Wisconsin Department of Transportation

WIS 75 Intersection 

Screening & Project 

Development Process 

SAFETY DATA CASE STUDY 

FHWA-SA-21-074 

Federal Highway Administration Office of Safety 

Roadway Safety Data Program 

http://safety.fhwa.dot.gov/rsdp
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SAFETY DATA CASE STUDY FHWA-SA-21-074

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SAFETY DATA CASE STUDY FHWA-SA-21-074

1. Report No.

FHWA-SA21-074

2. Government Accession 

No.

3. Recipient's Catalog No.

 

4. Title and Subtitle

WIS 75 Intersection Screening & Project Development Process

5. Report Date

September 2021

6. Performing Organization Code

7.Author(s) 

Ian Hamilton 

8. Performing Organization Report No.

9. Performing Organization Name and Address

Vanasse Hangen Brustlin, Inc (VHB)

940 Main Campus Drive 

Raleigh, NC 27606 

10. Work Unit No.

11. Contract or Grant No.

DTFH61-16-D-00052

12. Sponsoring Agency Name and Address

Federal Highway Administration Office of Safety 

1200 New Jersey Ave., SE

Washington, DC 20590

13. Type of Report and Period

Case Study, January 2020-January 

2022

14. Sponsoring Agency Code

FHWA

15. Supplementary Notes

The contract manager for this report was Jerry Roche. Funding for this effort provided in part by the Highway Safety 

Manual Implementation Pooled Fund, TPF-5(255).

16. Abstract

This case study presents a safety analysis conducted by the Wisconsin Department of Transportation (WisDOT) at the 

intersection of State Highway 75 (WIS 75) and Plank Road (County Road A) in Racine County, WI. WisDOT proactively 

identified key safety needs early in the project development process and used a data-driven approach to evaluate the safety 

effects of potential alternatives. The corridor is scheduled for resurfacing in 2023, and through the network screening 

process, WisDOT identified an opportunity to develop a Highway Safety Improvement Program-related project in 

conjunction with routine maintenance. WisDOT’s diagnosis process reviewed recent crash history for potential 

contributing factors (e.g., driver behavior, sight distance, curvature, intersection geometry, etc.) and underscored the need

to reduce failure-to-yield crashes. A preliminary intersection control evaluation eliminated infeasible alternatives early in 

the process and highlighted appropriate alternatives for further analysis. WisDOT applied State-calibrated safety 

performance functions in the Interactive Highway Safety Design Model software to predict crashes for each alternative and 

used State-approved crash modification factors where applicable. With these results, the economic appraisal step 

highlighted the most cost-effective alternative for this particular location. The State of the Practice methods and tools 

applied at each step in the process allowed WisDOT to thoroughly evaluate a safety need on its public road network as part 

of an institutional and readily repeatable planning process.

17. Key Words: 

Rural, Intersection, ICE, Safety, IHSDM, 

Highway Safety Manual

18. Distribution Statement

No restrictions.

19. Security Classif. (of this report)

Unclassified

20. Security Classif. (of this 

page) Unclassified

21. No. of Pages

 16

22. Price

Technical Documentation Page
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SAFETY DATA CASE STUDY FHWA-SA-21-074

Acronyms

Acronym Description

AADT annual average daily traffic

AASHTO American Association of State Highway and Transportation Officials 

BCR benefit/cost ratio

CMF crash modification factor

FHWA Federal Highway Administration

HSIP Highway Safety Improvement Program

HSM Highway Safety Manual 

ICE intersection control evaluation

IHSDM Interactive Highway Safety Design Model

LOSS level of service of safety

SPF safety performance function

WI Wisconsin

WisDOT Wisconsin Department of Transportation
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SAFETY DATA CASE STUDY FHWA-SA-21-074

Table of Contents

Introduction............................................................................................................................................... 1

Safety Performance Analysis ................................................................................................................... 3

Challenges and Opportunities ................................................................................................................. 8

Conclusions and Lessons Learned ........................................................................................................... 9

References ................................................................................................................................................ 10

List of Figures

Figure 1. Graphic. WIS 75/County Road A project location................................................................. 2

Figure 2. Graphic. Example distribution of sites by LOSS (Source: FHWA, 2011)............................ 3

Figure 3. Graphic. WIS 75 crash diagram............................................................................................... 5

 

List of Tables

Table 1. Predicted crashes for each traffic control alternative (2025-2034). ...................................... 7

Table 2. Economic analysis results for each traffic control alternative (2025-2034). ......................... 8
 

SAFETY DATA CASE STUDY FHWA-SA-21-074

Executive Summary

This case study presents a safety analysis conducted by the Wisconsin Department of Transportation (WisDOT) 

at the intersection of State Highway 75 (WIS 75) and Plank Road (County Road A) in Racine County, WI. 

WisDOT proactively identified key safety needs early in the project development process and used a data-driven 

approach to evaluate the safety effects of potential alternatives. The corridor is scheduled for resurfacing in 

2023, and through the network screening process, WisDOT identified an opportunity to develop a Highway 

Safety Improvement Program-related project in conjunction with routine maintenance. WisDOT’s diagnosis 

process reviewed recent crash history for potential contributing factors (e.g., driver behavior, sight distance, 

curvature, intersection geometry, etc.) and underscored the need to reduce failure-to-yield crashes. A 

preliminary intersection control evaluation eliminated infeasible alternatives early in the process and highlighted 

appropriate alternatives for further analysis. WisDOT applied State-calibrated safety performance functions in 

the Interactive Highway Safety Design Model software to predict crashes for each alternative and used Stateapproved crash modification factors where applicable. With these results, the economic appraisal step

highlighted the most cost-effective alternative for this particular location. The State of the Practice methods and 

tools applied at each step in the process allowed WisDOT to thoroughly evaluate a safety need on its public 

road network as part of an institutional and readily repeatable planning process.
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SAFETY DATA CASE STUDY FHWA-SA-21-074

Introduction 

The Transportation Research Board’s Safety Performance and Analysis (ACS20) User Liaison 

Subcommittee has an ongoing initiative focused on practical application of the American Association of 

State Highway and Transportation Officials (AASHTO) Highway Safety Manual (HSM) (i.e., “using the 

HSM in the real world”). The Federal Highway Administration (FHWA) administers the HSM

Implementation Pooled Fund, which includes 22 States focused on projects to help further HSM 

implementation. Development of HSM case studies will assist practitioners in performing data-driven 

safety analysis using the methods described in the HSM. The primary purpose of the HSM case studies is 

to highlight noteworthy applications of HSM methods, focus on common challenges, and feature 

agencies that overcame those challenges. These case studies serve as a source of lessons learned and 

noteworthy practices to help guide practitioners applying the HSM.

Background

This case study presents a safety analysis conducted by the Wisconsin Department of Transportation 

(WisDOT) at the intersection of State Highway 75 (WIS 75) and County Road A (Plank Road) in Racine 

County, WI (figure 1). WisDOT proactively identified key safety needs early in the project development

process and used a data-driven approach to evaluate the safety effects of potential alternatives. This 

comprehensive, institutionalized use of the HSM showcases the direct application of research into 

practice, as well as a variety of tools that help improve safety-related decision-making. Each step 

highlights practical examples of the HSM in the planning process: 

 WisDOT used customized screening tools to apply State-calibrated safety performance 

functions (SPFs) and rate intersections according to a level of service of safety (LOSS)

methodology based on expected and observed crash frequency.

 Based on this screening process, WisDOT identified an intersection with a demonstrated safety 

need and investigated the recent crash history to diagnose crash contributing factors. 

 Based on these findings, WisDOT identified suitable potential alternatives to the traffic control 

devices already in place.

 WisDOT applied the Interactive Highway Safety Design Model (IHSDM) software to evaluate 

these potential alternatives and assess predicted crashes.

 With predicted outcomes based on several alternatives, WisDOT used IHSDM’s Economic 

Analysis module to identify the most cost-effective alternative to improve safety at the candidate 

intersection. 
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SAFETY DATA CASE STUDY FHWA-SA-21-074

Purpose and Need

WisDOT has a resurfacing project planned in 2023 for WIS 75 in the Town of Dover, WI. In 2019, 

through the State’s network screening process, WisDOT identified the intersection of WIS 75 and 

County Road A as a location with a high potential for safety improvement. Further investigation into 

crash history revealed contributing circumstances that could potentially be addressed during routine 

maintenance in 2023, including traffic control compliance and high posted speed limits on all approaches 

(55 miles per hour). This application of data-driven safety analysis in the planning process allowed 

WisDOT to develop a Highway Safety Improvement Program (HSIP) project in conjunction with routine 

resurfacing.

Project Description

• Sponsoring agency: WisDOT. 

• Project location: Dover, WI. 

• Project bounds and length of project: Intersection of State Highway 75 (WIS 75) and 

County Road A (Plank Road). 

• Facility type(s): Four-leg, two-way stop-controlled intersection with 2-lane major collectors 

on all legs.

• Area type: Rural, flat terrain.

• Project status (as of spring 2021): Analysis completed; construction anticipated in 2023. 

Figure 1. Graphic. WIS 75/County Road A project location.

© 2021 Google® © 2021 Maxar Technologies. Modified by the authors. 

Note: The white labels were added by the authors to delineate the project bounds.
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SAFETY DATA CASE STUDY FHWA-SA-21-074

Safety Performance Analysis

WisDOT’s analysis covered several chapters from Part B (Chapters 4, 5, 6, and 7) and Part C of the 

HSM to identify sites with a safety need, diagnose the location-specific issues, select appropriate 

countermeasures, and produce a cost-effective solution (AASHTO, 2010). This section provides an 

overview of the safety analysis methods, proposed alternatives, and final results.

Analysis Overview

Prior to selecting countermeasures and assessing future performance, WisDOT conducted network 

screening and applied a diagnostic process to identify issues and focus on relevant solutions.

Network Screening

WisDOT assessed the entire WIS 75 resurfacing project corridor for safety needs using two Satespecific tools: 

1. The MetaManager tool screens segments using crash rates (although WisDOT plans to develop 

SPFs for segment network screening in the future). 

2. The Intersection Network Screening Spreadsheet screens intersections using LOSS for both 

total crashes and fatal and injury crashes.

The Intersection Network Screening Spreadsheet applies a LOSS analysis criterion to each intersection 

and assigns a value between one, indicating a low potential for crash reduction, and four, indicating a 

high potential for crash reduction (figure 2). LOSS compares the relative safety performance of a 

Figure 2. Graphic. Example distribution of sites by LOSS (Source: FHWA, 2011). 

Source: FHWA
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SAFETY DATA CASE STUDY FHWA-SA-21-074

location (i.e., observed crash frequency) to its expected safety performance based on State-calibrated 

SPFs. A LOSS value of four indicates that the location observed a crash frequency in excess of 1.5 

standard deviations above the mean. This elevated rating illustrates the magnitude of a potential safety 

issue at a given location. 

The intersection of WIS 75 and County Road A received a LOSS IV rating based on this network 

screening approach. The crash rate at the WIS 75/County Road A intersection between 2014 and 2019 

was relatively high compared to similar locations (3.7 crashes per million entering vehicles) with nearly 

50 percent of all crashes resulting in an injury. There were no fatalities during the study period.

Diagnosis

During the analysis period, the intersection was two-way stop-controlled with stop signs present on the 

east/west approaches (County Road A); the east/west approaches also had flashing beacons and “Traffic 

on WIS 75 Does Not Stop” signs installed in addition to the stop signs. There were no stop bars 

present on County Road A. A detailed investigation into the crash history did not reveal any significant 

geometric issues. However, it did highlight an important trend with respect to vehicles on County Road 

A (i.e., the stop-controlled approaches) failing to yield to through traffic on WIS 75 (i.e., no traffic 

control present). Most failure to yield-related crashes (fifteen of nineteen) involved vehicles making a 

complete stop on the east/west County Road A approaches before proceeding into the intersection and 

colliding with north/south traffic. Only four of nineteen crashes involved vehicles running the stop sign 

without coming to a stop (figure 3). 

Based on the relationship of the observed crash history, driver behavior, and traffic control devices 

present, WisDOT conducted an alternatives analysis using IHSDM to evaluate several different traffic 

control alternatives.
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SAFETY DATA CASE STUDY FHWA-SA-21-074

Figure 3. Graphic. WIS 75 crash diagram.

© WisDOT
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SAFETY DATA CASE STUDY FHWA-SA-21-074

Crash Prediction Analysis & Results

WisDOT used IHSDM (version 15.0) to predict crashes at the study intersection over a 10-year period 

between 2025 and 2034. Historic traffic count data were very limited for the study area; the last turning 

movement count at the intersection occurred in 1999. WisDOT collected tube counts near the 

intersection in 2011, and the results closely aligned with the 1999 turning movement count volumes. 

Given the timing of the safety analysis study (May 2020), the State’s Safer-at-Home order made new data 

collection unreliable for typical expected conditions. However, since the available data sources were 

generally consistent, average daily traffic was generally low (1,900 to 2,200 vehicles per day on all 

approaches), and the area had not experienced any significant development, WisDOT believed the 1999 

data to be a reasonable estimate for the purposes of the IHSDM analysis. WisDOT used forecast 

growth rates to grow the base year (2020) traffic volumes to yield design year (2045) volumes (0.18% 

on WIS 75 and 0.29% on County Road A).

Countermeasure Selection

WisDOT conducted a preliminary intersection control evaluation (ICE) to assess potential design 

impacts and eliminate infeasible alternatives early in the planning process. WisDOT used traffic warrants 

for all-way stop controls, traffic signals, and roundabouts to refine the potential list of traffic control 

alternatives. Although WisDOT estimated that all three options would have additional capacity through 

2045, the traffic counts did not meet traffic signal warrants. As a result, WisDOT only considered allway stop control and roundabout alternatives to compare to the existing two-way stop control base 

alternative: 

 For the two-way stop control base alternative, WisDOT used State-calibrated models (i.e., HSM 

models with a State-specific calibration factor on Wisconsin data) derived from Chapter 10 of 

the HSM (Rural Two-Lane Two-Way Roads) to predict crashes per year (AASHTO, 2010). 

 To derive a prediction for an all-way stop control alternative, WisDOT applied a State-approved

crash modification factor (CMF) of 0.52 to the base alternative predicted crashes (i.e., a 48 

percent reduction in crashes of all severities; CMF ID #315). 

o This reflected an anticipated safety benefit of converting the two-way stop control to an 

all-way stop control.

 For the four-leg, single lane roundabout alternative, WisDOT used roundabout-specific SPFs to 

predict future crashes (Ferguson et al., 2018). 

Table 1 documents the predicted crash results by severity for each alternative. The existing two-way 

stop control base alternative predicted the highest number of total crashes, as well as the highest

number of fatal and serious injury crashes. The all-way stop control alternative predicted the fewest 

number of total crashes, while the roundabout predicted the fewest number of fatal and serious injury 

crashes over the study period.
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SAFETY DATA CASE STUDY FHWA-SA-21-074

Table 1. Predicted crashes for each traffic control alternative (2025-2034). 

Alternative

Fatal 

(K)

Crashes 

Incapacitating 

Injury

(A) Crashes 

NonIncapacitating

Injury (B) 

Crashes 

Possible 

Injury 

(C)

Crashes 

No 

Injury

(O)

Crashes 

Total

Crashes 

Rural Two-Lane 

Two-Way Stop 

Control 

Intersection 

0.13 0.49 1.38 1.22 7.29 10.50

Rural Two-Lane

All-Way Stop 

Control 

Intersection 

0.07 0.25 0.72 0.63 3.79 5.46

Roundabout 

with 4 Legs and 

a Single 

Circulating Lane 

0.02 0.17 1.07 0.97 7.78 10.01

Economic Appraisal

Based on the alternatives analysis results, WisDOT conducted an economic analysis using State-specific 

crash costs that compared the expected benefits associated with predicted crashes reduced to the total 

cost of the traffic control treatment. For instance, WisDOT could compare a baseline, no-change

alternative (e.g., two-way stop control) that would lead to $2 million in predicted future crash costs 

during the study period to a new traffic control alternative (e.g., a roundabout) that would lead to 

$500,000 in predicted future crash costs. In this scenario, the new traffic control alternative, the 

roundabout, is expected to result in $1.5 million in crash-related cost savings or benefits relative to the 

existing condition. 

This analysis allowed WisDOT to develop a benefit/cost ratio (BCR) for each alternative (table 2). Based 

on this review, WisDOT determined that an all-way stop control alternative is expected to be the most 

cost-effective treatment (BCR = 13.67). Conversely, a roundabout is not expected to produce economic 

benefits (i.e., dollar value of expected crashes reduced) that outweigh the economic costs (i.e., costs 

associated with construction and maintenance of the project) due to the cost of right-of-way acquisition 

and construction.
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SAFETY DATA CASE STUDY FHWA-SA-21-074

Table 2. Economic analysis results for each traffic control alternative (2025-2034). 

Alternative

Present 

Value of 

Crash Cost 

Net Present 

Value of 

Benefits (B)

Net Present 

Value of 

Costs (C)

Present 

Value of 

Net Benefit

(B-C) 

BCR 

Rural Two-Lane TwoWay Stop Control 

Intersection 

$1,905,772.99 n/a n/a n/a n/a

Rural Two-Lane AllWay Stop Control

Intersection 

$991,001.96 $914,771.04 $66,940.00 $ 847,831.04 13.67

Roundabout with 4 Legs 

and a Single Circulating 

Lane 

$596,685.42 $1,309,087.57 $1,727,840.00 -$418,752.43 0.76 

Documentation and Use of Analysis Results

WisDOT documented its process, analysis, and findings in a formal safety certification document and 

associated ICE memorandum. These documents conform to the State’s Facilities Development Manual 

and methodically present the intersection evaluation process, including existing conditions, crash history, 

IHSDM outputs, conceptual designs and associated costs, and final recommendations. It also lists 

potential caveats and considerations for future implementation. For instance, the documentation notes 

that although the all-way stop control alternative is the most cost-effective and readily-implementable 

solution, compliance is a notable concern for the corridor. WisDOT would also need to alert drivers to 

the new traffic control if an all-way stop were installed. Conversely, although a roundabout would not 

be the most cost-effective solution, it would remove most concerns around compliance and would 

inherently alert drivers to operational changes. The document recommends that an all-way stop should 

be applied as an interim solution, but it should not be a permanent solution; a roundabout should be 

strongly considered in future HSIP project evaluations.

Challenges and Opportunities

In addition to concerns over driver compliance with regulatory and advisory signage, WisDOT noted 

considerable complexity associated with applying SPFs to compare intersection alternatives. WisDOT 

targeted the WIS 75/County Road A intersection as a result of the high number of severe injury and 

angle crashes; this was well above average for comparable facilities. However, when evaluating 

alternatives, WisDOT and the HSM methodology recommends using a calibrated or State-specific SPF 

to determine predicted performance and calculate potential benefits. This means that WisDOT’s 

predictions treat the study intersection according to the average performance for similar locations

around the State. Although this is the State of the Practice approach, it may not reflect local nuances 

that led to the high frequency of crashes in recent years. Furthermore, due to the significant changes in 

traffic control between alternatives, WisDOT was not able to apply the Empirical-Bayes methodology to 

crash prediction. This challenge highlights the importance of the diagnosis process. Although WisDOT 

continues to consider a roundabout as a more permanent solution to potential safety concerns, the 
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SAFETY DATA CASE STUDY FHWA-SA-21-074

agency is able to produce targeted interim solutions in a timely manner that suit the scale of the safety 

issue. 

Conclusions and Lessons Learned

The WIS 75 and County Road A intersection evaluation is a practical example of how data-driven safety 

analysis can be incorporated into the planning process. The corridor is scheduled for resurfacing in 

2023, and through the network screening process, WisDOT identified an opportunity to develop an 

HSIP project in conjunction with routine maintenance. WisDOT’s diagnosis process reviewed recent 

crash history for potential contributing factors (e.g., driver behavior, sight distance, curvature, 

intersection geometry, etc.) and underscored the need to reduce failure-to-yield crashes. The ICE 

evaluation eliminated infeasible alternatives (e.g., a traffic signal) early in the process and highlighted 

appropriate alternatives for further analysis. WisDOT applied State-calibrated SPFs in the IHSDM 

software to predict crashes for a baseline alternative and roundabout alternative, and the project team 

applied a State-approved CMF to the baseline alternative to determine predicted crashes for the all-way 

stop alternative. The economic appraisal produced the BCR and highlighted the most cost-effective 

alternative for this particular location. The State of the Practice methods and tools applied at each step 

in the process allowed WisDOT to thoroughly evaluate a safety need on its public road network as part 

of an institutional and readily repeatable planning process.
10

References

 American Association of State Highway and Transportation Officials. (2010). Highway Safety 

Manual: 1st Edition, Washington, D.C. Resources available online: 

http://www.highwaysafetymanual.org/Pages/default.aspx. 

 Federal Highway Administration. (2011). HSIP Noteworthy Practice Series, HSIP Project 

Identification (FHWA-SA-11-02). Available online: 

https://rspcb.safety.fhwa.dot.gov/noteworthy/html/projident_co.aspx. 

 Federal Highway Administration. (2021a). “CMF Clearinghouse” (website). Available online: 

http://www.cmfclearinghouse.org/index.cfm. 

 Federal Highway Administration. (2021b). “Interactive Highway Safety Design Model” 

(website). Available online: https://highways.dot.gov/research/safety/interactive-highway-safetydesign-model/interactive-highway-safety-design-model-ihsdm-overview. 

 Ferguson, E., Bonneson, J., Rodegerdts, L., Foster, N., Persaud, B., Lyon, C., & Rhoades, D. 

(2018). Development of Roundabout Crash Prediction Models and Methods (No. Project 17-70), 

Washington, D.C.

 Wisconsin Department of Transportation. (2020). Safety Certification Document 2420-00-70, 

Dover, WI.

Contact

Wisconsin Department of Transportation

Kevin M. Scopoline, Traffic Operations and Analysis Engineer

KevinM.Scopoline@dot.wi.gov