum of 100 man-hours were expended 

in the development of each model.

RSA projects that may be prime candidates for 3-D visualization are those characterized by any of 

the following:

• Large or complex projects

• Innovative or unusual designs 

• Significant differences in elevation and/or grade 

• Inaccessible locations (due to weather, terrain, security restrictions, etc ) 

• Potentially significant impacts to community, cultural, or historic interests 

The use of 3-D visualization in the RSA process provides the following benefits to the RSA team:

• Enabling persons who are not proficient at reading roadway design plans to comprehend the 

proposed improvements 

• Illustrating how proposed features supplemental to the roadway (e g , signs, structures, traffic 

signals, etc ) will affect the appearance of the roadway environment 

• Allowing users to view the proposed conditions from a countless number of vantage points 

• Providing visual support of the RSA team’s findings and recommendations 

• Helping to maximize the effective time of the RSA team members 

This case study document summarizes the key benefits of 3-D visualization observed for the four 

RSAs conducted under this effort, but additional benefits may be realized for other types of projects. 

This may be especially true for designs with complex vertical elements. For example, a good candidate for visualization may be an existing at-grade intersection in an urban or suburban environment 

at which grade-separation has been proposed. Additionally, the combination of roadway attributes 

may be difficult to assess from a safety standpoint without a clear picture of how these elements 

come together. These elements include changes in the roadway, introduction of grade alterations, 
Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

16

elevated structures that may limit sight distance or roadway perception, and the interactions of 

many types of roadway users.

Three-dimensional visualization can be a useful tool in assisting RSA teams to make a more thorough 

assessment of safety. Using 3-D visualization resulted in support for improvements identified during 

the RSA resulting in those changes being incorporated into the construction plans. The 3-D model 

assists the RSA team in understanding a future design. When used effectively, 3-D visualization is a 

tool that will save the RSA team time and yield a heightened awareness of safety issues related to 

the design project. It is recommended that 3-D visualization continue to be incorporated planning 

stage and design stage RSAs.
Appendix A: 

Road Safety Audit Case Studies:

Using Three-Dimensional Design Visualization in the Road Safety Audit Process
Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

18

Defense Highway/Burma Road Corridor, Middletown, Rhode Island
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Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

RSA No. 1—Defense Highway/Burma Road Corridor, Middletown, Rhode Island

Project Overview

Project Location Coddington Highway (in the vicinity of Gate 10) and Gate 17 Access Road from Gate 23 to Gate

32

Planned 

Improvements

• New two-lane, limited-access connector road to provide bypass route

• Intersections at either end of connector (Alt. 1 – signalized intersections; Alt. 2 – roundabouts)

Project Environment Suburban

Project Design Stage Preliminary Concept (0 to 1%)

Project Owner(s) Rhode Island Department of Transportation, Aquidneck Island Planning Commission, US Navy

RSA Overview

Date of RSA August 2 – 4, 2010

RSA Stage(s) Pre-construction (planning) and operational stage and RSA of existing roads

RSA Team Representatives from the Federal Highway Administration , Middletown Police Department, 

Naval Station Newport, Rhode Island Department of Transportation, and Vanasse Hangen 

Brustlin, Inc.

3-D Visualization Overview

Level of Effort 100 hours were expended to model the connector road alignment, and an additional 40 hours

were spent modeling the two pairs of intersection alternatives.

Information Provided 

by Designers

• Existing conditions and proposed improvements in CAD format

• Latest signing and pavement marking plan

Project Background

The objective of this study—which was cosponsored by the 

Rhode Island Department of Transportation (RIDOT) and 

the Aquidneck Island Planning Commission through the 

Aquidneck Island Technical Steering Committee and funded 

by the Federal Highway Administration (FHWA) Office 

of Safety—was to complete an RSA for a possible future 

bypass corridor in Middletown, Rhode Island on Aquidneck 

Island. The subject corridor included a preliminary concept 

2/3-mile-long roadway alignment across the US Navy’s 

Naval Station Newport (NAVSTA), the third largest employer 

in the state, which would provide a critical north-south link 

between Coddington Highway and Gate 17 Access Road.

Currently there are two primary north-south routes on 

Aquidneck Island that connect Newport in the south with 

Portsmouth to the north: W. Main Road (SR 114) and E. 

Main Road (SR 138) (see Figure 4). In general, both facilities 

have a four-lane cross section with two lanes in each 

direction. The large number of intersecting streets, driveway access points, and traffic signals, coupled with few exclusive turn lanes, creates significant delay 

for traffic seeking to go from one end of the island to the other. In response to this congestion, a 

Figure 4: Graphic showing primary routes in

Aquidneck Island Transportation Study 
Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

20

preliminary concept alignment of a new limited-access roadway across the NAVSTA facility was 

proposed. (Note that “limited-access” refers to the use by the general public, as the access and 

operations with respect to the US Navy and its facilities must not be adversely affected in any way.) 

The proposed roadway—referred to as Burma Road South—would parallel W. Main Road and connect intersecting roads Coddington Highway and Gate 17 Access Road. The corridor would continue 

north on Burma Road until it ends at Stringham Road in the north. As part of the Aquidneck Island 

Transportation Study, it was noted that a new alignment will be considered to extend Burma Road to 

the northeast and ultimately connect to Route 24.

Because the construction of the new Burma 

Road South would likely provide an appealing 

alternative route to W. Main Road and E. Main 

Road, an additional and entirely different set of 

users may begin to utilize the adjacent roadways 

(including Coddington Highway and Burma Road) 

as a bypass corridor to avoid the congestion of W. 

Main Road. Consequently, these roadways were 

analyzed during the RSA, not only in consideration 

of their existing conditions but also how the new 

“bypass” use may present an additional set of 

safety concerns.

The RSA included a field analysis of Coddington 

Highway at Gate 10, Gate 17 Access Road at Gate 

11, Gate 17 Access Road at Burma Road, and 

Burma Road at Gate 32, as well as a thorough 

review of the 3-D model of the preliminary concept Burma Road South alignment. Figure 5 shows 

the full extent of the RSA study area, and Figure 

6 depicts the limits of the area incorporated in 

the model.

Not only did the 3-D visualization bring to life 

a roadway that was in the preliminary concept 

design stage, it also enabled the RSA team to 

traverse (in a virtual sense) portions of the 

secured NAVSTA facility to which it did not otherwise have access. While the confines captured by the model were limited to the planned Burma 

Road South and its northern and southern termini, the total RSA study area exceeded the modeled 

area significantly along the north-south corridor.

Figure 5: Limits of the entire study area for the RI

RSA, including NAVSTA gates 10, 11, 17, 23, and 

32 
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Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

The RSA included a field analysis of Coddington 

Highway in the vicinity of Gate 10 and Gate 17 

Access Road, as well as a thorough review of the 

3-D model of the preliminary concept connector 

road alignment. Two alternatives were reviewed 

as part of the preliminary concept design of 

Burma Road South: the first included signalization of the intersections at the north and south 

limits, while the second included roundabouts. 

Figure 7 shows an image of Coddington Highway 

at the proposed connector road as viewed from 

each 3-D model.

Information used by the RSA team to conduct 

the review included the following:

• Crash data (2007-2009) 

• Existing (2009) Average Daily Traffic (ADT) 

• Projected (2030) ADT 

Key RSA Findings and Suggestion

Three-dimensional visualization was instrumental in the RSA team’s identification of a variety of 

potential safety issues—and not just those exclusive to the proposed designs.

Figure 7: Images from both 3-D models comparing the signalized intersection and roundabout alternatives at

Coddington Highway and the proposed connector road (Burma Road South) 

Figure 6: Plan view of area modeled as part of the RI RSA

(roundabout alternative) 
Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

22

Table 3 presents some key safety concerns and suggested actions along existing roadways that were 

either detected or reinforced by review of the 3-D visualization.

Table 3: Selected safety issues and suggested mitigating actions on modeled section of roadway 

Selected Safety Issue Suggested Action

Excessive speeds

Overall pavement width of 

Coddington Highway is 55-60 

ft, including outside travel 

lanes that measured 15-18 

ft wide. Wide travel lanes 

encourage speeds in excess 

of the posted speed limit of 

25 MPH.

Near-term

Restripe Coddington Hwy to provide three-lane cross section (a through lane in each 

direction and two-way left-turn lane [TWLTL]) with bike lane

If roadway is restriped, consider conducting speed study to evaluate appropriateness 

of posted speed limit.

Sight distance limitations and 

visual detractors

Vertical crest curve on 

Coddington Highway just east 

of Sherman Lane limits sight

distance for drivers traveling 

westbound from W. Main 

Road.

Driver sight distance is 

hindered at the intersection 

of the connector and Gate 17 

Access Road by combination 

of factors, including trees, 

poles, and sun-glare at dawn 

and dusk.

Near-term

Restripe existing pavement on Coddington Hwy to provide three-lane cross section 

(through lane in each direction and TWLTL) with bike lanes. The TWLTL would rem

left-turning traffic from inside through lanes.

Install backplates on the traffic signal heads for Gate 17 Access Road.

Intermediate-term

Consider removal/relocation of sight distance obstructions from the intersection of 

Gate 17 Access Rd/Gate 11.

Long-term

Consider rebuilding Coddington Hwy to flatten vertical curve.

Consider installation of roundabout at Coddington Hwy/Sherman Ln/Burma Rd South

to eliminate traditional left turns at intersection and slow approaching traffic through 

deflection-based design.

Consider installing raised median along Coddington Hwy west of Burma Rd South to 

eliminate left turns.

Consider installation of roundabout at intersection of Gate 17 Access Rd/ Gate 11; 

being a feature of the roadway itself, roundabout would lower the driver’s line of sight 

compared to a traffic signal, thereby lessening the impact of the sun’s glare.

Access management concerns

Close proximity of access 

points along Coddington Hwy.

Near-term

Restripe Coddington Hwy to three-lane cross section with bike lanes.

Long-term

Consider roundabout installation at Coddington Hwy/Sherman Ln/Burma Rd South

Consider installation of raised splitter islands on Coddington Hwy to control left turns.

Peak-hour turning 

movements

Because of the proximity 

between Chases Ln/Gate 23

and Burma Rd South along 

Gate 17 Access Rd, the heavy 

peak-hour turning volumes 

at the former can queue into 

the through lanes.

Near-term

Extend the eastbound Gate 17 Access Rd left-turn lane at Chases Ln to provide

additional storage for turning vehicles.

Long-term

If the existing traffic signal is removed and a roundabout is constructed at the 

intersection with Burma Rd South, consider the installation of a second roundabout at 

Chases Ln/Gate 23 to help the intersection operate more efficiently while increasing

safety through the elimination of traditional left turns.
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Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

Table 4 presents several suggestions pertaining directly to the preliminary concept designs that were 

made as a result of the review of the 3-D model. The final suggestion pertains to nonmotorized 

users along the Burma Road South corridor, and Figure 8 illustrates the sidewalk accommodations 

provided in the preliminary concept design.

Table 4: Suggestions on preliminary concept designs for proposed Burma Road South 

Suggestion

Shift proposed Coddington Hwy roundabout to the east so that Sherman Ln can become fourth leg; this should also

improve sight distance at the vertical crest curve by moving the roundabout further up the hill.

Incorporate lighting in roundabout design to improve nighttime visibility and awareness of conditions.

Emphasize deflection in approach leg geometry to enhance speed reduction for oncoming vehicles.

Because there may be future short-term need for NAVSTA to utilize Gate 10, design should accommodate a suitable 

connection.

Characteristics of pedestrian and bicycle traffic should be considered in the design of Burma Rd South. As a limited 

access facility, vehicle speeds will likely be high and expectancy of pedestrians may be low. Therefore, a parallel 

shared use path may be preferable to accommodate pedestrians. Bicyclists may also be accommodated on this facility, 

especially less-experienced bicyclists. Commuter bicyclists, already present on Burma Road to the north, could use a 

paved shoulder, which would also provide a safety benefit to motorists. A shared use path to the east of the proposed 

roadway will also provide connectivity to the neighboring residences. (Likewise, a pedestrian facility on the west side –

either a sidewalk or a shared use path – would not be able to access NAVSTA and is therefore less critical.) In addition, 

Coddington Hwy and Burma Rd both currently have (or will likely have in the future) designated bike lanes, therefore 

a bikeable shoulder would provide consistency with the rest of the corridor. Further discussion with the stakeholders 

regarding the accommodation of pedestrians and bicyclists is warranted.

Selected Issues beyond the 3-D Model

While the use of 3-D visualization constituted a major part of the study, the Defense Highway/Burma 

Road Corridor RSA also included a traditional field review of existing conditions in portions of the 

study area that did not include design visualization. In addition to the areas already mentioned, the 

RSA analysis also focused on the intersections of Gate 17 Access Road/Gate 11 and Burma Road/

Gate 32. Table 5 presents a few such safety issues and suggested actions.

Figure 8: Proposed crosswalk and sidewalk accommodations along Burma Rd South, looking north from Coddington

Hwy (left) and south from Gate 17 Access Rd (right) 
Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

24

Table 5: Selected safety issues and suggested actions for areas beyond the 3-D model 

Selected Safety Issue Suggested Action

Horizontal curvature

There is a very sharp horizontal 

curve for the through movement 

at the intersection of east-west 

Gate 17 Access Road and the 

north-south Burma Road, with no 

advance warning of the curve for 

approaching drivers.

Near Gate 32, Burma Road crosses 

the railroad tracks at-grade via a 

pair of reverse horizontal curves. 

Because of their low design speed, 

the curves are posted at 25 MPH, 

which violates driver expectancy 

since the remainder of the Burma 

Road corridor is posted at 35 MPH.

Near-term

Install advance curve warning signs for each approach of the through movement 

along Gate 17 Access Rd near Gate 11.

Long-term

Consider realigning the through movement of Gate 17 Access Rd near Gate 11 to 

provide a larger radius and higher design speed at the intersection.

Burma Road/Gate 32:

Consider “swapping” locations of the rail line and Burma Rd between Gate 17 

and Gate 32 such that the rail line would lie to the west of the roadway for the 

entire corridor. This would eliminate the reverse curvature and the at-grade 

crossings of Burma Rd. Note that this will require extensive coordination with 

NAVSTA, as such action could significantly impact Gate 17 and Building 119 and 

present new security risks to the secured naval facilities.

Consider the redesign of the reverse curvature along Burma Rd near Gate 32 to 

flatten the curves and increase the design speed such that the posted speed limit 

of 35 MPH may remain uninterrupted throughout the corridor.

Multiple at-grade rail crossings

Several aspects of the existing 

rail line location were observed 

to present safety issues, such as 

being located at the bottom of a 

downgrade and being adjacent to a 

busy intersection near Gate 11, and 

introducing two at-grade crossings 

along Burma Road within less than 

a mile (at Gate 11 and Gate 32).

Long-term

Consider “swapping” locations of the rail line and Burma Rd between Gate 17 

and Gate 32 such that the rail line would lie to the west of the roadway for the 

entire corridor and the two at-grade crossings of Burma Rd would be eliminated. 

Note that this will require extensive coordination with NAVSTA, as such action 

could significantly impact Gate 17 and Building 119 and present new security 

risks to the secured naval facilities.

Evaluate the long-term usefulness of the rail line in the overall Aquidneck 

Island Master Plan and consider removing it entirely if appropriate. On the 

other hand, if the railroad tracks can play a role in the enhancement of the 

area’s transportation network, then consider upgrading and improving the rail 

infrastructure throughout the corridor.

Inadequate signing and delineation

The RSA team noted that the 25 

MPH speed limit sign was missing 

along southbound Burma Rd 

just north of Gate 32, and there 

were no delineators found on the 

existing guardrail near the Gate 32 

intersection.

Near-term

Replace the missing 25 MPH speed limit sign (the post was present but the sign 

was not) and install delineators along the existing guardrail near the intersection, 

which will improve nighttime conspicuity.

Benefits of the 3-D Visualization

The 3-D model helped the RSA team to visualize and understand key engineering concepts, in this 

case the potential safety issues associated with different elements of the preliminary concept design 

and differences between the signalized intersection and roundabout alternatives. One of the potential benefits of a modern roundabout is a traffic calming effect on vehicular speeds at the intersection. While the departure legs are designed to allow vehicles to exit the circle efficiently, an element 

of horizontal deflection is incorporated into the design of the approach legs such that drivers are 

obliged to reduce their speeds in order to navigate the geometry. Excessive speed was a major 

concern on Coddington Highway, which is a four-lane arterial with a 2009 ADT of 18,600 vehicles per 

day. Posted at 25 mph, this roadway was characterized by exceptionally wide travel lanes (i.e., 15-18 
25

Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

ft) and commonly-observed speeds greater than 40 mph. During the team’s comparison between 

a roundabout and traffic signal along this corridor, the 3-D model was invaluable in illustrating 

how the geometric deflection applied to each approach of the roundabout would in essence slow 

every vehicle that traversed this intersection. The team virtually “drove” along each approach and 

observed directly how the horizontal deflection would combine to command deceleration and a 

heightened awareness of the impending intersection (Figure 9). The visualization of the roundabouts 

led to a better understanding of their benefits and, ultimately, to their selection as a preferred 

alternative over the signalized intersection.

By being able to rotate the model and look at the design aspects from different viewpoints, the RSA 

team was able to suggest alignments that were more conducive to safety. For example, the model 

showed the Coddington Highway roundabout located just west of the intersection with Sherman 

Lane. The team recognized that Sherman Lane could be incorporated as a fourth leg to the roundabout by shifting the circle approximately 100 ft to the east (Figure 10). Such a design revision woul

eliminate a separate full-access intersection located so close to the roundabout and would accommodate all vehicle movements within the circle.

The RSA team was able to see other benefits of 

the roundabout design as it related to existing 

issues on the roadway. During the morning and 

evening site visits, the RSA team noted that 

sun glare was an issue on several roads in the 

study area, see Figure 11. Being a feature of the 

roadway itself, a roundabout would lower the 

driver’s line of sight compared to a traffic signal, 

thereby lessening the impact of the sun’s glare.

Figure 9: Driver’s-eye view approaching roundabout

along Coddington Highway 

Figure 10: Image from model showing proximity of

Sherman Lane to proposed roundabout 

Figure 11: Early morning sun-glare as seen fro

eastbound Gate 17 Access Rd 
Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

26

The ability to describe the roundabout concept led to a broader discussion among the RSA team 

members regarding the implementation of roundabouts in pairs with a median installed between 

them. This scheme enables the conversion of all side streets and driveway access points between 

the roundabouts to right-in/right-out configurations by prohibiting left turns. Figure 12 presents a 

simple example of this approach—called the “dog-bone” concept because of its geometric characteristics. In the illustration, a single access point lies on the segment between the two roundabouts. 

A raised median separates the opposing through lanes on the mainline, which serves to prohibit 

all left turns between the roundabouts. The blue arrow illustrates the path for a vehicle seeking to 

turn left from the driveway, while the orange arrow shows the path of a vehicle wishing to turn left 

into the driveway. The same concept would apply regardless of the number of access points and 

side streets located within the segment, with all U-turn maneuvers being safely accommodated by 

the roundabouts.

The RSA team recognized the long-term potential of Coddington Highway’s conversion to a roundabout corridor with raised median, but near-term recommendations involving restriping were applied to provide an immediate impact on roadway safety (see Figure 13 and Figure 14). Additionally, 

as a result of the benefits demonstrated by the roundabout 3-D visualization, the City of Newport 

and RIDOT are currently designing a roundabout corridor as part of a bridge improvement project 

and the Town of Middletown and RIDOT considering the future application of multiple roundabouts. 

A series of roundabouts will be installed along JT Connell Highway and Admiral Kalbfus Road, and

construction is expected to begin by 2020.

Figure 12: Schematic diagram of the “dog-bone” concept

Figure 13: Recently implemented road diet on Coddington Hwy, Newport per RSA team recommendations (photo, left:

August 2010; photo, right: January 2013) 
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Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

Figure 14: Existing and proposed cross sections for Coddington Hwy developed by the RSA tea
Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

28

I-90 Interchanges, Belgrade, Montana
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Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

RSA No. 2—Road Safety Audit of I-90 Interchanges, Belgrade, Montana

Project Overview

Project Location Belgrade, Gallatin County, Montan

Planned 

Improvements

• New proposed on-ramp onto Interstate 90E

• New proposed exclusive right-turn lane

Project Environment Suburban

Project Design Stage Conceptual (1 to 25%)

Project Owner(s) Federal Highway Administration (FHWA) and Montana Department of Transportation (MDT)

RSA Overview

Date of RSA August 31-September 2, 2010

RSA Stage(s) Design stage and RSA of existing roads

RSA Team Representatives from the Federal Highway Administration (FHWA), Montana Department of 

Transportation (MDT), Montana Highway Patrol, and Vanasse Hangen Brustlin, Inc. (VHB)

3-D Visualization Overview

Level of Effort Approx. 120 hours were expended to model the overall roadway study area. The proposed

on-ramp designs took approximately 80 additional hours, as the 3-D model was created from a 

conceptual drawing.

Information 

Provided by 

Designers

• Existing conditions improvements in 2–D or 3–D CAD format

• Digital terrain models (DTMs) and design surface models for existing and proposed conditions

• Latest signing, pavement marking, and traffic signal plan

Project Background

The objective of this study was 

to complete an RSA of several 

design alternatives for a new onramp from Amsterdam Road (U602) to eastbound Interstate 90 

(I-90) and a proposed right-turn 

lane from southbound Jackrabbit 

Lane (N-85) to westbound

Amsterdam Road in Belgrade, 

MT. As part of the process, this 

case study was designed to evaluate two adjacent interchanges: 

one using the 3-D modeling 

process, while the other was 

not modeled. A map showing the general study areas is shown in Figure 15. (The Amsterdam Road/

Jackrabbit Lane location is highlighted in red.

The construction of an eastbound on-ramp from Amsterdam Road to I-90 was proposed as a result 

of a traffic study conducted in February 2009. The construction of an exclusive right-turn lane on 

southbound Jackrabbit Lane was also proposed. The improvements are intended to relieve

Figure 15: General project study area
Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

30

congestion on Amsterdam Road during the AM peak and on Jackrabbit Lane during the PM peak.

The overall purpose of the RSA was to determine if the additional on-ramp to the Interstate would 

potentially degrade safety when constructed within close proximity to two existing on-ramps from 

Jackrabbit Lane.

The initial proposed Amsterdam Road on-ramp alternative and the proposed Jackrabbit Lane rightturn lane are shown in plan view from the 3-D model in Figure 17.

Information used by the RSA team to conduct the review included the following:

• Crash data (2004-2008) 

• Annual Average Daily Traffic (AADT) for 2009, 2011, and 2031 

• AM and PM peak hour intersection turning movement counts and projected AM and PM peak 

hour ramp volumes for the proposed construction 

Figure 16: Significant traffic congestion on eastbound Amsterdam Road during weekday morning peak

Figure 17: 3-D model plan view of RSA study area with closeups of proposed right-turn at Jackrabbit Lane and

proposed on-ramp from Amsterdam Road 
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Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

Key RSA Findings and Suggestion

The RSA team evaluated the entire study area within the project limits to identify potential general 

safety issues. The general findings and suggested actions discussed during the RSA are summarized 

in Table 6.

The RSA team also evaluated several design options for the proposed construction of a new on-ramp 

from Amsterdam Road to eastbound I-90. The 3-D model was used to visualize existing and proposed conditions, which assisted the RSA team in performing the evaluation. The 3-D model allowed 

the team to evaluate the potential safety impacts of the initial design, as well as develop other 

alternatives during the course of the RSA. All alternatives were evaluated during the RSA workshop, 

including a comparison of the pros and cons associated with each. Table 6 summarizes the primary 

design alternatives, including advantages and disadvantages, discussed by the RSA team. Several 

additional variations of these alternatives were also evaluated, but are not summarized in this table.

Figure 18: Southbound right turn at the intersection of Jackrabbit Lane /Amsterdam Road – Existing (L) and Modele

(R) Views Significant right-turn traffic volume obstructs view of approaching through vehicles 
Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

32

Table 6: Comparison of the various design alternatives considered by the RSA team

Option Advantages Disadvantages

1: Restripe Amsterdam Road 

(existing)

Restripe Amsterdam Rd

(existing)

• Provides some minimal queue 

improvement.

• Accommodates EB right-turn.

• Provides minimal queue 

improvement, resulting in red-light 

running to make EB left turn.

• Promotes increased speeds in EB 

shared through/right-turn lane.

• Observed underutilization of 

shared through/right-turn lane.

2:Construct New EB On-ramp (3 

Interstate Access Points)

• Reduces congestion at Jackrabbit Lane

/ Amsterdam Road by accommodating 

300+ left turns in peak.

• Signalization introduces gaps for ramp 

traffic.

• Can be constructed within existing 

right-of-way.

• Relocates queuing problem into 

residential community and impacts 

operations at Thorpe Road.

• Introduces additional access / 

conflict point to Interstate.

• Increases potential for off-ramp 

wrong way driving.

• Creates potential speed differential 

between entering ramp traffic and 

mainline Interstate traffic (i.e., 25 

mph merge into 75 mph mainline).

• Does not address long-term 

growth.

3: Construct New EB On-ramp 

Connecting Directly to Existing EB 

Loop On-ramp (2 Interstate Access

Points)

• Reduces congestion at Jackrabbit Lane

/ Amsterdam Road by accommodating 

300+ left turns in peak.

• Does not introduce an additional 

access / conflict point to Interstate.

• Relocates queuing problem.

• Creates speed differential between 

ramp traffic streams.

• Impacts retention area in 

more significant manner than 

other alternatives.

• Conflicts with driver expectancy by 

introducing ramp traffic entering 

middle of loop ramp.

• Introduces new conflict point on 

Amsterdam Road, requiring ramp 

traffic to find adequate gaps in 

opposing WB traffic.

• New ramp queue may spill onto 

Amsterdam Road, depending on 

traffic control and volume.

4: Provide Two Through Lanes

through Amsterdam Road. 

Construct On-ramp from Alaska 

Road. Eliminate Existing Onramp from NB Jackrabbit Lane (2

Interstate Access Points)

• Creates additional capacity.

• Does not introduce additional access / 

conflict point to Interstate.

• Reduces number of conflict points by 

converting 4-approach intersection to 

3-approach intersection.

• Modifies traffic patterns by removing 

number of left-turning vehicles 

destined to I-90E.

• Introduces slight speed differential 

between ramp and Interstate traffic 

streams.

• Provides options to adjust peak signal 

timings by reducing number of phases.

• Provides opportunities to improve local 

road network.

• Requires right-of-way acquisition.

• Alters local traffic patterns by 

creating one-way eastbound traffic 

on Alaska Road.

• Requires trucks exiting truck stop 

to cross lane of traffic to turn left 

to access I-90W on-ramp.

• Introduces potential merging 

issues where two through lanes 

merge prior to joining Interstate.

• Requires upgrades to connecting 

roadways off Alaska Road.
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Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

Option Advantages Disadvantages

6: Provide EB Dual Left-turn Lane

from Amsterdam Road

• Increases capacity by adding lane.

• Does not introduce additional access / 

conflict point to Interstate.

• Requires right-of-way acquisition.

• Requires geometric changes 

throughout entire intersection.

• Depending on arrival patterns 

/ vehicle mix, creates potential 

underutilization of lanes.

Provide SB Right-turn Lane from

Jackrabbit Lane

• Removes large volume of right-turning 

traffic from SB through lane.

• Increases sight distance for motorists 

turning right from EB Amsterdam 

Road, if channelized.

• Can be constructed within existing 

right-of-way.

• Requires less geometric changes 

throughout intersection than other 

alternatives (e.g., dual left turns).

• Depending on arrival patterns 

/ vehicle mix, creates potential 

underutilization of lanes.

As an example of how the 3-D model was used by the RSA team, the initial design alternative 

(Option 2A) is illustrated in Figure 19. This alternative introduces a third eastbound access point to 

I-90 within the project limits (highlighted in blue in Figure 19) and signalizes the Amsterdam Road / 

I-90E off-ramp intersection. The RSA team discussed the possibility of altering the initial design by 

combining the left-turn and right-turn lanes on the off-ramp into a single shared lane (see area shaded in red in Figure 19). This alteration would provide additional space for the construction of the 

on-ramp, allowing for a larger design radius and speed as well as for a greater clear zone distance 

from existing utility poles located to the inside of the curve.

Figure 19: Modeled view of the existing (L) and proposed (R) design at Amsterdam Road and the I-90E on/off-ra

Utility Pole I-90

I-90

Table 6: Comparison of the various design alternatives considered by the RSA team (continued).
Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

34

Benefits of the 3-D Visualization

Use of the 3-D visualization allowed the RSA team to evaluate the safety effects of the initial design 

plan. The 3-D model assisted all team members with understanding the intended design. The 

majority of the team had only seen the design in 2–D on plan drawings prior to the RSA. By using 

the model, the team was able to visualize the “final product” as it may appear within the existing 

physical conditions of the study area. The 3-D model was also a major asset to team members 

who were not familiar with the overall RSA process (e.g., law enforcement) or roadway design 

plans (in 2-D format). Not only did the model introduce these members to the project, but also 

assisted with instructing the members as to the existing elements the team members would be 

looking for during the field review. This instruction and understanding increased participation in 

identifying problematic areas/situations (both existing and proposed) and potential opportunities 

for improvement.

As seen in the Key RSA Findings and Suggestions, the use of a single 3-D model for an initial design

spurred the evaluation of several design alternatives. Using the model, the team was able to compare pros and cons of the various design alternatives brainstormed during the RSA workshop for the 

interchange with Amsterdam Road / Jackrabbit Lane. The ability to develop alternative scenarios

gave the MDT other options to consider for future evaluation, which might not have been available 

if the RSA had not been conducted and/or the 3-D model had not been utilized. Comparing the pros 

and cons on the basis of safety and capacity brought an alternative to the top of the list that had 

not been previously considered. The interest exhibited by the MDT in this process resulted in their 

personnel inquiring about future possibilities for in-house design visualization to use in the 

design process.

The effectiveness of 

3-D visualization in 

the RSA process was 

further demonstrated with the team’s 

review of a proposed 

design for the new 

diamond interchange 

on I-90 at Gallatin 

Field Road to the 

east. This interchange 

was not modeled 

using the 3-D visualization tools, so that the team could compare the effectiveness of using different RSA approaches 

at two proximate sites. The design involved new horizontal and vertical alignments throughout the 

project limits, which would significantly alter roadway elevations and the surrounding landscape. 

Furthermore, the project would require the acquisition of right-of-way, including possible residential 

Figure 20: Conceptual illustration of the East Belgrade interchang
35

Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

relocations. A conceptual illustration of the interchange is shown in Figure 20. Basic suggestions of 

potential safety concerns were provided; however, without a visualization of the proposed design afforded by the 3-D model, the RSA team was unable to identify detailed concerns and suggestions for 

improvement. The team agreed that creating a 3-D model for the RSA would have greatly helped in 

the assessment of the safety effects of the proposed design, particularly in terms of the over/under 

alignment with the railroad tracks, the roundabout configurations, the access to existing surrounding 

development, and the connectivity to future construction on adjacent parcels.
Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

36

Purcell Road, Prince William County, Virginia 
37

Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

Purcell Road, Prince William County, Virginia 
Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

38

RSA No. 3—Road Safety Audit of Purcell Road (Route 643), 

Prince William County, Virginia

Project Overview

Project Location Prince William County, Virgini

Planned 

Improvements

• Roadway widening

• Horizontal and vertical realignment

Project Environment Suburban

Project Design Stage 90% Design

Project Owner(s) Prince William County Department of Transportation and Virginia Department of Transportation 

(VDOT)

RSA Overview

Date of RSA February 4, 2011

RSA Stage(s) Design stage and RSA of existing roads

RSA Team Representatives from the Federal Highway Administration (FHWA), Virginia Department of 

Transportation (VDOT), Prince William County Department of Transportation, Prince William 

County Police Department, Fairfax County Police Department, Rinker Design Associates, and 

Vanasse Hangen Brustlin, Inc. (VHB)

3-D Visualization Overview

Level of Effort: Approximately 120 hours were expended to model the proposed designs

Information 

Provided by 

Designers

• Existing conditions and proposed improvements in 2–D or 3–D CAD format

• Digital terrain models (DTMs) and design surface models for existing and proposed conditions

• Latest signing, pavement marking, and traffic signal plan

Project Background

The objective of this study was to complete an RSA of the proposed realignment and widening plans 

for Purcell Road (Route 643) in Prince William County, Virginia. The RSA also considered safety issues 

associated with severe horizontal and vertical alignments at the eastern edge of the proposed 

project limits. A map showing the general study area is shown in Figure 21.

The realignment and widening of Purcell Road 

is a project identified within Prince William 

County’s comprehensive transportation plan. 

Ultimately, the vision for this section of Purcell 

Road is to be a four-lane divided roadway. 

The first stage of the project is to realign and 

widen Purcell Road from Dumfries Road to 

approximately Vista Brooke Drive (Route 3305). 

The intent of the realignment and widening is 

twofold: first, the initial phase of the project will 

establish the ultimate alignment at Dumfries 

Road for future construction; second, the project will eliminate severe horizontal and vertical 

alignment changes that may contribute to safety issues along the roadway. The project scope also 

included improvements recommended in a Highway Safety Project Application submitted by VDOT 

for a sharp curve at the bottom of a steep downgrade, approximately 0.1 miles east of Vista Brooke 

Figure 21: General project study area
39

Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

Drive. The application recommended improving superelevation, replacing the existing metal culvert 

with a longer and wider concrete pipe, strengthening the shoulders, installing a flashing advance 

curve warning sign, and providing roadway lighting.

The overall purpose of this RSA was to evaluate if existing issues contributing to crashes are 

addressed through the proposed design, to identify design elements that may be modified or 

included to further enhance safety, and to address potential safety concerns associated with existing 

horizontal and vertical alignments beyond the realignment and widening project limits.

The proposed 90% design is shown in plan view from the 3-D model in Figure 22.

Information used by the RSA team to conduct the review included the following:

• Crash data (2005-2008) 

• Annual Average Daily Traffic (AADT) for 2005 through2009 

• 2008 speed study results 

Figure 22: 3-D model plan view of RSA study area on Purcell Road
Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

40

Key RSA Findings and Suggestion

The RSA team evaluated existing conditions as well as the proposed 90% design. A summary of key 

safety issues investigated with the assistance of the 3-D model and suggested mitigating actions is 

presented in Table 77.

Table 7: Key safety issues and suggested mitigating actions 

Selected Safety Issue Suggested Action

Speed

The realignment of Purcell Road 

between Dumfries Road and Vista 

Brooke Drive significantly straightens 

and widens the roadway, potentially 

increasing speed.

Lane Width

Reduce the lane width from 12 feet to 11 feet throughout the project 

corridor by adjusting the placement of edgeline striping.

Optical Speed Bars

Apply optical speed bars through severe curves. Optical speed bars are 

transverse stripes spaced at gradually decreasing distances along the 

edgelines of a curve.

Raised Pavement Markers (RPMs)

Install snowplowable RPMs through the curves in the vicinity of Rocky 

Brooke Court. RPMs are reflective devices that provide additional guidance 

through alignment changes, particularly during low-light conditions.

Convenience Store Access

A highly-recognizable convenience 

store is located in the northeast 

quadrant of the intersection of Purcell 

Road/Dumfries Road. The proposed 

design provides a right-turn lane into 

the convenience store property from 

Purcell Road; however, the distance 

between the access point and the 

intersection is relatively short. The 

lane use at the intersection is left only 

and right only. The situation may arise 

where an approaching motorist may 

mistakenly use the right-turn lane for 

the convenience store as the right-turn 

lane for access to northbound 

Dumfries Road.

Supplemental Signage

Install a supplemental “AT SIGNAL” sign (R10-31P) to the diagrammatic lane

use sign assembly in advance of the intersection of Purcell Road/Dumfries 

Road.

Pavement Marking Messages

Change the spacing of the lane use pavement marking messages on Purcell 

Road. The placement of this particular marking may indicate to some 

motorists to make a right turn to the convenience store. Changing the 

spacing of the pavement marking messages may reduce confusion and 

unnecessary lane changes.

Offset

Offset the right-turn lane with pavement markings at the convenience store 

access. The offset pavement markings would further reinforce that the 

right lane is for the convenience store access. Sight distance improvements 

could also be expected for vehicles exiting the store, as offsetting the rightturning traffic would increase visibility of motorists destined for 

Dumfries Road.

Two-Lane/Four-Lane Transition

The proposed design transitions from 

a 4-lane cross section to a 2-lane cross 

section in the vicinity of Vista Brooke 

Drive. In the eastbound direction, the 

transition is accomplished by using 

the rightmost travel lane as a rightturn “trap” lane into the Vista Brooke 

community.

Transition

Begin the lane transition west of Vista Brooke Drive instead of at the 

intersection. Create a lane drop on Purcell Road in the eastbound direction 

by striping out a section of the rightmost lane west of Vista Brooke Drive 

and installing appropriate signing (W4-2, W9-1, W9-2) and lane reduction 

arrow pavement markings. Downstream of the lane drop, use the rightmost 

lane pavement as a right-turn lane into Vista Brooke Drive. The right-turn 

lane “pocket” instead of the right-turn lane “trap” will more clearly indicate 

the intended use of the lane (i.e., accessing Vista Brooke Drive).

One corridor-wide observation was the significant elevation difference between the edge of pavement and the roadside. These areas pose a safety hazard to vehicles drifting off the paved surface. 

Although shoulder stabilization and roadside rehabilitation are included in the proposed design plan, 
41

Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

this safety issue could be considered for immediate attention by maintenance personnel. As a result 

of this RSA, the roadside drop-offs were immediately addressed, as shown in Figure 23.

Benefits of the 3-D Visualization

Three-dimensional visualization 

was an important element in 

demonstrating the proposed 

changes to the public. Since the 

project passed directly behind 

houses and by a neighboring 

community, it was important to 

be able to show the impacts on 

homeowners and the adjacent 

community. The extents of the 

proposed roadway widening and 

realignment as well as landscaping and fencing placements were 

all critical to demonstrating the 

overall project impact. 

Furthermore, realistically depicting existing features, such as the 

highly-recognizable convenience 

store (see Figure 24), was key to 

building confidence in the accuracy of the model. Ultimately, the 

model was utilized in a public 

meeting to illustrate the project 

Figure 23: Shoulder with edge drop-off before (L) and after (R) RSA was conducted The edge drop-off was immediately

corrected following the RSA workshop 

Figure 24: Bird’s-eye view of the convenience store and the neighborhood

in the background as seen from west of Dumfries Road 
Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

42

to all stakeholders. This included a video of the various “drive through” viewports that was continuously looped on a computer screen prior to the formal meeting.

Having the ability to navigate through the 

corridor and observe different views was helpful 

in understanding the comprehensiveness of the 

proposed design. Looking at the project from a

bird’s-eye view provided a better understanding 

of the design, especially the roadside features 

that were not easily understood when looking 

at a 2–D plan or even the “drive through” model 

view (see Figure 25).

“Driving” the corridor using the model was 

also critical to identifying potentially confusing 

signing and pavement markings, as well as 

driveway access concerns. A review of traditional 2–D roadway plans would not have provided the 

same insights as the 3-D model. For example, the placement of pavement markings combined with 

the curve of the road and location of trees may confuse drivers traveling westbound on Purcell Road 

approaching the convenience store and the intersection with Dumfries Road as to the proper lane 

placement based on their desired destination (see Figure 26).

In general, RSA team members commented that the 3-D model “brought the design to life”. Even 

those members who have been reading design plans for their professional careers appreciated 

the usefulness of the model, as it helped them to more accurately understand the intended 

project outcome.

Figure 25: Bird’s-eye view of realigned section of road at

the west end of the project 

Figure 26: View along westbound Purcell Road approaching convenience store and Dumfries Road

Right turn lane 

to convenience store
43

Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

Mid County Parkway, Riverside County, California
Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

44

RSA No. 4—Western Terminus of Proposed Mid County Parkway, Riverside County, 

California

Project Overview

Project Location: Interstate 215 from Nuevo Road to Harley Knox Bouleva

Planned 

Improvements:

• New 16-mile limited access, high-speed roadway that will terminate with a freeway-tofreeway connection

• Two new interchanges and a redesign of an existing one that will result in multiple 

interchanges in close proximity to one another

• Widening along Interstate to provide as many as six lanes in each direction

• Major realignment and signalization of parallel frontage road

Project Environment: Suburban

Project Design Stage: Preliminary (40 to 80%)

Project Owner(s): Riverside County Transportation Commission, California Department of Transportation

RSA Overview

Date of RSA: January 31 – February 2, 2012

RSA Stage(s): Design stage and RSA of existing roads

RSA Team: Representatives from California Department of Forestry and Fire Protection, California 

Department of Transportation, California Highway Patrol, City of Perris, Federal Highway 

Administration, Riverside County Transportation Commission, and Vanasse Hangen Brustlin, Inc.

3-D Visualization Overview

Level of Effort: 120 hours were expended to build 3-D model

Information Provided 

by Designers:

• Existing conditions and proposed improvements in CAD format

• Digital terrain models (DTMs) for existing and proposed conditions

• Latest signing, pavement marking, and traffic signal plan

Project Background

The objective of this study was to complete an RSA 

of a planned interchange between an Interstate 

highway and a multi-lane, limited-access facility 

(called the Mid County Parkway) in the City of 

Perris, Riverside County, California. The Mid County 

Parkway was proposed to help alleviate existing 

congestion and to meet the projected regional 

traffic demands by providing a critical new eastwest thoroughfare in Riverside County. As currently 

designed, Mid County Parkway will be 16 miles 

long and connect I-215 in Perris to State Route 

(SR) 79 in San Jacinto. The RSA study area is shown 

in Figure 27.

Following multiple rounds of environmental 

analyses, engineering studies, and public meetings, 

a preferred alignment was identified for the Mid 

County Parkway. Known as “Alternative 9,” this Figure 27: Study area for Mid County Parkway RS
45

Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

option included a freeway-to-freeway interchange between Mid County Parkway and I-215 to 

be located between Placentia Avenue and Nuevo Road (see Figure 28). The interchange would 

constitute the western terminus of Mid County Parkway.

Figure 28: Preferred alignment (Alternative 9) for the western terminus of Mid County Parkway
Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

46

The RSA and the 3-D visualization effort concentrated primarily on the following areas:

• The proposed freeway-to-freeway connection between Mid County Parkway and I-215, with 

emphasis on the westbound-to-northbound movement 

• A newly-proposed interchange at I-215 and Placentia Avenue 

• Interchange improvements at I-215 and Cajalco Expressway/Ramona Expressway 

• The proposed realignment of the I-215 East Frontage Road 

Information used by the RSA team to conduct the review included the following:

• Crash data (October 2007 – September 2010; for I-215 from D Street to Van Buren Boulevard) 

• Existing (2010) average annual daily traffic (AADT) and select peak hour counts 

• Projected (2040) AADT and select peak hour movements 

Key RSA Findings and Suggestion

A summary of selected safety issues and suggested mitigating actions is presented in Table 88.

Table 8: Summary of select safety issues and suggested actions 

Selected Safety Issue Suggested Action

Inadequate street lighting and delineation

Vertical crest curve at Placentia Ave. bridge overpass is unlit and obstructs 

driver visibility.

New series of reverse horizontal curves added to presently unlit Frontage Rd.

Potential for nighttime confusion for NB drivers on Frontage Rd. due to 

realignment.

Provide street lighting at and near 

the bridge.

Enhance delineation at the newlyintroduced horizontal curves.

Visibility concerns

Close proximity of SB exit ramps to bridge structures will restrict sight distance 

of right-turning traffic.

Safety issues related to the proposed dual right-turn lanes:

• Potential failure by drivers to consider pedestrians.

• Lead vehicles in left lanes will obstruct sight distance for drivers in both rightturn lanes

• Vehicle in left most right-turn lane must cross multiple lanes.

With up to six lanes along I-215, types of guide signs currently in use may be 

obscured and, therefore, largely ineffective.

Consider prohibiting right turns on 

red from the SB exit ramps.

Install sign bridge structures to 

allow all critical guide signage to 

be installed above the Interstate 

through lanes.

Roadside safety

Currently no detailed plans for application of guardrail, median barrier, etc. in 

conjunction with proposed improvements.

Identify the specific applications of 

traffic safety systems, particularly 

in light of numerous bridge support 

and sign structures, grading limits, 

etc.

Capacity and operational concerns

Close interchange spacing (less than one mile) along I-215 combined with high 

entering/exiting volumes and expected extensive weaving maneuvers.

Consider revisiting the traffic 

analysis by applying detailed 

assumptions regarding the lane 

selection and merge/ diverge 

behavior among drivers within the 

study corridor to ensure there will 

be adequate capacity in peak hours.
47

Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

Table 8: Summary of select safety issues and suggested actions (continued).

Selected Safety Issue Suggested Action

Wayfinding

Development of in-depth signing and pavement marking plans are critical to 

overall project and should commence as soon as possible.

Close interchange spacing combined with high speeds and projected high 

volumes will require drivers to process information and make decisions very 

quickly; therefore, application and placement of guide signs will have huge 

impact on safety and operations within the corridor.

Develop detailed signing 

and marking plans. Consider 

incorporating diagrammatic and 

lane-assigning overhead signs to 

encourage drivers to change lanes 

in advance of the merge/diverge 

conditions.

Benefits of the 3-D Visualization

The review of the 3-D model supported a comprehensive approach to the planning and design of the 

project—one that included consideration of key components of the roadway environment, such as 

wayfinding signs, pavement markings, and roadside barriers. Because of the scale of the Mid County 

Parkway project, it was not feasible to build a 3-D model that would incorporate all of the proposed 

roadway improvements. Based on conversations between the project team, FHWA, the project 

owners, and others, it was decided that the model would focus primarily on northbound movements 

along I-215 at Mid County Parkway, Placentia Avenue, and Cajalco Expressway/Ramona Expressway. 

The area selected for 3-D visualization was considered critical to the RSA in large part because of the 

proximity among interchange ramps, which is characterized by the following:

• Approximately 1,000 ft (0 2 mi) between the northbound exit ramps at Mid County Parkway 

and Placentia Avenue;

• Approximately 1,200 ft (0 2 mi) between the northbound entrance ramps from Placentia Avenue and Mid County Parkway; and

• Approximately 3,700 ft (0 7 mi) between the northbound entrance ramp from Mid County Parkway and the northbound exit ramp at Cajalco Expressway/Ramona Expressway 

This close ramp spacing creates an environment in which a multitude of merging and weaving maneuvers can be expected over a short distance. Figure 29 illustrates the proposed lane configurations 

and key projected peak hour volumes along northbound I-215 within the study area.

Figure 29: Illustration of proposed lane configurations and key 2040 AM peak hour volumes for NB I-215
Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

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Vehicles entering I-215 from Placentia Avenue must merge into the four mainline lanes, while the 

two lanes coming from Mid County Parkway will join I-215 to create a six-lane cross section (see 

Figure 30). The rightmost lane will become an exit-only lane onto Cajalco Expressway/Ramona 

Expressway, with the adjacent lane allowing vehicles to either exit or continue north along I-215.

By traveling along the northbound 

paths within the model, the RSA 

team gained a realistic sense 

of what the proximate ramp 

connections would look like upon 

construction. It was noted that 

Caltrans has been known to use 

2,200 vehicles per lane per hour 

as an upper limit of “stop-and-go” 

capacity along its freeways. Evenly 

dividing the total projected I-215 

volume across the lanes resulted 

in per-lane volumes below 

capacity; however, if the projected 

volumes were assigned to the 

proposed cross section based on 

consideration of expected driver behavior and interactions and not through an even distribution, 

then the potential for certain lanes to become over-saturated may be realized. From this discussion, 

the RSA team made three recommendations:

1. The development of detailed signing and pavement marking plans should commence early in the 

design process and not be left as a final step.

2. Diagrammatic and lane-assigning signs should be included in the signing plan to encourage 

drivers to maneuver into the appropriate lanes well before they encounter the merge/diverge 

conditions. (Some examples of such signs are provided in Figure 31 and Figure 32).

3. Consider the reassessment of per-lane capacity by applying human factors considerations to the 

lane selection and merging/diverging behavior in this segment of I-215.

Figure 30: Image from 3-D model showing proximity of northbound I-215

entrance ramps from Placentia Ave and Mid County Pkwy 

Figure 31: Mock up of freeway guide signs on Mid-County Parkway Figure 32: Mock up of exit sig

along I-215 
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Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

Another concern highlighted by the 3-D model was that the sign types currently in use along I-215 

(see Figure 33) may be obscured by heavy vehicles and, therefore, largely ineffective in delivering 

information to drivers in the leftmost lanes. The rendering of the driver’s vantage emphasized the 

vastness of the cross section and supported the notion of diminished value of roadside signs to 

left-lane drivers due to the distance from their vehicles to the right side of the road (see Figure 34). 

Therefore, it was recommended that the designers consider the installation of sign bridge structures 

to allow all critical guide signing to be placed above the Interstate through lanes, which will promote 

sign visibility to drivers in all of the travel lanes.

The 3-D model also helped identify the potential for nighttime confusion among northbound drivers 

on the I-215 east frontage road. Drivers here will be looking almost directly at the proposed traffic 

signal at the realigned northbound I-215 exit ramp at Ramona Expressway. Figure 35 and Figure 36 

show the vantage of the northbound driver in plan view and in 3-D, respectively. This perspective 

could lead drivers to expect that they will be following a path toward the ramp signal and not curving toward the right, as per the proposed designs. The concern became much more apparent to 

the RSA team by virtually “driving” the frontage road in the 3-D model than it would have by only 

conducting a review of the 2-D roadway design plans.

Figure 33: Photo of existing freeway guide sign in use

along I-215 

Figure 34: 3-D image showing wide cross section of I-215

and distance from left lanes to the right edge of the 

roadway 

Figure 35: Vantage of NB driver on

frontage road as seen in plan view 

Figure 36: 3-D Image from 3-D model showing vantage of NB driver on

frontage road 
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50

Just as the 3-D model proved valuable in its ability to illustrate the vertical qualities of the traffic 

signal, it also helped the RSA team to visualize the impacts of other 3-D features in the roadway 

environment. The proximity of the southbound I-215 exit ramps to the bridge overpasses at Cajalco 

Expressway/Ramona Expressway and Placentia Avenue was noted as a safety concern. This closeness gives the bridge structures the potential to obstruct sight distance for drivers looking to turn 

right on a red signal indication. (See Figure 37, Figure 38 and Figure 39 for supporting images from 

the 3-D model.) This example also highlights the benefits of including as much detail in the model 

as possible, as the more accurate information that can be input into the model, the more accurate 

assessment that can be made of it on the total design—in this case, the impacts of the bridge design 

on various users of the roadway.

In the end, 3-D visualization was instrumental in the RSA of the western terminus of Mid County 

Parkway. By bringing the planned complex interchange to life, the multidisciplinary RSA team was 

able to travel the conceptual roadway segments and view them from the vantage of prospective 

users. The model played an integral role in both the discussions among team members and those 

between the team and the stakeholders by providing a visual representation to the abstract design. 

Additionally, 3-D visualization helped bring to light issues that may have otherwise gone unnoticed 

from a review of only the 2-D plans, such as the concern about the traffic signal vantage for drivers 

on the east frontage road.

Figure 37: Image from 3-D model showing

proximity of bridge structure to ramp 

terminus 

Figure 38: Image from 3-D model showing potential for overpass

structure to obstruct sight distance of drivers at SB exit ramp 

Figure 39: Image from 3-D model showing closeness of interchange ramps and multilane cross section
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Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

Appendix B: Creati
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52

Appe

Creation of 3-D PD

This appendix presents an outline of the procedure used to create the 3-D PDFs used for the RSAs in 

this study.

Software used:

• Bentley Microstation (v8) 

Version 08 05 02 70

• Bentley Microstation (v8i) 

Version 08 11 07 443

• Bentley InRoads 

Version 08 09 03 06

• Adobe Acrobat Pro 

Version 9 4 0

Base Information:

• Existing feature DTM or 3–D Contours

• Proposed feature DTM or 3–D Contours

• 2–D or 3–D survey 

(3–D preferred)

• 2–D or 3–D proposed design 

(3–D preferred)

• 2–D or 3–D pavement markings 

(3–D preferred)

Displaying and Breaking-out Base Information:

• Open InRoads > open existing and proposed DTMs. 

• If only 3–D contours exist, import each as a separate surface. 

• Display Proposed perimeter. 

• Select and Import Proposed perimeter as external boundary for the existing surface. 

• Display existing and proposed surface triangles on separate layers. 

• Breakout the triangles into separate layers/colors based on the feature as needed:

> Existing roadway, existing sidewalk, existing ground, existing water, etc.

> Proposed roadway, proposed sidewalk, proposed ground, proposed wall, etc.

• Create pavement markings by offsetting the line string of the pavement marking to the correct 

width. Line thickness cannot be read by the 3–D PDF.

• Import the pavement markings shapes/lines and drape on the proposed/existing surface. 

• Display triangles and modify and delete triangles where necessary. 

• Check the model and modify, add, or remove points as necessary to create desired result. 
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Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

Creating 3-D objects

• Building Objects:

> Objects like buildings, non standard signs, and other unique items are best if built on their 

own level/color using the tools in the 3–D main toolbar.

• Importing Objects:

> Microstation can import or reference a large number of formats including skp (Sketchup) and 

3–Ds (3–D studio).

• Use the snap buttons to snap to the 3–D surface when placing objects so they will show up at 

the correct elevation.

• Quick Check: View the model from the front or side and locate any rogue objects or triangles 

and modify them to the correct elevation.

Creating Materials

• Using the material editor, create a material for each surface class.

• Place that material by color/layer.

• In some instances, buildings for example, it may be preferable to place a material on the face. 

• Using an aerial photo for the existing ground material can be a good way to provide extra contrast in the model without additional 3–D objects. 

Setting View Locations

• In Microstation, create a vehicle path by snapping 50 ft (or other predetermined spacing) line 

segments on the proposed surface.

• Select the vehicle path level and increase the z elevation by 6 ft This simulates the view from 

the eyes of the driver.

• Turn on the camera in View 1. 

• Using two windows, View 1 as the camera and View 2 as top, manipulate the camera so the 

view is from the first point of your vehicle path and the target point about 100 ft from the 

view point. 

• Use the define camera tool to help keep consistency in each view. 

• Preferred settings: Projection > two point, reference point > eye, focal distance > 100’. 

• Once the camera view is established, create a new saved view, using the station/road name and 

direction as a view name (for example, Sta 100+00 EB or Main St EB).
Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

54

• Move the camera using View 2 to the next point. 

• Continue moving the camera and saving the view for each of the vehicle paths. 

• Include a plan, elevation, and isometric as saved views, as well. 

Rendering

• The final rendering should be done in v8i or higher.

• Open the print dialogue box. 

• Select the pdf pltcfg that comes with Microstation v8i.

• Select the print to 3–D check box. 

• Settings > 3–D plotting options. 

• These settings will need to be modified depending on how complex the model that has been 

developed is Enabling the “Place Walk on PDF Toolbar” will assist the end user.

• Print to desired location. 

PDF Modification

• Open the model tree Here the views that have been saved in Microstation can be seen using 

the arrows in the views box, you can toggle quickly through the created views.

• In the model tree dialogue box, one can also modify the levels and references and save new 

views, but note that any modifications here will not be reflected if a new PDF is printed 

from Microstation.

Viewing Tips

• The model is best viewed in the latest release of Acrobat Pro, Standard or Reader. 

• Change the following setting to optimize the appearance of the PDF:

> Edit > Preferences > 3–D & multimedia.

> Optimization scheme for a low frame rate: NONE.

> Make sure “Enable View Transitions” is checked.

• Advance the model through the preset views in two ways:

> Manually selecting the view from the views tab.

> Clicking the model tree button to the right of the views tab, in the middle window there is the 

option to move forward or backward through the preset views.
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Road Safety Audit Case Studies: Using Three-Dimensional Design Visualization in the Road Safety Audit Process

• At each view, the “walk” tool can be used to look around, move forward or backwards Use this 

tool by selecting it from the tool bar, clicking a point on the screen, and—keeping the mouse 

button depressed—moving the mouse in the direction that you want to look (left or right) or 

move (top or bottom). 

Internet Resources

• 3–D Google Warehouse: http://sketchup.google.com/3–Dwarehouse/

• Federal Lands Highway Division Design Visualization Guide:

http://www.efl.fhwa.dot.gov/manuals/dv/

• Bing Birds-Eye Maps: http://www.bing.com/maps/

• Google Maps: http://maps.google.com/

• Bentley Communities: http://communities.bentley.com/

• Adobe PDF Reader: http://get.adobe.com/reader/