Traffic Analysis Toolbox Volume IX:

PUBLICATION NO. FHWA-HOP-09-001 March 2009

Office of Operations

1200 New Jersey Avenue, SE

Washington, DC 20590

Work Zone Modeling and Simulation—

A Guide for Analysts

i

Foreword

Work zone planning and management has become increasingly challenging because of increasing 

travel demand and an aging roadway network infrastructure facing both more frequent maintenance 

and major rehabilitation projects. These two factors have sharpened interest in analytical tools to 

assist in better understanding projected work zone mobility impacts. An understanding of projected 

mobility impacts is critical for two reasons. First, the work zone planner/manager must be able 

to consider mobility impacts in a complex balance of life-cycle costs, safety, environmental, and 

other impacts. Second, mobility impact measures are used to support the analysis of other impacts 

(e.g., environmental impacts).

This document is the second volume in the FHWA Traffic Analysis Toolbox: Work Zone Analysis

series. Whereas the first volume provides guidance to decision-makers at agencies and jurisdictions 

considering the role of analytical tools in work zone planning and management, this volume 

provides specific guidance to the analyst, researcher, or manager in charge of conducting a specific 

work zone analysis project or who has been charged with developing an overall work zone 

modeling program or approach. This volume includes numerous case study examples, discussion 

and analysis designed to provide the prospective work zone analyst with information pertaining to 

the selection of a transportation modeling approach (including the identification of opportunities 

for use, managing technical risk and examples) as well as specific project applications (including 

constructability, scheduling and transportation management plan design and evaluation). 

This document serves as Volume IX in the FHWA Traffic Analysis Toolbox. Preceding volumes in the 

toolbox include: Volume I: Traffic Analysis Tools Primer, Volume II: Decision Support Methodology 

for Selecting Traffic Analysis Tools, Volume III: Guidelines for Applying Traffic Microsimulation 

Modeling Software, Volume IV: Guidelines for Applying CORSIM Microsimulation Modeling 

Software, Volume V: Traffic Analysis Tools Case Studies - Benefits and Best Practices, Volume VI: 

Definition, Interpretation, and Calculation of Traffic Analysis Tools Measures of Effectiveness, 

Volume VII: Predicting Performance with Traffic Analysis Tools: Case Studies, and Volume VIII: 

Work Zone Modeling and Simulation—A Guide for Decision-Makers.

Paul Pisano

Acting Director

Office of Transportation Operations
ii

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.

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

object of the document.

Quality Assurance Statement

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

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

Standards and policies are used to ensure and maximize the quality, objectivity, utility, and

integrity of its information. FHWA periodically reviews quality issues and adjusts its programs

and processes to ensure continuous quality improvement.
iii

Technical Report Documentation Page 

1. Report No. 

 FHWA—HOP-09-001 

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

5. Report Date 

 March 2009 

4. Title and Subtitle 

Traffic Analysis Tools Volume IX: 

Work Zone Modeling and Simulation—A Guide for 

Analysts

6. Performing Organization Code 

7. Author(s) 

 Matthew Hardy 

 Karl Wunderlich, Ph.D 

8. Performing Organization Report No. 

9. Performing Organization Name and Address 10. Work Unit No. (TRAIS) 

 Noblis 

 600 Maryland Ave, SW 

 Suite 755 

 Washington, DC 20024 

11. Contract or Grant No. 

12. Sponsoring Agency Name and Address 13. Type of Report and Period Covered 

 Federal Highway Administration 

 Office of Operations 

 Room E86-205 

 1200 New Jersey Avenue, SE 

 Washington, DC 20590 

14. Sponsoring Agency Code 

 

15. Supplementary Notes 

16. Abstract 

This document is the second volume in the FHWA Traffic Analysis Toolbox: Work Zone Analysis series. 

Whereas the first volume provides guidance to decision-makers at agencies and jurisdictions considering the role 

of analytical tools in work zone planning and management, this volume provides specific guidance to the analyst, 

researcher, or manager in charge of conducting a specific work zone analysis project or who has been charged 

with developing an overall work zone modeling program or approach. This volume includes numerous case 

study examples, discussion and analysis designed to provide the prospective work zone analyst with information 

pertaining to the selection of a transportation modeling approach (including the identification of opportunities for 

use, managing technical risk and examples) as well as specific project applications (including constructability, 

scheduling and transportation management plan design and evaluation). This document serves as Volume IX in 

the FHWA Traffic Analysis Toolbox. 

17. Key Words 

 Work Zones, Modeling, Simulation, Traffic 

Analysis 

18. Distribution Statement 

 No restriction. This document is available to the 

 public from the sponsoring agency at the website 

 http://www.ops.fhwa.dot.gov. 

19. Security Classif. (of this report) 

Unclassified 

20. Security Classif. (of this page) 

Unclassified 

21. No. of Pages 

138 

22. Price 

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

iii
iv

SI* (MODERN METRIC) CONVERSION FACTORS

APPROXIMATE CONVERSIONS TO SI UNITS

Symbol When You Know Multiply By To Find Symbol

LENGTH

in inches 25.4 millimeters mm

ft feet 0.305 meters m

yd yards 0.914 meters m

mi miles 1.61 kilometers km

AREA

in2 square inches 645.2 square millimeters mm2

ft

2 square feet 0.093 square meters m2

yd2 square yard 0.836 square meters m2

ac acres 0.405 hectares ha

mi

2 square miles 2.59 square kilometers km2

VOLUME

fl oz fluid ounces 29.57 milliliters mL

gal gallons 3.785 liters L

ft

3 cubic feet 0.028 cubic meters m3

yd3 cubic yards 0.765 cubic meters m3

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

MASS oz ounces 28.35 grams g

lb pounds 0.454 kilograms kg

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

TEMPERATURE (exact degrees) °F Fahrenheit 5 (F-32)/9 Celsius °C

or (F-32)/1.8

ILLUMINATION

fc foot-candles 10.76 lux lx

fl foot-Lamberts 3.426 candela/m2 cd/m2

FORCE and PRESSURE or STRESS

lbf poundforce 4.45 newtons N

lbf/in2 poundforce per square inch 6.89 kilopascals kPa

APPROXIMATE CONVERSIONS FROM SI UNITS

Symbol When You Know Multiply By To Find Symbol

LENGTH mm millimeters 0.039 inches in

m meters 3.28 feet ft

m meters 1.09 yards yd

km kilometers 0.621 miles mi

AREA mm2 square millimeters 0.0016 square inches in2

m2 square meters 10.764 square feet ft

2

m2 square meters 1.195 square yards yd2

ha hectares 2.47 acres ac

km2 square kilometers 0.386 square miles mi

2

VOLUME mL milliliters 0.034 fluid ounces fl oz

L liters 0.264 gallons gal

m3 cubic meters 35.314 cubic feet ft

3

m3 cubic meters 1.307 cubic yards yd3

MASS

g grams 0.035 ounces oz

kg kilograms 2.202 pounds lb

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

TEMPERATURE (exact degrees) °C Celsius 1.8C+32 Fahrenheit °F

ILLUMINATION

lx lux 0.0929 foot-candles fc

cd/m2 candela/m2 0.2919 foot-Lamberts fl

FORCE and PRESSURE or STRESS

N newtons 0.225 poundforce lbf

kPa kilopascals 0.145 poundforce per square inch lbf/in2

iv
v

Table of Contents

1.0 Introduction..................................................................................................................... 1

1.1 Transportation Modeling Approaches............................................................................... 2

1.2 Work Zone Analysis Decision Making ............................................................................. 4

1.3 Case Studies...................................................................................................................... 5

1.4 Document Organization .................................................................................................... 8

2.0 Work Zone Analysis Factors.......................................................................................... 9

2.1 Work Zone Characteristics.............................................................................................. 11

2.2 Transportation Management Plan Strategies .................................................................. 24

2.3 Data ................................................................................................................................. 36

2.4 Agency Resources........................................................................................................... 42

2.5 Work Zone Performance Measures................................................................................. 45

3.0 Establishing a Strategic Methodology for Work Zone Analysis............................... 53

3.1 Mono-Scale ..................................................................................................................... 54

3.2 Screening......................................................................................................................... 55

3.3 Multi-Scale...................................................................................................................... 56

4.0 Identifying a Transportation Modeling Approach for Work Zone Analysis........... 58

4.1 Deciding to Analyze or Not Analyze .............................................................................. 58

4.2 Characterizing Case Studies by Transportation Modeling Approach............................. 59

4.3 Developing a Transportation Modeling Approach.......................................................... 61

5.0 Summary and Synthesis............................................................................................... 66

5.1 Key Points....................................................................................................................... 67

5.2 Where Do I Go from Here? ............................................................................................ 68

References.................................................................................................................................. 71

Case Studies............................................................................................................................... 72
vi

Table of Figures

Figure 1 Work Zone Modeling Spectrum ..................................................................................................... 3

Figure 2 Work Zone Decision-Making Process............................................................................................ 4

Figure 3 Work Zone Decision-Making Engine............................................................................................. 5

Figure 4 Case Study Locations..................................................................................................................... 6

Figure 5 Work Zone Analysis Factors......................................................................................................... 10

Figure 6 Isolated Network Form................................................................................................................. 16

Figure 7 Pipe Network Form ...................................................................................................................... 17

Figure 8 Grid Network Form...................................................................................................................... 17

Figure 9 Work Zone Data Spectrum ........................................................................................................... 49

Figure 10 Comprehensive Work Zone Analysis Methodologies................................................................ 54

Figure 11 Analytical Work Zone Decision Framework .............................................................................. 59

Figure 12 Analytical Work Zone Decision Framework—Case Studies...................................................... 60

Figure 13 Analytical Work Zone Decision Framework—Modeling Approaches....................................... 61

Figure 14 Work Zone Decision-Making Engine Process............................................................................ 66

Figure 15 I-15 Pavement Reconstruction Analysis Area ............................................................................ 74

Figure 16 I-15 Analysis Process ................................................................................................................. 75

Figure 17 GTSR Rehabilitation Project...................................................................................................... 81

Figure 18 MDOT METSIM Geographic Coverage.................................................................................... 88

Figure 19 Ambassador Gateway Bridge MOTSIM Network Overview .................................................... 89

Figure 20 Reeves Street Intersection .......................................................................................................... 96

Figure 21 Reeves Street Network Model.................................................................................................... 96

Figure 22 Construction Impact Modeling Methodology .......................................................................... 100

Figure 23 Salt Lake Valley Area ............................................................................................................... 101

Figure 24 VISUM Salt Lake Valley Network........................................................................................... 101

Figure 25 User Delay................................................................................................................................ 102

Figure 26 Travel Time............................................................................................................................... 103

Figure 27 Congestion................................................................................................................................ 103

Figure 28 Crash Rates............................................................................................................................... 104

Figure 29 Synchro/SimTraffic Model of a Work Zone with Two-Way One-Lane Operation .................. 106

Figure 30 Capacity vs Length for Two-Way One-Lane Flagging Operations.......................................... 106

Figure 31 Structural failure on Daniel Webster Hoan Memorial Bridge, December 13, 2000................. 107

Figure 32 WisDOT Transportation Management Plan Development Process.......................................... 108

Figure 33 Lane Closure Analysis Process................................................................................................. 110

Figure 34 Analysis tools used for the Woodrow Wilson Bridge Reconstruction Project ......................... 117

Figure 35 MD 210/I-295 Interchange Reconstruction.............................................................................. 120

Figure 36 US 1 Interchange Traffic Switch Using CORSIM ................................................................... 121

Figure 37 MD 210 Girder Placement Using CLV .................................................................................... 122

Figure 38 2006 Inner Loop Traffic Switch Using QuickZone.................................................................. 123

Figure 39 2006 Outer Loop Traffic Switch Using QuickZone ................................................................. 124

Figure 40 Yosemite Case Study Area....................................................................................... 128

Figure 41 Yosemite Traffic Modeling Networks...................................................................... 129

Figure 42 2004 Hourly Demand Pattern By Day of Week (from HI-STAR) .......................... 130

Figure 43 Zion National Park Overview.................................................................................. 132

Figure 44 Zion National Park South Visitors Entrance............................................................ 132
1

1.0 Introduction

This document is the second volume in the FHWA Traffic Analysis Toolbox: Work Zone Modeling 

and Simulation series. The intent of this volume (TAT Volume IX) is to provide guidance to the 

analyst, researcher, or manager in charge of conducting a specific work zone analysis project or 

who has been charged with developing an overall work zone modeling program or approach. 

This volume is not intended to be a specific how-to guide on using transportation analysis 

tools. This volume complements Traffic Analysis Tools Volume VIII: Work Zone Modeling and 

Simulations—A Guide for Decision-Makers, which was published with the intent to provide local 

decision-makers with a broad, fundamental understanding of how transportation analysis tools can 

be used to support work zone decision making throughout the complete project life cycle. These 

documents are rooted in an overall philosophy that “one size does NOT fit all” with respect to the 

best transportation modeling approach, that is, no single transportation analysis tool or strategic 

methodology is the right answer for all work zone analyses. 

Similarly, it is important to recognize that using modeling and simulation tools for work zone 

impacts analysis may not be necessary for every project. The sophistication of the impacts analysis 

needs to be matched to the complexity and expected degree of impacts of the project. Work zone 

impacts analysis may involve a high-level, qualitative review for some projects, and a detailed, 

quantitative analysis using modeling and/or simulation tools for other projects. An agency should 

use modeling and simulation tools as helpful and appropriate for supporting its overall efforts to 

conduct work zone impacts analysis and making decisions to manage the impacts of projects

The results from analyzing work zone impacts can serve to improve decision making as well as 

improve overall understanding of the relationships between the many forces affecting work zone 

decision making: mobility, financial, environmental, safety, and user costs. Critical to the work zone 

decision-making process is that a work zone analysis should never be used to make key decisions 

but instead developed as a trusted resource for understanding the potential mobility impacts and 

using this information to inform key decisions. The informative value of analysis is directly related 

to how well the analyst has considered both the context for analysis (decisions to be supported and 

relevant performance measures) and the context for validation (data and staff resources). The job of 

the work zone analyst extends beyond merely conducting an analysis and reporting results; instead 

the work zone analyst provides decision-makers with a broader understanding that connects the 

findings of the analysis within the decision-making context.

TAT Volume IX includes numerous case study examples, discussion and analysis designed to 

provide the prospective work zone analyst with information pertaining to:

1. Developing An Appropriate Analytical Approach

a) Identifying opportunities for analysis throughout the project life-cycle

b) Managing technical risk

c) Incorporating lessons learned from case studies analyzing both simple and complex 

projects
2

2. Specific Project Applications

b) Constructability—Constructability is defined as the optimum use of construction 

resources throughout the project life-cycle to achieve project objectives in a costeffective manner. Opportunities to integrate mobility impacts assessment into 

constructability analyses, when identified and considered jointly, can often lead to 

innovative and high-payoff approaches minimizing mobility impacts and maximizing 

return on project investment.

c) Scheduling—Transportation modeling approaches have the potential to provide 

analysts and decision makers with better information on how to time lane closures 

and other construction-related roadway capacity reducing measures to best reduce 

work zone mobility impacts. Scheduling activity can occur on a broad time scale, 

from assessing various alternative multi-year, multi-season approaches to scheduling 

hourly lane closures.

d) Transportation Management Plan Design and Evaluation—Developing a 

Transportation Management Plan (TMP) is a critical component of many work zone 

projects. The use of transportation analysis tools can better evaluate the array of TMP 

options available to a transportation agency in order to identify the most effective 

options (or combination of options) with best potential to mitigate disruptions caused 

by roadway construction. 

1.1 Transportation Modeling Approaches

The use of transportation analysis tools enables a decision-maker to better understand the impact a 

proposed alternative will have on the transportation network. The categorization of transportation 

modeling approaches found in TAT Volume VIII and Volume IX is based upon the FHWA Traffic 

Analysis Toolbox (2). The FHWA TAT organizes the available tools into six categories: SketchPlanning and Analytical/Deterministic Tools (HCM-Based), Travel Demand Models, Traffic Signal 

Optimization, Macroscopic Simulation, Mesoscopic Simulation, and Microscopic Simulation. A 

brief description of each category is provided here:

	Sketch-Planning/HCM—Specialized tools utilizing traffic count data and capacity analyses 

to predict transportation systems impact.

	Travel Demand Models—Mathematical models that forecast future regional travel demand 

based on current conditions, and future projections of household and employment centers.

	Traffic Signal Optimization—Optimization tools used to develop signal timing plans for 

isolated signal intersections, signalized arterial corridors, and signal networks.

	Macroscopic Simulation—Models based on deterministic relationships of the flow, speed, 

and density of the traffic stream. Macroscopic model simulations assess traffic conditions 

on a section-by-section basis rather than by tracking individual vehicles and treat traffic 

flows as an aggregated quantity; they do not model the movement of individual vehicles on 

a network.

	Mesoscopic Simulation—Intermediate approaches tailored for larger networks associated 

with Macroscopic and Travel Demand Models but preserving some aspects of the detail of 

Microscopic Simulation. Mesoscopic models estimate congestion effects based on the flow 

of vehicles across a link over time, but typically do not represent individual lanes on the link.
3

	Microscopic Simulation—These tools simulate the movement of individual vehicles 

based on car-following and lane-changing algorithms and other parameters associated 

with individual driver behavior. Microscopic Simulation models update the position of 

individual vehicles every second (or fraction of a second) as they move through a network 

by lane for every link the vehicle traverses.

TAT Volume VIII includes a detailed discussion of the various transportation modeling approaches 

available to analysts in order to analyze work zone impacts (1). In Figure 1, these transportation 

modeling approaches are placed on a continuum from simple to complex. Above the continuum 

are specific examples of transportation analysis tools that have been used to conduct a work zone 

analysis (these examples do not represent all of the product choices). Simpler tools include the 

categories of HCM and sketch-planning while the more complex tools include macro, meso, 

and microscopic simulation software. The spectrum includes seven examples of commonly-used 

transportation analysis tools used to assess the impacts of roadway construction projects. A wider 

range of transportation analysis tools across the spectrum are described in more detail on the TAT 

website (2). 

Figure 1 Work Zone Modeling 

It is important to clarify some terminology used throughout the document. First, a transportation 

modeling approach is defined as one of the six model classifications identified in the work zone 

modeling spectrum (sketch planning/HCM through microscopic). Second, a transportation 

analysis tool is a specific computer program that is classified as one of the transportation modeling 

approaches. These tools are either freely available for download and use or through a commercial 

vendor. Finally, a work zone analysis is the process of an analyst using a transportation analysis 

tool to generate results for use by decision makers.

Which transportation modeling approach is best suited to a particular work zone analysis? This 

document is intended to be a guide to assist analysts with answering this question, carefully 

considering the many factors associated with a specific transportation modeling approach or 

analysis tool. These factors include work zone characteristics, transportation management plan 

Sketch-planning Travel Demand

Simple

Complex

Meso Micro

Limited

Rough Estimation

Shorter

Limited

Lower

Comprehensive

Precise Representation

Longer

Required

Higher

LEVEL OF DETAIL

FUNCTIONALITY

TRAINING

COST

DEVELOPMENT TIME

Signal Optimization Macro

Dynasmart

SYNCHRO CORSIM

QuickZone

EMME/2

Highway

Capacity Manual

HCS 2000
4

strategies, available data archives, agency resources and modeling capabilities, and work zone 

performance measures. Choosing a transportation modeling approach is generally a tradeoff 

among these five categories of factors. However, the key to successful work zone analysis does 

not begin or end with just transportation modeling approach selection, but rather in the successful 

integration of data and tools to provide a meaningful assessment of work zone impacts relevant to 

one or more key project decisions. 

In essence, the sophistication of the analysis needs to be matched to the complexity of the project. 

For example, developing a microscopic simulation model would probably be “overkill” for a 

simple bridge replacement project on a minor rural highway. Similarly, a sketch planning tool 

alone would probably be insufficient for a comprehensive analysis of the impacts of a high-volume 

urban freeway-to-freeway interchange replacement project.

1.2 Work Zone Analysis Decision Making

Figure 2 shows how the work zone decision making process, which consists of Planning, PE/

Design and Construction, was developed based upon the FHWA publication Work Zone Impacts 

Assessment: An Approach to Assess and Manage Work Zone Safety and Mobility Impacts of Road 

Projects. 

Figure 2 Work Zone Decision-Making Process

While the decision-making process is important and transportation analysis tools have a potential 

role in all three stages of the project life-cycle, more important to the discussion at hand are the 

types of decisions that need to be made. These decisions are represented by three inter-related 

decision types that drive the overall work zone decision-making process as a three-part work 

zone decision-making engine (Figure 3). The decision-making engine concept is represented 

by three decision areas including Scheduling (circle on top denoted with an “S”); Application

(circle on the bottom left with an “A”); and Transportation Management Plan (circle on the 

right with “TMP”). Adjacent to each circle is a smaller circle used to indicate a relative level of 

finality regarding the decisions within each category. For example, in Figure 3, all of the decisions 

regarding the Application have been made indicating there is little, if any, room to make adjustments 

Planning

PE/Design

Construction
5

or refine those decisions. In contrast, the decision regarding TMP is shown approximately 25 

percent complete indicating that many of these decisions have not yet been finalized, implying 

considerable flexibility potentially remaining in this area. 

 

Figure 3 Work Zone Decision-Making Engine

All of the three circles are connected indicating each decision type does not operate in isolation but 

is influenced by decisions made in other areas. Thus, a decision made about the application (e.g., 

cast-in-place concrete) may dictate the scheduling of the work (e.g., to work in warmer-weather 

months) which in turn impacts the transportation management plan that could be implemented. In 

summary, the decision-making engine shown in Figure 3 conveys four key pieces of information:

1. The decision making process is dynamic. 

2. Decisions made in one category (scheduling, application, or traffic management) impacts 

decisions in other categories. 

3. Decisions made in earlier stages of the project life-cycle will have an impact in later stages. 

4. Once momentum is gained early in the planning process it becomes more difficult to deviate 

from that course of action later in the process.

1.3 Case Studies

A critical component for TAT Volume IX is the inclusion of case studies to demonstrate how 

different transportation agencies have applied transportation analysis tools for the purpose of 

work zone impacts assessment. The case studies appear in various elements of the document with 

varying levels of detail in their description. First, a brief summary of the case studies is provided 

in this section. Second, the case studies are used as specific examples throughout the document to 

S

A TMP

S = Scheduling

Legend

= Application

= Transportation Management Plan

= Level of completion

= Momentum

TMP

A
6

highlight various aspects of the factors that go into developing a modeling approach (Section 2.0) 

or the process that a transportation agency has established to guide analysts in selecting a modeling 

approach (Section 3.0). Third, a summary of each case study is provided in the Case Studies 

section with references to additional reports and contacts for each case study.

A total of 17 case studies have been included in this volume (13 project applications and 4 strategic 

modeling approaches) and are shown in Figure 4 below. The 17 case studies have been categorized 

as either Project Applications or Strategic Modeling Approaches and are indicated by the diamond 

and fill, respectively, in the figure. The case studies that are included in this document were selected 

based upon access to the analysts and/or decision makers, availability of reports and data regarding 

the work zone application, geographic diversity, and project application (uniqueness). A summary 

of the categories and brief description are provided following the figure.

Figure 4 Case Study Locations

Project Applications—Project applications are specific examples of work zones associated with 

roadway construction projects that have used a transportation analysis tool to conduct a work zone 

analysis as part of the overall decision-making process. 

1. Caltrans I-15 Pavement Reconstruction Project (CA I-15)—Application of an HCM-based 

constructability tool and mesoscopic simulation model during the design stage to address 

construction staging and mobility impacts.

2. Glacier National Park: Going to the Sun Road Rehabilitation Project (GNP)—Application 

of a sketch-planning tool in the planning stage to help assess scheduling and constructability 

issues surrounding a high-profile, multi-year construction project. 

Project Applications

Legend

Strategic Modeling

Approaches
7

3. Michigan DOT: Ambassador Gateway Bridge MOTSIM (MI AMB)—Application of a 

microscopic simulation model during the final stages of design and beginning of construction 

in order to address maintenance of traffic issues. 

4. Michigan DOT: I-94 Rehab MOTSIM (MI I-94)—Leveraged the Ambassador Gateway 

Bridge microscopic simulation model (see above) as part of the initial design stage in order 

to address constructability, staging, and maintenance of traffic. 

5. Michigan DOT: I-75 Trade Corridor MOTSIM (MI I-75)—Leveraged and built upon 

the overall process developed as part of the Ambassador Gateway Bridge microscopic 

simulation model (see above) to address mobility, constructability, and staging from the 

planning stage forward. 

6. Nova Scotia, Canada: Reeves Street (NS-Reeves)—Application of a sketch planning tool 

for a simple work zone which includes a detour route.

7. Utah DOT I-15 Reconstruction Design-Build Evaluation (UT I-15)—Use of a travel 

demand model to determine the impact of selecting an innovative contracting technique 

(design-build) in terms of mobility, cost effectiveness, and safety. 

8. Wisconsin DOT Work Zone Signal Optimization—Two examples of work zone signal 

optimization applications for work zones including a hypothetical case study used for 

training and a real-world application involving the Daniel Webster Hoan Memorial Bridge. 

9. Woodrow Wilson Bridge Reconstruction: Lane Closure Analysis (WWB-LCA)—Application 

of an HCM-based tool to address contractor requests for additional lane closures during the 

construction stage.

10. Woodrow Wilson Bridge Reconstruction: Roadway Operations Analysis (WWB-ROA)—

Application of a microscopic simulation tool during the construction stage to determine the 

optimal design of a traffic switch connecting old roadways to new alignments. 

11. Woodrow Wilson Bridge Reconstruction: Roadway Closure Analysis (WWB-RCA)—

Application of a sketch-planning tool during the construction stage to determine impact of 

significant lane closures and full closures for extended weekend work.

12. Yosemite National Park: Yosemite Village Roadway Reconstruction (YOS)—Application 

of a sketch-planning tool during the design stage to determine work zone staging and 

constructability.

13. Zion National Park: Entrance Booth Reconstruction (ZION)—Application of a sketchplanning tool during the design stage to determine construction scheduling.

Strategic Modeling Approaches—Strategic modeling approaches are examples of agencies setting 

up a systematic process to facilitate rapid assessment of work zone impacts and to ensure best 

practices when more complex modeling approaches are warranted.

1. Maryland SHA Lane Closure Analysis Program (MD-LCAP)—The Maryland State 

Highway Administration developed the Lane Closure Analysis Program (LCAP) to support 

state traffic engineers with a structured method to analyze work zone impacts.

2. Michigan DOT: Southeastern Michigan Simulation Network (MDOT-SEMSIN)—Michigan 

DOT has developed a relatively complex microscopic simulation network and analysis 

process whereby decision-makers can leverage previous analyses for current work.

3. New Jersey Turnpike Authority: Lane Closure Application (NJTA-LCA)—The New Jersey 

Turnpike Authority established an approach whereby a simple GIS-based tool was developed 
8

to assist personnel in determining optimal timing of routine roadway maintenance work for 

the simplest of work zones. 

4. Wisconsin DOT: Transportation Management Plan Development Process (WisDOT)—The 

Wisconsin DOT has established a formal Transportation Management Plan Development 

Process which includes a decision-tree on recommended tools to use based upon certain 

work zone characteristics. In addition, for the most high-profile work zones requiring 

detailed microscopic simulation analysis, they have also established a review process to 

ensure the proper use of these complex tools.

1.4 Document Organization

TAT Volume IX is structured around three broad categories of decisions associated with selecting 

and using a transportation modeling approach for better understanding work zone impacts on 

roadway construction projects: factors associated with conducting a work zone analysis; various 

strategic methodologies in addressing work zone analyses; and how to ultimately identify and 

develop a comprehensive transportation modeling approach for work zone analysis. Each of these 

three categories builds upon each other taking the reader from very detailed and finite elements 

associated with work zone analysis in general (do I have enough data or financial resources?) 

through the general concerns and questions that need to be addressed when ultimately deploying 

the transportation modeling approach. 

The organization of the document reflects these three broad categories of considerations and is 

organized as follows:

	Section 2.0 Work Zone Analysis Factors—Provides a detailed discussion regarding 

five categories of work zone analysis factors that should be considered when deciding 

whether or not to conduct a work zone analysis and those data elements necessary to 

successfully conduct a work zone analysis. Section 2.0 includes a number of tables that 

provide a summary of the transportation modeling approach best suited based upon the 

factor being discussed. The summary tables are based upon the suitability classification 

system developed in TAT Volume I and are slightly modified as needed for each of the work 

zone analysis factors being discussed (2). 

	Section 3.0 Establishing a Strategic Methodology for Work Zone Analysis—Presents 

three strategic methodologies to systematically incorporate transportation modeling into 

the overall work zone decision-making process.

	Section 4.0 Identifying a Transportation Modeling Approach for Work ZoneAnalysis—

Provides a framework and process that can be used to select an overall transportation 

modeling approach appropriate for the given circumstances. 

	Section 5.0 Summary and Synthesis—Provides a synthesis of the document.
9

2.0 Work Zone Analysis Factors

The ultimate reason for developing and deploying a transportation modeling approach is to help 

make an informed decision regarding the implementation of one or more work zones. These key 

decisions can occur at any stage during the project life cycle including Planning, PE/Design, and 

Construction. For example, during the Construction stage, a contractor may propose a change to 

an approved lane closure plan in order to better utilize available time in the roadway by extending 

the overnight work hours into the morning commute. The analyst employed by the transportation 

agency will need to assess the merits of the proposed change and consider how to develop a 

feasible analytical assessment strategy by answering a number of questions related to the work 

zone1. First, how complex is the work zone area to be modeled? Is it an isolated element or part 

of a larger network? Second, what type of data is available to conduct an assessment such as 

traffic volumes? How will the proposed changes affect the transportation management plan? What 

resources are available to the analyst including staff resources, model and data availability, as 

well as the time available to actually conduct the analysis? Finally, what is the critical measure of 

system performance that will characterize mobility impacts of the proposed change: vehicle queue 

extent, vehicle delay, cumulative travel time? All of these considerations create constraints or 

opportunities for developing an effective analytical approach.

This example highlights an important issue for many transportation agencies. If the agency has 

already developed a robust analytical capability regarding a particular work zone, analyzing 

the contractor’s proposal is relatively straight forward (plug the new alternative into an existing 

model). Conversely, an agency that needs to respond to the contractor’s proposal quickly may not 

be readily able to conduct an analysis given the analytical capability does not exist and a work 

zone model has to be built from scratch. This could result in a rushed analysis that lacks accuracy 

or uses a tool that is too simple to analyze the proposal correctly. Therefore, many transportation 

agencies are beginning to think of work zone analyses in terms of an ongoing process that begins 

during project planning, is refined during preliminary engineering and final design, and is available 

for quick response during construction.

Regardless of project stage, a number of factors will ultimately influence the selection and use of a 

specific transportation analysis tool by an analyst. Figure 5 provides a graphical representation of 

the categories of factors influencing the selection of a work zone analysis approach.

 

1

 The assumption at this point is that a work zone analysis will be conducted. Section 4.1, Deciding to Analyze or 

Not Analyze, provides a detailed discussion related to the opportunities and risks associated with conducting a work 

zone analysis. 
10

Figure 5 Work Zone Analysis Factors

	Work Zone Characteristics—Facility type, network form, and geographical scale of the 

potential work zone impact area.

	Transportation Management Plan Strategies—Temporary traffic control strategies, 

public information campaigns, and transportation operations.

	Data—Availability of data types (roadway characteristics, travel demand) as well as 

sources and quality of the data. 

	Agency Resources—Institutional arrangements as well as the technical capability of the 

agency including modeling experience, model availability, and funding.

	Work Zone Performance Measures—The critical metrics used to differentiate alternatives 

and characterize impacts (e.g., maximum queue or additional travel time) as well as the 

precision of the results..

All of these factors have to be evaluated in order to select an appropriate work zone analysis 

approach. As represented by the black dotted lines, one category of factors may influence other 

categories. Thus, agency resources (in terms of budget constraints) may limit the quality and 

amount of data available which may affect the selection of a transportation modeling approach. 

What is important to note is that the connection between the work zone analysis approach and 

TMP is bidirectional indicating a work zone analysis approach is influenced by the TMP as well 

as influencing development of the TMP. The TMP cannot be treated as simply another factor in 

Agency

Resources

Work Zone

Characteristics

Data TMP

Performance

Measures

Work Zone

Analysis

Approach
11

deciding which work zone analysis approach to select, but also to help guide the analyst in the 

selection of a work zone analysis approach as well.

The following five subsections will discuss each of these categories in more detail by providing 

a definition of the various terms and concepts, what is meant by each, and providing case study 

examples of how analysts have successfully addressed these factors in a work zone assessment. 

2.1 Work Zone Characteristics

These sub-sections discuss how the physical attributes of the work zone itself, including the type 

of work zone, network form, and the geographic scale of the work zone impact area, shape and 

influence the modeling approach to be used. 

2.1.1 Type

The first work zone characteristics is the work zone type which is an indication of the expected 

level of impact a work zone will have on travelers. FHWA provides example definitions in the 

report FHWA Work Zone Self Assessment Guide (3). TAT Volume IX uses the work zone types 

as defined in the Work Zone Self Assessment Guide which categorizes work zones as being one 

of four types based upon the magnitude of expected impact. The most severe work zone is a 

Type I work zone which have the most impact on the traveling public and usually occur over a 

long duration. Examples include the Springfield Interchange “Mixing Bowl” project in Northern 

Virginia and the Big Dig in Boston. A Type IV work zone will have little disruption on traffic flow 

as well as a short duration. Minor maintenance operations such as guardrail repair, sign repair, and 

mowing are typical Type I

Work zone type is often a strong indicator of the level of resources available to conduct a work 

zone analysis. The physical characteristics of the highway network may have a strong influence 

on the impacts caused by the project. For example, rural highways in sparsely populated areas 

may lack good alternate routes. In addition, the perceived impacts of a highway project may vary 

depending on local expectations about what is an acceptable level of congestion. For example, 

residents of a major metropolitan area may be more accustomed to driving in congested conditions 

than residents of a small town. Thus, selecting a transportation modeling approach for work zone 

analysis should not be based solely upon the work zone type but rather augmenting that decision 

with a consideration of the complete range of factors addressed in this document.

Type I—Type I work zones affect the traveling public at the metropolitan, regional, intra- and 

interstate levels over lengthy periods of time. They attract significant public interest, impact large 

numbers of road users, and are deployed at significant cost. The consideration of Type I work zones 

often includes quantitative analysis of work zone impacts for both internal agency use and shaping 

public expectation. In many cases, an impact assessment for these major projects is required 

by agency policy. The transportation modeling approach developed is tailored to the needs of 

the agency and resources available to perform the analysis. Analytical tool categories deployed 

to support Type I work zones include the full range of tools from sketch-planning and HCM 

methodologies to microscopic simulation. However, the tools are used quite differently depending 

on the decisions being supported. Type I projects typically cause both localized and area-wide 

impacts on travel demand and traffic. Often a Type I work zone will employ various work zone 

analysis tools including a regional travel demand model to estimate region-wide travel impacts, 
12

and then use a sketch planning tool to determine traffic impacts on individual highway segments. 

Given the complex nature of these work zone types, it is important that the agency identify its 

goals and objectives, needs, and available resources to identify the specific tool or tools that will 

provide the agency with the outcomes it desires. These projects have the largest potential impact 

and generally have more substantial resources allocated to the assessment of predicted work zone 

impacts. Examples of Type I work zones include:

	Woodrow Wilson Bridge in Maryland/Virginia/District of Columbia 

	Central Artery/Tunnel in Boston, Massachusetts 

	Springfield Interchange “Mixing Bowl” in Springfield, Virginia 

	I-15 reconstruction in Salt Lake City, Utah.

Woodrow Wilson Bridge Replacement

The replacement of the Woodrow Wilson Bridge, along Interstate 95 in the Metropolitan 

Washington, DC area, is an extremely large and complex construction project requiring 

the close coordination of numerous contractors and various state and local government 

agencies. The Woodrow Wilson Bridge carries upwards of 100,000 vehicles per day 

along Interstate 95 which spans the Potomac River. The Woodrow Wilson Bridge 

Project spans a 7.5 mile-long corridor extending from the MD 210 interchange in 

Maryland to Telegraph Road in Virginia, crossing over the Potomac River. The current 

6-lane bridge is being replaced with a dual-span bridge that will more than double the 

number of traffic lanes. 

This project is categorized as the most severe work zone—Type I. This project 

directly impacted several miles of major roads and interchanges in two states including 

I-95/I-495 (Capital Beltway) from Maryland to Virginia, I-295, MD 414, and MD210 in Maryland, and Telegraph Road, Route 1, and Washington Street in Virginia. 

To keep traffic moving throughout the multi-year project, the construction work for 

the Woodrow Wilson Bridge project had to be completed in individual phases instead 

of one large permanent work zone. Work zone plans had to be developed for each 

phase of this construction project. The WWB project used a number of different 

modeling approaches to understand work zone impacts ranging from the simplest HCM 

methodologies to microscopic simulation primarily during the construction stage. More 

information can be found in the Woodrow Wilson Bridge Reconstruction case study.

Type II—Type II work zones impact travelers at the regional and metropolitan levels. They 

directly impact a range of road users and can attract significant public interest. The cost impacts 

are usually moderate to high and the work zones will usually be set up for a long period of time. 

Analysts considering Type II work zones will benefit from a quantitative analysis to evaluate 

impacts to the public. Often, this analysis is required by the agency. Similar to Type I, the full 

range of transportation modeling approaches are well suited for Type II work zones. This is not 

to suggest that any of the tools identified here are appropriate for a specific work zone project 
13

application. Rather, it is important to identify an appropriate role for a work zone analysis tool 

based upon the many opportunities and constraints available to the analyst. In some cases, the use 

of a specific transportation analysis tool will be required by agency policy. Examples of Type II 

work zones include:

	Major corridor reconstruction 

	High-impact interchange improvements 

	Full closures on high-volume facilities 

	Major bridge repair 

	Repaving projects that require long term lane closures

CALTRANS I-15 Rehabilitation

The existing four mile section of I-15 in Ontario, California consists of four to six lanes 

in each direction and carries an AADT of approximately 200,000, with a particularly 

high percentage of heavy truck traffic (about 12 percent on average on weekdays). 

In addition, the corridor has consistently high weekday commuter peaks and similar 

volumes on weekends due to leisure travelers from Los Angeles headed to and from Las 

Vegas and resort locations along the Colorado River. The reconstruction will rebuild 

two to three truck lanes in each direction. 

This construction project exhibits the characteristics of a Type II work zone because of 

the consistently high volumes and heavy truck traffic and the work zone impacts are 

moderate. Caltrans employed the use of three traffic modeling tools: a sketch-planning 

tool, an HCM model, and a mesoscopic traffic network analysis tool. The sketchplanning analysis and HCM analysis were used to analyze alternative construction 

scenarios and the mesoscopic analysis tool was used to assist in the development of 

the transportation management plan and to provide supplemental construction staging 

analysis. More information can be found in the Caltrans I-15 Pavement Reconstruction 

Project case study.

Type III—Type III work zones have a low to moderate level of public interest. They can affect 

travelers at the metropolitan or regional level, but travelers are usually affected at a low to moderate 

level. The cost impacts will be less and the duration of the work zone will not be lengthy. The work 

zone may include lane closures, but these are implemented for only short periods of time. While 

the full spectrum of modeling approaches can be applied to Type III work zones, agency resources 

are frequently limited in nature when considering these types of projects. Thus, the opportunity to 

set up and use more complex tools such as microscopic and mesoscopic simulation tools may be 

limited because of resource constraints. A region may have a number of Type III work zones in the 

pipeline ready for planning, design, and construction. In this case, the use of simplified screening 

approaches (such as sketch planning and HCM tools) that can rapidly and cost-effectively analyze 

numerous different variations may be appropriate to determine those work zones requiring further 

and more detailed analysis. Examples of Type III work zones include:
14

	Repaving work on roadways and the National Highway System (NHS) with moderate 

Average Daily Traffic (ADT) 

	Minor bridge repair 

	Shoulder repair and construction 

	Minor interchange repairs

Zion National Park

Zion National Park is an example of a Type III work zone. The repaving of the entrance 

booth area was of moderate public interest, primarily related to those businesses in the 

town of Springdale who would be impacted by any significant queuing caused by the 

temporary closure of entrance lanes. The National Park Service decided to use a sketchplanning tool during the final aspects of design to specifically address the scheduling 

of the work zone and determine whether or not it was justified to shift construction to 

night work. More information is available in the Zion National Park: Entrance Booth 

Reconstruction case study.

Type IV—Type IV work zones are expected to have little impact, if any, on the traveling public. 

They attract little public interest and work zone duration is short to moderate. It is sometimes 

difficult to provide information to travelers for these types of projects because they will usually be 

out of the roadway or off the shoulder before the message is relayed to the travelers. These types 

of work zones are usually mobile. While the full spectrum of transportation modeling approaches 

can be used to analyze a Type IV work zone, in all likelihood, many Type IV work zone projects 

may be effectively assessed either by a simple transportation modeling approach (e.g., sketch 

planning or HCM methodology) or the expert knowledge internalized by operations managers 

after years of experience. However, developing a strategic methodology to analyzing these types 

of work zones may be useful to ensure any roadwork does not unintentionally impact mobility. In 

this situation, it may be most cost-effective to establish an agency-wide program to assist personnel 

in quickly screening these types of work zones rapidly and effectively. Examples of Type IV work 

zones include:

	Certain low-impact striping work 

	Guardrail repair 

	Minor shoulder repair 

	Pothole patching 

	Very minor joint sealing 

	Minor bridge painting 

	Sign repair 

	Mowing
15

New Jersey Turnpike Authority: Lane Closure Application

The New Jersey Turnpike Authority developed a GIS-based Lane Closure Application 

designed specifically to quantify the impacts associated with Type IV work zones, 

typically routine maintenance work that includes shoulder work or short-duration lane 

closures such as roadway sign or maintenance. A more detailed discussion of the tool is 

available in the New Jersey Turnpike Authority: Lane Closure Application case study.
16

2.1.2 Network Form

The second work zone factor that must be accounted for when deciding to use a work zone analysis 

tool is network form (also commonly referred to as network configuration or network structure). 

In a sense, network form is a surrogate for the overall complexity of the roadway where the work 

zone impacts will be evaluated and which are not accounted for within the FHWA work zone types. 

For work zone analysis, network form is composed of three general categories: isolated, pipe, and 

grid.

Isolated—An isolated network form consists of a single work zone that has limited interaction 

with the surrounding infrastructure and facilities. Because of the limited interaction, the work 

zone may only have periodic impact on the immediate surroundings depending on the size and 

duration of the construction project and the traffic demand for the facility. Examples of isolated 

networks include some bridge deck replacement projects, rural lane closures, or a redesigned 

interchange. Figure 6 provides a visual representation of two isolated work zones in the fictitious 

Hillsboro County. In the figure are two circles representing two work zones that are isolated from 

other roadway infrastructure as well as each other.

Figure 6 Isolated Network Form

Pipe—A pipe network form (sometimes referred to as a corridor network form) consists of a 

roadway segment with two or more work zones interacting with each other and includes some 

limited access points and connections with other roadway segments (such as interstate entrance 

ramps). However, these work zones typically do not include any type of viable alternate or detour 

route. An example of a pipe network form would be a long interstate corridor reconstruction 

outside an urban area. Figure 7 provides a visual representation of a pipe network form work zone 

in the fictitious Hillsboro County. In the figure are three circles representing three work zones that 

are located close to each other resulting in an interaction among the three.

I-62

Hillsboro County

I-19 I-419
17

Figure 7 Pipe Network Form

Grid—A grid network form is a connected, inter-dependent structure with multiple access points 

and one or more viable alternate routes. Examples of grid network forms include urban interstate 

reconstruction, reconstruction involving full roadway closures, signalized arterial roadway 

reconstruction, and work zones located in urban centers. Figure 8 provides a visual representation 

of two grid network form work zones in the fictitious Hillsboro County. In the figure is one circle 

representing the location of a work zone involving three interstate roadways. Also indicated by the 

arrow is the downtown CBD. 

Figure 8 Grid Network Form

I-62

Hillsboro County

I-19 I-419

I-62

Hillsboro County

I-19 I-419
18

The network form will have an impact on the effectiveness of various transportation modeling 

approaches. Work zones with impacts limited to a single mainline facility (e.g., isolated network 

form) are generally easier to model than more complex work zones with impact across a broader 

network of parallel facilities and cross-streets (e.g. grid network form). Many of the tools on 

the simpler end of the work zone modeling spectrum (e.g., HCM tools, or sketch-planning tools) 

assume that traffic demand follows a simple in/out pattern through the work zone. For isolated 

and pipe network forms, such an assumption is often reasonable. Sketch-planning tools have often 

been selected to analyze isolated work zones and there are numerous case study examples included 

in this document. A sketch-planning tool is often deemed a cost-effective approach in these cases, 

particularly if limited demand and capacity data are available. 

The incorporation of detour and alternate routes (a major characteristic of grid network forms) 

limit which modeling approaches can be used. Many of the macroscopic simulation models do not 

have the ability to account for detour and alternate routes. Thus, if a detour route is required it is 

important the model selected has the functionality to account for traffic volume diverted to other 

facilities in the network because certain classes of vehicles are not permitted in the work zone or 

because road users are attempting to avoid delays from one or more work zones.

When work zone impacts create significant changes to an overall network traffic pattern (through 

diversion or other changes to routes normally taken in the network) a more detailed modeling 

approach must be considered. Often, an origin-destination pattern must be estimated. These 

potentially time-varying demand patterns are then input into a separate simulation model (typically 

microscopic or mesoscopic) to more realistically capture diversion effects. In very congested 

networks or networks with frequent fluctuations in demand or work zone capacity, the use of a 

dynamic traffic assignment (DTA) modeling component may be necessary. DTA can effectively 

account for the re-routing of traffic based upon rapidly changing conditions such as intermittent 

lane closures or congestion on detour routes. However, DTA functionality is only found on the 

more complex end of the work zone modeling spectrum with mesoscopic and microscopic models 

and adds considerably to the level of effort required for the study. More information on DTA can 

be found at http://ops.fhwa.dot.gov/trafficanalysistools/dta.htm.
19

2.1.3 Geographic Scale

The third factor under work zone characteristics is the geographic scale of the work zone. 

Geographical scale refers to the size of the area impacted by the work zone. Simpler projects 

typically have a relatively small geographical scale. For example, a bridge replacement on a rural

highway might affect only the road where the bridge is located and one or two nearby routes. At 

the other extreme, complex projects may influence the traffic patterns in a very large area. For 

example, the effects of a freeway-to-freeway interchange replacement project might extend all the 

way to the next freeway-to-freeway interchange.

Work Zone Size—The work zone size encompasses the physical construction zone and the 

immediate area near the work zone that will be affected by the implementation. These sizes refer 

to the physical size of the work zone and may or may not be related to the type of work zone. For 

example, a large construction project does not necessarily have to be a Type I work zone. The 

construction project may cover a large geographic area, but not impact a large number of travelers 

or be set up for a long duration. Work zones are divided into three sizes, small, medium and large.

	Small—A work zone implemented on a short segment of an individual roadway or a single 

intersection.

	Medium—One or more work zones on longer stretches of a single facility and/or portions 

of adjacent facilities.

	Large—Interacting work zones implemented on significant elements of a larger roadway 

network.

The size of the work zone will be directly related to the type of analysis that needs to be 

performed. In general, simpler tools can be used successfully for projects with small 

geographical scope, while more complex tools are necessary if the analysis extends over a large 

area. If the analysis area is quite large, meoscopic or microscopic traffic models are typically 

used. It is important to understand that as the geographical scale increases, so does the level of 

time, effort and skill required to calibrate the model to match real-world conditions. In resourceconstrained cases, transportation modeling approaches may need to be limited to sketch-planning 

tools, HCM methodologies, or traffic signal optimization tools (if warranted). In other cases, a 

combination of tools can be used together to offset issues of scale and complexity. There is also 

the possibility of separating larger work zones into smaller ones, thus focusing resources on more 

critical elements of the overall work zone. In these situations, the analyst will have to be diligent 

about accounting for individual work zone impacts in a cumulative manner.
20

CALTRANS I-15 Rehabilitation Project

An existing four mile section of I-15 in Ontario, California consists of four to six lanes 

in each direction and planned reconstruction will rebuild two to three truck lanes in each 

direction. This project exhibits the characteristics of a medium size work zone because it 

consists of a corridor that covers four miles of existing interstate and the work zone area 

encompasses three parallel routes to the east and west of the corridor. This medium sized 

project was analyzed using sketch-planning, HCM, and mesoscopic simulation models. 

The mesoscopic model analyzed a variety of detour routes. More information can be 

found in the Caltrans I-15 Pavement Reconstruction Project case study.

Analysis Area Dimension—The analysis area dimension identifies the full area impacted by the 

work zone. In many cases, the impact of the project will extend beyond the limits of the work 

zone itself. This may seem self-evident to some analysts, but all too often it is overlooked when 

establishing the scope and budget for the work zone analysis, and selecting a methodology that 

matches the requirements of the project. For example, the construction project might encompass 

one or two large interchanges along an interstate corridor, but the impact of that project may extend 

to a larger area depending on traffic demand, lane and ramp closures, and detours and alternate 

routes. There are transportation modeling approaches that can evaluate each of these types of areas 

depending on the requirements of the agency. The analysis area dimension is divided into three 

categories: site, local, and metropolitan. 

	Site—Restricted to the immediate area surrounding the work zone.

	Local—Includes surrounding area beyond the work zone to account for detour routes or 

other localized impacts.

	Metropolitan—Includes multiple jurisdictions (counties, cities, etc.) or facilities. 

Michigan DOT: I-75 Trade Corridor MOTSIM

Michigan DOT is developing analytical capabilities to conduct a large-scale analysis of 

the 19-mile segment of I-75 between Detroit and the City of Pontiac. The microscopic 

simulation network will consist of the entire metropolitan area associated with the 19-

mile segment and builds upon previous analyses of adjacent roadways. Currently in 

the planning stage, the project entails widening the road from three to four lanes and 

will enable Michigan DOT to test various scenarios to ensure that mobility is provided 

throughout the work zone, constructability is maintained, and staging is adequate. More 

information can be found in the Michigan DOT: Southeastern Michigan Simulation 

Network case study. 

Table 1 provides a summary of the work zone characteristics as they relate to the project application 

case studies while Table 2 provides a summary of the work zone analysis approaches that have 

been historically used in previous work zone assessments. In most cases involving large or high 

impact projects, sketch planning tools should only be used to augment other tools as part of a 

multi-scale approach. For example, a valid approach would be to use a network-based model 
21

(such as an existing regional travel demand model) to determine the redistribution of traffic in the 

network, and then the HCM method or sketch planning tool would be used to analyze the localized 

impacts on affected links. Sketch planning tools cannot carry out traffic redistribution. Therefore, 

directly applying a sketch planning tool to a complex network carries significant technical risk: 

the tool is likely to over-estimate the congestion in the immediate vicinity of the work zone, and 

under-estimate the impacts of redistributed traffic farther away from the work zone.

Traffic signal timing tools have important applications for projects in urban and suburban areas. 

The signal optimization tool can be used to identify the need for temporary traffic signals and 

to revise the signal timing plans for existing signals where volumes are expected to increase or 

decrease as a result of the construction. As with the sketch planning tools, a network-based analysis 

may be necessary to determine the new traffic pattern resulting from lane closures, link closures, 

or temporarily reduced link capacity. Once the new traffic pattern is developed with the networkbased tool, specific timing plans can be developed to make the best use of the available capacity.

The suitability classification system has the following definition in Table 2: 

	 = Often analyzed by the transportation modeling approach. 

	 = Sometimes analyzed by the transportation modeling approach. 

	 = Rarely analyzed by the transportation modeling approach. 

n/a = No examples of the transportation modeling approach being applied.
22

Case Study Category Modeling Approach Project Life-Cycle 

Stage

Work Zone Characteristics

Type Configuration Size Analysis Area

Dimensions

CA I-15 Application Sketch Planning

Mesoscopic Simulation Planning II Pipe Medium Metropolitan

GNP Application Sketch Planning Planning I Pipe Medium Local

MD-LCAP Approach Sketch Planning All II, III, IV Pipe Small Local

MDOTSEMSN Approach Microscopic All I, II Grid Large Metropolitan

MI AMB Application Microscopic Simulation PE/Design I Grid Medium Metropolitan

MI I-75 Application Microscopic Simulation Planning I Grid Large Metropolitan

MI I-94 Application Microscopic Simulation Planning II Grid Medium Metropolitan

NJTA-LCA Approach HCM Planning, Operations IV Pipe Small Local

NS-Reeves Application Sketch Planning Planning III Isolated Small Local

UT I-15 Application Travel Demand Model PE/Design I Grid Large Metropolitan

Wisconsin Application Traffic Signal 

Optimization Operations III Pipe Medium Local

WisDOT Approach Various Planning III, IV Pipe Small Local

WWB-LCA Application HCM Construction I Pipe Small Site

WWB-RCA Application Sketch Planning Construction I Grid Large Metropolitan

WWB-ROA Application Microscopic Simulation PE/Design I Grid Small Local

YOS Application Sketch Planning Planning II Pipe Medium Local

ZION Application Sketch Planning PE/Design III Isolated Small Local

Table 1 Work Zone Characteristics Case Study Attributes
23

Factors

Work Zone 

Charateristics

Summary

Transportation Modeling Approach

Case Study

SketchPlanning 

and HCM 

Methodologies

Travel 

Demand 

Models

Traffic 

Signal 

Optimization

Macroscopic 

Simulation

Mesoscopic 

Simulation

Microscopic 

Simulation

Type

Type I

Affects a large number of traveler at the regional scale, with high public interest, significant user cost impacts and a long duration.

      GNP, MI AMB, MI I-75, UT I-15

Type II Similar to Type I but moderate impact.       CA I-15, MI I-94, YOS, MD-LCAPType III Similar to Type I but low impact.       NS-Reeves, ZION, Wisconsin, MD-LCAPType IV Short-duration work zone with low visibility and public interest.       NJTA-LCA, MD-LCAP

Network Configuration

Isolated Single work zone with limited interaction of surrounding infrastructure.       NS-Reeves, ZION, Wisconsin, MD-LCAPPipe Roadway segment with multiple, interacting work zones.       CA I-15, GNP, WWB-LCA, YOSGrid Connected, inter-dependent network structure with multiple access points and alternate routes.       MI AMB, MI I-75, MI I-94, UT I-15, WWB-RCA, WWB-ROA

Geographic Scale: Work Zone Size

Small A work zone implemented on a short segment of an individual roadway or a single intersection.       NS-Reeves, WWB-LCA, WWB- ROA, ZION, MD-LCAPMedium One or more work zones on longer stretches of a single facility and/or portions of adjacent facilities.       CA I-15, GNP, MI AMB, MI I-94, YOS, WisconsinLarge Interacting work zones implemented on significant elements of a larger roadway network.       MI I-75, UT I-15, WWB-RCA

Geographic Scale: Analysis Area Dimension

Site Analysis area is restricted to the immediate area surrounding the work zone.       WWB-LCA, Wisconsin, MD-LCAPLocal

Analysis area includes surrounding area beyond the work zone to account for detour routes or other localized impacts.

      GNP, NS-Reeves, , WWB-ROA, YOS, ZION

Metropolitan Analysis area includes multiple jurisdictions (counties, cities, etc.) or facilities.       CA I-15, MI AMB, MI I-75, MI I-94, UT I-15, WWB-RCA

= Often analyzed by the transportation modeling approach. = Sometimes analyzed by the transportation modeling approach. = Rarely analyzed by the transportation modeling approach. n/a = No examples of the transportation modeling approach being applied.

Table 2 Work Zone Characteristics Factors
24

2.2 Transportation Management Plan Strategies2

Transportation Management Plan (TMP) strategies should be considered for all work zones, but the 

amount of effort and resources needed to produce the TMP will depend on the construction project 

and the characteristics of the work zone (4). Smaller maintenance projects may utilize a simple 

TMP whereas a significant project that anticipates considerable traffic impacts requires a more 

detailed TMP. The use of a transportation modeling tool depends primarily upon the elements of 

the TMP. The following sections provide a discussion of the use of transportation modeling tools 

for the three categories of TMP strategies: Temporary Traffic Control, Public Information, and 

Transportation Operations. 

2.2.1 Temporary Traffic Control

The TMP for all projects must contain a temporary traffic control (TTC) plan. TTC strategies 

include conceptual decisions on possible construction approaches, traffic control and management 

approaches, and time of construction. The scope of the TTC plan is dependent on the project 

characteristics and the traffic safety and control requirements required by the agency. The TTC plan 

consists of traffic control/design strategies, traffic control devices, and coordinating/ contracting/

innovation.

Control Strategies—Control strategies include traffic control approaches used to accommodate 

travelers within the work zone area, while providing adequate access to the roadway for the 

required construction work to be performed. The impacts of the work zone on traffic will be 

dependent on the types of control strategies that are established for a project. Control strategies for 

temporary traffic control include those listed below. Those in bold are control strategies that could 

be analyzed using the transportation modeling approaches described in Section 1.1 :

2

 The discussion of Transportation Management Plans is based upon the classification developed by FHWA in the 

report Developing and Implementing Transportation Management Plans for Work Zones available at http://ops.fhwa.

dot.gov/wz/resources/publications/trans_mgmt_plans/index.htm. A detailed discussion of each individual strategy 

discussed in the following sub-sections is available in the FHWA TMP document.
25

	Construction phasing/staging

	Full roadway closures

	Lane shifts or closures

	One-lane, two-way operation

	Two-way traffic on one side of a divided facility

	Reversible lanes

	Ramp closures/relocation

	Freeway-to-freeway interchange closures

	Night work

	Weekend work

	Work hour restrictions for peak travel

	Pedestrian/bicycle access improvements

	Business access improvements

	Off-site detours/use of alternate routes

All of the control strategies can be analyzed using various modeling approaches. The decision 

to use a certain modeling approach is often based upon the stage in the project life-cycle. For 

example, the decision to use a certain construction technique requiring full roadway closure may 

rest upon whether or not the identified detour routes can handle the increased volume. In this case, 

the ability to use certain tools will be constrained by the decision to be made. Often, the use of a 

specific control strategy will be decided early in the decision-making process based upon a specific 

DOT policy either encouraging or disallowing a certain strategy. 

Currently, the most prevalent modeling approaches used by analysts include sketch-planning/

HCM methodologies, mesoscopic simulation, and microscopic simulation tools. The tradeoff 

between these modeling approaches lies within the level of detail required and resources 

available. Microscopic and mesoscopic simulation tools can provide detailed analysis to evaluate 

detailed control strategy alternatives for the work zone. However, the resources and data 

requirements are significant. For example, an analyst may be required to determine allowable 

times for partial lane closures for a significant construction project during the PE/Design stage. 

Overall accuracy may be an important component to the overall cost of the construction project. 

In this case, a detailed modeling tool, such as microscopic simulation, may be warranted to 

provide the detailed analysis. However, time constraints may limit the analysis period to less than 

two weeks thus the use of a sketch-planning tool may be the best option. In the end, the modeling 

tool utilized may be determined in large part by the control strategy(ies) to be assessed and the 

ability of the modeling tool to provide useful results.
26

Michigan DOT: Ambassador Bridge Gateway MOTSIM

MDOT’s Metro Region has a network simulation of an interstate freeway closure for 

the Ambassador Bridge Gateway Project (2008-2009). Mobility plans were developed 

and implemented. A second model was run to incorporate other planned lane closures 

during the summer of 2008, and as expected the combined effects of the multiple 

closures undermined the original mobility plan. A third model for closures during the 

summer of 2009 is planned. However, in neither case were the 2008 and 2009 models 

ready in time to inform the project selection decisions. While these models are useful 

in allowing MDOT to tweak the TMP of the Gateway Project, they would have been 

much more useful if they had been performed in time to influence the project selection 

and the TMPs of the other projects. More information can be found in the Michigan 

DOT: Southeastern Michigan Simulation Network case study.

Traffic Control Devices—Traffic control devices used for temporary traffic control plans need to 

follow Part 6 of the Manual on Uniform Traffic Control Devices (MUTCD). The MUTCD provides 

standards and guidelines for utilizing traffic control devices within a work zone. In addition, other 

information is provided for installing, maintaining, and operating the work zone traffic control 

devices. The traffic control devices are applicable to all types of construction projects from small 

maintenance projects to significant construction projects. Traffic control devices utilized within 

work zones for temporary traffic control include those listed below. Those in bold are traffic 

control devices that have been analyzed using the transportation modeling approaches described 

in Section 1.1:

	Temporary signs

	Changeable message signs

	Arrow panels

	Channelizing devices

	Temporary pavement markings

	Flaggers and uniformed traffic control officers

	Temporary traffic signals

	Lighting devices

Three of the eight traffic control devices can be analyzed using various modeling approaches. 

Signing and marking cannot be analyzed with work zone analysis tools since the tools are based 

upon traffic flow theory. Thus, variables associated with the number of lanes open to traffic, lane 

width, free-flow design speed, percent trucks, etc. can be evaluated. In practical terms, the analyst 

can determine the impacts of using changeable message signs to convey traveler information, 

using flaggers for traffic control, and the use of temporary traffic signals: 

	There are a handful of tools that can analyze the capacity of flagging operations.

	Traffic signal optimization tools are designed to analyze signal timing (permanent or 

temporary).

	There are many generic and specialized tools that can model reductions in the number of 

lanes and/or reduction in the capacity of the individual lanes.
27

Depending on other work zone characteristics, traffic control devices can be analyzed using the 

full spectrum of modeling approaches. Often, the selection of these devices will be made later in 

the project life-cycle, making it more likely that a previous modeling effort has taken place. Thus, 

an analyst may be able to leverage previous efforts. The ultimate decision to use one approach 

over the other will depend upon the resources available and the specific traffic control device to be 

included and whether the modeling approach is able to produce useful results.

Glacier National Park

The Going to the Sun Road in Glacier National Park was slated for an extensive multiyear rehabilitation project over a seven to eight year period. Since the Going to the Sun 

Road is a key reason for visiting Glacier National Park and has no alternative route, the 

roadway must remain open throughout the project to both allow access to facilities and 

serve as a scenic roadway with minimal disruption and delay for park visitors.

The development of the TMP included temporary traffic signals. It is typical practice on 

the Going to the Sun Road to use a fixed timing plan for the control of short work zones 

and to vary the fixed timing plan over the course of the day for longer work zones.

In the Glacier case study, analysts investigated a complete range of control options for 

the temporary traffic signals from the simplest (single fixed plan) to the most complex 

(all actuated) and estimated how likely the 30 minute maximum user delay threshold 

might be exceeded over the life of the rehabilitation project. Base signal timing in this 

case study represents a single fixed plan used in the night and weekend periods when 

flaggers are not present. 

A sketch-planning analysis tool was used to identify projected delays and queue 

length over the course of the project and to assess the likely effects of actuated signal 

control for 2-way, 1-lane operations, as well as the impact of reduced travel demand. 

More information can be found in the Glacier National Park: Going to the Sun Road 

Rehabilitation Project case study.

Coordination/Contracting/Innovation—Project coordination strategies have the potential to 

reduce the mobility and safety impacts of the work zone. Contracting strategies involve agreements 

to reduce project duration and traffic impact. Innovative construction strategies include construction 

techniques that speed up the construction process to complete the project in a shorter period of 

time. Project coordination strategies include coordinating with other projects, utilities and rightof-way coordination, and coordination with other non-highway transportation facilities such as 

railroads and transit. Contracting strategies include design-build contracting, A+B bidding to 

reduce construction time, incentive/disincentive clauses, and lane rental—assessing a fee to the 

contractor for the time the lane is unavailable to traffic. Innovative construction techniques could 

include quick curing concrete or using precast items to minimize traffic restrictions and allow 

roadways to be reopened sooner.
28

Traffic impact analysis as it relates to coordination, contracting, and innovative construction 

strategies is more difficult to directly model using any of the transportation modeling approaches. 

If the agency has identified several projects that should be coordinated due to the potential of 

network-wide effects, then using a microscopic or mesoscopic simulation tool that can model all the 

projects would be a useful task to determine the traffic impacts overall. The analysis could possibly 

identify collaboration among projects that could be beneficial for the agency. Both contracting 

strategies and innovative construction strategies that result in shorter construction periods should 

be modeled to identify the most efficient approaches. There are some travel demand models and 

macroscopic models that might provide outcomes that would satisfy the agency’s requirements to 

identify the impact of the work zone that may not be as resource intensive.

An important component to coordination, contracting and innovative construction strategies is the 

incorporation of road user costs. There are three main categories of road user costs: delay (extra 

travel time caused by the construction), vehicle operating costs (extra fuel consumed by detouring 

to a longer route) and safety (increased risk of crashes caused by detouring onto a road built to 

lower standards). By computing the road user costs associated with each alternative, it becomes 

straightforward to do a trade-off analysis. For example, one might find that building a project using 

the “standard” construction method has a direct cost to the agency of $1 million and creates $3 

million of indirect costs to road users. However, the “quick” construction method has a direct cost 

of $1.2 million and reduces the impact on road users to $2 million. In that case, one could say that 

spending an extra $200,000 of the agency’s money results in $1 million of savings to road users, 

a 5:1 benefit/cost ratio.

CALTRANS I-15 Rehabilitation Project

The existing four mile section of I-15 in Ontario, California consists of four to six lanes 

in each direction and the reconstruction will rebuild two to three truck lanes in each 

direction. The project analysis was divided into two phases. 

	 Phase I used an innovative sketch-planning tool to evaluate a number of “what 

if” scenarios to identify solutions to balance schedule production, traffic 

inconvenience, and agency costs. This tool could also be easily integrated with 

other traffic simulation tools to quantify road user costs during construction. 

	 During Phase II, a mesoscopic simulation analysis was performed on the 

network to assist in the development of the TMP.

Caltrans used a variety of analysis tools to address different construction strategies 

and was able to use the results from these tools to help prepare an overall cost estimate 

analysis. More information can be found in the Caltrans I-15 Pavement Reconstruction 

Project case study.
29

2.2.2 Public Information

Many construction projects, especially those that will result in significant impact to the traveling 

public will benefit from including a public information component in the Transportation 

Management Plan. For significant projects, public information is a required component of a 

TMP. Providing specific information to the public that alerts them to potential impacts due to 

construction and associated work zones can help drivers make informed choices on when to travel 

to avoid construction or delays associated with construction or when to take alternate routes 

to avoid construction altogether. Keeping the public informed throughout the duration of the 

project will help an agency identify potential impacts and ensure effective mitigation strategies are 

implemented. Agencies should coordinate with their public information office in the early stages 

of project development. Public information strategies include both public awareness and motorist 

information strategies.

Woodrow Wilson Bridge Replacement

The replacement of the Woodrow Wilson Bridge (WWB), along Interstate 95 in the 

Metropolitan Washington, DC area, is an extremely large and complex construction 

project. The current 6-lane bridge is being replaced with a dual-span bridge that will 

more than double the number of traffic lanes. The WWB team relied upon an extensive 

public information campaign that included both public awareness strategies and 

motorist information strategies, to inform users of the bridge about planned, upcoming, 

and on-going construction activities

As part of their effort to inform users, WWB personnel employed the use of sketchplanning tools to estimate potential queuing and delay associated with several highprofile and extended weekend roadway closures. The results of the sketch planning tool 

(after initially being verified with smaller lane closure events) were disseminated to the 

public via various media sources and were designed to encourage travelers to avoid the 

area during the certain periods. More information can be found in the Woodrow Wilson 

Bridge Reconstruction case study.

Public Awareness Strategies—Public awareness strategies include different methods to educate 

and reach out to the public and the community pertaining to upcoming construction projects 

and related work zones. The agency should develop strategies that can continually be updated 

throughout the duration of the project. There are many strategies available to provide public 

awareness which include the following:

	Brochures and mailers

	Press releases and media alerts

	Paid advertisements

	Public information center

	Telephone hotline

	Planned lane closure Web site

	Project Web site

	Public meetings and hearings

	Community task forces

	Coordination with media/schools/

businesses/emergency services

	Work zone education and safety campaigns
30

	Work zone safety highway signs

	Rideshare promotions

	Visual information (videos, slides, presentations) for meetings or for web-based 

dissemination.

None of these public awareness strategies have been directly assessed using a modeling approach. 

While some of these strategies (e.g., coordination with media, press releases) are low cost or even 

free, some of these strategies (e.g., paid advertising) can be costly to implement and are typically 

associated with major projects. More significant projects in large metropolitan areas will require 

an intense public awareness campaign, while projects with relatively low impacts will rely on 

less expensive public awareness strategies that utilize existing outreach mechanisms (e.g., DOT 

website) and other media. While no single tool can directly model these strategies, many modeling 

approaches are able to be used to conduct “what if” scenarios to determine what level of demand 

reductions are necessary to ensure mobility measures are met. A realistic estimate of the travel 

demand reduction (either through changing when a trip occurs, what mode is used or canceling 

a trip altogether) is an essential input for most work zone analyses tools. For example, in the 

Milwaukee area, recent experience indicates that major freeway reconstruction projects result in 

30 to 40% reduction in peak hour demand. If we analyzed our Milwaukee freeway work zones 

without taking this into account, we would severely over-predict the impacts of the construction. In 

this situation, ex-post studies documenting demand reductions associated with completed projects 

using one or more of the strategies could be compared with the model outputs.

Motorist Information Strategies—Motorist information strategies focus on providing real time 

traveler information to travelers regarding the project work zone. Examples of motorist information 

strategies include those listed below. Those in bold are motorist information strategies that have 

been analyzed using the approaches described in Section 1.1:

	Traffic radio

	Changeable message signs

	Temporary motorist information signs

	Dynamic speed message signs

	Highway advisory radio

	Extinguishable signs

	Web-based highway information network

	511 traveler information systems

	Freight travel information

	Transportation Management Centers

Four of the 10 motorist information strategies have been analyzed using one of the modeling 

approaches. Generally, these analyses focused on the general use of traveler information (e.g., via 

en-route signs, cell phones, or pre-trip information from a web-site). Also, these analyses have 

been significant efforts using mesoscopic and microscopic simulation tools to model motorist 

information strategies such as dynamic message signs to determine the impact these strategies 

could have on traveler diversions either through or around work zone and surrounding area.
31

2.2.3 Transportation Operations

Transportation operations strategies include improved transportation operations and management of 

the transportation network to help mitigate work zone impacts. Transportation operation strategies 

include demand management, corridor/network management, work zone safety management 

strategies, and traffic/incident management and enforcement strategies. For significant projects, 

transportation operations is a required component of a TMP. 

Demand Management Strategies—Demand management strategies use techniques that are 

intended to reduce the volume of traffic that travels through a work zone by encouraging the 

motorist to consider when and how they travel. Examples include diverting motorists to alternate 

modes of travel, shifting motorists to alternate routes, and encouraging off-peak travel trips. 

Demand management strategies include those listed below. Those in bold are demand management 

strategies that have been analyzed using the transportation modeling approaches described in 

Section 1.1:

	Transit service improvements

	Transit incentives

	Shuttle services

	Ridesharing/carpooling incentives

	Park and ride promotion

	High occupancy vehicle lanes

	Tolling/congestion pricing

	Ramp metering

	Parking supply management

	Variable work hours

	Telecommuting

Four of the 11 demand management strategies have been analyzed using one of the modeling 

approaches. Demand management strategies are usually reserved for large construction projects 

that have a lengthy duration because most of these strategies deal with altering the motorists travel 

behavior. However, it is often difficult to predict the impact that demand management strategies, 

such as transit service improvement, will have on roadway user behavior since changes to overall 

demand are estimated separately, with the analyst identifying likely impacts from a range of 

potential responses based upon other work zone performance assessments. Thus, the work zone 

analysis tends to provide the decision maker with a range of potential impacts based upon previous 

results.

Previous efforts to model these strategies have included the entire spectrum of modeling 

approaches except for traffic signal optimization. However, the level of detail provided by these 

various approaches varies significantly. Sketch-planning tools may be able to model the impact of 

improved transit service on overall traffic volume, but this is likely to be an external calculation 

(increased transit mode split) which is then entered into the model. The fidelity associated with 

travel demand models (due to their ability to analyze large geographic areas) limits their ability 

to provide detailed impacts of demand management strategies specific to the work zone site. 

Mesoscopic and microscopic simulation tools are better able to provide the level of detail necessary 

to account for the impact of all four demand management strategies but require a greater amount 

of detail and fine-tuning.

In the realm of transportation economics, models have been developed to estimate the impacts of

all of the transportation policy changes listed above. STEAM (Surface Transportation Efficiency
32

Analysis Model) and STM (Strategic Transport Model) are two examples. These models typically 

use cross-elasticities to estimate demand for certain policy instruments (e.g., mode shift to HOV, 

transit, or HOT lanes). For example, if carpooling incentives are implemented, the models estimate 

the resulting reductions in the number of solo drivers. Some travel demand forecasting packages 

also incorporate these techniques to some extent. The output from these economic models could 

be used to adjust the travel demand for the work zone analysis.

Corridor/Network Management Strategies—Corridor and network management strategies are 

used to optimize traffic flow through the work zone corridor and adjacent roadways using various 

traffic operations techniques and technologies. Corridor and network management strategies 

include those listed below. Those in bold are corridor/network management strategies that have 

been analyzed using the transportation modeling approaches described in Section 1.1 :

	Signal timing and coordination 

improvements

	Temporary traffic signals

	Street and intersection improvements

	Bus turnouts

	Turn restrictions

	Parking restrictions

	Truck and heavy vehicle restrictions

	Separate truck lanes

	Reversible lanes

	Dynamic lane closure systems

	Ramp metering/temporary 

suspension of ramp metering

	Ramp closures

	Railroad crossing controls

	Coordination with adjacent 

construction sites

Ten of the fourteen corridor/network management strategies have been analyzed using one of 

the modeling approaches. Corridor and network management strategies can be very effective in 

improving traffic flow through and around a work zone. The full spectrum of modeling approaches 

can be used to model these strategies with microscopic simulation being a typical modeling 

approach that analysts employ when evaluating these strategies. Other tools, including sketchplanning, may be useful for better understanding the impact of adjacent construction projects. 

Often, these network-based strategies and the use of a modeling approach will require that 

institutional barriers be broken down. For example, some agencies may already be using traffic signal 

optimization tools and can work with the planning division to develop alternate route optimization 

scenarios or to optimize the addition of temporary traffic signals in the system as part of a work 

zone. This will likely require coordination efforts between the traffic engineering, planning, and 

construction divisions within the agency and possibly even with some outside agencies (e.g., state 

construction project within a city jurisdiction for signal timing). Good working relationships and 

communication between the divisions and the agencies will improve efforts to optimize traffic flow 

through the work zone. These types of agency interactions will be discussed later in this chapter.

Work Zone Safety Management Strategies—Work zone safety management strategies address 

traffic safety concerns in work zones by analyzing devices, features, and management procedures. 

Work zone safety management strategies include those listed below. Those in bold are work 
33

zone safety management strategies that have been analyzed using the transportation modeling 

approaches described in Section 1.1:

	Speed limit reduction and variable 

speed limits

	Temporary traffic signals

	Temporary traffic barriers

	Moveable traffic barrier systems

	Crash-cushions

	Temporary rumble strips

	Intrusion alarms

	Warning lights

	Automated flagger assistance devices

	Project task force and committees

	Construction safety supervisor and inspectors

	Road safety audits

	TMP monitor and inspection team

	Team meetings

	Project on-site safety training

	Safety awards and incentives

	Windshield surveys

While work zone management strategies are considered significant strategies in the success of a 

construction project, the application of modeling approaches are infrequently applied to evaluate 

the impact of these strategies on the work zone area. Generally speaking, modeling tools are not 

directly applicable to evaluating the impact these strategies have on the work zone area. These 

strategies cannot be directly modeled to determine the impact the work zone will have on the 

surrounding area; however they are required to some degree on all construction projects. There 

are some specialized safety analysis tools available to analysts (e.g., QUADRO, Safety Analyst, 

SafeNet, and Road Safety Risk Manager) but these generally do not address the specific work zone 

safety strategies listed here. 

The safety analysis module in Quadro is designed specifically for work zone applications. It 

contains an internal database of the average number of crashes per mile traveled for various facility 

types, with and without construction. This information is used to compute the expected number of 

crashes in the work zone (the probability that there will be a crash). Quadro also converts this to a 

monetary value by multiplying by the expected increase in crashes by the average comprehensive 

cost of a crash. Using this method, the analyst can prepare a broad comparison of the relative safety 

of two construction alternatives.

Traffic/Incident Management and Enforcement Strategies—Traffic and incident management 

and enforcement strategies include many techniques to manage the traffic operations of the work 

zone. Work zone traffic management strategies entail monitoring prevailing traffic conditions and 

making adjustments to traffic operations as necessary. Traffic incidents during construction are 

situations where specific management strategies are useful to minimize the exacerbation of other 

work zone impacts. Incident management and enforcement strategies involve improved detection, 

verification, response, and clearance of crashes, mechanical failures, and other incidents in work 

zones and on detour routes. Traffic and incident management and enforcement strategies include 

those listed below. Those in bold are traffic and incident management and enforcement strategies 

that have been analyzed using the transportation modeling approaches described in Section 1.1:
34

Traffic and incident management and enforcement strategies are significant to the success of a 

construction project; however, transportation analysis tools are infrequently used to assess the 

impact of these strategies on the work zone area. The full spectrum of modeling approaches (except 

traffic signal optimization models) may be applicable to evaluating traffic/incident management 

and enforcement strategies that the agency could consider; however, most of these strategies 

cannot be directly modeled to determine the impact the work zone will have on the surrounding 

area. Generally, the analysis is limited to conducting “what if” scenarios. One exception is the 

use of safety service patrols where both sketch-planning and more complex tools have been used 

to assess the impact of reduced clearance time on work zone performance measures such as delay.

Table 3 provides a summary of the transportation modeling approaches that have been historically 

used to evaluate various TMP strategies. The suitability classification system has the following 

definition for Table 3:

	= TMP components have often been evaluated by the transportation modeling approach.

	= TMP components have sometimes been evaluated by the transportation modeling approach.

	= TMP components have rarely been evaluated by the transportation modeling approach.

n/a = No examples of the transportation modeling approach being used to evaluate TMP components.

	 ITS for traffic monitoring and management

	 Transportation management centers

	 Surveillance [Closed-Circuit Television 

(CCTV), loop detectors, lasers, probe vehicles]

	 Helicopter for aerial surveillance

	 Traffic screens

	 Call boxes

	 Mile-post markers

	 Safety service patrols

	 Total station units

	 Photogrammetry

	 Coordination with media

	 Local detour routes

	 Contract support for incident management

	 Incident and emergency management 

coordinator

	 Incident and emergency response plan

	 Dedicated police enforcement – paid by 

project

	 Cooperative police enforcement

	 Automated enforcement

	 Increased penalties for work zone 

violations
35

Table 3 TMP Strategy Factors

Factors

TMP Strategies Summary

Transportation Modeling Approach

Case Study

SketchPlanning 

and HCM 

Methodologies

Travel 

Demand 

Models

Traffic Signal 

Optimization

Macroscopic 

Simulation

Mesoscopic 

Simulation

Microscopic 

Simulation

Temporary Traffic ControlControl Strategies

Traffic control approaches used to accommodate road users within the work zone and adjoining corridor in an efficient and safe manner.

     

Michigan DOT: Ambassador Gateway Bridge MOTSIMCaltrans I-15 Pavement Reconstruction Project

Traffic Control Devices

Use of signs, panels, pavement markings, signals and lighting devices for temporary traffic control

   n/a   Glacier National Park: Going to the Sun Road Rehabilitation Project

Coordination/Contracting/Innovative Construction Strategies

Project coordination, contracting strategies and construction techniques to improve work zone operations.

  n/a   

Caltrans I-15 Pavement Reconstruction ProjectUtah DOT I-15 Reconstruction DesignBuild Evaluation

Public InformationPublic Awareness Strategies

Methods to educate and reach out to the public, businesses and community concerning the road project and work zone.

  n/a n/a n/a n/a Woodrow Wilson Bridge Replacement

Motorist Information Strategies

Provision of current/real-time information to road users regarding the project work zone.

  n/a n/a n/a  Woodrow Wilson Bridge Replacement

Transportation OperationsDemand Management Strategies

Techniques intended to reduce the volume of traffic traveling through the work zone

  n/a    Woodrow Wilson Bridge Replacement

Corridor/Network Management (traffic operations) Strategies

One or more work zones on longer stretches of a single facility and/or portions of adjacent facilities.

  n/a    Michigan DOT: Ambassador Gateway Bridge MOTSIM

Work Zone Safety Management Strategies

Devices, features, and management procedures used to address traffic safety concerns in work zones.

 n/a n/a n/a n/a 

Utah DOT I-15 Reconstruction DesignBuild EvaluationWisconsin DOT: Transportation Management Plan Development Process

Traffic/Incident Management and Enforcement Strategies

Strategies to manage work zone traffic operations.   n/a   

= TMP components have often been evaluated by the Transportation Modeling Approach. = TMP components have sometimes been evaluated by the Transportation Modeling Approach. = TMP components have rarely been evaluated by the Transportation Modeling Approach. n/a = No examples of the Transportation Modeling Approach being used to evaluate TMP components.
36

2.3 Data

One of the most important factors when deciding to use a transportation modeling approach to assess 

work zone impacts is the availability and quality of data regarding the project. Regardless, any work 

zone impact analysis will be a balance between the type of data that are needed, where the data come 

from, and the quality of the data. Often, an analyst will also have to account for the project development 

phase and, ultimately, the required precision of the results3. 

2.3.1 Type

Important elements to work zone analysis are data describing the roadway network, the traffic on the 

roadway network, and cost variables such as value of time and construction costs. The extent to which 

these data are needed depends upon both the stage of the project life-cycle and the modeling approach 

being used. The roadway characteristic data are generally easily available; the most difficult being 

the availability of signal timing plans. Travel demand characteristics are more difficult to obtain and 

there are no hard and fast rules regarding the use of this data when using a transportation modeling 

approach except that, in general, the more accurate the data the more accurate the results regardless of 

the modeling approach being used. 

Roadway Characteristics—These data can be thought of as describing the roadway network 

infrastructure such as physical attributes (lane configuration, intersection location, traffic signal 

location, alternate routes, etc.) and policy attributes (estimated roadway capacity, signal timing plans, 

etc.). Together, these attributes are required in order to create the necessary network that the model will 

use to generate results. Most models and analysis tools will require some form of roadway characteristic 

data. The type and amount of data will vary by which tool is selected. Roadway characteristic data 

can usually be collected from construction drawings, field surveys, aerial photographs or geographic 

information system files. This data is usually sufficient for sketch-planning models, traffic signal 

optimization, and macroscopic and mesoscopic modeling. For microscopic modeling, to improve the 

accuracy of the information, the analyst may want to verify the roadway characteristics with field data.

Travel Demand Characteristics—These data describe how the roadway network infrastructure is 

utilized by the user. This would include traffic counts, vehicle demand data, and transit data if applicable. 

Travel demand characteristics pertain to vehicle and traffic demand data needed to assess the impact of 

the work zone. Traffic counts, vehicle mix, delay data, transit data, origin-destination data, etc. are the 

types of travel demand data that will be required to prepare an assessment model of the work zone. Like 

roadway characteristic data, all the models and analysis tools discussed in this report will need some 

form of travel demand characteristic data. The tools chosen will determine to what extent data is needed. 

Sketch-planning and HCM methodologies will require less data requirements, whereas macroscopic, 

mesoscopic, and microscopic simulation models may require more data. As stated previously, the more 

site-specific data provided, and the more accurate the data, the better the results of the model. If site-specific 

data is unavailable and the resources to collect travel demand data are not available, there are sources that 

can provide default values for some of these parameters. Many of the models and tools themselves will 

include default variables to be used in situations where data is not available. Using default data should 

be done cautiously, as the default values may not reasonably approximate the site-specific conditions.

3

 A detailed discussion on the precision of the results is provided in Section 2.5.2, Precision of Results.
37

Cost Attributes—These data include parameters such as the value of time for different vehicle 

classes (passenger cars and trucks), the cost for different construction alternatives, and the effects 

on revenue that local businesses might incur due to the work zone. There are a few analysis tools 

that use the sketch-planning or mesoscopic approach and can input different cost attributes to 

evaluate the value of time and cost of the impact the work zone will have on the surrounding 

environment. These attributes include the revenue from a local business that might be impacted 

by the construction zone, or the cost and time of vehicles or trucks that have to alter their schedules 

and routes because of the work zone, among other factors.

2.3.2 Source

There are many sources of data related to a work zone analysis. In general, these data sources are 

separated into two categories: primary and archived. 

Primary—Primary sources of data include any number of data collection techniques whereby 

traffic data counts are collected in the field either using automated sensors such as video cameras, 

electronic toll collection (ETC) transponders, loop detectors, station counters, etc. Models 

that require field traffic counts for analysis are traffic signal optimization and mesoscopic and 

microscopic simulation. The more recent the data collection is performed, the more accurate the 

modeling results will be. Primary sources of data also include any number of analytical models 

available to an analyst from previous studies or other agencies such as a regional planning 

organization.

Yosemite National Park: Yosemite Village Roadway Reconstruction

The Federal Lands Highway Division used a combination of archived data and field 

traffic counts for the analysis of the Yosemite Village Roadway Reconstruction. FLH 

engineers conducted a first-cut distribution of hourly and daily travel demand factors 

obtained from a 1998 traffic study. These values were combined with two-short term 

collection activities to refine the hourly and daily distributions and establish a rate 

of travel demand growth from 1998-2004. The field traffic counts were conducted 

using portable traffic counters which are available agency-wide within FLH. More 

information can be found in the Yosemite National Park: Yosemite Village Roadway 

Reconstruction case study.

Archived—Archived data is used most often in sketch-planning and HCM transportation modeling 

approaches. Depending on the analysis tool chosen and the required accuracy of the results, it 

can also be used to some degree by travel demand models, traffic signal optimization models, 

and macroscopic, mesoscopic, and microscopic simulation models. There are many sources of 

archived data including public entities such as a regional planning organization or departments in 

a transportation agency as well as commercial vendors. Using archived data can be a cost effective 

solution to conducting a work zone analysis if limited resources are available or a quick decision 

needs to be made. 
38

New Jersey Turnpike Authority: Lane Closure Application

Based upon HCM methodologies, the New Jersey Turnpike Authority Lane Closure 

Application relies on archived data in order to conduct analyses. Typically, these data 

are between one to two months old. More information is available in the New Jersey 

Turnpike Authority: Lane Closure Application case study.

2.3.3 Quality

An important component to using data is the quality of the data. The purpose of using data (be it 

primary or archived) is to prepare models that best represent actual field conditions resulting in 

an analysis producing the most accurate results possible. Primary data can often provide the most 

valuable data for modeling; however, collecting this data is resource intensive and costly. Many 

analyses for work zone planning purposes are conducted without this type of resource intensive 

primary data collection. In the case of significant Type I work zones that will affect a large 

number of travelers for long durations, field data collection may be beneficial to evaluate the work 

zone impacts more accurately. An analyst can benefit from visual observation because they can 

identify behavior in the field that is not as obvious in other data collection methods. This allows 

the analyst to adjust the model to better reflect existing conditions and improve the results when 

modeling for work zone implementation. In general, the analyst is concerned with the following 

four characteristics regarding the quality of the data: collection frequency, geographic coverage, 

archive length, and accuracy. 

Collection Frequency—Collection frequency describes how often data is collected. This is 

important based upon the type of work zone being analyzed and the project stage. Work zone 

analyses occurring in the planning and design stage may need sample data collected only once 

in order to characterize daily travel demand or hourly roadway capacity to support a high-level 

decision about work zone scheduling. Projects in the construction stage may need data that is 

collected more frequently (e.g., traffic counts or travel times at five-minute intervals) to assess 

model outputs. 

Geographic Coverage—An important consideration of data quality is the extent to which data 

is available for a specific location or region. Depending upon the location of the work zone, 

traffic data may not be available for a certain location (e.g., rural interchange or intersection). In 

these situations representative data may need to be used from other sources. Also, larger Type I 

work zones may need to have data available that encompasses an entire region rather than only 

surrounding the immediate vicinity of the work zone.

Archive Length—Archive length is concerned with the extent to which historical/archived data is 

available to an analyst. The length of the archive is important when temporal variations need to 

be considered as part of the work zone analysis. For example, work zones with a long durations 

occurring over multiple construction seasons will need to account for seasonal fluctuations in 

traffic demand as part of the analysis. Also, analysts considering the timing of a construction 

project in terms of taking place now or over the next five years will need to estimate the change in 

traffic demand over a number of years in order to project out future travel demand. 
39

Accuracy—Accuracy is concerned with comparing outputs of the model with real-world conditions 

and the requirements of the analyst such that the model can be validated. In other words, what are 

the tolerances of the model? In some cases, such as a high-level analysis during the planning stage, 

a rough order of magnitude or directionality is sufficient. However, a work zone analysis occurring 

during the construction stage may require higher accuracies such that the analyst can estimate queue 

formation every 15 minutes. Accuracy will depend not just on the project stage but the measure 

of effectiveness as well. An analyst should always strive to identify and utilize accurate data. The 

key point with respect to understanding the inherent accuracy of a data source is to understand the 

level to which one can accurately apply the data. For example, a multi-year dependable archive of 

sample traffic counts taken a few times each year may be a useful and accurate source of data for 

estimating rough seasonal trends. However, these data may not be accurate enough to support a 

peak recurrent delay estimate for a specific day not in the sample set. 

Woodrow Wilson Bridge Replacement

The WWB project was concerned with all four aspects of data quality as part of several 

of the modeling projects. For the microscopic simulation analysis, previous field 

observations were used to help calibrate the model. In the case of using the sketchplanning tool for the first time, engineers ran the model to estimate queuing and delay 

and then verified those results in the field by observing the actual queue length and 

driving the work zone to measure travel times and determine delay. The initial field 

observations were used to ensure the model was calibrated correctly for future use. 

More information can be found in the Woodrow Wilson Bridge Replacement case study.

Table 4 provides a summary of the three categories of data factors associated with work zone 

modeling. Type provides an assessment of the level of detail historically used for each of the 

three data types: Roadway Characteristics, Travel Demand Characteristics and Cost Attributes. 

The suitability classification system has the following definition:

	 = High level of detail historically used as part of the transportation modeling approach.

	 = Medium level of detail historically used as part of the transportation modeling approach.

	 = Low level of detail historically used as part of the transportation modeling approach.

n/a = Data type is not typically used as part of the transportation modeling approach.
40

Table 4, under the heading Source, provides a summary of the sources of data commonly used 

for each of the transportation modeling approaches. The suitability classification system has the 

following definition:

 = Data source is commonly used for the transportation modeling approach

 = Data source is not commonly used for the transportation modeling approach.

Table 4, under the heading Quality, provides an assessment as to the overall quality required 

for each of the quality aspects (collection frequency, geographic coverage, archive length, and 

accuracy). In all cases, it is important that the data available be of high quality such that the outputs 

of the model are useful in supporting the decisions being made.

Table 4 Data Factors
41

Table 4 Data Factor

Factors

Data Summary

Transportation Modeling Approach

Case Study

SketchPlanning 

and HCM 

Methodologies

Travel 

Demand 

Models

Traffic Signal 

Optimization

Macroscopic 

Simulation

Mesoscopic 

Simulation

Microscopic 

Simulation

Type Roadway Characteristics

Information regarding the physical design and operational characteristics of the roadway to be modeled.

      New Jersey Turnpike Authority: Lane Closure Application

Travel Demand Characteristics

Information regarding vehicle and traffic demand associated with a roadway segment or system beginning analyzed.

      Caltrans I-15 Pavement Reconstruction Project

Cost Attributes

Value of time for various vehicles classes (passenger cars and trucks) as well as revenue for local businesses impacted by roadway construction.

  n/a   

Yosemite National Park: Yosemite Village Roadway ReconstructionWoodrow Wilson Bridge Replacement

SourcePrimary

Roadway detection, probe vehicle, floating cars, ETC, analytical models (e.g., regional travel demand models), etc.

      Woodrow Wilson Bridge Replacement

Archived

Using historic/archived traffic data available from planning agencies, transportation agency, or commercial vendors (e.g., traffic.com).

      New Jersey Turnpike Authority: Lane Closure Application

QualityCollection Frequency How often data is collected.       Woodrow Wilson Bridge ReplacementGeographic Coverage Extent to which data is available for a specific region or location.       Woodrow Wilson Bridge ReplacementArchive Length Extent to which historical/archived data is available.       Woodrow Wilson Bridge ReplacementAccuracy Comparing model results with actual conditions to validate model.       Woodrow Wilson Bridge Replacement

= High level of detail historically used as part of the transportation modeling approach. = Medium level of detail historically used as part of the transportation modeling approach. = Low level of detail historically used as part of the transportation modeling approach. n/a = Data type is not typically used as part of the transportation modeling approach.= Data source is commonly used for the transportation modeling approach. = Data source is not commonly used for the transportation modeling approach.= The transportation modeling approach requires high quality data. = The transportation modeling approach does not require high quality data.

In all cases, it is important that the data available be 

of high quality such that the outputs of the model 

are useful in supporting the decisions being made
42

2.4 Agency Resources

Developing an analytical approach will be strongly dependent upon the resources the transportation 

agency has available and dedicates to these analyses. These resources can be categorized as 

institutional arrangements within the organization that enable or hinder the flow of information; 

technical staff that are able to conduct the required analysis and/or data collection; funding to 

acquire the technical expertise or models; and scheduling requirements. All four of these agency 

resource categories play an important role when making a determination to deploy a transportation 

modeling approach. 

2.4.1 Institutional Arrangements

The Work Zone Safety and Mobility Rule is characterized by a policy-driven focus to institutionalize 

work zone processes and procedures, with specific provisions for application at the project-level 

(3). This may mean involving additional agencies in the Planning, PE/Design, and Construction of 

roadway projects. Each agency needs to recognize that the traveling public is not concerned about 

lines on the map, but about moving quickly, safely, and efficiently through the network. Therefore, 

transportation officials need to focus on this system-level result.

For example, operational personnel at successful traffic management centers have found innovative 

ways to overcome institutional and technical limitations to maintain traffic incident management 

coordination. By developing small personal groups, a trust is established that permeates throughout 

the corresponding organizations. The co-location of agencies within an incident management 

center helps to strengthen the interagency relationships. 

While there are many transportation and planning agencies which have developed comprehensive 

institutional arrangements regarding the use of travel demand modeling for short and long range 

planning, similar examples for work zone analysis are not all that common. Many of the Type 

I work zones (Mega Projects) have in place a mechanism to deploy the use of a transportation 

modeling approach as part of the overall project delivery process. Often, work zone analysis will 

be included. However, the smaller-scale projects such as Type II, III, and IV work zones do not 

necessarily include a budget for transportation modeling, let alone work zone analysis. 

Often, the lack of an integrated or strategic methodology for work zone analysis can be characterized 

by four key institutional barriers:

	Culture—There exists within many transportation agencies a culture of compartmentalization 

whereby planners do not interact with designers who do not interact with operations 

personnel. In order for work zone impacts to be accounted for during the entire project 

life-cycle, these barriers need to be broken for a continuous flow of information and data.

	Leadership—Leaders are important to ensuring the successful deployment and use of 

transportation analysis tools for work zone analysis. Often, successful examples of work 

zone analyses will focus upon a single individual who took it upon themselves to change an 

organization’s culture or institutional arrangements to enable the use of work zone analysis 

throughout the project life-cycle. 
43

	Data Management—Because of the compartmentalization of many transportation 

agencies, it is sometimes difficult to acquire the necessary data. Often, an analyst will have 

to go to multiple departments or organizations in order to get the data (e.g., operations, 

planning, transit). 

	Contracting—As discussed below, acquiring the technical expertise to conduct a work 

zone analysis may require the use of contractors with specialized knowledge and tools. 

Agencies will need to have in place flexible contracting arrangements (such as contractors 

on-call) whereby services can be obtained quickly and easily. 

Working together to overcome institutional challenges and carefully planning and managing the 

challenges can provide significant benefits for all agencies involved. The benefits of establishing 

a strategic methodology for work zone analysis are much greater than what could be achieved 

through the deployment of a number of components operating in isolation. For example, deploying 

the use of a transportation modeling approach for work zone analysis early in the project life cycle 

(such as the Planning stage) can engage key players and stakeholders such that if future work zone 

analysis is needed later to answer questions on lane closures during the Construction stage, results 

can be generated quickly and cost effectively.

Michigan DOT: Southeastern Michigan Simulation Network

As part of developing the Southeastern Michigan Simulation Network (SEMSIN) 

Michigan DOT’s Metro Region addressed many of the institutional barriers discussed 

above. As part of creating Regional Mobility Teams, the culture of the organization 

changed whereby planners, traffic engineers, and safety personnel now consistently 

work together to address mobility within work zones throughout the project lifecycle. Also, as part of creating the SEMSIN, a wealth of modeling data resources were 

discovered and are now readily available to any agency personnel for future use. The 

successful creation of the SEMSIN can be traced back to a single person who worked 

for its implementation and use. More information on the development of SEMSIN can 

be found in the Michigan DOT: Southeastern Michigan Simulation Network case study.

2.4.2 Technical Staff

A critical component to the successful use and deployment of work zone modeling tools is the 

technical expertise to use them. Often, transportation agencies will have either in-house expertise 

regarding the use of a specific model or access to a consultant with the expertise through a 

contractual arrangement. In this situation, an agency may be limited to a specific model based 

upon the technical capability at hand. For example, many transportation agencies make a decision 

to use modeling products from a specific vendor. In this case, if an agency/analyst wanted to use a 

different modeling tool that is not available from the vendor, additional time and resources would 

need to be made available in order to acquire and run the model. Even if an outside contractor is 

used to conduct the analysis, the transportation agency will still need to have enough expertise onhand in order to oversee and validate the work zone analysis findings. 
44

The other aspect to this is leveraging resources outside of one transportation agency. Many 

localities have a federally mandated regional planning organization (commonly referred to as a 

metropolitan planning organization or council of governments) chartered to conduct long-term 

planning analysis. In this situation, the planning organization may provide a base transportation 

network that could be used by the transportation agency in a work zone analysis.

2.4.3 Funding

Funding availability to conduct a work zone modeling analysis is another critical component of 

the agency resources. While there are many progressive transportation agencies trying to account 

for and mitigate the impact of work zones on the traveling public, an argument may still need to 

be made to allocate project funding to conduct a comprehensive work zone analysis. Sometimes, 

funding availability may limit the extent to which a work zone analysis can be conducted because 

money is not available for acquiring the necessary modeling tool or issuing a contract for the 

analysis to be conducted by a consultant. Regardless, any type of work zone analysis will require 

at least a minimum amount of funding and the accuracy and results of the analysis will depend 

to a certain degree on the amount of money available. As the use of more complicated tools is 

warranted, such as moving from a simplified delay estimation tool to a mesoscopic or microscopic 

transportation simulation tool, the costs will likely increase.

2.4.4 Schedule

A critical element in selecting a modeling approach is the project schedule. The amount of time 

required to conduct an analysis generally increases as one moves from the simplified to the more 

complex modeling approaches identified in Figure 1, the Work Zone Modeling Spectrum. In order 

to reduce the constraints of schedule to a work zone analysis, analysts should try to leverage 

other resources as much as possible. This includes seeking resources in-house that have conducted 

previous analyses related to the specific work zone area or general location as well as looking to 

other agencies and analyses that have used similar modeling tools. The point here is to leverage to 

the fullest extent possible the work that others have done so as not to “recreate the wheel”. 

Agencies who have taken a strategic approach to incorporating modeling into the overall work 

zone decision-making process have an advantage in addressing the schedule constraint. Agencies 

that have invested in developing modeling resources from the beginning (be it on-call contractors 

or in-house technical expertise) with a deployed capability in “stand-by” mode are better able 

address unanticipated questions when they arise and a decision must be made quickly. Those 

agencies that have invested in standing analytical capabilities will be more nimble in responding 

to these situations than those who start from scratch for each analysis. Thus, these agencies limit 

the impact that a schedule constraint has on generating useful results from the models as part of 

the decision-making process.
45

2.5 Work Zone Performance Measures

An important aspect in selecting a work zone analysis tool will be selecting a tool that outputs 

results that can be used to evaluate the work zone performance measures established by the 

transportation agency at the precision that is required to make a decision. Many transportation 

agencies use different types of measures of effectiveness for work zone impacts which can range 

from maximum additional travel time to maximum queue lengths caused by the work zone. Thus, if 

an agency has a requirement that no work zone may contribute more than 20 minutes of additional 

travel time delay, then the tool selected must be able to accurately predict that value. In addition, 

if the model will be used to assess financial incentives and disincentives, then it is imperative the 

model be able to predict the results accurately in order to set those levels.

2.5.1 Measures of Effectiveness

The following seven work zone measures of effectiveness come from the Work Zone Performance 

Assessment Measures compiled by FHWA in the publication Work Zone Impacts Assessment: 

An Approach to Assess and Manage Work Zone Safety and Mobility Impacts of Road Projects 

(3). These seven were distilled from a larger list based upon the ability for currently available 

transportation analysis tools to calculate the performance measures.

Most of the transportation modeling approaches presented in Section 1.1 are capable of reporting 

the various work zone measures of effectiveness an agency requires. If agency policy stipulates a 

need to measure lane-by-lane queue lengths, the most accurate results will most likely be generated 

by a microscopic transportation simulation program since it provides results at the vehicle and lane 

level. However, microscopic tools are particularly complex and costly to deploy when modeling 

large corridors and regions. In these cases a mesoscopic model or regional planning model could 

be used to predict queue lengths when lane-level result are not critical. What is important is to 

select the approach that best provides the needed measures relative to the available data and work 

zone attributes. 

Travel Time—A performance objective for many agencies might be to maintain an average travel 

time through the work zone for a certain period of time. Travel time is one of the most common 

measures used to track work zone delay. Microscopic and mesoscopic simulation can determine 

these results at the vehicle level, whereas sketch-planning, HCM methodologies, and travel 

demand models will provide travel time results based on the average for the system or work zone 

area. Some agencies may also collect real-time travel data during construction implementation 

and provide this information directly to travelers

Utah DOT I-15 Reconstruction

See the Utah DOT I-15 Reconstruction Design-Build Evaluation case study 

for a discussion on the use of travel time as a performance measure.
46

Delay—To improve safety and mobility through a work zone, most agencies will measure 

delay through the work zone. Delay is defined as the amount of additional travel time 

drivers spend traveling which is caused by the work zone. Delay and travel time are directly 

related. Some agencies provide a delay rule that states a construction project can not cause 

more than 20 minutes of additional delay or total delay through a work zone. Work zone 

analysis is used to estimate various delay measures (e.g., maximum or average delay) in 

order for construction to be staged accordingly. Mesoscopic and microscopic simulation 

models can model vehicle delay and total delay through the work zone. Sketch-planning 

tools, some travel demand tools, and some macroscopic simulation tools can model average 

vehicle or total delay through the work zone. Depending on the size and type of work 

zone and the data available for modeling, these tools may be sufficient for determining the 

impact the work zone has on delay.

Yosemite National Park

See the Yosemite National Park: Yosemite Village Roadway Reconstruction

case study for a discussion on how a maximum user delay policy impacted 

the work zone. 

Queue Length—Queue length is also a common performance measure that many agencies 

use to determine the impact of a work zone. Some agencies use queue length measures to 

determine when to set up lane closures or even when to remove lane closures if the queues 

get too long. Queue length is defined as the number of vehicles or length of vehicles queued 

to travel through the work zone due to the reduction of roadway capacity caused by the 

construction. Mesoscopic and microscopic simulation models can analyze queue lengths 

on a lane-by-lane basis. Data collection for these models will need to be more accurate 

so the model can properly represent the field conditions. Some sketch-planning tools 

and some macroscopic simulation models may also estimate queue length, representing 

the average queues for the time period. If detailed data is not available, sketch-planning 

models are often used for developing construction schedules that specify when or when not 

to close lanes.

Zion National Park

See the Zion National Park: Entrance Booth Reconstruction case study on 

the impact that queue length had in the decision to shift construction to 

night-time.

Speed—Speed is another traffic flow characteristic like delay that some agencies might 

measure to determine work zone impact. Similar to delay and travel time, speed is a 

common measure for assessing mobility through the work zone. Results from modeling 

tools that determine speed can also be used to establish the speed limits for the work zone 
47

during design. There are many transportation modeling approaches to analyze speed. There 

are analysis tools within sketch-planning models, HCM models, travel demand models, 

macroscopic simulation, mesoscopic simulation, and microscopic simulation models that 

provide speed as an endogenous variable in the model output. 

Woodrow Wilson Bridge Reconstruction

See the Woodrow Wilson Bridge Reconstruction case study for more 

information on the use of a microscopic simulation tool to evaluate variable 

speed limits within a work zone project.

Volume—Traffic volume as a performance measure is defined as the reduction in the 

amount of vehicles traveling on the roadway due to the work zone. Volume is directly 

related to capacity when determining the impact the work zone will have on the project. 

Travel demand models, traffic signal optimization tools, and mesoscopic and microscopic 

simulation models all measure volume as it relates to the reduction of capacity through the 

work zone.

In all cases, volume is a count of vehicles passing over a certain point (e.g., vehicles per 

hour or vehicles per hour per lane). However, interpreting the volume value is different 

based upon where it is measured. For example, if the work zone to be analyzed creates a 

bottleneck on the roadway resulting in queuing, volume through the work zone is a measure 

of throughput. In situations where the work zone is not causing any queuing, volume is a 

measure of travel demand.

User Cost—User cost refers to the estimated loss of productivity from road user delay 

caused by the construction project and the work zone. User costs are more difficult to 

analyze and there are few analysis models that can provide this performance measure as 

a result. In addition some agencies find it difficult and more time consuming to place 

values on productivity loss. Road user costs might be considered early in the design stage 

to determine the best construction staging and they can also be used as an incentive or 

disincentive in contracts to reduce the overall construction schedule.

Caltrans I-15 Pavement Reconstruction Project

See the Caltrans I-15 Pavement Reconstruction Project case study for a 

discussion on the use of cost data (including hard and soft costs) in selecting 

a work zone construction scenario.

Incidents—Incidents as a performance measure refers to the quantity of vehicle incidents 

that occur as a result of the construction project and the work zone area. When agencies 

establish goals and objectives to improve the safety and mobility through the work zone, the 
48

performance measures established will be related to traffic flow, delay and the number of 

incidents. There is always a strategic goal to reduce incidents in work zones; however there 

are very few models available to analyze how to reduce or mitigate incidents. Some agencies 

use historical data to analyze future work zones. There may be a microscopic simulation 

tool that can analyze this data depending on the needs of the agency. Determining the 

quantity of vehicle incidents will most likely be reserved for Type I or Type II construction 

projects.

Utah DOT I-15 Reconstruction

See the Utah DOT I-15 Reconstruction Design-Build Evaluation case study 

for an example on how a crash analysis was used to influence roadway 

construction policy.

Cumulative Impact—The cumulative impact refers to assessing the impact of multiple 

or linking construction projects within a corridor or a region. This includes situations in 

a region where multiple construction projects occur simultaneously as well as a single 

construction project involving multiple work zones that may create an interaction with 

other. The impact globally may be more significant than the individual impact of each work 

zone and therefore needs to be considered. The Work Zone Rule definition of significant 

project addresses work zone impacts from either individual projects or the combined 

effects of a project’s impacts with those of other concurrent projects nearby. Minimizing 

cumulative work zone impacts can be achieved by adjusting construction scheduling and 

project coordination. Mesoscopic simulation or sketch-planning models will provide the 

best results for evaluating the impact of multiple construction projects within a region. 

There may also be travel demand models or macroscopic simulation models that can 

perform this analysis depending on the needs of the agency.

Michigan DOT

See the Michigan DOT: Southeastern Michigan Simulation Network case 

study for an example of addressing the cumulative impact of multiple 

construction projects in a region.

Glacier National Park

See the Glacier National Park: Going to the Sun Road Rehabilitation 

Project case study for a detailed discussion on the impact multiple work 

zones have on work zone staging and design for a single project.
49

2.5.2 Precision of Results

The precision of results will be directly related to the modeling tool chosen to analyze work zone 

impacts. The size and characteristics of the work zone, the needs of the agency, the measures 

of effectiveness to be evaluated and those the model reports, and funding available for analysis 

will all determine which type of modeling analysis is best suited to examine work zone impacts. 

The stage or phase of the work zone may also affect which analysis tool is best for the situation. 

During the planning stage, the agency may be interested in high-level results, whereas during 

implementation of a large Type I construction project, more detailed results may be required when 

more data is available. 

While the need for precision is often driven by the stage of the project life-cycle (Planning, PE/

Design, or Construction), other external factors related to agency resources (discussed in Section 

2.4) may limit the available transportation modeling approaches, thus the overall level of precision. 

A summary of these tradeoffs is presented in Figure 9 below.

Figure 9 Work Zone Data Spectrum

The bottom bar shows the level of precision generally needed for the project life cycle stages with 

more precision desired as one moves from Planning to PE/Design to Construction. The top bar 

shows a progressive refinement of impact parameters (data quality and data availability) to enable 

more and more precise work zone impact estimation. 

Projects within the domain of the Planning stage generally need less precise results and, therefore, 

less precise data. When rough estimates are required, it is often worthwhile to consider existing 

data sources when getting started with an analysis. In this case the cost to collect detailed data is 

often unwarranted and existing data assimilated from multiple sources, such as template libraries 

and historical data, are generally sufficient to conduct an analysis to support rough estimation. 

Planning

Low Precision High Precision

Rough Estimation Detailed Data

PE/Design Construction

Demand Templates

Archived Data

Field Trac

Count Data Collection

Field Observations

and Validation
50

Projects in the PE/Design stage would require more refined and accurate data than those in 

the planning stage but not as detailed as those within the construction stage. In this stage of 

development, depending on the situation, historical data combined with more recent traffic count 

or visitor data may be sufficient to get the desired results. In some cases it is warranted to use 

some of the available resources to collect more detailed field data, especially if performancebased contracting is to be used or if liquidated damages will be established, in which case the 

most detailed data available needs to be used. On the other hand, projects entering or within the 

Construction stage would need much more accurate and timely data since the analysis will more 

than likely require differentiation between very similar alternatives that require a higher fidelity of 

data. For example, a contractor may request an additional lane of traffic be taken away for an extra 

two hours each Sunday morning in order to more quickly perform the work. Analyzing this type of 

request is a situation where highly precise results would be warranted in an operational work zone. 

In this situation, it would be possible to collect field data such as first-hand queue observations 

and traffic volume. Overall, the amount and types of data required will depend primarily upon 

the characteristics of the work zone, the analysis area dimensions, the needs and resources of the 

agency, and the accuracy required to evaluate the performance measures. Data collection will 

involve a combination of existing and available sources, and new data collected before and during 

work zone implementation.

An example of the precision of results is the difference between outputs from a sketch-planning 

tool and a microscopic simulation model. Sketch-planning tools designed specifically for work 

zone analysis (such as QUEWZ-98 or QuickZone) often provide results in one hour time slices. 

However, microscopic simulation models provide results on the minute-by-minute level. Thus, if 

a particular work zone analysis requires results every five minutes (such as a variable speed limit 

system), a transportation modeling approach providing higher precision of results may be required. 

Modeling analysis results can be divided into two categories: rough estimation and detailed 

assessment.

	Rough Estimation—Sketch-planning tools, HCM methodologies, travel demand models, 

macroscopic simulation models, and some traffic signal optimization tools will produce 

results that are often expressed as “maximum” or “average”. These tools do not analyze 

traffic at the individual vehicle level. Results are considered average for the time period 

and the network and give the analyst an idea of what traffic impact might be like during 

work zone implementation. These tools are usually less data intensive and may provide 

enough detail for many work zone analyses.

	Detailed Assessment—Mesoscopic and microscopic simulation models and some traffic 

signal optimization tools provide detailed results. Tools in these categories provide results 

that model individual vehicle movements and turning patterns. These tools are usually 

more resource intensive and require much more data. The results provided give a detailed 

assessment of existing conditions and multiple work zone alternatives and provide the 

agency with a good representation of what field conditions will be like during work zone 

implementation. Detailed assessments are often reserved for large, Type I work zones that 

will affect large numbers of travelers for a long duration. Another possibility for using 
51

mesoscopic or microscopic simulation would be if the agency already has a simulation 

model prepared for the region or area where the construction will be performed. The 

analyst can populate the model with the alternatives and new data to determine the best 

work zone alternative.

Table 5 provides a summary of the transportation modeling approaches that have been 

historically used to calculate the measures of effectiveness as well as the precision of results 

generated by the modeling approaches. The suitability classification system is different for each. 

The measures of effectiveness use the following definition in Table 5: 

	 = Performance measure is often calculated by the transportation modeling approach.

	 = Performance measure is sometimes calculated by the transportation modeling approach.

	 = Performance measure is rarely calculated by the transportation modeling approach.

n/a = Transportation modeling approach should not be used to calculate the performance measure.

The precision of results use the following definition in Table 5:

ü = The transportation modeling approach commonly produces results at this level of precision.

û = The transportation modeling approach does not commonly produce results at this level

 of precision
52

Factors

Performance

Measures

Summary

Transportation Modeling Approach

Case Study Planning 

Sketchand HCM 

Methodologies

Travel 

Models

Demand Optimization Traffic Signal Macroscopic Simulation Simulation Mesoscopic Simulation Microscopic 

Travel TimeEffectiveness Measure of

travel through the work zone.Amount of time it takes vehicles to 



 n/a







ProjectCaltrans I-15 Pavement Reconstruction Road Rehabilitation ProjectGlacier National Park: Going to the Sun Build EvaluationUtah DOT I-15 Reconstruction DesignDelay traveling through the work zone. Amount of time drivers spend in 



 n/a





 Roadway Reconstruction Yosemite Nation Park: Yosemite Village 

Queue Length

construction.roadway capacity caused by the the work zone due to reduction in of vehicles queued to travel through Number of vehicles or total length 

 n/a n/a







Closure AnalysisWoodrow Wilson Bridge: Roadway ReconstructionZion National Park: Entrance Booth 

Speed Vehicle speed through the work zone.



 n/a





 Woodrow Wilson Bridge Replacement

Volume

work zone.operating on the roadway due to the Reduction in amount of vehicles 



 n/a







User Cost

zone.driver delay caused by the work Estimated productivity loss due to 



 n/a





 Project Caltrans I-15 Pavement Reconstruction 

Incidents

project.occur as a result of work zone Quantity of vehicle incidents that 



 n/a





 Build Evaluation Utah DOT I-15 Reconstruction DesignCumulative Impact

a region or corridor.roadway construction projects within Assessing the impact of multiple 



 n/a







Michigan DOT: I-94 Rehab MOTSIMRoad Rehabilitation ProjectGlacier National Park: Going to the Sun 

Rough EstimationPrecision of Results

“maximum” or “average”.Results often expressed as vehicles or turning movements. tools that do not model individual Results produced by traffic analysis 













ReconstructionZion National Park: Entrance Booth Closure ApplicationNew Jersey Turnpike Authority: Lane 

Detailed Assessment

movements and turning patterns.tools modeling individual vehicle Results produced by traffic analysis 











 Simulation Network Michigan DOT: Southeastern Michigan 

Table 5 Performance Measure Factors

= Performance measure is often calculated by the transportation modeling approach. 

= Performance measure is sometimes calculated by the transportation modeling approach.

= Performance measure is rarely calculated by the transportation modeling approach. n/a = Transportation modeling approach should not be used to calculate the performance measure.= The transportation modeling approach commonly produces results at this level of precision.= The transportation modeling approach does not commonly produce results at this level of precision.Approach.
53

3.0 Establishing a Strategic Methodology for Work Zone Analysis

Section 2.0 provided a detailed discussion of the myriad factors that influence which type of 

transportation modeling approach to choose. As observed earlier, the need to conduct a work zone 

analysis can occur at any stage during the project life cycle including Planning, PE/Design, and 

Construction. This breadth of application is evident in Table 1 which lists each of the case studies 

and where during the project life-cycle the analysis took place. Of the 13 project application case 

studies, seven occurred during Planning, four during PE/Design, and two during Construction. 

Clearly, the need for work zone analyses is not limited to a single stage. Thus it becomes important 

to develop a strategic methodology to applying transportation modeling approaches throughout the 

work zone project life-cycle. 

To that end, this section deals with establishing a strategic methodology for work zone analysis in 

order to maintain analytical consistency when work zone planning and analysis spans the project 

life-cycle. As mentioned previously, the benefits of establishing a strategic methodology for work 

zone analysis are much greater than what could be achieved through the deployment of a number of 

components operating in isolation. Thus, strengths and weaknesses of strategic methodologies that 

utilize more generalized transportation analysis tools (e.g., sketch-planning and HCM) to screen 

projects for issues and then commit to more detailed transportation analysis tools are contrasted 

against other strategic methodologies where one (or more) transportation analysis tools are initially 

developed in detail in the Planning stage and utilized consistently as the project evolves. Three 

general strategic methodologies are presented in Figure 10 and described below:

	Mono-Scale—The mono-scale methodology features a single transportation analysis tool 

applied consistently throughout the project life-cycle. This is represented by the single bar 

in the figure. Michigan DOT’s SEMSIN is an example of a Mono-Scale methodology. 

	Screening—The screening methodology utilizes a series of transportation analysis tools 

throughout the project life-cycle, in an attempt to match the best transportation analysis tool 

to the specific decision being supported. This is portrayed by the vertically segmented bar 

in the figure with each segment representing a different transportation modeling approach 

being used based upon the project life-cycle stage. The Wisconsin DOT: Transportation 

Management Plan Development Process is an example of a Screening methodology. 

	Multi-Scale—The multi-scale methodology involves the deployment of multiple 

transportation modeling approaches in an integrated and strategic way to support decision 

making throughout the project life-cycle. This is portrayed by the horizontally segmented 

bar in the figure with each segmented representing a modeling approach to be used 

based upon the need rather than the project life-cycle stage. The Woodrow Wilson Bridge 

Reconstruction is an example of a Multi-Scale methodology. 

Just as no single transportation analysis tool is right for all work zone analyses, no single work 

zone analysis methodology represents the single best match for all projects. Sections 3.1 through 

3.3 provides discussion about the strengths and weaknesses of these various strategies relative 

to the analysis factors (primarily the agency resources and performance measures) discussed in 

Section 2.0. 
54

Figure 10 Comprehensive Work Zone Analysis Methodologies

3.1 Mono-Scale

The mono-scale methodology features a single transportation analysis tool applied consistently 

throughout the project life-cycle. The advantage of this methodology is that model consistency 

is essentially guaranteed throughout the project life-cycle. Resources invested in developing the 

tool and its supporting data are passed along as the project proceeds. The disadvantage of this 

methodology is that a single tool may be well-suited to support some types of decisions but not 

well-suited to others. For example, a mono-scale methodology using microscopic simulation 

of the immediate work zone area may capture detailed elements of traffic control (work zone 

geometry and traffic signal operations) but have only limited capability to predict impacts 

from diversion on parallel routes. A mono-scale methodology may be an attractive option if a 

calibrated, well-maintained model of the work zone impact area is already in hand. If there is not 

a good match between the transportation modeling approach and model type in-hand, and there 

are some resources in hand to extend or enhance the analysis, a multi-scale methodology can be 

considered.

S

A TMP

S

A TMP

Planning

Mono-scale

Screening

Multi-scale

PE/Design Construction
55

Michigan DOT: Southeastern Michigan Simulation Network

Development of Michigan DOT’s SEMSIM Network was undertaken, in part, to 

leverage the up-front costs associated with developing a microscopic simulation 

network across multiple projects as well as multiple stages within the project lifecycle. The Michigan DOT Detroit Metro Region expended lots of resources (both 

time and money) in developing the initial application of the SEMSIM Network for the 

Ambassador Gateway Bridge MOTSIM during the PE/Design stage and will continue 

to use the network as needed during construction. The same network was expanded 

to use for two other projects, I-75 Trade Corridor and I-94 Rehab, which are in the 

Planning and PE/Design stages, respectively. More information can be found in the 

Michigan DOT: Southeastern Michigan Simulation Network case study.

3.2 Screening

This methodology is characterized by the use of simpler tools using archived data to screen work 

zone projects to determine which may warrant more in-depth analysis. This concept has been used 

to allocate resources for work zone analysis when looking across a number of projects to identify 

potential mobility impacts. For single projects this includes the use of simpler transportation 

modeling approaches such as sketch-planning and HCM in early project phases and the use of a 

more complex transportation modeling approaches (if warranted) later in the project.

The advantages of this methodology include the focusing of agency resources (institutional, 

financial, and technical) on projects or issues that have the most potential mobility impact. It 

can be difficult early in project development or when looking across many projects to accurately 

identify where significant congestion is likely to be induced by work zone activity. The screening 

method allows for a uniform method to find the locations, times, and projected impacts as early 

as possible so these issues can be dealt with before the work zone decision engine has generated 

significant momentum.

The disadvantage of this methodology is that the high-level screening transportation analysis tools 

used in earlier stages may not produce consistent predictions of impacts with more detailed tools 

used in later stages. The detailed analysis in later stages may reveal a nuance to the problem 

that may be contradictory to the direction the analysis with the screening tool has directed the 

decision engine. For example, using archived data in the planning stage, a screening tool may 

indicate that mid-day lane closures will not result in congestion. Thus, scheduling and application 

decisions later made in the PE/Design stage may count on a 4-6 hour window for mid-day work 

zone activity. However, a more detailed analysis with field traffic counts (e.g., travel demand data) 

collected specifically for the project in the PE/Design stage could indicate that unacceptably long 

delays are likely to result from mid-day lane closures.
56

Wisconsin DOT: Transportation Management Plan Development Process

The Wisconsin DOT has established a screening approach in order to provide traffic 

engineers and planners in the various regional offices guidance on the selection of 

an appropriate transportation modeling approach. The screening approach developed 

by Wisconsin DOT is used to filter through those projects requiring more in-depth 

analysis (what they classify as Type IV and III work zones). If a project does require 

in-depth analysis (typically the use of microcopic or mesoscopic simulation tools) then 

a secondary model scoping worksheet is employed to further determine data needs and 

requirements. 

To further reinforce the use of overall work zone analysis and the application of 

transportation models throughout the project life-cycle, Wisconsin DOT developed a 

training course which includes an exercise in applying transportation analysis models 

for a simple bridge replacement project beginning in the planning stage.

More information can be found in the Wisconsin DOT: Transportation Management 

Plan Development Process case study.

3.3 Multi-Scale

This methodology deploys several tools in combination from project planning through 

construction, and any inconsistencies between models are identified and resolved throughout 

the process. This type of methodology is effective for looking at a complete range of issues 

using the most appropriate tool with the added value of cross-validation among tools and data 

types. The disadvantage of this methodology is that the agency resources (the technical staff, 

funding, and scheduling) are significant as well as the required data (specifically its quality and 

availability). This type of methodology is likely to be deployed only on the largest projects with 

a large work zone impact area, longer duration, and significant resources devoted to mobility 

impacts mitigation.
57

Woodrow Wilson Bridge Replacement

Planning for the reconstruction of the Woodrow Wilson Bridge began in the 1990s 

with record of decision on the locally preferred alternative made in November 1997. 

Construction began in October 2000 with final design completed in June 2003. 

Construction of the bridge is planned to be completed in December 2009. All throughout 

this time, transportation models were being used for both the design of the facility itself 

as well as the design of the work zones to be implemented as part of the construction. 

The use of transportation models for work zone analysis primarily occurred during 

the construction stage as refinements to the staging of the various work zones were 

required. During this time, the transportation consultants used a variety of modeling 

approaches depending upon the requirements of the TMP, available data, and required 

performance measures. More information can be found in the Woodrow Wilson Bridge 

Replacement case study.
58

4.0 Identifying a Transportation Modeling Approach for Work

Zone Analysis

The preceding two sections provided a detailed overview of the factors that influence the 

development of a transportation modeling approach and three strategic methodologies applied to 

maximize value from work zone analyses. Once an analyst has a better understanding of the factors 

influencing an overall work zone analysis, the next step is to consider two critical questions:

1) Does it make sense to move forward with work zone analysis for a given project?

2) What criteria should be used to select an actual modeling approach for a project?

The following two sub-sections discuss each of these questions in more detail. Section 4.1, Deciding 

to Analyze or Not Analyze, provides a framework to better understand the technical risk and 

rewards associated with ultimately deciding to deploy a transportation modeling approach. Section 

4.2, Characterizing Case Studies by Transportation Modeling Approach, uses the same framework 

to classify the transportation modeling approaches utilized in the selected work zone analysis case 

studies. Finally, Section 4.3, Developing a Transportation Modeling Approach, provides a set of 

worksheets to guide an analyst in developing an appropriate transportation modeling approach and 

strategic methodology. 

4.1 Deciding to Analyze or Not Analyze

In order to better understand which work zones warrant analysis, and to what extent, an analytical 

work zone decision framework was created. Figure 11 provides a notional representation of 

this framework for the work zone analyst considering the complex tradeoff between analytical 

opportunity and technical risk. Managing these two concepts is based on two high-level 

considerations shown on the two axes of Figure 11 the level of detail required to support decisionmaking on the X-axis (Level of Detail), and resources available to conduct a work zone analysis 

on the Y-axis (Resource Availability). The axes were developed based upon the five categories of 

work zone analysis factors discussed in Section 2.0 whereby resource availability incorporates 

data and agency resources, and level of detail incorporates work zone characteristics, desired TMP 

strategies, and required work zone performance measures. Effectively managing this tradeoff 

between analytical opportunity and technical risk is one of the most important responsibilities of the 

work zone analyst. Failure to realistically account for technical risk is the most frequent underlying 

issue when analytical efforts fail to meet the expectations of both analysts and decision-makers. 

This failure can manifest itself in failure to meet schedule, budget overrun, or an abandonment of 

the technical approach even after the expenditure of significant agency resources. 

 
59

Figure 11 Analytical Work Zone Decision Framework

As seen in Figure 11, when significant data and staff resources are available, there are many more 

options in matching a transportation modeling approach with the decisions to be supported. When 

resources are limited, however, the analyst must consider whether a less detailed analysis using a 

simpler tool is adequate to the requirements of the analysis. If the mis-match between the necessary 

level of detail and resource availability is high enough, the corresponding technical risk may be so 

high that a drastic re-consideration of modeling approach may be appropriate. 

In some cases, the technical risk of attempting to conduct a work zone analysis with little reliable 

data or too few resources may outweigh the benefits of conducting it. In these cases, there is 

a risk that rushed or poorly-informed work zone analyses will provide highly inaccurate or 

misleading assessments of mobility impacts. Such analyses are to be avoided, since they not only 

represent a waste of project resources, but also because they may entrench institutional mistrust of 

transportation analysis tools and analytical results, even in cases where well-calibrated models do 

provide meaningful results.

4.2 Characterizing Case Studies by Transportation Modeling Approach

The decision about what transportation modeling approach to select for a work zone analysis is 

secondary to the decision to deploy a transportation modeling approach at all. However, once the 

decision is made to use a transportation analysis tool, the question turns to which tool is best suited 

given my circumstances? The difficult part is balancing the available resources (time, money, 

data, etc.) with the desired level of detail (e.g., ability to model one-lane/two way operations using 

historic traffic counts for a Type I project). 

Resource

Availability

Level of Detail

Modelig Opportunities

Signicant Technical Risk

Low High

High
60

Given the fact that each work zone analysis will be different, developing a comprehensive 

checklist or decision-tree will never be adequate enough in selecting “the right tool”. However, 

the case studies included in this document illustrate generally successful examples of managing 

technical risk as a part of an overall modeling approach. Using the Analytical Work Zone Decision 

Framework discussed previously, all of the 13 project application case studies and two of the 

strategic modeling case studies were placed on the framework to indicate how each ranked in 

terms of level of detail needed (low-medium-high) and available resources (low-medium-high). 

As shown in Figure 12, what the case studies reveal is a diverse mix of transportation modeling 

approaches based upon the level of detail needed and available resources. 

Figure 12 Analytical Work Zone Decision Framework—Case Studies

From these case studies, a number of clusters can be created based upon the modeling approach 

chosen. These clusters are shown in Figure 13 and characterize the modeling approaches observed 

across the case studies based upon relative availability of resources and required detail for analysis. 

Figure 13 should not be considered specific recommendations but rather a reflection of the diversity 

of approaches developed by the analysts across the case studies. The transportation modeling 

approach clusters are highly consistent with the work zone modeling spectrum presented in Figure 

1. As one moves along the modeling boundary bisecting the areas of significant technical risk 

and modeling opportunities, the complexity of the transportation modeling approaches increase. 

When both resource availability and the level of detail needed are low, the most appropriate 

transportation modeling approaches are likely to be sketch-planning and HCM methodologies. 

As resources increase, the available transportation modeling approaches increase and include 

Resource

Availability

Level of Detail

Signicant Technical Risk

Low High

High

ZION

NS-Reeves YOS

WWB-LCA

WWB-RCA

WWB-ROA

CA I-15

UT I-15

Wisconsin

WisDOT

MI I-94

MI AMB

MI I-75

GNP

New Jersey Turnpike

Authority: LCA
61

macroscopic models for pipe network forms and travel demand models for those analyses with a 

grid network form. As the requirement for detail increases, the available transportation modeling 

approaches shift to mesoscopic and microscopic modeling tools. Mesoscopic applications include 

both pipe and network forms. Microscopic modeling tools are applied alone or as a part of a multiscale approach, where the model is designed to be used strategically throughout the project lifecycle in conjunction with other tools.

Resource

Availability

Level of Detail

Signicant Technical Risk

Low High

High

Sketch Plannig

and HCM

Macroscopic

(Pipe)

Microscopic

Microscopic

(Multi-scale)

Mesoscopic

(Pipe)

Mesoscopic

(Network)

Travel Demand Model

(Network)

Figure 13 Analytical Work Zone Decision Framework—Modeling Approaches

4.3 Developing a Transportation Modeling Approach

The preceding two sections established a strategic framework which can be used identify a 

specific transportation modeling approach. Some analysts, however, would like a tool to assist 

with identifying an appropriate transportation modeling approach and strategic methodology. To 

that end, the following two worksheets were developed to provide an analyst with a tool to conduct 

a detailed assessment of a work zone analysis project and ultimately identify a transportation 

modeling approach and strategic methodology. These worksheets are intended to be used as a 

tool to guide an analyst and should not be considered the final decision in choosing a specific 

transportation modeling approach. In other words, this is an additional input into the overall 

decision-making process. 

The two worksheets are discussed below and include instructions for filling each out. Using the 

worksheets requires the analyst to have read through this document and have a good understanding 

of a work zone analysis project. 
62

Work Zone Analysis Scoping Worksheet Instructions

The scoping worksheet should be used to document the various components of a work zone 

project that need to be analyzed using a transportation analysis tool. The scoping worksheet 

is based primarily upon Section 2.0, Work Zone Analysis Factors. The following instructions 

provide more detail on how to fill-in the scoping worksheet.

1. Key Decisions—List the Key Decisions that need to be supported using the transportation 

modeling approach. References on the importance of articulating key decisions to be 

supported: 

	Section 1.2, Work Zone Analysis Decision Making

2. Work Zone Charcteristics—Identify the Type, Network Configuration, Size, and Analysis 

Area Dimension of your work zone analysis project. Refer to Section 2.1 for more 

information on definitions.

3. Agency Resources—Under each heading mark the following and refer to Section 2.4 for 

more information on definitions:

a. Institutional: Circle those institutional categories which have been addressed by 

your agency.

b. Technical Staff: Circle whether the technical expertise to run the transportation 

analysis tools resides in-house, via consultant or both.

c. Funding: Indicate the amount of funding available. 

$ = $10,000 and $ = $100,000

d. Time to Analyze: Circle the amount of time available to conduct the analysis

short = Less than 2 months

medium = 3 months to 6 months

long = Greater than 6 months

4. Performance Measures

a. Measures of Effectiveness: Fill in each circle based upon the classification system 

indicated. Refer to Section 2.5 for more information and definitions.

b. Precision of Results: Indicate on the bar whether the Key Decisions that need to be 

supported are either a rough estimation or a detailed assessment. 

5. Data—Indicate the following and refer to Section 2.3 for more information and definitions.

a. Type: Indicate availability.

b. Source: Indicate which data is available through archived or primary sources.

c. Quality: Indicate availability.

6. Transportation Management Plan Strategies—Indicate which transportation management 

plan strategies need to be included in the analysis based upon the classification system 

indicated. Refer to Section 2.2 for more information and definitions.

7. Fill-in Scoring Worksheet
63

Work Zone Analysis Scoring Worksheet Instructions

The scoring worksheet should be used after the scoping worksheet has been filled in. The following 

instructions provide more detail on how to fill-in the scoring worksheet.

1. Develop a Transportation Modeling Approach—This table should be filled in using the 

classification system indicated in the bottom left corner of the table. Each heading refers 

to a certain work zone factor from this document (Section 2.0) the analyst will need to 

reference in order to indicate whether the transportation modeling approach is appropriate. 

Based upon the scoping worksheet, the analyst should fill out each cell after reviewing the 

discussion and summary table for each section. The following provides a reference to the 

sections in the document:

a. Work Zone Characteristics: Section 2.1 Work Zone Characteristics

b. Agency Resources: Section 2.4 Agency Resources

c. Performance Measures: Section 2.5 Work Zone Permance Measures

d. Data: Section 2.3 Data

e. Transportation Management Plan: Section 2.2 Transportation Management Plan 

Strategies

2. Summary—Once each of the cells for each work zone factor is filled in, the analyst should 

provide an overall ranking (using the same classification system as in Step 1 above) for 

each transportation modeling approach. The analyst should rely on visual inspection of the 

results to indicate whether the transportation modeling approach is appropriate or not.

3. Identify a Strategic Methodology—This section asks three basic questions regarding the 

work zone analysis to assist the analyst in identifying one of the three Strategic Methodologies 

discussed in Section 3.0 Establishing a Strategic Methodology for Work Zone Analysis

4. Answer—Once the three previous steps have been completed both a Transportation 

Modeling Approach and Strategic Methodology should become evident. The space 

provided in the Answer section should be used to describe and justify the analyst’s reason 

for choosing each.
64

 What key decision are you supporting?

Work Zone Characteristics

Select One for Each Category

Agency Resources

Type I / II / III / IV Institutional culture / leadership / data / contracting

Network Configuration isolated / pipe / grid Technical Staff consultant / in-house

Size small / medium / large Funding $ $ $ $ $ $ $ $ $ $ $ $ $

Analysis Area Dimension site / local / metropolitan Time to Analyze short / medium / long

Performance Measures = Key Performance Measure; = Secondary; = Not Important 

Travel Time  Volume 

Delay  User Cost 

Queue Length  Incidents 

Speed  Cumulative Impacts 

Precision of Results

rough estimation detailed assessment

Data

 Availability Notes

Type

Roadway Characteristics

Travel Demand Characteristics

Cost Attributes

Source

Primary

Archived

Quality

Collection Frequency

Geographic Coverage

Archive Length

Accuracy

Transportation Management Plan Strategies Key TMP Strategy; Minor TMP Strategy; TMP Strategy Not Considered

Temporary Traffic Control Public Info. Transportation Operations

Control Strategies Traffic Control 

Devices Project Innovation Motorist Information

Demand Mgmt 

Strategies

Corridor/Network 

Mgmt Strategies

Work Zone Safety 

Mgmt

Traffic/Incident 

Management

Construction phasing/ 

staging

Full roadway closure

Lane shifts or closures

One-lane, two way 

operations

Two-way traffic on one 

side of divided facility

Reversible lanes

Ramp closures/ 

relocation

Freeway-to-freeway 

interchange closures

Night work

Weekend work

Work hour restrictions 

for peak travel

Off-site detours/use of 

alternate routes

Changeable message 

signs

Flaggers and uniformed 

traffic control officers

Temporary traffic 

signals

Project Coordination

Contracting Strategies

Innovative construction 

techniques

Changeable message 

signs

Dynamic speed 

message sign

Highway advisory radio

511 traveler information 

systems

Transit service 

improvements

High-occupancy vehicle 

lanes

Toll/congestion pricing

Ramp metering

Signal timing/ 

coordination

Temp. traffic signals

Street/intersection 

improvements

Bus turnouts

Turn restrictions

Separate truck lanes

Reversible lanes

Ramp metering

Temporary suspension 

of ramp metering

Ramp closures

Coordination with 

adjacent construction 

sites

Speed limit reduction/ 

variable speed limits

Temporary traffic 

signals

ITS for traffic Monitoring

Transportation 

management center

Tow/freeway service 

patrol

Local detour routes

Work Zone Analysis Scoping Worksheet

In the space adjacent to the circle, note any key policy 

requirements associated with the performance measure.
65

Work Zone Analysis Scoring Worksheet

Develop a Transportation Modeling Approach

Sketch-Planning 

and HCM 

Methodologies

Travel Demand 

Models

Traffic Signal 

Optimization

Macroscopic 

Simulation

Mesoscopic 

Simulation

Microscopic 

Simulation

Work Zone Characteristics

Type

Network Configuration

Size

Analysis Area

Agency Resources

Institutional

Technical Staff

Funding

Schedule

Performance Measures

Travel Time

Delay

Queue Length

Speed

Volume

User Cost

Incidents

Cumulative Impacts

Data

Type

Source

Quality

Transportation Management Plan

Control Strategies

Traffic Control Devices

Project Innovation

Motorist Information

Demand Mgmt Strategies

Corridor/Network Management 

Work Safety Management

Traffic/Incident Management

SUMMARY

= Transportation modeling approach address work zone factor.

= Transportation modeling approach may or may not address work zone factor.

= Transportation modeling approach does not address work zone factor.

Identify a Strategic Methodology

Where are you in the project life-cycle?

Planning Multi-scale or Screening

PE/Design Multi-scale or Screening

Construction Mono-scale

Are there other key decisions that will need to be made?

Yes Multi-scale or Screening

No Mono-scale

Is there uncertainty in the scale of the work zone type?

Yes Screening

No Multi-scale or Mono-scale

Answer

Describe your transportation modeling approach below. Provide justification from the analysis above.
66

5.0 Summary and Synthesis

The intent of this work zone modeling and simulation guide for analysts is to provide practical 

guidance on the identification and development of a transportation modeling approach for work 

zone analysis. The guidance is grounded in a detailed understanding of the key work zone factors 

in developing a transportation modeling approach (Section 2.0). This understanding is considered 

jointly with a strategic methodology for work zone analysis (Section 3.0). These two elements 

provide the foundation for a worksheet-driven exercise to assist the analyst in the development 

of transportation modeling approach for a specific work zone analysis project (Section 4.0). 

Throughout this process, a series of case study examples were used to illustrate how analysts 

have successfully identified modeling opportunities, mitigated technical risk, and conducted 

work zone impacts analyses to support key decisions across a range of considerations, including 

constructability, scheduling and TMP design, and evaluation. 

What the preceding discussion and case study examples demonstrate is that work zone decisionmaking is an evolutionary process. Any work zone analysis should be linked to a specific decision 

with the knowledge that decisions made early in the project life-cycle have a large impact on 

future decisions. Placed within the context of analyzing work zone impacts, the further along in 

the project life-cycle one is, the lower the relative opportunity for transportation models to have a 

role in supporting the decision-making process. As seen in Figure 14 below, the decision-making 

evolution process combines the work zone decision-making process along with the work zone 

decision-making engine. Below it, represented by two polygons, are the tradeoffs that are made 

between modeling opportunities and data requirements as the decision-making process evolves 

over time.

Figure 14 Work Zone Decision-Making Engine Process

In the end, the options available to an analyst in deploying a transportation modeling approach 

decrease as more decisions are made regarding application techniques, scheduling, and TMP 

strategies. For example, once planning is complete and the decision to conduct a full-closure has 

Planning

Decision Evolution

Modeling Opportunities

PE/Design Construction

Data Requirements

S

A TMP

S

A TMP

S

A TMP
67

been made, the use of a transportation modeling approach to help mitigate the mobility impacts 

is limited in that the decisions to be supported are much narrower. However, as seen in many of 

the case studies, the use of a transportation analysis tool may still be warranted regardless of the 

project life-cycle stage.

5.1 Key Points

TAT Volume IX highlighted four key points that are important to consider when an analyst is 

deciding upon which transportation modeling approach to ultimately develop and use:

	Work zone decision-making is an evolutionary process which supports a number of key 

questions to be answered.—As seen in Figure 14 and discussed throughout this document, 

work zone analysis evolves over time as the roadway construction project moves forward 

from Planning to PE/Design to Construction and key decisions need to be supported. For 

example, during the planning stage, the work zone analysis may focus on numerous TMP 

alternatives and the key question is centered upon which alternatives are feasible given 

certain criteria. Later, a new set of questions may need to be answered that places more 

constraints on the feasible list of TMP alternatives (e.g., available funding or political 

pressure). Thus, as the overall project moves forward it is always evolving and the use of a 

transportation modeling approach is always predicated on certain key decisions that have 

to be made. 

	Data requirements are a driving force behind developing a transportation modeling 

approach—Section 2.0 provides a detailed discussion of the many different factors that 

need to be considered when selecting a transportation modeling approach. For example, 

selecting an approach may be constrained by agency resources in terms of budget and 

staff resource. Or, the tool selection may be driven by the utilization of a cutting-edge 

TMP strategy such as variable speed limits through a work zone which requires a detailed 

vehicle-based evaluation. Regardless, it is a complex issue to unravel. However, what each 

of these examples shows is that data requirements are an important factor to consider. As 

seen in Figure 14 above, data requirements increase as the project evolves from planning to 

construction thereby placing constraints on the use of a transportation modeling approach. 

Thus, as the project evolves and different questions need to be answered, so too will 

different data need to be used/collected which may create both constraints and opportunities 

in developing a transportation modeling approach. 

	Identifying a Strategic Methodology early in the project life-cycle can mitigate future 

work zone analysis problems—As discussed in Section 3.0, three strategic methodologies 

were presented representing various modeling opportunities for work zone analysis: 

mono-scale, screening, and multi-scale. These methodologies serve as a foundation on 

which transportation modeling approaches could be incorporated into the overall work 

zone decision-making framework. As shown in the Figure 14, the opportunity associated 

with choosing a transportation modeling approach is much greater early on in the 

project life-cycle. For example, during the planning stage relatively few decisions have 

been made and the availability and use of a transportation analysis tool are fairly large. 

This is in contrast to the construction stage at which time the application technique, 
68

scheduling, and TMP have been finalized and the opportunity to select a transportation 

analysis tool and for it to generate useful information are much more limited. However, 

by identifying a strategic methodology in the beginning of the project life-cycle, the work 

zone analysis opportunities do not necessarily decrease over time but rather grow as the 

model can be leveraged and applied to more work zone analyses as warranted or needed.

	Developing a transportation modeling approach is unique to each work zone analysis—

While many people desire a prescriptive “cookbook” method to direct them in determining 

which transportation modeling approach to use, making that determination based solely 

upon one particular factor is problematic. What this document demonstrates is that there 

are many factors that go into developing a transportation modeling approach. For example, 

the Woodrow Wilson Bridge, a Type I work zone, used both simple HCM methodologies 

and complex microscopic simulation tools. Thus, the use of the worksheets developed in 

Section 4.0 are intended as a tool to guide analysts and provide a framework with which 

to better conceptualize and address the complexities associated with conducting a work 

zone analysis. Some agencies have developed specific procedures to guide the analyst 

in the development of an appropriate modeling approaches (such as the Wisconsin DOT 

Transportation Management Plan Development Process discussed in the case study), and 

these systematic approaches can both speed the modeling approach development process 

as well as ensure consistency when different staff consider projects independently. 

5.2 Where Do I Go from Here?

Ultimately, the questions for many analysts boils downs to which transportation analysis tool should 

I use? Where do I get the data from? And, how do I overcome my institutional issues? These are 

difficult questions to answer and it is not the intent of this document to specifically address them 

given that each circumstance is unique. However, the following provides some direction on where 

one can turn to for help. 

	Individual Transportation Analysis Tool Resources—It is not the intent of this document 

to provide guidance on the use or application of any one specific transportation analysis 

tool. Rather, this guidance is intended to help an analyst identify a certain transportation 

modeling approach for work zone analysis. There are many unique transportation analysis 

tools available under each modeling approach. Often, these tools are constantly changing 

as capabilities are added as well as being routinely updated and tweaked. Also, new tools 

become available on a regular basis. Recently, many commercial vendors have begun 

offering hybrid models that span more than one class of tools such as mesoscopic models 

that also operate on the microscopic level. For more information on using an individual 

transportation analysis tool refer to the following:

	FHWA Traffic Analysis Toolbox (TAT): The Traffic Analysis Tools Program was 

formulated by FHWA in an attempt to strike a balance between efforts to develop 

new, improved tools in support of traffic operations analysis and efforts to facilitate 

the deployment and use of existing tools. The TAT provides a detailed description of 

traffic modeling tools.

http://ops.fhwa.dot.gov/trafficanalysistools/index.htm.
69

	McTrans: Centeter for Microcomputers in Transportation (McTrans) serves as a 

resource for the distribution and support of microcomputer software in the highway 

transportation field. McTrans provides expert technical advice, information exchange 

and a wide range of transportation-related software at very reasonable costs. 

http://mctrans.ce.ufl.edu/

	Data Collection—Data collection is routinely cited as a barrier to using transportation 

modeling. As the expression goes: “garbage in, garbage out”. With the increasing use of 

sensors located throughout the transportation system, the ability to cost effectively collect 

traffic data has increased. Often, much of the required data has probably already been 

collected and simply requires contacting another department within the agency. Some 

examples are as follows:

	Many transportation agencies have permanent count stations on Interstate and arterial 

roadways from which traffic count data is routinely collected, cleaned, and archived. 

A case in point is the Minnesota Department of Transportation Traffic Forecasting 

& Analysis unit which makes its data available on its website (http://www.dot.state.

mn.us/traffic/data/html/traffic.html). 

	Another opportunity for data collection is the use of portable traffic counters. The 

Federal Lands Highway Division purchased a number of counters for the sole 

purpose of data collection for transportation modeling. See the Yosemite National 

Park: Yosemite Village Roadway Reconstruction case study for more information.

	For major roadway reconstruction projects the use of real-time monitoring may yield 

useful data. This occurred as part of the Woodrow Wilson Bridge project where a 

traffic data collection effort was undertaken to establish a formalized process for 

collecting and archiving traffic data as part of the project for use in future studies 

and analyses. See the Woodrow Wilson Bridge Reconstruction case study for more 

information.

 

	Addressing Institutional and Policy Issues—Institutional polices can often be a significant 

driver in developing a transportation modeling approach. The discussion on Institutional 

Arrangements (Section 2.4.1) lists four areas general areas that can impact transportation 

modeling: culture, leadership, data management, and contracting. Many progressive 

transportation agencies have addressed these areas and the FHWA has available numerous 

resources addressing the subject. Another institutional area that needs to be addressed is 

work zone policies that have been created. For example, many agencies now have restrictions 

on lane closures in work zones, available work hours, maximum user delay, etc. These 

policies, created by the transportation institutions, have an impact on the overall usefulness 

of a transportation modeling approach. For example, a policy limiting the maximum user 

delay may negate the results of a model that demonstrate a larger maximum user delay for 

a shorter duration is a better choice overall for a construction project. While many of these 
70

policies are developed with good intentions, the use of a transportation analysis tool may 

contribute to the development a more refined approach. For more information on work 

zone policy issues refer to the following FHWA material concerning the Final Rule on 

Work Zone Safety and Mobility: 

	Implementing the Rule on Work Zone Safety and Mobility (HTML, PDF)—

Provides a general overview of the Rule, as well as guidance, examples, best practices, 

tools, and resources to help implement the Rule’s provisions.

	Work Zone Impacts Assessment: An Approach to Assess and Manage Work 

Zone Safety and Mobility Impacts of Road Projects (HTML, PDF)—Provides 

guidance on developing procedures to assess and manage work zone impacts of road 

projects, as well as examples and practices of how agencies are currently assessing 

and managing work zone impacts.

	Developing and Implementing Transportation Management Plans for Work 

Zones (HTML, PDF)—Provides information about developing and implementing 

Transportation Management Plans (TMP), including information on how and where 

a TMP fits into project-level processes and procedures, a list of components that 

can be considered for inclusion in a TMP, descriptions of work zone management 

strategies, and examples and practices of how agencies are currently using TMPs. 

	Work Zone Public Information and Outreach Strategies (HTML, PDF)—Provides 

tips, examples, and practices on designing a public information and outreach campaign 

for work zones and offers a variety of strategies that can be used in a campaign.
71

References

(1) Federal Highway Administration, Work Zone Modeling and Simulation: A Guide for 

Decision-Makers. 2008.

(2) Federal Highway Administration, Traffic Analysis Toolbox, Volume 1: Traffic Analysis 

Tools Primer. 2004.

(3) Federal Highway Administration, Work Zone Impacts Assessment: An Approach to Assess 

and Manage Work Zone Safety and Mobility Impacts of Road Projects. 2006.

(4) Federal Highway Administration, Developing and Implementing Transportation 

Management Plans for Work Zones. 2005.
72

Case Studies

1. Caltrans I-15 Pavement Reconstruction Project

 

2. Glacier National Park: Going to the Sun Road Rehabilitation Project

3. Maryland SHA Lane Closure Analysis Program

4. Michigan DOT: Southeastern Michigan Simulation Network

i. Ambassador Gateway Bridge MOTSIM

ii. I-94 Rehab MOTSIM

iii. I-75 Trade Corridor MOTSIM

5. New Jersey Turnpike Authority: Lane Closure Application

6. Nova Scotia, Canada: Reeves Street

7. Utah DOT I-15 Reconstruction Design-Build Evaluation

8. Wisconsin DOT Work Zone Signal Optimization

9. Wisconsin DOT: Transportation Management Plan Development Process

10. Woodrow Wilson Bridge Reconstruction

i. Lane Closure Analysis

ii. Roadway Operations Analysis

iii. Roadway Closure Analysis

11. Yosemite National Park: Yosemite Village Roadway Reconstruction

12. Zion National Park: Entrance Booth Reconstruction
73

California Department of Transportation

I-15 Pavement Reconstruction Project4

Work Zone Characteristics 

Transportation Analysis:

Approach Sketch-Planning

Mesoscale

Modeling Tools CA4PRS

HCM

DynamEq

Work Zones:

Type Type II

Network Configuration Pipe

Geographic Scale: 

Work Zone Size Medium

Analysis Area local

Overview

The I-15 Pavement Reconstruction project (began construction in October 2008) will improve a 

four-mile stretch of I-15 near the interchange with I-10 in Ontario, California (referred to as the 

I-15 Ontario corridor). The reconstruction will rebuild two to three truck lanes in each direction, 

replacing damaged concrete slabs and base pavements with new concrete slabs using Rapid Strength 

Concrete (RSC) and new Asphalt Concrete (AC) base. Currently, this section of I-15 includes four to 

six lanes in each direction and carries an AADT of approximately 200,000, with a particularly high 

percentage of heavy truck traffic (about 12 percent on average on weekdays). In addition, the I-15 

Ontario corridor has consistently high weekday commuter peaks and similar volumes on weekends 

due to leisure travelers from Los Angeles headed to and from Las Vegas and resort locations along 

the Colorado River. The project scope and study area are shown in Figure 15. 

4

 This case study was adapted from the reports: I-15 Pavement Reconstruction Project: Construction Operational 

Analysis prepared by Cambridge Systematics, June 7, 2007; Pre-Construction Analysis and Construction Staging Plan 

for The I-15 Ontario Pavement Reconstruction Project prepared by EBL Consulting and RBF Consulting, October 

2006; and TAT Volume VII: Predicting Performance with Traffic Analysis Tools: Case Studies to be published in 2008.

Caltrans I-15 Pavement Reconstruction Project
74

Figure 15 I-15 Pavement Reconstruction Analysis Area

Caltrans gave the preliminary notice to proceed with the design and analysis of the project in 

December 2004 after an extensive planning process. During the design stage, the integrated preconstruction analysis was to help Caltrans compare all feasible scenarios for the I-15 Ontario project 

and select the best approach in terms of production schedule, traffic delay, and total cost. To that 

end, Caltrans employed the use of three traffic modeling tools including the Construction Analysis 

for Pavement Rehabilitation Strategies (CA4PRS), Highway Capacity Manual Demand-Capacity 

Model (HCM), and the DynamEq mesoscopic traffic network analysis tool. The use of CA4PRS 

and HCM represent Phase I of the preconstruction analysis whereby six alternative construction 

scenarios were analyzed. The use of DynamEq represents phase II of the pre-construction analysis 

which entailed the development of traffic management plans. This process is shown in Figure 16.

Caltrans I-15 Pavement Reconstruction Project
75

Closure

Schedule

CA4PRS

Duration

Timing

Traffic

Delay

DemandCapacity

RUC

Queues

Economic

Evaluation

Total Cost

Selected

Scenario

Value

Analysis

PSSR

Alternatives

Scope

Traffic

Simulation

Macro/Micro/

Masoscopic

Network Impact

TMP

PS&E Package

Construction

Staging-plan

Bid-proposal

Contract

Construction

Traffic Monitor

Lessons -Learned

Database

Future

Implementation

Lane Closure

Review Committee

Presentation

Phase I

Phase II

Budget

Approval

Figure 16 I-15 Analysis Process

The following sections will provide more detail on the use CA4PRS, HCM and DynamEq in the 

two phases of the pre-construction analysis.

Phase I: Preconstruction Analysis

In the Phase I analysis, six construction scenarios were developed and analyzed using the CA4RPS 

tool in order to compare number of closures and the HCM to quantify queues and delay costs. The 

results of these two traffic models were included in an overall cost estimate analysis to determine 

the most appropriate construction scenario in terms of construction scheduling, impact on drivers 

and project costs. The following six construction scenarios were analyzed:

	Median widening (Original scheme) 

	Value Analysis (VA) By-pass (eventually eliminated from overall analysis) 

	Rapid Rehab (55-hour Weekend) 

	Rapid Rehab (Continuous Progressive) 

	Traditional nighttime (PCC slab replacement) 

	Crack-Seat and AC overlay 

Closure Assessment:CA4RPS—The CA4PRS was employed because it easily evaluates “what 

if” scenarios for highway rehabilitation in order to identify solutions that balance on-schedule 

construction production, traffic inconvenience, and agency costs. In addition, the CA4PRS 

Caltrans I-15 Pavement Reconstruction Project
76

results are easily integrated with various traffic simulation tools for quantifying road user costs 

during construction. This feature helped the project team determine rehabilitation strategies 

that maximize production and minimize inconvenience to the public. Caltrans collected data 

for the I-15 CA4RPS analysis using previous analyses of similar projects from around the state 

including I-10 Pomona, I-710 Long Beach and I-15 Devore. Results of the CA4RPS included 

the total number of closures as listed in the column labeled Number of Closures in Table X.

Traffic Analysis: HCM— The impacts of construction work zone closures analyzed using 

the CA4RPS on freeway traffic were quantified using the HCM Demand-Capacity Model. The 

model was created in Microsoft Excel based upon the methodology articulated in the HCM. 

First, total and maximum delays were calculated with variable traffic demand reduction by 

percentage and work zone roadway capacity. Second, road user cost (the time value of travelers 

adjusted by an annual growth factor) was estimated based on the calculated vehicle-delay 

hours during construction for each scenario. Finally, the California Freeway Performance 

Measurement System (PeMS) was used to estimate traffic demand. The results of this analysis 

(which included various sensitivity analyses) included two values: road user cost (RUC) and 

maximum roadway user delay per person. These results are listed in Table 6.

Cost Analysis—A typical construction cost analysis was conducted for each of the scenarios 

that did not include any type of traffic modeling component.

Results from the Closure Assessment, Traffic Analysis and Cost Analysis are listed in Table 6. 

As can be seen in the results, the outputs from the Closure Assessment, Traffic Analysis and Cost 

Analysis were used to develop an overall Total Cost. The Closure Assessment values were used 

to estimate the RUC and Delay for the Traffic Analysis. The RUC was discounted by one-third 

and added to the Cost Analysis value to create a Total Cost. These results indicate that Scenario 1, 

Original, is the most cost-effective after considering all of the critical variables involved. 

Caltrans I-15 Pavement Reconstruction Project
77

Table 6 I-15 Reconstruction Assessment Result

Scenario Name Closure

Scheme

Closure 

Assessment

(Number of 

Closures)

Traffic Analysis Cost 

Analysis

Total

Cost5

RUC 

($M)

Delay 

(Min)

Original Median + Structure 

Widening 35 weekends 3 16 78 79

Rapid Rehab 1 Full closure

One roadbed 35 weekends 119 363 83 123

Rapid Rehab 2 Full closure

One roadbed 8 weeks 123 363 77 118

Traditional Partial closure 1,220 nights 133 22 88 113

Long-life CSOL Full closure

One roadbed 20 weekends 69 363 60 83

Phase II: DynamEq5

The Phase II analysis for the I-15 Ontario project entailed two sub-studies: (1) a traffic network 

simulation using DynamEq to assist in the development of a TMP; and (2) a supplemental 

construction staging plan analysis which involved a more detailed analysis using the CA4RPS 

tool. Of primary concern here is the use of the DynamEq traffic modeling tool for developing the 

TMP. Based upon the Phase I Preconstruction Analysis, the recommended construction scenario 

was number 1 which entailed a total of 35 55-hour long weekend road closures. DynamEq was 

specifically used to analyze the detailed Construction Staging Plan and conduct an operational 

analysis of the primary detour routes for six key stages in the construction process where detours 

were considered to be critical. The six staging scenarios analyzed are summarized below:

	2B—Closure of I-10W to I-15S and I-15S to Jurupa ramps 

	2C—Closure of I-10E to I-15S ramp 

	2D—Closures of I-15S to I-10W and from 4th Street to I-15S ramps 

	3D—Closures of Jurupa to I-15N and I-15N to I-10E and I-10W ramps 

	3F—Closure of EB I-10 to NB I-15 connector and both NB ramps at 4th Street 

	4B—Closure of SB I-15 to WB and EB SR 60 

DynamEq was employed for use in this analysis due to the relatively large study area and the 

number of detour routes involved. While DynamEq is a user equilibrium model (meaning vehicles 

make optimal use of the network with the goal of minimizing overall system delay) the reality 

is that many of the vehicles operating on the network are unfamiliar to the area and do not have 

perfect information. Thus, there will be in-equilibrium in system usage. In order to account for this 

behavior in the DynamEq model, a new class of vehicles was created that are unfamiliar with the 

area and will always follow posted detour routes regardless of congestion levels.

5

 Total Cost = (RUC/3) + Cost Analysis

Caltrans I-15 Pavement Reconstruction Project
78

Results of the study indicated significant user delay ranging from 8 to 121.4 minutes. Four of the 

six staging scenarios had significant delays of more than 30 minutes. The analysis results had 

two major impacts on the overall project design and development of the TMP. First, the results 

indicated the need for more than one detour route for some of the staging scenarios. This problem 

was not previously identified in other analyses. Second, a public outreach campaign is critical to 

ensuring demand reductions and detour routing.

Caltrans I-15 Pavement Reconstruction Project
79

Glacier National Park

Going to the Sun Road Rehabilitation Project6

Work Zone Characteristics 

Transportation Analysis:

Approach Sketch-Planning

Modeling Tools QuickZone

Work Zones:

Type Type III

Network Configuration Pipe

Geographic Scale: 

Work Zone Size Large

Analysis Area local

Overview

The Going-to-the-Sun Road (GTSR) in Glacier National Park (GNP), Montana, is a prime attraction 

for visitors to the park and the only east-west link within the park. The scenic 50-mile roadway, 

completed in the 1930s, traverses the park and provides access to the Logan Pass Visitors Center 

from either the St. Mary’s Entrance (East) or the West Entrance. While portions of the GTSR are 

open throughout the year, in the higher alpine sections, the roadway is closed and often snowcovered throughout the winter months. The roadway offers the visitor a number of incredible 

vistas as well as access to trailheads and other facilities along its length. Given the rugged terrain, 

the GTSR is the only roadway within the park that connects the eastern and western sections of 

the park. Alternative east-west connections outside the park do exist, however, the GTSR itself 

or one of the facilities along its length are the destinations of the vast majority of vehicles visiting 

the park. 

The GTSR is slated for an extensive multi-year rehabilitation project over a seven to eight year 

period. Since the GTSR is a key reason for visiting GNP and has no alternative route, the roadway 

must remain open throughout the project to both allow access to facilities and to remain open 

as a scenic roadway with minimal disruption and delay for park visitors. The steep terrain, the 

complexity and duration of the work to be performed, and the limited construction season for 

roadwork in the summer season (coinciding with peak visitor travel demand) are factors that need 

to be considered in the planning stage to determine if the GTSR Rehabilitation Project can be 

completed in a timely manner while still maintaining an acceptable level of delay to visitors using 

the GTSR.

6

 This case study was adapted from the report FLH-QuickZone Case Studies: The Application of FLH-QuickZone in 

Six Federal Lands Projects available from Federal Lands Highway Division.

Glacier National Park: Going to the Sun Road Rehabilitation Project
80

Because of the key role the GTSR plays within the park as a destination itself and in providing eastwest access in the park, there was significant concern that extended and onerous delays from work 

zones would impact park visitation as well as the segments of the local economy that depended 

on tourism. An agreement was reached between the National Park Service, Western Federal Lands 

Highway Division (WFLHD) and representatives of the local community outlining the extent to 

which closures and delays on the GTSR would be tolerated. One key tenet of this agreement was 

to limit end-to-end delays on the GTSR in one direction to no more than 30 minutes (total). 

The role of FLH-QuickZone in the GTSR Rehabilitation Project was to assess likely travel delays 

(and in particular, the end-to-end delays from multiple work zones) expected over the course of 

the multi-year project. Since the project was, at the time, in the relatively early planning phase, 

the details of roadwork phasing and staging could not be identified in detail. However, given 

the outline of a likely phasing plan and expected traffic control developed by WFLHD, FLHQuickZone was used to identify projected delays and queue length over the course of the project. 

FLH-QuickZone was also employed to assess the likely effects of actuated signal control for 

2-way, 1-lane operations, as well as the impact of reduced travel demand. Reduced travel demand 

is projected during roadwork, as well as a result of the provision of a transit alternative.

Work Zone Alternatives

Eight alternatives were coded and analyzed using FLH-QuickZone for the GTSR Rehabilitation 

Project (see Figure 17). The eight alternatives (Table 7) are combinations of four expectations 

for travel demand and the utilization of actuated signal control for nighttime and weekend 2-way, 

1-lane operations. The reduction in demand is from two potential sources. The first reflects an 

estimate in the EIS that the presence of major roadwork will cause overall GTSR travel demand to 

decline by approximately 6 percent.7 The second is a planning level target by planners to reduce 

travel demand by 2 to 7 percent by shifting visitors into transit buses. The 6 percent demand 

reduction case assumes just the overall GTSR decline from the presence of roadwork. The -8 

percent and -13 percent demand reduction cases reflect a combination of general decline with the 

high and low estimates of transit demand shift.

7

 The EIS also reported that without the presence of major roadwork overall park visitation was expected to increase 

by 0.6 percent. The estimated decrease in visitation of 6.4 percent due to major roadwork is detailed in the EIS for 

Alternative 3 (Preferred Alternative).

Glacier National Park: Going to the Sun Road Rehabilitation Project
81

MP 11.0

MP 0.0

WEST ENTRANCE

ST. MARY’S

ENTRANCE

STA: 23050

STA: 2302

MP 16.4

STA: 2314

STA: 2304

STA: 2312

MP 32.0

MP 42.8

STA: 23010

AADT

wb: 556

eb: 564

AADT

wb: 664

eb: 672

AADT

wb: 769

eb: 781

AADT

wb: 1040

eb: 1073

AADT

wb: 501

eb: 504

AADT

wb: 558

eb: 560

25 mph

40 mph

40 mph

40 mph

40 mph

35 mph

40 mph

25 mph

40 mph

40 mph

40 mph

25 mph

25 mph

35

mph

45 mph

45 mph

25 mph 45 mph

35 mph

MP 50.0

Inbound is Westbound

XI

VII

IX

VI

XII

X

VIII a

VIII b

X Denotes Work Area from EIS

Figure 17 GTSR Rehabilitation Project

The use of a single fixed timing plan for the control of short work zones has been a typical practice 

on GTSR, as is the use of varying fixed timing plans over the course of the day for longer work 

zones. In the Glacier case study, WFLHD and NPS staff wanted to investigate the complete range 

of delay from the simplest (single fixed plan) to the most complex (all actuated) and to estimate 

how likely the 30 minute maximum user delay threshold might be exceeded over the life of the 

rehabilitation project. Base signal timing in this case study represents a single fixed plan used in 

the night and weekend periods when flaggers are not present.

Glacier National Park: Going to the Sun Road Rehabilitation Project
82

Table 7 GTSR Alternatives Evaluated with FLH-QuickZone

Work Zone Traffic Control

# Alternative Name Travel 

Demand

Weekday Day 

7am-7pm

Weekend (all hours) 

and Weekday Night 

7pm-7am

1 Base 2004 Level Flaggers Fixed Time Signals

2 Actuated Signal 2004 Level Flaggers Actuated Signals

3 -6% Demand -6% Flaggers Fixed Time Signals

4 -6% Dem + Actuated -6% Flaggers Actuated Signals

5 -8% Demand -8% Flaggers Fixed Time Signals

6 -8% Dem + Actuated -8% Flaggers Actuated Signals

7 -13% Demand -13% Flaggers Fixed Time Signals

8 -13% Dem + Actuated -13% Flaggers Actuated Signals

Application

For the FLH-QuickZone analysis of the GTSR project, there were two critical measures of 

effectiveness to consider, both related to the designation of 30 minutes or more of delay in either 

direction as ‘unacceptable” throughout the project. In order to describe the worst delay seen in 

a phase, maximum user delay was used.. This measure reflects the longest possible delay on the 

GTSR from all work zones encountered in one direction. During 2-way, 1-lane operations, the 

assumption implies that some unlucky traveler will arrive at a work zone to experience the longest 

wait possible in that time period. The second measure of effectiveness is the number of hours per 

week that the maximum delay exceeds the 30 minute threshold in one or more directions. This 

measure provides insight into how long unacceptable delays are in effect throughout the week.

Base Case--In general, the FLH-QuickZone results indicate that delays in the base 

roadwork case are frequently in the unacceptable range, and remain in that range for 

a significant portion of the week for several phases. In the base case, the delays are 

particularly noteworthy during night operations and in specific high-volume (July) time 

frames. During high-volume time frames, flaggers are not expected to be able to allow 

all cars in the queue to pass through before a maximum time of 30 minutes is reached. 

The result is oversaturation and queue development. This development is relatively shortlived, however—no delay exceeds 44.9 minutes.

During night operations, delay is high because a single fixed plan must be used to cover 

high demand weekend patterns as well as low-demand night patterns. The result is that 

relatively long cycle lengths are imposed to prevent saturation on weekends, but cause long 

waits at red lights at night (up to roughly 12 minutes). It is also clear that 12 minute wait 

times under low flow conditions may be unsafe since the road user may presume that the 

signals are broken after a few minutes, proceed and eventually encounter oncoming traffic 

in the single open lane of the work zone. Before such unrealistic situations were to actually 

occur, it is likely that timing plans that change periodically throughout the evenings and 

weekends would be put into place. This option was not analyzed in QuickZone-FLH 

Glacier National Park: Going to the Sun Road Rehabilitation Project
83

as a part of this study at the direction of WFLHD and NPS staff because of a lack of 

time to explore every possible variant within the limitations of the case study. Given the 

preliminary nature of the case study, WFLHD and NPS staff wanted to concentrate effort 

on identifying the likely worst case and best case delay outcomes. 

Signal Actuation—The impact of signal actuation is significant in the reduction of delays 

during night operations. By allowing the signal timing to vary with actual travel demand, 

more appropriate (short) cycle lengths can be provided at night, and longer ones during 

weekend and weekday evenings (after flaggers are finished for the day). Results indicated 

that the use of actuated signals eliminates unacceptable delays at night, although delays 

up to 25.3 minutes are predicted. Signal actuation alone is not enough to eliminate 

unacceptable delays during the July and Late Summer peak, however, particularly in 2011 

and later. Here, travel demand exceeds the capacity of the expected work zones, regardless 

of signal timing. 

Reduced Travel Demand—The reduction in demand is effective in reducing daytime delay 

during flagger operations but has no effect on night operations when fixed timing plans 

are in place. Results indicated that this effect is highest with the -13 percent demand 

case and somewhat lower in the other two cases. Overall, the demand reduction is only a 

critical factor when the highest seasonal travel demand is expected: July. In other months, 

the delay from the flagger operations is often at acceptable levels. Actuated signals, in 

combination with reduced demand (-13 percent), eliminates unacceptable delays in all 

phases except for July 2011, when five concurrent work zones are in place.

Table 8 provides a summary of both the fixed signal timing plan impacts and the actuated signal 

impacts respectively. Again, using fixed signal timing plans results in unacceptable delay in more 

than half (21) of the nighttime FLH-QuickZone phases. Switching to actuated signals eliminates 

all delays of greater than 30 minutes. Switching to actuated signals during the daytime FLHQuickZone phases helps to reduce the occurrences of unacceptable delays but does not eliminate 

them as was done with the nighttime operations. Nor does the use of actuated signals reduce the 

severity of the delay. The minimum and maximum duration of the delay during daytime operations 

remains around 35 minutes with actuated signals. Other mitigation measures beyond those studied 

here, or a reduction in work zone activity in the peak of the summer visitation season, will likely 

need to be considered if all potential instances of user delay exceeding 30 minutes are to be 

eliminated. 

Glacier National Park: Going to the Sun Road Rehabilitation Project
84

Table 8 Fixed and Actuated Signal Timing Impacts

Signal

Operation

Number of QZ

Phases

Hours/Weeks > 30 min Delay

(hours)

Delay

(minutes)

Low High Low High Min Max Min Max

Fixed Act. Fixed Act. Fixed Act.

Base 

Alternative

Day 8 5 3 40 7 35 30.2 44.9 31.1 36.3

Night 21 0 48 48 0 0 30.3 37 0 0

-13% 

Demand 

Alternative

Day 1 1 – 30 – 30 – 32.4 – 32.4

Night 21 0 48 48 0 0 30.3 37 0 0

-6%

Demand 

Alternative

Day 4 3 8 30 20 30 32.3 36.1 30.5 34.3

Night 21 0 48 48 0 0 30.3 37 0 0

-8%

Demand 

Alternative

Day 4 3 5 30 10 30 30.6 33.7 30.2 33.7

Night 21 0 48 48 0 0 30.3 37 0 0

Based on this planning-phase analysis of the GTSR, it is clear that Alternative #1 will result in 

unacceptable delays on a regular basis during both nighttime and day work zone operations. The 

predicted value of actuated signals is large given the high variability of travel demand expected 

during the course of the project. If actuated signals cannot be reliably implemented, it is possible 

that a fixed plan that varies by time of day could also be implemented to mitigate delays, although 

such a plan has not been evaluated in FLH-QuickZone. The case for demand reduction is less clear 

– the problem lies primarily with reducing (or potentially redistributing) travel demand in the peak 

month of July, rather than in all time frames.

Glacier National Park: Going to the Sun Road Rehabilitation Project
85

Maryland State Highway Administration 

Lane Closure Analysis Program8

Work Zone Characteristics 

Transportation Analysis:

Approach Sketch-Planning

Modeling Tools Lane closure analysis program built 

with Microsoft Excel

Work Zones:

Type Type II – IV

Network Configuration Isolated

Geographic Scale: 

Work Zone Size Small

Analysis Area Local

Overview

The Maryland State Highway Administration (SHA) has developed the Lane Closure Analysis 

Program (LCAP) to support state traffic engineers with a structured method to analyze work zone 

impacts. The LCAP tool was developed based upon the guidance written in the Work Zone Lane 

Closure Analysis Guidelines which present allowable thresholds for decreasing mobility measured 

in terms of queues and delays in work zones. LCAP is part of a tiered approach to work zone 

analysis that SHA has developed. Depending on the complexity of a project, SHA recommends 

starting with LCAP for simple cases, QuickZone for simple cases with network impacts, and then 

simulation tools such as CORSIM, VISSIM, and SimTraffic for relatively complex scenarios 

requiring detailed analysis.

LCAP Description

LCAP is an analytical tool designed to quantify queues and delays resulting from capacity decreases 

in freeway work zones. LCAP is written as a program within Microsoft Excel and compares 

expected travel demand against work zone capacity on an hour-by-hour basis to estimate delay 

and mainline queue growth.

LCAP consists of a four-step process:

STEP 1

Open existing file or Start new file. The user has the choice of opening an existing LCAP 

file or starting a new case for analysis. 

8

 This case study was adapted from the LCAP User Guide available at http://marylandroads.com/safety/workzone.asp.

Maryland State Highway Administration—Lane Closure Analysis Program
86

Enter project information. The Project Information screen allows the user to input data that 

defines the project. The project description, analyst’s name and date of analysis should be 

input here. The project description should contain information to identify the project, such 

as roadway name, direction of travel, segment of road, and work being performed.

STEP 2

Input demand. The demand is an essential part of the LCAP program. Users may enter their 

own data or access SHA’s traffic data from the Traffic Monitoring website (http://www.

marylandroads.com/tmsreports/). 

STEP 3

Describe the work zone. The closure analysis screen is used to determine the hours during 

the day when lanes can be closed without causing excessive queuing or delays. The user is 

prompted to select input options in terms of maximum allowable queue length or maximum 

allowable delay (to be highlighted in red or yellow when exceeded) and proposed lane 

closure hours. Using trial and error in the start and finish times of the work zone, lane 

closure schedules can be determined based on allowable queues or delays.

	Lane Closure Information—The user enters the total number of freeway lanes and 

the number of open lanes with the lane closure in effect.

	Capacity Information—The user enters the roadway capacity without and with the 

work zone in vehicles per hour per lane. The work zone capacity can be determined 

in four ways: 

1. engineering judgment,

2. 1997 Highway Capacity Manual, 

3. University of Maryland Capacity Estimation equation, or 

4. 2000 Highway Capacity Manual equation. 

	Output Type—The user selects queue length or delay as the measure of the work 

zones mobility impact. The user has the option of highlighting the output in red 

or yellow if the queue exceeds a specified length (miles) or the delay exceeds a 

specified period of time (minutes).

STEP 4

Save File. LCAP has the ability to save all of the data associated with the project.

Maryland State Highway Administration—Lane Closure Analysis Program
87

Michigan Department of Transportation

Southeastern Michigan Simulation Network (SEMSIN)

Overview

In 2005, the Michigan Department of Transportation (MDOT) was involved in the environmental 

clearance process for several major projects dealing with long-distance interstate and international 

trade. Since each of these projects would have major impacts on network freight flows, especially 

on the Detroit area freeway network, there was a need to analyze the individual projects within 

the framework of the larger system and in relation to each other. In addition, much of the Detroit 

area freeway system operates at or near capacity. Traditional travel demand models and highway 

capacity analysis could not fully capture the dynamic effects of these impacts on the network. 

Lastly, divisions of the MDOT responsible for operations (for example, work zone mobility) 

needed a traffic tool that would enable them to examine the network effects of major road closures 

and/or detours. Thus, the MDOT saw a need to develop a large-scale, network simulation model, 

capable of modeling passenger cars, domestic trucks and international trucks, and which would 

support planning and operational decisions. An SPR-funded pilot project was initiated to develop 

a network a simulation model. Initially, the core of the Detroit freeway network would be modeled, 

plus the I-75 corridor extending from the City of Detroit in Wayne County, to the industrial heart 

of Oakland County, a distance of 30 miles. This project was called the Southeastern Michigan 

Simulation (SEMSIM). 

However, before the SEMSIM, which was a pilot study, was completed, there was an immediate 

need by three other very large projects for network simulation. The SEMSIM, in its then current 

state of development, served as the platform, or seed model for these three projects. Specifically, 

each project, The Ambassador Bridge Gateway Project, the I-94 Rehabilitation Project, and the 

I-75 Trade Corridor Project, cut out large sections of the SEMSIM network, extending freeway 

links and adding surface arterial corridors as needed. 

The SEMSIM network was created using the Paramics microscopic simulation model and is show 

in Figure 18 on the left. The network incorporates the Central Detroit Freeway Network and the 

I-75 corridor extending to Pontiac, Michigan. The overall size is approximately 30 miles north/

south and 15 miles east/west. It includes all freeways and most major arterial roads. On the right 

are the locations of three maintenance of traffic simulation (MOTSIM) assessments that have 

been or are being conducted based upon the SEMSIM network. These three projects include the 

Ambassador Gateway Bridge MOTSIM (red), I-75 Trade Corridor MOTSIM (Purple), and the 

I-94 Rehab MOTSIM (green). The following sections will describe in more detail the application 

of the SEMSIN network for the three MOTSIM projects.

Michigan Department of Transportation—Southeastern Michigan Simulation Network (SEMSIN)
88

Figure 18 MDOT METSIM Geographic Coverage

Ambassador Gateway Bridge MOTSIM

The first application of the SEMSIM network was the rehabilitation and reconstruction of the I-96/

I75 interchange adjacent to the Ambassador Bridge that provides the major commercial connection 

between Canada and the United States (Figure 19). The overall project includes reconstructing 

and realigning a 1.5 mile segment of I-75 and 1 mile segment of I-96, and construction of a new 

interchange with direct access ramps for trucks to the to the Ambassador Bridge, which is the 

largest commercial border crossing in North America. The reconstruction includes the full closure 

of many sections of the elevated freeway near the interchange which provides critical connections 

for freight movement both across the boarder and within the Detroit area. The project began in 

February 2008 with an estimated completion date of December 2009. A contractor incentive bonus 

of up to $8 million is being offered for early completion. In all, three separate analyses were 

conducted as part of the project during the construction stage:

	Gateway MOTSIM 1—Initial assessment which included surrounding roads near the 

construction project and interstate and arterial roads leading into and around the construction 

project (red boarder in Figure 2). 

	Gateway MOTSIM 2—An expansion of the MOTSIM 1 network to include proposed 

lane closures for the Summer 2008 construction season along I-75 to the north and south 

(highlighted purple sections in Figure 2).

	Gateway MOTSIM 3—Developed in March 2008 based upon actual traffic conditions 

occurring as part of the full closure that began in February 2008. This analysis included a 

further assessment of Gateway MOTSIM 2 based upon actual conditions.

Michigan Department of Transportation—Southeastern Michigan Simulation Network (SEMSIN)
89

Figure 19 Ambassador Gateway Bridge MOTSIM Network Overview

The results of the Gateway MOTSIM 1 analysis did not reveal any significant queuing or delay 

associated with the reconstruction project given the mitigation efforts that were to be implemented 

as well as the excess capacity available on other roadway links. However, during 2007 MDOT 

planned lane closures along section of I-75 to the north and south of the construction area that 

had not been included in the original analysis. The planning of the I-75 lane closures did not take 

into account the increased traffic due to the I-75/I-96 interchange reconstruction. The Gateway 

MOTSIM 2 analysis included the route diversions that would take place due to the I-75/I-96 

reconstruction. The analysis revealed some areas of concern that lead MDOT officials to modify 

some of the planned mitigation efforts including travel advisories along I-94 and I-96, the major 

detour routes.

Gateway MOTSIM 3 began development in June of 2008 in response to feedback from stakeholders 

that lead MDOT management to alter some of the maintaining traffic ramp closures planned for 

July to October 2008. Also, traffic volume has been significantly lower since January of 2008. The 

results of MOTSIM 3 will point to further areas of mitigation and better performance measuring. 

I-94 Rehab MOTSIM

The rehabilitation of I-94 in Detroit is an approximately six mile rehabilitation which will include 

the reconstruction of three interchanges (M-10, I-96 and I-75). The planning process has been 

occurring for the past 10 years at a cost of $11 million. Currently, the project is in the design stage 

of the decision-making process. MDOT refers to the current status as the Engineering Report (also 

known as pre-design or 10 percent of base plans) and has provided an initial construction cost of $1.3 

billion. The purpose of the network simulation is to support the project in terms of constructability, 

staging, maintenance of traffic, cost estimates, financial plans, horizontal and vertical alignments 

Michigan Department of Transportation—Southeastern Michigan Simulation Network (SEMSIN)

Gateway MOTSIM 1

Gateway MOTSIM 2
90

and right-of-way planning. Currently, the team involved in the I-94 Rehabilitation project is using 

the I-94 Rehab MOTSIM to begin screening construction staging alternatives.

In addition to being another application of the SEMSIM data, the I-94 Rehab MOTSIM is the 

beginning of developing a new business process for MDOT whereby planners, traffic engineers and 

designers are all working together and incorporating the use of traffic models early in the decisionmaking process and using it to help answer many different types of questions. Documenting this 

process will provide a template for further process improvement.

I-75 Trade Corridor MOTSIM

The I-75 corridor between Detroit and Pontiac, Michigan is part of the truck network that supports 

critical supply chains linking automobile parts suppliers and manufacturers in Michigan and Ohio 

in the United States to each other and to the Province of Ontario in Canada. MDOT is currently 

planning for widening a 19-mile segment from outside Detroit to the City of Pontiac from three 

to four lanes. Currently in the planning stages (nearing completion of Engineering Report), the 

I-75 Trade Corridor MOTSIM will enable MDOT planners, engineers and designers to work 

together and test various scenarios to ensure mobility throughout the work zone, constructability 

is maintained and staging is adequate. The I-75 Trade Corridor MOTSIM will build upon the 

SEMSIM network, adding additional freeway links of I-696 and M-59, and Michigan surface 

arterial roads.

Findings

Process

Early in the development of the SEMSIM and Gateway MOTSIM, process issues 

immediately started appearing. With the then-current processes in MDOT, large network 

simulation could turn out to be a very resource intensive undertaking. Unless processes were 

developed to expedite model development and maintenance, network simulation might be 

unfeasible. And if each simulation model were limited to a single use or application, this 

cost might not be justified. The following describes three process issues that emerged.

Approach: Stand-alone, top-down, or bottom-up?

Before SEMSIM was conceived, all of MDOT’s microsimulation models were projectspecific, stand-alone models. They did not encompass or relate to the larger network, 

and they did not relate to each other. Thus, while each project had potentially profound 

consequences for the network, none of the models were capable of analyzing these. The 

technology of the time did not provide the needed plasticity for large, multi-purpose, multiapplication models. Subsequently newer microsimulation software packages with cutand-paste capability emerged and this advance allowed an ambitious project like SEMSIM 

to be conceived. For the first time, an existing model could be modified and reused by 

multiple applications. The technological problem appeared to have been solved.

Initially, the SEMSIM was conceived to become a complete top-down metropolitan 

area-wide or “master model”, to be updated, and maintained on an ongoing basis, with 

a dedicated staff and budget, much like an MPO (Metropolitan Planning Organization) 

Michigan Department of Transportation—Southeastern Michigan Simulation Network (SEMSIN)
91

model. It soon became apparent that this approach would be resource intensive, and in any 

case, events were overtaking the process and MDOT’s ability to implement this idea. What 

evolved by necessity was a bottom-up, incremental approach, whereby the SEMSIM and 

each subsequent derived, would serve as a core network for the next baby model. Instead 

of maintaining a “Master Model”, each project would take whatever models had been 

developed to date, and update and customize them to its own needs. The costs of each 

customized model would be born by each project which used it. This leads to a problem of 

assuring uniformity between and among models, but this problem could be addressed by 

QA/QC or other institutional devices.

Data

Large scale, network simulation uses lots of data, especially traffic data. Initially, the 

fear was that there would not be enough data. It soon became apparent however, that the 

problem was not insufficient data, but rather poor or non-existent data processes. In a 

scramble to assemble system-wide data in a format that lent itself to mass data analysis 

and processing, several underlying process issues came to light. At the same time, MDOT 

had several tools or initiatives that held potential to resolve the problem, most notably, the 

Michigan Framework. The Framework was a unified GIS system that serves all agencies 

at all levels of government and even private industry. The Framework allowed every single 

directional link or structure, or any item that could be located in three-dimensional space, 

to be assigned a unique identifier (such as a physical reference number and milepoint). 

MDOT was in the process of inventorying and storing all its traffic and structure data 

(such as roads, ramps, bridges, traffic counts, bill boards, guardrails, and even ash trees) as 

Framework layers. This was to be an ideal platform for storing and retrieving traffic data 

and even coding the SEMSIM network.

The first issue was assembling large masses of freeway volume data from hundreds of 

stations across the system. The process of geo-coding traffic data collection sites to be 

Framework layers was accelerated to serve the SEMSIM. In addition, the project scope 

included the development of traffic analysis tools, such as would aid in cleansing and 

inputting traffic data and balancing in and out volumes along a corridor. A second issue was 

turning-movement traffic counts at signals. The traffic signal re-timing studies that were 

being performed were being collected by various consultants under different contracts, 

administered by engineers in the various Transportation Service Centers around the State. 

Not only were these traffic studies not centrally stored, they were not even known to a 

central data collection office. In fact, there was no central data collection office for the 

whole Department. A few quick phone calls to DOT’s around the Country, confirmed 

that MDOT was not unique in this respect. Presently, MDOT is undergoing a systematic 

process improvement to rationalize and integrate all Departmental traffic data, and to geocode it so it can be layered on the Michigan Framework. Finally, Michigan now has six 

inch resolution aerial photography of all its counties, in a projection that is consistent with 

the Framework. Thus, a Framework trunkline map and a “Sufficiency” file (with road 

segment characteristics data) can be layered on an aerial photo, with a zoom factor that 

allows pavement markings to be observed. These can be exported as bitmaps and imported 

into the simulation software, and network coding greatly expedited. 

Michigan Department of Transportation—Southeastern Michigan Simulation Network (SEMSIN)
92

Organization

Simulation models and data collection are the easy part. They have to do with technology 

and software and numbers. The really difficult process issues have to do with the 

Organization itself. The best technology in the world can’t solve a DOT’s problems if 

its organizational processes are not compatible, or do not “fit”, the new possibilities of 

the technology. For example, it took almost an entire generation, from 1970’s to the 

1990’s before most government organizations fully adapted to the potential and promise of 

computer technology. Today, few could imagine an office or business without computer 

technology. They have transformed our processes, and at the same time, have pushed out 

our production possibilities curve. Likewise with simulation. Old simulation models lie in 

dusty files around MDOT, under- or unused, because they didn’t get the right information 

to the right people at the right time. Much of this was due to the limited capabilities of the 

old technology. But it was also due to the fact that the old organizational structure hadn’t 

caught up to the new possibilities. A lot more cross-organizational integration would be 

required. More organizational flexibility would be needed, so that processes that need to 

iteratively test scenarios can get traffic model updates as needed, and then pass output to 

downstream processes which may also need customized traffic model output. 

In 2008, a concept for integrating MDOT’s business processes to support an Operationsoriented environment was developed, called “Integrated Transportation Systems Operations 

and Management” or ITSOM. Concomitantly, the Department was reorganized and a 

new Division of Operations was created. The emphasis throughout, is integration of 

tasks and functions across MDOT to support an integrated approach to Operations. The 

Division of Operations combines and extends previous functions such as ITS, Vehicle 

and Infrastructure Integration (VII), Work Zone Mobility and Safety, Traffic and Safety, 

and Maintenance. Strategic objectives and task forces charged with implementing these 

strategic objectives were established. Two of these objectives illustrate the new emphasis on 

cross-organizational integration and flexibility: 1. “Data Data Data” which would integrate 

data and data systems across the Department, and 2. “Integrate across the Organization”, 

which includes, for instance, new channels and forums for communications and interdivisional training. With implementation of ITSOM, MDOT will be positioned to fully 

harvest the potential of simulation to support all its Operations functions.

Michigan Department of Transportation—Southeastern Michigan Simulation Network (SEMSIN)
93

New Jersey Turnpike Authority and Rutgers University

New Jersey Lane Closure Application9

Overview

The New Jersey Turnpike Authority, consisting of both the New Jersey Turnpike (150 miles) 

and Garden State Parkway (180 miles), funded the development of a modeling application that 

provides operations managers and engineers with information regarding queue and delays resulting 

from lane closure events. The tool, known as the Rutgers Interactive Lane Closure Application 

or RILCA is GIS-based and was developed by the Rutgers University Intelligent Transportation 

System Laboratory. The impetus for the development of tool was, in part, to put into electronic 

format hard-copy versions of traffic volume tables that operation managers would reference in 

order to approve or disapprove maintenance and contractor applications for lane closures related 

to roadway maintenance (guardrail repair, sign repair, etc.). 

The lane closure tool was developed using the ArcGIS software package as the main development 

environment. Included in the GIS database is detailed geometric data for all of the roadway links 

for both the New Jersey Turnpike and Garden State Parkway including surrounding highways and 

local streets. Now, the RICLA tool provides operations managers, supervisors and engineers with 

the following features:

	Traffic Demand—Volume information on selected links at a given time period on 

any given date.

	Roadway Data—Link characteristics including number of lanes, AADT, milepost 

and link length.

	Lane Closure Schedule—A function that generates lane closure schedule for 

selected links based upon hourly volume data processed by the Rutgers Intelligent 

Transportation Systems (RITS) team.

	Visualization—A simple visualization function that shows the extent of expected 

queuing and delays as a result of lane closure and spill back onto upstream links 

in the form of link colors.

	Cost Impact—Integrated lane closure cost estimation function.

Today, two versions of the tool currently exist: one for the New Jersey Turnpike (called the Rutgers 

Interactive Lane Closure Application or RILCA) and one for the Garden State Parkway (called the 

Parkway Operations Lane Closure Application or POLCA). A third version is being developed for 

the New Jersey Department of Transportation. 

9

 This case study references the Rutgers Interactive Lane Closure for Work Zone Planning Manual prepared by the 

Rutgers University Intelligent Transportation Systems Laboratory (November 2007 edition).

New Jersey Turnpike Authority and Rutgers University—New Jersey Lane Closure Application
94

Applications

The following applications are available in both RILCA and POLCA

	Lane Closure Schedule—A schedule for the minimum number of lanes to be 

open on a roadway section can be generated. These schedules are generated using 

the Annual Average Daily Traffic (AADT) data for the selected day. Lane closure 

schedules can be generated for a selected day or a week starting with a selected 

day for each month. An annual percentage increase in traffic can also be entered 

as an input to obtain the schedules for the future traffic demand.

	Lane Closure Info—The Lane Closure Info option is used to generate estimates 

of user delay and queuing resulting from a particular lane closure scenario. 

Outputs include Level of Service (based on the HCM procedure for work zone 

studies), minimum number of lanes to be open, hourly number of vehicles in 

queue, average hourly delay per vehicle, total hourly delay, and queue length.

	Incident Analysis— The Incident Analysis option is used to generate delays 

and queues resulting from an incident. It operates in similar fashion to the Lane 

Closure Function but includes the two additional outputs of time of maximum 

queue length and time of queue clearance.

The New Jersey Turnpike Authority has not developed any specific polices or procedures regarding 

the use of the lane closure application tool. Currently, users of the tool are advised to use the results 

of the analysis as just one piece of the overall analysis and to also consider personal experience 

with lane closures and previous examples comparing estimated values to actual values.

Data

Data for the lane closure applications are routinely updated but are quite different for each version 

of the tool. For the RILCA version, hourly traffic volume data is generated from a combination 

of roadway sensor data and electronic toll collection (ETC) tag data. These data are combined to 

generate hourly traffic volume data which is entered into the GIS database every two months. 

The POLCA version also use ETC tag data but this data is not as accurate as the New Jersey 

Turnpike since users only pay when they enter the parkway. The ETC tag data is combined with toll 

plaza hourly factors to estimate hourly traffic volumes for roadway links. These data are updated 

monthly, but the data is three months old due to the amount of processing. 

New Jersey Turnpike Authority and Rutgers University—New Jersey Lane Closure Application
95

Nova Scotia Department of Transportation & Public Works (Canada) Reeves Street10

Work Zone Characteristics 

Transportation Analysis:

Approach Sketch-Planning

Modeling Tools QuickZone

Work Zones:

Type Type III

Network Configuration Isolated

Geographic Scale: 

Work Zone Size Small

Analysis Area Local

Overview

Nova Scotia is one of Canada’s Atlantic maritime provinces located on the east coast with 

a provincial population just under 1 million. Nova Scotia is composed of several islands and 

peninsulas with key commercial and population centers connected by the Trans Canada Highway. 

Port Hawkesbury is a key commercial location on Cape Breton Island just south of the Trans 

Canada Highway. The town of Port Hawkesbury includes a number of major industrial facilities 

representing companies such as Georgia-Pacific, Statia Terminals, USG, and the Sable Offshore 

Oil Company. The town also includes a number of residential communities.

In 2001, the intersection of Reeves Street and Trunk 4 in Port Hawkesbury, a location along a key 

access route to the Trans Canada Highway, was slated to be upgraded. Both Reeves Street and 

Trunk 4 are generally 2-lane highways with certain sections upgraded to include designated turn 

lanes in built-up areas. Average Annual Daily Traffic (AADT) was on the order of 8,000 vehicles 

per day with approximately 10% of those being trucks. Truck traffic is concentrated during the 

daytime on weekdays, while trucks make up fewer than 5% of traffic volume on weekends. Most 

of the traffic volume at this location in Port Hawkesbury is through traffic continuing on to some 

of the industrial centers near the town or to points further north.

The reconstruction involved a major upgrade of the intersection including additional dedicated 

turn lanes to accommodate higher traffic volumes and to improve safety. In order for construction 

to take place, overall capacity of the intersection would be reduced due to narrow lanes widths and 

periodic lane closures. Construction was slated to take place only during daylight hours because of 

cost and safety concerns. However, it was also evident that any construction taking place during 

the day would have an impact on motorists, since the Reeves Street/Trunk 4 intersection carries a 

10 This case study was adapted from the report The Application of QuickZone in Eight Common Construction Projects

available from the FHWA Office of Operations.

Nova Scotia Department of Transportation & Public Works (Canada)—Reeves Street
96

large amount of traffic. Therefore, in order to reduce the impact to motorists as much as possible, 

a sketch planning traffic modeling tool was used to test various construction phasing alternatives, 

including analyzing the possibility of a detour route, and to also provide the necessary data to 

justify the additional expense of night work.

Work Zone Characteristics

Reeves Street intersection is a fairly basic design and consists of the signalized intersection and 

a detour route as shown in the figure below. Reeves Street ends at a “T” intersection with roads 

Trunk 4 and Trunk 4a to the left and right. The left turning movement continues on to Trunk 4 

and carries a majority of the traffic volume. The right turning movement continues on to Trunk 

4a and terminates shortly thereafter in large industrial area. In order to analyze the salient traffic 

movements, only the left turning movement headed north-east and the right turn movement headed 

south-west were modeled. This can be considered a corridor unto itself with the capacity limited 

primarily by the left turning movement lanes and signal phasing. The detour route consisted of 

Sydney Road which cut through a mostly residential section.

Detailed traffic data was available for this intersection from a traffic study which was carried out 

in 2000. The demand data, along with the signal timing plans, helped to determine the capacity 

of the intersection. Thus, the capacities of the various turning movements helped to determine 

the capacity of each link. Capacities under work zone conditions were estimated by the resident 

engineer from prior experience with flagging operations. The capacity and demand along the 

detour route was measured during the peak periods and on weekends by hand. 

Application

The local engineers suspected that the reconstruction of the Reeves Street intersection would result 

in significant queuing and delay and that performing the construction at night could potentially 

mitigate many of these impacts. Initial results from traffic model proved these suspicions and 

showed an estimated maximum queue of 4.1 miles resulting in a 70 minute delay occurring on 

Friday evenings. Queuing and delay were also seen on Monday, Tuesday, Wednesday and Thursday 

Nova Scotia Department of Transportation & Public Works (Canada)—Reeves Street

4

4 4

4

1

1

2

3

4

5

11

6

8

9

10

12 7

2

3 4

5

6

Trunk 4

Reeves Street

Intersection

Port Hawkesbury Reeves Street

Figure 20 Reeves Street Intersection Figure 21 Reeves Street Network Model
97

but were approximately half the length and duration as seen on Friday evenings. Detour traffic 

was estimated at 10,000 vehicles per week. Knowing that the queuing, delay and detour volumes 

through the residential areas would be contentious issues with residents, the local engineers tested 

various construction phasing scenarios.

The first scenario had the work zone in place and operating with reduced capacity 24 hours a day, 

7 days a week. Queuing during the day on Friday and Saturday were predicted to be especially 

severe. The engineers noted that queuing and delay did not form during the overnight hours on 

any day and tested a scenario that eliminated construction during daylight hours on Friday and 

Saturday (essentially shifting work to night). The results of this scenario cut in half the queuing 

and delay associated with the construction to 2.19 miles and 36.4 minutes respectively. In addition, 

the number of weekly vehicles on the detour route was reduced to 6,000, a 40% reduction. 

Additional refinements in the work zone design, including tweaking the hours and days of operation, 

enabled the engineers to better schedule the construction activities so as to not impact motorists. 

Also, the Nova Scotia Department of Transportation & Public Works did not have a night-time 

construction policy and did not routinely approve projects for night work due to cost and safety 

concerns. Because of the results generated by traffic model, the decision was made to carry out 

some of the most disruptive phases of construction at the Reeves Street intersection at night.

Nova Scotia Department of Transportation & Public Works (Canada)—Reeves Street
98

Utah Department of Transportation & University of Utah

Evaluation of the I-15 Reconstruction Design-Build11

Work Zone Characteristics 

Transportation Analysis:

Approach Travel Demand Model

Modeling Tools VISUM

TP+

Work Zones:

Type Type I

Network Configuration Network

Geographic Scale: 

Work Zone Size Large

Analysis Area Metropolitan

Overview

In 1996, the Utah Department of Transportation began reconstructing a 17-mile segment of I-15 

in Salt Lake City, Utah in preparation for the 2002 Winter Olympic Games. The reconstruction 

of I-15 was the culmination of nearly ten years worth of planning and analysis that resulted in 

the decision to widen I-15, construct HOV lanes and install a new a light rail system serving 

downtown Salt Lake City. In deciding to reconstruct I-15, the Utah Department of Transportation 

(UDOT) ultimately made the decision to move forward with a Design-Build construction method 

for two reasons: 1) the public strongly supported timely I-15 completion so as to minimize traffic 

congestion on alternate routes; and 2) Design-Build would complete reconstruction before the 

2002 Winter Olympic Games began in Salt Lake City.

The decision to move forward with a Design-Build methodology for I-15 in Utah was the first of 

its kind for the state. Thus, a number of state procurement laws had to be changed in order to make 

it possible. In addition, UDOT had to restructure the manner in which they oversaw construction 

projects of this size and impact. Overall, the decision to use Design-Build was a leap-of-faith for 

UDOT with the understanding that the overall project would be constructed more quickly, include 

lower costs and not as greatly impact the traveling public.

11 This case study was adapted from the reports Evaluating Design-Build vs. Traditional Contracting Methods for 

STIP Projects: An Assessment of Travel Impact & Delay Cost (July 2004) and I-15 Reconstruction In Ogden, Utah:

Evaluation of Various Traffic Maintenance Plans (July 2005) prepared by Dr. Peter Martin at the University of Utah.

Utah Department of Transportation & University of Utah—Evaluation of the I-15 Reconstruction Design-Build
99

Because the I-15 reconstruction was the first use of Design-Build for UDOT, an ex ante evaluation 

of the project was conducted by the Utah Traffic Lab at the University of Utah. The evaluation 

consisted of modeling three construction scenarios:

	Design-Build (aka Fast Track)—Innovative construction technique whereby time savings 

are gained as design and construction occur simultaneously. Cost savings occur from 

shorter construction duration and lower user delay and costs.

	Traditional-Build—More common design and construction method that typically 

includes lower capital costs but protracted construction duration and congestion.

	No-Build (aka Do Nothing)—Planned transportation improvements in the region would 

be implemented. Structural and pavement deficiencies on I-15 would be corrected. 

The Utah Traffic Lab used the VISUM travel demand model to evaluate the three construction 

scenarios. Evaluations were based upon three criteria: user delay, I-15 corridor travel times and 

network congestion. In addition, an accident analysis was conducted to see the impact of the 

construction methods on safety. In the end, the evaluation of the reconstruction of I-15 in Salt Lake 

City led to the development of a construction impact modeling methodology (Figure1 below) that 

local jurisdictions can employ to justify the use of the Design-Build contracting. The methodology 

has been applied to five projects within Utah’s Statewide Transportation Improvement Program 

with the recommendation that all five use Design-Build.

Utah Department of Transportation & University of Utah—Evaluation of the I-15 Reconstruction Design-Build
100

Figure 22 Construction Impact Modeling Methodology

Overall, the evaluation of the Design-Build construction scenario estimated a savings of 60 

million hours of user-delay over the Traditional-Build scenario representing approximately $600 

million (2002 dollars) in savings to travelers (value of time = $10 per hour). In addition, the 

accident analysis estimated a reduction in vehicles crashes, injuries and fatalities of 287, 100 and 

1 respectively. This is an estimated savings of $120 million (2002 dollars).

Model Selection

The study area for the evaluation comprised the entire Salt Lake Valley (Figure 23 below), about 

500 square miles. The study area includes four major types of roadways: freeways, principal and 

minor arterials and collector roads (local and residential streets were excluded). Freeways include 

I-15, I-80 and I-215. In all, the area to be modeled included more than 5,000 roadway links. 

In order to model such a large geographic area, the Utah Traffic Lab considered various 

transportation modeling software tools which included travel demand models (TransCAD, TP+, 

Utah Department of Transportation & University of Utah—Evaluation of the I-15 Reconstruction Design-Build

Identify Select STIP Projects

Run Simulations in VISUM

(Transportation Planning Model)

Build three simulation scenarios:

a) No-Build (NB)

b) Traditional Build (TB)

c) Design Build - Fast Track (FT)

1. Based on impact area

2. Limitation of the model ne

3. UDOT Recommendation

twork

Identify Goals and Objectives

Quantify the travel impact in

terms of MOEs:

 a) VMT b) VHD c) VHD/VMT

Identify the cost implication of

the contracting methods

Findings and conclusions

Use Partial Assignment Algorithm

Time of day runs:

1. AM Peak 2. PM

3. MD 4. EV

Peak
101

EMME/2, VISUM), mesoscopic simulation models (Integration) and microscopic simulation 

models (Paramics). Model selection was made based upon the following criteria:

	Quality of traffic assignment functionality

	Size of the network - number of nodes and links that can be handled

	Available traffic assignment routines

	Potential to export inputs/outputs to a microscopic simulation software package

	Number and variety of performance measures produced

	Price of the software (discounts, academic versions, technical support)

	User interface

	Peer reviews on the weaknesses and advantages of the software

VISUM was selected because it satisfied the given criteria. VISUM data is efficient as it can 

be directly exported to the VISSIM traffic simulation package giving the analyst an opportunity 

to use compatible microscopic simulation models for operational analyses. Practically speaking, 

Utah Traffic Lab owned a version of VISUM and the VISSIM model, keeping costs down. Also, 

the Wasatch Front Regional Council (the local metropolitan planning organization) modeled the 

region using the TP+ travel demand model which can be easily imported into VISUM. The VISUM 

Salt Lake Valley network is shown below in Figure 24.

Figure 23 Salt Lake Valley Area Figure 24 VISUM Salt Lake Valley Network

Utah Department of Transportation & University of Utah—Evaluation of the I-15 Reconstruction Design-Build
102

Measures of Effectiveness

User Delay

User Delay was measured in terms of annual user delay and cumulative user delay. The 

values were calculated from VISUM output of Vehicle Hours of Delay (VHD) which is 

standard model output and is a region-wide measure of traffic in the system. VHD represents 

the difference between vehicle-hours on a link when it is congested and in free-flow 

conditions. Results (shown in Figure 25) indicate that the Design-Build scenario produces 

less user delay during the study period than both the Traditional-Build and No-Build.

Utah Department of Transportation & University of Utah—Evaluation of the I-15 Reconstruction Design-Build

Figure 25 User Delay

Travel Time

Travel Time was measured only on certain sections of I-15 using the route-search option 

in the VISUM software. This measure was used to evaluate the impact of different traffic 

loads during and after the I-15 reconstruction periods. Figure 26 shows that travel time are 

generally less for the Design-Build over the Traditional-Build and significantly less than 

the No-Build.

20

30

40

50

60

70

80

90

100

110

1996 1998 2000 2002 2004 2006 2008 2010

Year

Vehicle Hours of Delay [millions]

TB

DB

N-B
103

Figure 26 Travel Time

Congestion

Congestion was measured in terms of volume-to-capacity ratios where saturation occurs 

with a value greater than 0.9 (1.0 represents volume equal to capacity). Conducting this part 

of the analysis was done off-line from VISUM using Microsoft Excel. Results are shown 

in Figure 27 and are difficult to interpret. Suffice it to say, the Design-Build produces more 

congestion early-on but less overall compared to both the Traditional-Build and No-Build.

Utah Department of Transportation & University of Utah—Evaluation of the I-15 Reconstruction Design-Build

Figure 27 Congestion

15

20

25

30

35

40

45

50

1996 1998 2000 2002 2004 2006 2008 2010

Year

Travel Time (min) 

N-B

DB

TB

20

25

30

35

40

45

1996 1998 2000 2002 2004 2006 2008 2010

Year

Percentage of congested links [%]

N-B

DB

TB

DB yields higher congestion

Inuence of STIP Projects

DB ends here

TB ends here

TB yields higher congestion

Inuence

of road

closures

Inuence of

higher trac

demand
104

Crash Analysis

An important component to the evaluation of the Design-Build scenario was the impact on 

accidents. In order to conduct a comparison among the three alternatives, a regression model 

was constructed which included a traveler exposure component represented by the vehicle-miles 

traveled (VMT) output from the VISUM model. Other regression components included work zone 

length, number of interchanges opened and congestion on the network. The regression model was 

calibrated to actual condition between 1996 and 2001 in order to predict accidents and accident 

rates for the three construction scenarios.

Results were expressed in terms of crash rate and total number of crashes. Figure 28 shows the 

calculated accident rates for the three construction alternatives for both highways and surface 

streets. Overall, the Design-Build scenario has a lower rate for the duration of the study period 

even though it is greater during certain periods. The total number of crashes during the study period 

is smallest for Design-Build (65.3 thousand) compared to both Traditional-Build (69.7 thousand) 

and No-Build (66.2 thousand).

Figure 28 Crash Rates

Utah Department of Transportation & University of Utah—Evaluation of the I-15 Reconstruction Design-Build

-

50

100

150

200

250

300

350

1996 1998 2000 2002 2004 2006 2008 2010

Year

Accident Rate

DB

TB

NB
105

Wisconsin DOT Work Zone Signal Optimization

Work Zone Characteristics 

Transportation Analysis:

Approach Traffic Signal Optimization

Modeling Tools Synchro/SimTraffic

Work Zones:

Type Type I and IV

Network Configuration Isolated

Geographic Scale: 

Work Zone Size Small

Analysis Area Local

Use of Signal Optimization Tools in Work Zone Traffic Analysis

Signal optimization tools such as Passer, Synchro/SimTraffic, and Transyt 7F have a variety of 

applications for work zone analysis, especially in urban and suburban environments. Broadly 

speaking, these applications can be grouped in three categories:

1. Preparing timing plans for temporary signals used to manage traffic within a 

construction site.

2. Adjusting signal timing on corridors that are directly impacted by construction.

3. Adjusting signal timing to improve progression on corridors that serve as alternate 

routes or detours around a work zone.

Temporary Signals. Figure 29 shows an example of the use of Synchro/SimTraffic to optimize 

the timing of a temporary traffic signal. In this case, two-way one-lane operation will be in effect 

during a bridge construction project (in other words, eastbound and westbound traffic will be 

sharing a single lane). Synchro’s Ring/Barrier Editor was used to create a configuration that mimics 

the operation of the temporary signal by alternately sending eastbound and westbound traffic 

along the restricted section. Synchro’s signal optimization algorithm was then used to establish a 

timing plan that minimizes traffic delays. The analysis also provides an indication of the extent of 

queuing on the approaches to the one-lane segment, which is useful in determining whether access 

to side roads will be blocked by queued traffic. 

Wisconsin DOT—Work Zone Signal Optimization
106

Source: Wisconsin Department of Transportation

Figure 29 Synchro/SimTraffic Model of a Work Zone with Two-Way One-Lane Operation

*Note the westbound vehicles queuing while eastbound traffic is allowed to proceed. 

This method can also be used to evaluate the impact of work zone length on capacity and throughput 

for sites with two-way one-lane operations. As shown in Figure 30, the capacity of two-way onelane sections is sensitive to the length of the restricted section. Therefore, in many cases there is a 

trade-off between what is convenient for construction operations and what is acceptable in terms 

of traffic impact.

Wisconsin DOT—Work Zone Signal Optimization

Source: UK Department for Transport, Safety at Street Works and Road Works.

Figure 30 Capacity vs Length for Two-Way One-Lane Flagging Operations

Adjusting Timing on Corridors Affected by Construction. Normally, signal timing plans are 

developed based on the assumption that all of the lanes that exist at each intersection will be 

available for traffic to use. This assumption may not be true during construction. For example, 

take an intersection where a two of the three lanes have been closed to traffic. In this case, all traffic 

is directed to use the right lane, severely impacting the capacity of the signalized intersection. 

Capacity

(Vehicles per Hour)

Both Directions

Combined

0

200

400

600

800

1000

1200

1400

1600

0 200 400 600 800 1000 1200 1400 1600 1800

Length of Two-Way, One-Lane Section (Feet)
107

Wisconsin DOT—Work Zone Signal Optimization

In such situations, to avoid excessive queuing and delay it may be necessary to make fundamental 

changes in the signal timing at individual intersections or along an entire corridor. In the example 

shown in the photo, it may be desirable to increase the cycle length to compensate for the fact that 

left, thru, and right turning vehicles are sharing a single lane. To maintain good traffic progression 

along the corridor, signal offsets may need to be adjusted to account for reduced travel speeds. In 

addition, temporary changes in access to business properties along the corridor may affect turn 

patterns, requiring adjustments in signal phasing and splits. The use of a signal optimization tool 

allows all of these variables to be addressed comprehensively. 

Adjusting Timing on Parallel Routes. The Daniel Webster Hoan Memorial Bridge carries 

Interstate 794 over the Milwaukee River in Milwaukee, Wisconsin. As shown in Figure 31, on 

December 13, 2000 there was a structural failure on one span of the bridge. The failure required 

immediate lane closures, resulting diversion of all traffic to other routes. 

To accommodate increased traffic on the arterial street that runs directly parallel to I-794, the 

City of Milwaukee used signal optimization tools to prepare a revised traffic signal timing plan 

for the Kinnickinnic Avenue/First Street corridor (WIS 32). The revised signal timing plan was 

implemented less than 48 hours after the incident occurred (and at minimal cost). It increased the 

green time allocated to north-south thru traffic, and reduced the amount of time allocated to side 

streets. The revised signal timing is believed to have been instrumental in reducing traffic delays 

and minimizing the overall impacts of the bridge failure and subsequent reconstruction activities. 

Source: Unknown

Figure 31 Structural failure on Daniel Webster Hoan Memorial Bridge, December 13, 2000.
108

Wisconsin Department of Transportation

Work Zone Transportation Management Plans12

Overview

The Wisconsin DOT (WisDOT) has established guidelines on the development of Transportation 

Management Plans (TMP) as part of overall project delivery process during the design and 

construction stages. The formal process for developing a TMP is shown in Figure 1 below. 

12 This case study references the document Guidelines for Developing Work Zone Transportation Management 

Plans (January 2008) prepared by the Wisconsin Department of Transportation.

Wisconsin Department of Transportation—Work Zone Transportation Management Plans

Figure 32 WisDOT Transportation Management Plan Developement Process
109

While the extent of the TMP depends upon the nature of the project (location, size, duration, 

etc.), WisDOT recommends that a systematic assessment of work zone impacts be conducted 

for construction projects that impact travel lanes. (Minor maintenance projects that do not affect 

roadway capacity, classified as Type 1 TMPs in Wisconsin, generally do not require an analysis). 

Development of the TMP is designed to mitigate, to the greatest extent possible, safety and mobility 

impacts to workers and the public. 

In order to conduct the work zone impact assessment, WisDOT has formalized guidance used by 

regional offices in determining the extent to which work zone impacts need to be analyzed. This 

document is called the Lane Closure and Delay Guideline. With the guideline, WisDOT provides 

recommendations on the selection and use of traffic modeling tools for assessing the impact of 

various types of work zones. 

A web-based database called the Lane Closure System (LCS) has been developed to handle the 

administrative process of approving lane closures. It is also used to keep track of lane closure 

status and will feed closure data to Wisconsin’s 511 traveler information system.

Lane Closure and Delay Guidelines

In 2007 WisDOT updated their Facilities Development Manual to include guidelines for planning 

typical lane closures and methodologies for considering regularly occurring high volume periods 

with special considerations for holidays and planned special events. The lane closure guidelines 

establish a formal process which planners, engineers and operations managers follow in order to 

evaluate proposed lane closures. The process includes the following six steps (visually represented 

in Figure 33):

1. Determine route-specific maximum delay guideline and recommended lane closure times.

2. Estimate capacity under proposed lane closure.

3. Estimate hourly demand profile.

4. Estimate queues and delays using appropriate tools.

5. Identify appropriate mitigation strategies.

6. Plan and prepare for special conditions.

Wisconsin Department of Transportation—Work Zone Transportation Management Plans
110

Figure 33 Lane Closure Analysis Process

The guidelines include suggested procedures and methodologies to estimate the capacity of a 

roadway segment, determine traffic demand, and quantify resulting queues and delays using traffic 

volume data. Important to the discussion at hand is the recommendation of using traffic modeling 

tools with which step 4, Estimate queues and delays using appropriate tools, can be accomplished.

In addition to developing a formal procedure to systematically quantify queues and delays, 

WisDOT also developed a formal policy on acceptable delay values for construction projects on 

the Interstate system and other major multi-lane highways. The policy recommends no more than 

15 minutes of delay above the normal travel time between key city nodes and within each city 

node. The guidelines suggest that a rough threshold estimate is when a queue length in excess of 

one mile is sustained for more than thirty minutes then the work zone is likely not meet the 15 

minute delay criteria.

Wisconsin Department of Transportation—Work Zone Transportation Management Plans

Program Level

Scoping (Select road

segment of

anticipated lane

closure location) 

1. Determine

anticipated day(s) & 

times of week for 

closure

Will work occur on

holiday or during

special event?

Input day/segment

info into LCS tool

Select time when

under capacity

Select different

day or time for

work

6. Revise Staging or

Scheduling or 

Determine Additional

Mitigation Methods

4. Do estimated

delays exceed

acceptable criteria?

NO

YES

YES

NO

YES

YES

NO

NO

5. Would other 

staging or mitigation

methods have

potential to be cost

effective?

YES

3. Review & adjust

hourly traffic

volume data. Is

lane closure

appropriate per 

LCS tool?

Are there other 

proposed WZ in

same corridor or 

segment?

Review road user 

impacts of multiple

projects

Prepare

TMP

2. Estimate

capacity under 

proposed lane

closure

NO

Complete

exception

acceptance

Estimate process

queues &

delay

NO

OR
111

The following sections will provide more discussion on WisDOT’s guidelines on the selection, use 

and implementation of various traffic modeling tools to be used for estimating queues and delays. 

Queue and Delay Estimation Tool Recommendations

HCM Methodologies

	Work Zone Type: 1, 2, ~3

	Network Configuration: Isolated

	Work Zone Size: Small

	Analysis Area Dimension: Local or Site 

WisDOT recommends the use of HCM-based traffic modeling tools for work zone Types 1 and 2, 

and perhaps certain Type 3 work zones. In order to support WisDOT engineers, WisDOT developed 

the Work Zone Capacity Analysis Tool (WZCAT). It is primarily intended to help predict delays 

and queues associated with short-term (daily) lane closures on rural freeways. The current version 

of WZCAT uses HCM methodology to calculate delay due to work zone operations based on two 

inputs. One input is “work zone capacity” which is simply the capacity estimated for the work 

zone and the second input is demand which is traffic volume usually estimated from a single 

detector location upstream of the work zone. This tool is limited by the use of only a single work 

zone location, and it does not take into account the impact of heavy vehicles on queue estimations 

(though a revised version is being developed). WZCAT calculates only the queues and delays 

associated with an over-capacity situation; currently the spreadsheet does not attempt to compute 

the delays associated with changes in travel speeds resulting from other characteristics of the work 

zone such as reductions in lane width and speed limits.

Sketch Planning Tools

	Work Zone Type: 2, 3, ~4

	Network Configuration: Isolated, Pipe, Network (limited)

	Work Zone Size: Small, Medium, or Large

	Analysis Area Dimension: Metropolitan, Local, or Site 

WisDOT recommends the use of mode robust sketch planning tools (such as QuickZone or 

Quadro) for work zones of Types 2 and 3, perhaps certain Type 4. In Wisconsin, these tools are 

used primarily for analysis of projects on freeways and rural highways. With the sketch planning 

tools, users can compare the impacts of multiple construction staging and phasing alternatives, 

work times, lane closures, traffic diversions, and various mitigation strategies. 

Sketch planning tools require more data than HCM based methods. Typical requirements include 

route length, free flow speed, project duration, road closure times, and traffic volumes for primary 

and alternate routes. QuickZone requires creation of a network of links and nodes, while Quadro 

uses a simplified network consisting of two parallel links (one link represents the route that is under 

Wisconsin Department of Transportation—Work Zone Transportation Management Plans
112

construction and the other represents an alternate or detour route). In Wisconsin the additional data 

is relatively easy to obtain, and it is generally perceived that for projects of moderate complexity, 

the extra information provided by the software is worth the additional effort.

WisDOT has found that sketch planning tools are quite sensitive to assumptions about the capacity 

of the work zone. QuickZone requires capacity values to be supplied by the analyst. Quadro has 

built-in default capacity values for various types of work zones, which can be overridden if the 

analyst has suitable local data.

Wisconsin DOT advocates the use of sketch planning tools to help evaluate trade-offs between 

construction traffic management strategies, such as deciding whether the cost of implementing a 

more expensive strategy is justified by user delay cost savings. Sketch planning tools are used to 

prepare a road user delay cost analysis that assigns a monetary value to delays caused by queues, 

reductions in speed through the work zone, and increases in travel time and vehicle operating costs 

associated with diversion to alternate routes. Since detours often involve sending traffic onto roads 

built to lower standards, the Quadro software also estimates crash probabilities and converts them 

to a monetary value. 

Intersection Analysis Tools

	Work Zone Type: 2, 3, 4

	Network Configuration: Network

	Work Zone Size: Small, Medium, or Large

	Analysis Area Dimension: Metropolitan, Local, or Site 

In general, sketch planning tools do not directly account for “control delays” associated with 

signalized intersections, roundabouts, or other traffic control devices. These delays can be 

significant for urban arterial projects and other locations where construction activities are likely 

to disrupt normal traffic patterns and redistribute traffic in the network. In these cases WisDOT 

recommends checking and updating signal timing plans using the estimated volumes that will 

be present during construction. In Wisconsin this is usually done using a signal analysis and 

optimization tool such as Signal 2000, Synchro, or Transyt7F. These tools can also be used to 

evaluate the need for temporary signals. WisDOT uses Rodel to verify roundabout capacities.

Wisconsin Department of Transportation—Work Zone Transportation Management Plans
113

Microscopic Simulation

	Work Zone Type: 4

	Network Configuration: Generally Network

	Work Zone Size: Generally Medium, Large, or Very Large

	Analysis Area Dimension: Metropolitan, Local, or Site 

In Wisconsin, the Type 4 TMP designation generally applies to large, complex projects with 

regional impacts, such as freeway-to-freeway interchange reconstruction projects. For these 

projects a microscopic traffic simulation program is often appropriate to determine the extent 

of queuing, user delays, and traffic redistribution in the network. Using microscopic simulation, 

individual vehicles are modeled in fine detail for the duration of their entire trip, providing traffic 

flow, travel time and congestion information, as well as potentially enabling the modeling of the 

interface between drivers and ITS. These programs provide a highly detailed analysisbut require 

detailed traffic and roadway data. Creating a properly calibrated model can take an extensive 

amount of time. As a result, in Wisconsin microsimulation analysis to support the TMP is often 

integrated with constructability analysis and other traffic modeling done to verify and refine the 

overall design of the project.

To assist regional offices in conducting microscopic simulation analysis, WisDOT developed the 

Microsimulation Model Scoping Worksheet which is used by Bureau of Highway Operations to 

determine whether or not microscoping simulation is a) appropriate and b) technically feasible. 

The scoping worksheet is attached.

Wisconsin Department of Transportation—Work Zone Transportation Management Plans
114

Wisconsin Department of Transportation—Work Zone Transportation Management Plans
115

Maryland State Highway Administration and the Virginia Department of Transportation 

Woodrow Wilson Bridge Reconstruction

Work Zone Characteristics 

Transportation Analysis:

Approach Sketch-Planning

Mesoscale

Microscale

Modeling Tools QuickZone

HCM

CLV

VISSIM

CORSIM

Work Zones:

Type Type I

Network Configuration Network

Geographic Scale: 

Work Zone Size Small

Analysis Area Metropolitan

Overview

The replacement of the Woodrow Wilson Bridge (WWB), along Interstate 95 in the Metropolitan 

Washington, DC area, is an extremely large and complex construction project requiring the close 

coordination of numerous contractors and various state and local government agencies. The Woodrow 

Wilson Bridge carries upwards of 100,000 vehicles per day along Interstate 95 which spans the 

Potomac River. The Woodrow Wilson Bridge Project spans a 7.5 mile-long corridor extending from 

the MD 210 interchange in Maryland to Telegraph Road in Virginia, crossing over the Potomac 

River. The current 6-lane bridge is being replaced with a dual-span bridge that will more than double 

the number of traffic lanes. See Figure 34 for an overview of the construction site.

The management of the construction project primarily involves the Maryland State Highway 

Administration (MD-SHA) and the Virginia Department of Transportation (VDOT) who are 

responsible for overseeing daily operations of the construction site including scheduled lane 

closures. An important aspect to the replacement of the Woodrow Wilson Bridge is to maintain 

current roadway capacity during peak periods while construction takes place. This requires limited, 

if any, lane closures during peak periods and daylight hours. In general, any necessary lane closures 

were conducted at night to minimize the impact on drivers. 

Due to the complexity of the project, the Woodrow Wilson Bridge Project is being completed under 

several phases over the span of more than a decade. In addition to the new bridge construction, 

a number of interchanges also have to be reconfigured both on the Virginia and Maryland sides 

Maryland State Highway Administration and the Virginia Department of Transportation

—Woodrow Wilson Bridge Reconstruction
116

to join to the new bridge alignment. With several jurisdictions involved, the long duration of the 

project, and 100,000 vehicles per day utilizing the bridge, traffic management during construction 

of the bridge and interchanges was a major concern. There were several types of work zones 

implemented throughout this project with which several different work zone modeling tools were 

used including the following:

	Lane Closure Analysis: CLV

	Roadway Operations Analysis: CORSIM

	Roadway Closure Analysis: QuickZone

Work Zone Characteristics

The Woodrow Wilson Bridge reconstruction project affected several miles of major roads and 

interchanges in two states including I-95/I-495 (Capital Beltway) from Maryland to Virginia, 

I-295, MD 414, and MD-210 in Maryland, and Telegraph Road, Route 1, and Washington Street in 

Virginia. To keep traffic moving throughout the longevity of the project, the construction work for 

the Woodrow Wilson Bridge project had to be completed in many steps instead of one large work 

zone. Work zone plans had to be developed for each step of this construction project and therefore, 

the Woodrow Wilson Bridge Project work zones are categorized as the most severe, Type I, work 

zones. 

The Woodrow Wilson Bridge team faced many challenges in developing work zone plans, 

implementing detours, and maintaining traffic patterns while minimizing delays. In addition, the 

possibility of traffic delays and the visibility of this project made it imperative to provide accurate 

traffic information to commuters using the bridge during its reconstruction. The complex nature of 

the work zones on this project required extensive analysis of traffic impacts caused by work zones 

and traffic detours. The Woodrow Wilson Bridge team used several different work zone analysis 

tools to provide insight regarding traffic impacts and also predict delays to the public. Figure 34 

shows the different work zone analysis tools used in this project.

Maryland State Highway Administration and the Virginia Department of Transportation

—Woodrow Wilson Bridge Reconstruction
117

Figure 34 Analysis tools used for the Woodrow Wilson Bridge Reconstruction Project

Transportation Management Plan Strategies

Traffic engineers on this project had the challenge of dealing with designs and maintenance of traffic 

(MOT) plans from two different jurisdictions. In addition, Virginia and Maryland had different 

philosophies for their MOT plans. The MOT plans for the Maryland side were very detailed and 

utilized models to evaluate their MOT phasing for some of their contracts including Synchro, 

Critical Lane Volume (CLV) and Highway Capacity Software (HCS). In addition, they used CLV to 

obtain hourly and 15 minutes traffic volumes during the construction phase. Conversely, the MOT 

plans for the Virginia side were much more fluid and changed significantly during the construction 

phase. They used both Synchro and QuickZone analysis during the construction phase to evaluate 

their work zone impacts.

There were numerous work zone plans required for the Woodrow Wilson Bridge Project varying 

between a Type I and Type III work zone. For example, the first use of QuickZone was for a Type 

III work zone associated with the reconstruction of the Maryland 210 interchange. There were 

three Type 1 work zones occurring throughout the project which involved major traffic switches 

and disruption to the traveling public. The first was a full closure of the bridge during overnight 

hours in the spring of 2006. The second and third involved two major traffic switches during the 

summers of 2005 and 2006. The following will provide an overview of each of the four work zones 

mentioned previously. 

Maryland State Highway Administration and the Virginia Department of Transportation

—Woodrow Wilson Bridge Reconstruction

VISSIM

CORSIM

Area Where QuickZone Analysis Was Used

To the Springfield

Interchange
118

Maryland State Highway Administration and the Virginia Department of Transportation

—Woodrow Wilson Bridge Reconstruction

	Fall 2001 MD 210/I-295 Interchange Reconstruction (QuickZone)—In the fall of 

2001, a contractor for the Maryland State Highway Administration was in the process of 

constructing one of many new bridges as part of the replacement and refurbishment of the 

Woodrow Wilson Bridge at the MD 210/I-295/I-95 interchange just east of the Potomac 

River shoreline (Figure 35). The construction involved the demolition of existing bridges 

and the construction of new bridges. The plan included closing lanes during the overnight 

hours (midnight to 4:00am) and two temporary openings in the median barrier in order to 

divert traffic safely around the construction area while construction was taking place. This 

work zone plan configuration was scheduled to take between 4 and 6 months to complete.

The need for QuickZone arose when the contractor determined that to more efficiently 

utilize available resources, a four-hour window of construction would not be sufficient. 

The original work zone plan had lane closures occurring between midnight and 4:00am 

and the contractor estimated it would take 1.5 hours for work zone set up and take down, 

leaving 2.5 hours of actual production time. The analysis required a quick turn-around 

of multiple scenarios of when lane closures could take place without severely impacting 

motorists so that the contractor could extend lane closure durations.

	Summer 2005 US 1 Traffic Switch (CORSIM)—During Summer 2005, the US Route 1 

Interchange contract was completed and included new ramp connections to the bridge. A 

traffic switch was needed to move from the old ramp connections to the new alignment as 

seen in Figure 36. This was a major undertaking and detailed traffic information was needed 

to assess the impacts to traffic. The design of the new alignment was complex and included 

a flyover ramp from southbound Route 1 to the northbound ramp of I-95. The engineers 

used CORSIM to analyze the switch because there were ramp alignment questions that 

could be answered with this software. The analysis took approximately 4 months (from late 

2004 to early 2005). They used count data for the ramps that were performed in 2003 and 

mainline count data that were obtained from cameras mounted at the site.

	Spring 2006 MD 210 Girder Placement (CLV Analysis)—In the spring of 2006, a contractor 

for the Maryland State Highway Administration was in the process of replacing the MD 

210 Bridge that goes over the I-495 Beltway. As part of this work, the contractor needed 

to erect very large steel girders for the MD 210 Bridge. The contractor could not place 

the girders while traffic was moving because the work would be done above the Beltway 

(I-495). The original plan included 15 minute lane closures for the placement of these 

girders but due to their large size, it was clear that the work could not be completed in these 

short time spans. Instead, all lanes of the Beltway (I-495) in both directions approaching 

the Woodrow Wilson Bridge were temporarily closed overnight for several consecutive 

nights. The traffic engineers on this project developed a plan to detour traffic during the full 

closure as seen in Figure 37. It was very important that the Woodrow Wilson Bridge team 

analyze the impacts to the capacity of traffic based on the detour route. They needed to find 

out what the volume needs would be during the closure and therefore used CLV analysis to 

obtain the critical lane volumes and figure out how the detour would affect capacity.
119

	Summer 2006 Traffic Switch (QuickZone)—In the summer of 2006, the first of the two 

new WWB bridges was completed. A major traffic switch was performed on both the inner 

and outer loops of the beltway, as shown in Figure 38 and Figure 39, respectively, where 

all of the traffic needed to be switched from the old bridge to the new bridge alignment 

so that the old bridge could be demolished. There was pressure to provide an accurate 

assessment of the traffic impacts and relay those impacts to the public. The analysis was 

performed using QuickZone. QuickZone was chosen in part because it was very important 

to know accurate queues and delays due to construction and related those numbers to the 

WWB traffic call center. In addition, QuickZone was chosen because the switch would 

result in higher capacity and therefore it was expected that conditions would improve due 

to the switch.

Maryland State Highway Administration and the Virginia Department of Transportation

—Woodrow Wilson Bridge Reconstruction
120

Maryland State Highway Administration and the Virginia Department of Transportation

—Woodrow Wilson Bridge Reconstruction Figure 35 MD 210/I-295 Interchange Reconstruction

Construction with Lane ClosuresTemporary Median OpeningTemporary Diversion Area

South

North
121

Maryland State Highway Administration and the Virginia Department of Transportation

—Woodrow Wilson Bridge Reconstruction Figure 36 US 1 Interchange Traffic Switch Using CORSIM Reconstruction of Existing Roadway Temporary Traffic Shift (“swoop”)

South

North

Existing roadway reconstructedand second half of bridge built

I-95 shifted underneathfirst half of new bridge
122

Maryland State Highway Administration and the Virginia Department of Transportation

—Woodrow Wilson Bridge Reconstruction Figure 37 MD 210 Girder Placement Using CLV Traffic Signal I-95 Southbound Detour Route I-95 Northbound Detour Route Lanes Closed for Girder Placement South

North

Bridge being reconstructed
123

Maryland State Highway Administration and the Virginia Department of Transportation

—Woodrow Wilson Bridge Reconstruction Figure 38 2006 Inner Loop Traffic Switch Using QuickZone I-95 South (inner loop) Reduced to 1 Lane QuickZone Impact Analysis Area

South

North

Work Zone
124

Maryland State Highway Administration and the Virginia Department of Transportation

—Woodrow Wilson Bridge Reconstruction Figure 39 2006 Outer Loop Traffic Switch Using QuickZone QuickZone Impact Analysis Area I-95 North (outer loop) Reduced to 1 Lane

South

North

Work Zone
125

Maryland State Highway Administration and the Virginia Department of Transportation

—Woodrow Wilson Bridge Reconstruction

Data

Data collection was very important to the traffic analysts working on this project. Although data 

availability was scarce in the beginning, specifically existing volume data in Maryland, as the 

project continued, the analysts were able to obtain better data that was essential in the analysis 

of traffic impacts. These data include daily real time data on the beltway provided by Mobility 

Technologies, 24-hour intersection counts and tube counts taken for Virginia and Maryland, ramp 

data as recent as June 2007 and the entire network of Synchro files for Virginia provided by VDOT 

(NOVA district)

Demand data for the inner-loop was acquired from the various MD-SHA permanent traffic count 

stations set up prior to the construction site and available at the Maryland Roads web site (www.

marylandroads.com). Demand data for the outer-loop was made available through special traffic 

counts conducted by the VDOT on the Virginia approach to the Woodrow Wilson Bridge. Lane 

capacities, lengths, and free-flow speeds were gathered from historical data.

Agency Resources

Although the management of the construction project primarily involved MD-SHA and VDOT, the 

joint vengture General Engineering Consultants (GEC) was hired to oversee the construction. This 

joint venture included Parsons Brinkerhoff, URS Corporation, Rummel Klepper and Kahl (RK&K) 

and several sub-consultants including 8 DBEs. GEC had on-site technical expertise with modeling 

software and therefore much of the simpler work zone modeling that was done periodically, such 

as QuickZone, was performed in house. 

Work Zone Modeling Tools

In addition to the major work zones discussed previously in this case study, there were other 

work zone modeling opportunities throughout the project and a range of modeling tools was 

used to support decision-making. QuickZone was used extensively, approximately 3 to 4 times 

per year, to understand impacts of the open span of the bridge and discuss the impacts with the 

Port Authority. The analysts used QuickZone for mainline analysis but chose other software for 

portions of the analysis where turning movements were important. The QuickZone software is 

a sketch planning tool that was “developed to help state and local transportation agencies better 

understand and consider the impacts of work zones as they plan, design, and implement their 

highway projects”. This software can help estimate work zone delay and user costs, quantify 

corridor delays from capacity decreases in work zones, identify the impact of delay on different 

construction plan alternatives and estimate the impact of delay when developing mitigation 

strategies such as alternate routes, detours, lane closures. 

Critical Lane Volume Analysis (CLV) is a planning tool that was used by the Maryland side to 

analyze level of service at individual intersections. CLV identifies levels of congestion at signalized 

intersections and it is useful because the results are easy to understand and to report to the general 

public. In the WWB project, hourly and 15 minute traffic volumes were provided using CLV.

Highway Capacity Software (HCS) is an operational tool that was used to model the expected 

added travel time that will be generated from the each construction zone. The outcome of this 

analysis can determine Level of Service (LOS) of the facility.
126

On the Virginia side, Synchro was used as a traffic signal optimization tool to understand the work 

zone impacts. Synchro’s outcomes include LOS, signal phasing improvements for alternate routes 

and detours during construction, and travel delay estimations. 

For the more complex modeling, microscopic simulation tools were used including VISSIM and 

CORSIM. Both of these software packages can simulate the movement of individual vehicles 

using car-following and lane change theories. For VISSIM, a base network is set up to run test 

simulations under different scenarios during construction. It can evaluate delays of the multiple 

scenarios using variable speed limits. CORSIM outputs maximum and average queue lengths, 

determines LOS and provides estimations of delays in work zones.

Maryland State Highway Administration and the Virginia Department of Transportation

—Woodrow Wilson Bridge Reconstruction
127

Yosemite National Park

Yosemite Village Roadway Reconstruction13

Work Zone Characteristics 

Transportation Analysis:

Approach Sketch-Planning

Modeling Tools QuickZone

Work Zones:

Type Type IV

Network Configuration Pipe

Geographic Scale: 

Work Zone Size Small

Analysis Area Local

Overview

Yosemite National Park in California is one of the most popular national park destinations in the 

nation, averaging more than 40,000 visitors through its entrance gates each day throughout the 

year. One of the primary entrance destinations for park visitors is Yosemite Village, the primary 

hub of activity within the park and home to the Valley Visitors Center, a wide variety of lodging 

and dining options, trail heads, and other visitor services.

The shape of Yosemite Valley Figure 40 makes access to Yosemite Village scenic for the park 

visitor but quite limiting for a traffic manager. Given the steep terrain around the valley, the only 

roadways into and out of Yosemite Village are Northside and Southside Drives running along the 

Merced River which flows through the center of the valley. Both facilities are two-lane, one-way 

facilities with stop-controlled intersections along their length at two bridge crossings.

These two key valley roadways are scheduled for a significant repaving and rehabilitation project 

scheduled to start in 2006 but subsequently delayed through funding and legal issues to this day 

(August 2008). The Federal Lands Highway Division (FLH) of the FHWA is responsible for the 

planning, design and construction phases of the project, working in conjunction with the National 

Park Service to minimize impact on park visitors and the environment while cost-effectively 

conducting the needed roadwork.

13 This case study was adapted from the report FLH-QuickZone Case Studies: The Application of FLH-QuickZone in 

Six Federal Lands Projects available from Federal Lands Highway Division.

Yosemite National Park—Yosemite Village Roadway Reconstruction
128

Yosemite National Park—Yosemite Village Roadway Reconstruction

Figure 40 Yosemite Case Study Area

Concern regarding significant delays in the construction phase led FLH staff and NPS personnel to 

consider a range of phasing and staging alternatives. This concern is nontrivial given current (no 

roadwork) traffic conditions, where weekend congestion and delays are already a recurring event 

during peak travel months.

One alternative considered was an alternating full closure plan where work on Southside Drive 

could be conducted quickly while all inbound/outbound traffic would be directed onto Northside 

Drive (temporarily configured to support 2-way traffic). In a second phase, Northside Drive would 

be closed and all traffic diverted onto Southside Drive. The advantage of this alternative was 

that the project could be completed faster (one season) and more efficiently at a lower cost. The 

disadvantage of such an approach was that capacity reductions from the roadwork had to be in 

place around the clock, and could not be timed to avoid weekly and daily peaks in travel demand.

A second alternative was to pursue project planning under a more traditional approach where one 

lane of each facility would be repaved while the other remained open to traffic. This approach 

would allow for work to be suspended during peak demand hours but would be less efficient to 

conduct, lengthening the project duration to two seasons and incurring additional costs.

The original role of modeling the work zone impacts in the Yosemite project was to identify the 

likely travel delays expected under the two alternatives, allowing FLH and NPS staff to make an 

informed choice between the two, trading off road user delay against project cost. As the case 

study progressed, however, the traffic model became integral in the incremental refinement of a 

phasing and staging plan combining advantageous aspects of both alternatives.

1

11 2

3

4

5

12

8

9

Project Limits

(West)

Outbound Change

to 1-Way

Project Limits

(East)

Wawona Road

Intersection

El Capitan

Crossover

7

6

Sentinel Dr.

Crossover
129

Network Design and Modeling Approach

Network design for each alternative was different given the significant changes in geometry and 

traffic flow associated with the full closure components of the single-season alternative. The 

first alternative was coded using two networks (Figure 41). In the first phase, links representing 

Southside Drive are removed from the network and new links representing inbound operations on 

Northside Drive are added. The reverse is true for phase 2, where links representing Northside 

Drive are removed from the network and new links added to Southside Drive for outbound 

operations. These networks were run as separate files in traffic modeling software and results were 

combined external to the model. The second alternative was coded using a single network for all 

project phases.

Yosemite National Park—Yosemite Village Roadway Reconstruction

Figure 41 Yosemite Traffic Modeling Networks

A key element for the work zone analysis was obtaining accurate travel demand. Travel demand data 

were assembled from a number of sources and then refined through two short-term data collection 

activities. A first-cut distribution of hourly and daily travel demand factors were obtained from a 

1998 traffic study. Monthly variations in travel demand were obtained from park entrance station 

data. Finally, two-short term collection activities (one two-week collection activity in June 2004 

and one one-week collection activity in August 2004) were conducted to refine hourly and daily 

distributions and to establish a rate of travel demand growth from 1998-2004. Given that recurrent 

weekend congestion had worsened over the period, data were collected to identify when and by 

how much visitors had shifted departure or arrival times to avoid congested periods since 1998 

(Figure 42). The supplementary data collection effort in 2004 was conducted using NuMetrics HiStar portable traffic counters, a commonly utilized technology within FLH.

1

4

5

6

7 9

8

12

11

Phase 1:

Southside Dr. Closed

2-Way on Northside Dr.

3

2

1

3

6

7 9

8

12

11 2

4

5

closed

closed

2-Way Traffic

2-Way Traffic

Phase 2:

Northside Dr. Closed

2-Way on Southside Dr.
130

Figure 42 2004 Hourly Demand Pattern By Day of Week (from HI-STAR)

Traffic control operations modeled included lane closures, flagger operations, and full closures. 

Capacity of flagger operations were estimated external to the model and then input for affected 

links.

Application

The single-season alternative, although cost-saving and shorter in total duration, was predicted to 

generate long and unacceptable delays for park visitors, particularly on weekend afternoons during 

summer months. The two-season alternative, when no-work hours had been refined by additional 

work zone analysis, produced no more than 10 minutes of additional visitor delay. The differential 

in road user delay between the single-season and two-season alternative was too large to justify the 

reduced cost of the single-season alternative.

In discussing the results, however, it became clear that the full-closure elements of the single-season 

alternative could be viable if the delay during the peak months of July, August and September 

could be avoided. In response, FLH staff developed a hybrid third alternative plan that combined 

full closure activity during relatively low-demand months (March-June, October-November), and 

traditional one-lane paving operations in the peak summer months.

This third alternative plan had the advantage of recouping most of the cost savings of the singleseason approach with significantly lower travel delays. Delay was not eliminated, however. In 

June, outbound delays were predicted to approach 30 minutes for outbound traffic on Sunday 

afternoons. Likewise, in October, inbound delays on weekends could approach 60 minutes.

Yosemite National Park—Yosemite Village Roadway Reconstruction

0.00%

2.00%

4.00%

6.00%

8.00%

10.00%

12.00%

14.00%

IN M-Th IN FRI IN SAT IN SUN OUT M-Th OUT FRI OUT SAT OUT SUN

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
131

Zion National Park

Entrance Booth Reconstruction14

Work Zone Characteristics 

Transportation Analysis:

Approach Sketch-Planning

Modeling Tools QuickZone

Work Zones:

Type Type III

Network Configuration Isolated

Geographic Scale: 

Work Zone Size Small

Analysis Area Local

Overview

Designated a National Park in 1919, Zion National Park is Utah’s oldest national park. Zion canyon 

features soaring towers and monoliths that suggest a quiet grandeur. Zion is also known for its 

incredible slot canyons, including “The Narrows,” which attract hikers from around the world. 

With nearly three million visitors per year, Zion is Utah’s most popular National park. Entrance 

fees are $20 per vehicle and $10 per person arriving on foot.

There are two major entrances to Zion National Park, a south and an east entrance. A third entrance, 

located on the west side of the park, provides access only to Zion’s Kolob Canyon. The South 

Entrance is the larger and most frequently-used of the three entrances. The South Entrance is 

on Utah Route 9 about 60 miles south from Cedar City, via I-15 and Utah Route 17 (see Figure 

44 below). The East Entrance is on Utah Route 9, 12 miles east of Mt. Carmel Junction, at U.S. 

Route 89. The park contains over 12 miles of road. To ease traffic congestion within the park, a 

shuttle system is available to take visitors to the most popular areas. A shuttle bus service is also 

available from the town of Springdale, just outside of the park. Shuttles operate from April through 

October; during that period private automobiles are not allowed on the 6.5 mile stretch of road 

in Zion Canyon. The shuttles provide the only access to marquee attractions like the Great White 

Throne, the Watchman, the Grotto, Angels Landing, Weeping Rock and the Temple of Sinawava. 

Automobiles are allowed on other park roads, including all of Hwy 9, which provides access to the 

lower part of the park, the Tunnel and the East Entrance/Checkerboard Mesa area.

14 This case study was adapted from the report FLH-QuickZone Case Studies: The Application of FLH-QuickZone in 

Six Federal Lands Projects available from Federal Lands Highway Division.

Zion National Park—Entrance Booth Reconstruction
132

Figure 43 Zion National Park Overview Figure 44 Zion National Park

South Visitors Entrance

Approximately 90% of park visitors utilize the south visitor’s entrance. The entrance includes 2 

visitor lanes and 1 employee lane, controlled by a radio-frequency tag system. Employees are able 

to process approximately 240 visitor vehicles an hour of which 50% are cash transactions, 40% 

credit card and 10% National Park Pass. 75% of the vehicles entering the park are passenger cars/

trucks and 25% are RVs. During the peak season, recurring queue can extend as much as 1⁄4 mile 

from the entrance.

In 2004, a major rehabilitation of the main road through Zion, beginning at the south visitor’s 

entrance and extending into Zion Canyon was scheduled to take place. This included widening and 

structural repairs of certain sections of the existing road and milling/paving of the entire 7 mile 

stretch. A major concern of the National Park Service was the impact to visitors coming to Zion 

National Park through the town of Springdale. Traffic congestion on roads inside the park was not 

a concern since visitors are required to use the free shuttle bus service. 

Significant queuing and delay at the south visitor’s entrance, where recurrent queues were already 

present, was of major concern to park administrators. The original work zone plan called for 

shutting down one visitor entrance lane at a time for construction. The National Park Service 

did not want construction to cause a queue to form that extended into the town of Springdale, 

approximately 1/2 mile from the south visitor’s entrance. A queue of this length would not only 

impact traffic in the town, but employees getting to the park and the operation of the shuttle bus 

service from the town to the park. The work zone analysis and use of the traffic modeling tool 

was used to estimate the length of queue and number of vehicles in queue if one of the two visitor 

entrance lanes were to be closed for construction. This was conducted for the peak tourist months 

of June, July, August, September and October.

Zion National Park—Entrance Booth Reconstruction

Zion National

Park

I-15 North to

Salt Lake City

South

Entrance

Springdale

Tunnel

9

9
133

Work Zone Characteristics

The Zion National Park work zone is simple in design and can be considered an isolated work zone 

with no interaction of surrounding infrastructure. For the purposes of this work zone analysis, only 

the south visitor’s entrance was modeled since there was no concern about queuing or delay along 

the seven mile stretch of road within the park. 

A critical element regarding this work zone was estimating the capacity of the south visitor’s 

entrance. This entailed calculating the number of vehicles that can be processed in an hour and is 

similar to estimating the capacity of a signalized intersection or toll plaza. Work zone capacity was 

calculated using average transaction time per vehicle and a breakdown of average transaction types 

per day. It was calibrated against historical queuing data to arrive at an overall facility capacity. 

Hourly counts were generated from a simple traffic study conducted in April 2002 for an average 

day both during the week and on the weekend. Seasonality was taken into account by using April 

as a baseline point and scaling up demand based upon historical knowledge for the months of June, 

July, August, September and October. 

Construction at the south visitor’s entrance was just one component of the overall construction 

project and was estimated to take between two to three weeks. The use of the traffic model was 

being used to estimate queuing impacts if construction were to occur during the months of June, 

July, August, September or October and to determine which month would cause the least amount 

of impact.

Application

The roadway construction at Zion National Park was planned to only occur Monday through 

Friday and during daylight hours. This was done to avoid impacting the larger crowds visiting on 

the weekends and disturbing those visitors camping during the evening and overnight hours. As a 

result, the work zone analysis focused upon the weekdays. Baseline queuing was calibrated against 

actual demand seen in the field during the month of April. Once the calibration was complete, 

traffic model was run where capacity of the south visitor’s entrance was reduced by 50% (the 

equivalent of one lane of traffic entering the park).

The results of the work zone analysis indicated that the queue will impact the town of Springdale 

in each of the five months analyzed: 

	June: .58 mile queue, 463 vehicles in queue

	July: .66 mile queue, 513 vehicles in queue

	August: .66 mile queue, 513 vehicles in queue

	September: .58 mile queue, 461 vehicles in queue

	October: .45 mile queue, 361 vehicles in queue

The order of magnitude for delay was around 300 minutes or 5 hours with the queue beginning to 

form around 9 AM, peaking at 3 PM and dissipating by 9 PM. Clearly, people will not wait 5 hours 

to get into the park. The key data point for this analysis was the estimated number of vehicles in 

queue and whether that queue will impact the town of Springdale. 

Zion National Park—Entrance Booth Reconstruction
134

Results of the Zion work zone analysis provided the local engineers with the necessary data 

to reevaluate the construction phasing. After seeing the results engineers knew that the current 

construction phasing could not take place as originally designed and began to brainstorm on 

various alternatives including opening up temporary entrance booths and shifting construction to 

the early evening hours to not coincide with the peak demand. In the end, the results of the work 

zone analysis provided the engineers with necessary evidence to require the reconstruction to take 

place at night. 

Zion National Park—Entrance Booth Reconstruction

Office of Operations

Room E86-205

1200 New Jersey Avenue, SE

Washington, DC 20590

www.ops.fhwa.dot.gov

FHWA-HOP-09-001