Indiana Department of Transportation

Indiana’s State Road 37 

Improvement Project 

SAFETY DATA CASE STUDY 

FHWA-SA-21-019 

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-21-019

Notice 

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SAFETY DATA CASE STUDY FHWA-SA-21-019

1. Report No.

FHWA-SA-21-019

2. Government Accession 

No.

3. Recipient's Catalog No.

 

4. Title and Subtitle

Indiana’s State Road 37 Improvement Project

5. Report Date

February 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 an interchange alternatives analysis from the Indiana Department of Transportation (INDOT). The analysis supported a 

multi-agency planning and engineering effort that involved INDOT, the Indianapolis Metropolitan Planning Organization, Hamilton County, 

Town of Fishers, and City of Noblesville. These agencies identified State Road (SR) 37 from 126th Street in Fishers to SR 32/38 in Noblesville 

as a candidate for significant mobility and safety improvements. The SR 37 corridor project had two primary needs: 1) reduce existing and 

forecasted congestion at signalized intersections within the study area, and 2) reduce the crash frequency and rate at identified intersections. 

INDOT targeted five, at-grade signalized intersections along the study corridor for interchange improvements. The safety analysis applied 

State-specific safety performance functions (SPFs) and crash modification factors (CMFs) derived from the American Associate of State 

Highway and Transportation Officials (AASHTO) Highway Safety Manual (HSM) to predict crashes for “Build” and “No-Build” scenarios 

over a 20-year period between 2018 and 2038. The INDOT analysis encountered several key challenges, including key technical inputs for the 

Interactive Highway Safety Design Model (IHSDM) software and the application of the HSM to future design alternatives; for instance, INDOT 

did not apply the Empirical-Bayes (EB) method due to the significant change in the design and operational performance of the corridor between 

the Build and No-Build scenarios. INDOT’s ingenuity and engineering judgment allowed the agency to navigate many of these challenges, and 

the analysis predicted that the Build alternative, although originally proposed for its traffic operational improvements, should yield a safety 

benefit and reduce crashes compared to the No-Build alternative future.

17. Key Words: 

Highway Safety Manual, HSM, Urban, Freeway, 

Roundabout, Interchange

18. Distribution Statement

No restrictions.

19. Security Classif. (of this report)

Unclassified

20. Security Classif. (of this 

page) Unclassified

21. No. of Pages

 17 

22. Price

Technical Documentation Page
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SAFETY DATA CASE STUDY FHWA-SA-21-019

Acronyms

Acronym Description

AADT annual average daily traffic

AASHTO American Association of State Highway and Transportation Officials

CMF crash modification factor

EB Empirical-Bayes 

FHWA Federal Highway Administration 

FI fatal and injury

HSM Highway Safety Manual

IHSDM Interactive Highway Safety Design Model

IN Indiana

INDOT Indiana Department of Transportation

LOS level of service

PDO property damage only

RoadHAT Road Hazard Analysis Tool

SPF safety performance function

SPI Single Point Interchange

SR State Road

TOA traffic operations analysis
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SAFETY DATA CASE STUDY FHWA-SA-21-019

Table of Contents

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

Safety Performance Analysis ................................................................................................................... 2

Challenges.................................................................................................................................................. 9

Conclusions and Lessons Learned ......................................................................................................... 10

References ................................................................................................................................................ 11

List of Figures

Figure 1. Graphic. SR 37 project location............................................................................................... 1

Figure 2. Graphic. Proposed teardrop roundabout interchange at SR 37 and 126th Street. ............. 4

Figure 3. Graphic. Proposed diamond roundabout interchange at SR 37 and 135th Street. ............. 4

Figure 4. Graphic. Proposed SPI at SR 37 and 146th Street. ................................................................. 5

 

List of Tables

Table 1. Existing conditions at study intersections. ............................................................................... 3

Table 2. SR 37 No-Build Alternative – crash prediction results by location. ...................................... 7

Table 3. SR 37 No-Build Alternative – crash prediction results; entire project.................................. 7

Table 4. SR 37 Build Alternative – crash prediction results by location.............................................. 8

Table 5. SR 37 Build Alternative – crash prediction results; entire project........................................ 9

Table 6. SR 37 final crash prediction results (crashes per year; 2018-2038). ...................................... 9
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SAFETY DATA CASE STUDY FHWA-SA-21-019

Executive Summary

This case study presents an interchange alternatives analysis from the Indiana Department of Transportation 

(INDOT). The analysis supported a multi-agency planning and engineering effort that involved INDOT, the 

Indianapolis Metropolitan Planning Organization, Hamilton County, Town of Fishers, and City of Noblesville. 

These agencies identified State Road (SR) 37 from 126th Street in Fishers to SR 32/38 in Noblesville as a 

candidate for significant mobility and safety improvements. The SR 37 corridor project had two primary needs: 

1) reduce existing and forecasted congestion at signalized intersections within the study area, and 2) reduce the 

crash frequency and rate at identified intersections. INDOT targeted five, at-grade signalized intersections along 

the study corridor for interchange improvements. The safety analysis applied State-specific safety performance 

functions (SPFs) and crash modification factors (CMFs) derived from the American Associate of State Highway 

and Transportation Officials (AASHTO) Highway Safety Manual (HSM) to predict crashes for “Build” and “NoBuild” scenarios over a 20-year period between 2018 and 2038. The INDOT analysis encountered several key 

challenges, including key technical inputs for the Interactive Highway Safety Design Model (IHSDM) software and 

the application of the HSM to future design alternatives; for instance, INDOT did not apply the Empirical-Bayes 

(EB) method due to the significant change in the design and operational performance of the corridor between 

the Build and No-Build scenarios. INDOT’s ingenuity and engineering judgment allowed the agency to navigate 

many of these challenges, and the analysis predicted that the Build alternative, although originally proposed for 

its traffic operational improvements, should yield a safety benefit and reduce crashes compared to the No-Build 

alternative future.
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SAFETY DATA CASE STUDY FHWA-SA-21-019

Introduction 

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

has an on-going 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”). FHWA also 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 advanced 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 an interchange alternatives analysis from the Indiana Department of 

Transportation (INDOT). The analysis supported a multi-agency planning and engineering effort that 

involved INDOT, the Indianapolis Metropolitan Planning Organization, Hamilton County, and the cities 

of Fishers and Noblesville. These agencies identified State Road (SR) 37 from 126th Street in Fishers to 

SR 32/38 in Noblesville as a candidate for significant mobility and safety improvements (figure 1). The 

primary improvement was a proposed conversion of an urban arterial street with at-grade intersections 

to a freeway configuration. As part of this freeway conversion, INDOT prepared a mobility report that 

considered the operational impacts of a substantial conversion of at-grade signalized intersections to 

two interchange build alternatives: 1) a teardrop roundabout interchange alternative and 2) a tight 

diamond interchange alternative with traffic signals at ramp terminals where needed. 

Figure 1. Graphic. SR 37 project location.

© 2021 Google® © 2021 Landsat/Copernicus. Modified by the authors. 

Note: The white location pins and white dashed line were added by the authors to delineate the project bounds.
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SAFETY DATA CASE STUDY FHWA-SA-21-019

Purpose and Need

The SR 37 corridor project had two primary needs:

1. Reduce existing and forecasted congestion at signalized intersections within the study area.

2. Reduce the crash frequency and rate at identified intersections.

INDOT conducted a traffic operations analysis (TOA) to determine the effect of each alternative on 

traffic congestion in the base year (2010) and forecast year (2036). The TOA projected that teardrop 

roundabout interchanges are expected to improve the typical level of service (LOS) at each of the 

studied intersection legs from a C or D in the base year conditions (2010) to a LOS of A or B in 2036. 

Based on these results, the multi-agency project steering committee and elected officials decided to 

pursue teardrop roundabouts as the preferred alternative; this design became the “Build” option.

INDOT compared this Build alternative with the existing “No-Build” alternative for safety performance 

using HSM methods.

Project Description

• Sponsoring agency: INDOT. 

• Project location: Cities of Fishers and Noblesville, IN. 

• Project bounds and length of project: SR 37 between 126th Street and 146th Street

(2.8 miles).

• Area and Facility type(s): 4-lane urban, divided arterial (to be converted to a freeway).

• Area type: Urban.

• Project status (summer 2020): Analysis complete and pending construction.

Safety Performance Analysis

This section provides an overview of the safety analysis methods, proposed alternatives, and final results.

Analysis Overview 

INDOT targeted five, at-grade signalized intersections along the study corridor for interchange 

improvements. 

• SR 37 at 126th Street.

• SR 37 at 131st Street. 

• SR 37 at 135th Street. 

• SR 37 at 141st Street. 

• SR 37 at 146th Street. 

Before alternative designs could be developed, INDOT performed a preliminary analysis of historic 

crashes at these five intersections; the agency used an internal tool, the Road Hazard Analysis Tool

(RoadHAT), to analyze a recent four-year study period (2010-2013). The RoadHAT tool is a softwarebased version of the workflow described in INDOT’s Guidelines for Roadway Safety Improvements (Tarko 
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SAFETY DATA CASE STUDY FHWA-SA-21-019

and Romero, 2016). This document outlines standards for identifying high-crash locations, reviewing 

these high-crash locations, and evaluating economic impacts of proposed safety projects. 

This analysis revealed that all five intersections have higher than average crash rates for comparable 

intersections in the State, and all study intersections are in the highest one-third of crash rates for 

comparable intersections. Furthermore, the intersections at 126th and 146th Streets are specifically 

flagged as high-crash intersections (top five percent of comparable intersections in the State) with the 

intersection at 146th Street falling in the top one percent of crash rates at comparable intersections. 

The SR 37 mainline consists of 2 northbound and 2 southbound 12-ft wide travel lanes with a 10-ft 

outside paved shoulder. Inside shoulders are paved and 4-ft wide with a roughly 40-ft wide grass median; 

right- and left-turn lanes are present approaching these intersections. There are no pedestrian or bicycle 

facilities parallel to SR 37 or crossing SR 37 at the intersections. The existing right-of-way (ROW) along 

SR 37 varies from 175- to 460-ft wide with the widest portion at the intersections. Table 1 provides an 

overview of the existing conditions at each study intersection.

Table 1. Existing conditions at study intersections. 

Approach Design Features

SR 37 at 

126th 

Street 

SR 37 at 

131st 

Street 

SR 37 at 

135th 

Street 

SR 37 at 

141st 

Street 

SR 37 at 

146th 

Street 

Overall

Number of Legs 4 4 4 4 4 

Traffic Control Signalized Signalized Signalized Signalized Signalized

Minor Leg - 

ROW Width

(feet)

80-90 90-125 95-145 55-80 185-220

East Leg

Approach Lanes - 

Number 2 1 1 1 2 

Approach Lanes – 

Width (feet) 12 12 12 12 12

West Leg

Approach Lanes - 

Number 1 1 1 1 2 

Approach Lanes – 

Width (feet) 12 12 12 12 12

The TOA, mobility study, and subsequent stakeholder discussions identified teardrop roundabout 

interchanges as the preferred design alternative (figure 2). However, subsequent design decisions 

determined that the interchange at 135th Street would be a diamond roundabout design with 

buttonhook ramps, thereby removing the through movement across SR 37 (figure 3), and a Single Point 

Interchange (SPI) design would be applied to 146th Street (figure 4). INDOT compared the proposed 

alternative to the existing, No-Build design using predictive methods from chapter 12 (Urban and 

Suburban Arterials), chapter 18 (Predictive Method for Freeways), and chapter 19 (Predictive Method for 

Ramps) in the HSM (AASHTO, 2010; AASHTO, 2014). 
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SAFETY DATA CASE STUDY FHWA-SA-21-019

Figure 3. Graphic. Proposed diamond roundabout interchange at SR 37 and 135th Street. 

© City of Fishers, IN

© City of Fishers, IN

Figure 2. Graphic. Proposed teardrop roundabout interchange at SR 37 and 126th Street.
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SAFETY DATA CASE STUDY FHWA-SA-21-019

INDOT developed future crash predictions for a 21-year period between 2018 and 2038. A joint 

research effort between Purdue University and INDOT re-estimated a series of project-level safety 

performance functions (SPFs) and crash modification factors (CMFs) using observed Indiana data over a 

three-year study period. These SPFs and CMFs more accurately reflect Indiana’s observed outcomes, 

and the resulting SPFs and CMFs can be incorporated into the Interactive Highway Safety Design Model 

(IHSDM) software format.

The DOT applied the Indiana-specific SPFs to predict crashes for individual design alternatives and 

applied Indiana-specific CMFs to augment predictions based on proposed infrastructure changes. If 

relevant CMFs were unavailable, INDOT considered crash history and applied engineering judgment to 

refine assessments of future safety conditions. INDOT separately analyzed individual facility types for the 

No-Build and proposed designs using the IHSDM software (version 14.0.0). These individual 

components included:

• Mainline segments.

• Intersections. 

• Entrance and exit ramps.

• Ramp terminals.

• Crossing street segments.

Figure 4. Graphic. Proposed SPI at SR 37 and 146th Street. 

© City of Fishers, IN
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SAFETY DATA CASE STUDY FHWA-SA-21-019

INDOT obtained the necessary geometric and operational inputs including segment length, design speed, 

annual average daily traffic (AADT), ramp locations, merge distances, and horizontal curvature. INDOT 

derived analysis inputs from the design plan sets, survey files, and aerial photography. INDOT used 

traffic volume data based on the most recent historical data (2018) and the design-year volume forecasts 

(2038).

Analysis Details

The No-Build option consisted of 63 homogenous mainline segments (e.g., non-intersection sections) 

and the 5 intersection locations in IHSDM. The Build alternative has a simpler mainline segment design 

(i.e., consistent mainline cross-section geometry throughout the study area); however, the freeway 

conversion required INDOT to consider crash impacts at speed change lanes, entrance and exit ramps, 

and ramp terminals on the cross street.

INDOT applied a State-approved CMF to ramp terminal crashes for the three teardrop roundabout 

interchange locations at 126th, 131st, and 141st Street. The CMF to convert signalized intersection to a 

roundabout was 0.876 for total crashes, and 0.339 for fatal and injury (FI) crashes; this means that the 

installation of teardrop roundabouts at the interchange ramp terminals would result in a 22-percent 

reduction in total crashes and 66-percent reduction in FI crashes when compared to the signalized 

intersections in the No-Build option.

Since there are no cross-street terminals in the proposed 135th Street design, there is no direct 

comparison between the Build and No-Build options; however, the Build option had to consider 

predicted ramp and speed change-lane crashes. The report indicated that there is no CMF for the 

conversion of a signalized intersection to an SPI interchange terminal. INDOT used the percentage of 

AADT along each approach to convert the two signalized ramp terminals to a simplified diamond 

interchange with a single signalized interchange terminal. Although INDOT noted that this approach may 

result in an inaccurate crash prediction, crash estimates at this interchange location made a negligible 

difference in the project-wide analysis outcome. 

INDOT did not apply an Empirical-Bayes (EB) approach when analyzing both alternatives. The EB 

method relies on historic crash data to determine the expected number of crashes on a corridor or at 

an intersection given a set of geometric and operational conditions. As INDOT notes in their final 

report (INDOT, 2018, p. 8): 

“When major alignment or intersection geometry changes are proposed (such as the 

proposed Teardrop Roundabout Interchange or SPI), it is not used because there is only 

a small difference in the results obtained from the predictive method when it is used 

with or without the EB Method. Therefore, ‘if the EB Method is not applied consistently, 

such differences will likely introduce a small bias in the comparison of expected crash 

frequency among alternatives’ (HSM Supplement, 2014). Therefore, the results are 

presented without the EB method adjustment.”

INDOT relied on the predicted number of crashes to compare the Build and No-Build alternatives.
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SAFETY DATA CASE STUDY FHWA-SA-21-019

Results

Tables 2 and 3 summarize the total, FI, and property damage only (PDO) crash prediction results for the 

No-Build alternative, and tables 4 and 5 detail the crash prediction results of the Build alternative.

Table 2. SR 37 No-Build Alternative – crash prediction results by location. 

Location Description

Predicted 

Total 

Crashes 

(2018-2038) 

Predicted 

FI Crashes

(2018-2038) 

Predicted 

PDO 

Crashes 

(2018-2038) 

Segment 1-6 Begin Project to 126th 178 46 132

Intersection SR 37 and 126th 271 100 171

Segment 7-18 126th to 131st 278 74 204

Intersection SR 37 and 131st 225 83 142

Segment 19-30 131st to 135th 235 63 172

Intersection SR 37 and 135th 138 52 86

Segment 31-42 135th to 141st 276 72 203

Intersection SR 37 and 141st 234 86 148

Segment 43-55 141st to 146th 239 63 176

Intersection SR 37 and 146th 201 72 129

Segment 56-63 146th to End Project 162 41 121

Table 3. SR 37 No-Build Alternative – crash prediction results; entire project. 

Description

Predicted 

Total 

Crashes 

(2018-2038) 

Predicted 

FI Crashes

(2018-2038) 

Predicted 

PDO 

Crashes 

(2018-2038) 

No-Build Intersection Total 1,070 394 676

Intersection Total per Year 51 19 32 

No-Build Segment Total 1,368 360 1,009

Segment Total per Year 65 17 48 

No-Build Project Total 2,438 753 1,685

Project Total per Year 116 36 80 
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SAFETY DATA CASE STUDY FHWA-SA-21-019

Table 4. SR 37 Build Alternative – crash prediction results by location. 

Location Description

Predicted

Total 

Crashes

(2018-2038)

Predicted

FI Crashes

(2018-2038)

Predicted

PDO 

Crashes

(2018-2038)

Freeway

Through Lanes 617 193 424

Ramp Connection Sections (Speed 

Change Lanes) 203 65 138

Interchange

126th NW Ramp (SB Off Ramp) 14 5 8

126th SE Ramp (NB Off Ramp) 18 7 11

126th NE Ramp (NB On Ramp) 5 2 3

126th SW Ramp (SB On Ramp) 12 5 7

126th NB Ramp Terminal 175 22 153

126th SB Ramp Terminal 182 22 160

Interchange

131st NW Ramp (SB Off Ramp) 7 3 4

131st SE Ramp (NB Off Ramp) 10 4 6

131st NE Ramp (NB On Ramp) 4 2 2

131st SW Ramp (SB On Ramp) 6 3 3

131st NB Ramp Terminal 90 12 78

131st SB Ramp Terminal 102 13 89

Interchange

135th NW Ramp (SB Off Ramp) 3 1 2

135th SE Ramp (NB Off Ramp) 2 1 1

135th NE Ramp (NB On Ramp) 3 1 2

135th SW Ramp (SB On Ramp) 3 1 2

Interchange

141st NW Ramp (SB Off Ramp) 14 6 8

141st SE Ramp (NB Off Ramp) 14 6 8

141st NE Ramp (NB On Ramp) 5 2 3

141st SW Ramp (SB On Ramp) 10 4 6

141st NB Ramp Terminal 170 19 151

141st SB Ramp Terminal 136 15 121

Interchange

146th NW Right Ramp (SB Off) 8 3 5

146th SE Right Ramp (NB Off) 4 2 2

146th NE Right Ramp (NB On) 2 1 1

146th SW Right Ramp (SB On) 3 1 2

146th NW Ramp (SB Off Ramp) 25 10 16

146th SE Ramp (NB Off Ramp) 21 8 13

146th NE Ramp (NB On Ramp) 20 8 12

146th SW Ramp (SB On Ramp) 21 8 13

146th Ramp Terminal 205 69 136
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SAFETY DATA CASE STUDY FHWA-SA-21-019

Table 5. SR 37 Build Alternative – crash prediction results; entire project. 

Description

Predicted 

Total 

Crashes 

(2018-2038) 

Predicted 

FI Crashes

(2018-2038) 

Predicted 

PDO 

Crashes 

(2018-2038) 

Build Interchange Total 1,295 268 1,027

Interchange Total per Year 62 13 49 

Build Freeway Total 820 258 562

Freeway Total per Year 39 12 27 

Build Project Total 2,115 527 1,590

Project Total per Year 101 25 76 

Table 6 summarizes the detailed results in tables 2 through 5 to directly compare the crash prediction 

results for the Build and No-Build alternatives.

Table 6. SR 37 final crash prediction results (crashes per year; 2018-2038). 

Alternative

Segment/ 

Freeway 

Intersection/ 

Interchange Total

Total 

Crashes 

FI 

Crashes 

Total 

Crashes 

FI 

Crashes 

Total 

Crashes 

FI 

Crashes 

No-Build 64 17 51 19 116 36

Build 39 12 62 13 101 25

Based on INDOT’s analysis, the Build option would result in 13-percent fewer total crashes per year, as 

well as 30-percent fewer FI crashes per year.

Documentation and Use of Analysis Results

While the final report is not available to the public, INDOT developed a comprehensive final report of 

the analysis that contains the results of the original mobility report and the outputs of the IHSDM crash 

analysis (INDOT, 2018). The results of the analysis pointed to a critical tradeoff in the teardrop 

roundabout design. Although the roundabout design led to a significant reduction in FI crashes, the 

analysis also predicted a higher total crash frequency at intersections/interchanges over the 21-year 

study period compared to the No-Build alternative. For the project as a whole, INDOT predicted that 

both total crashes and FI crashes will decrease as a result of the conversion to a controlled-access 

freeway.

Challenges

INDOT identified several key challenges. First, the IHSDM ramp terminal method does not specifically 

allow users to program a teardrop roundabout or an SPI as the terminal configuration. This is limited to 

a more typical diamond or partial cloverleaf design. INDOT analysts applied a simplifying assumption to 

create an operationally similar diamond interchange design and applied the roundabout CMF to calculate 

crash predictions at relevant ramp terminals. 

For the interchange at 146th Street, INDOT made simplifying assumptions based on the distribution of 

AADT to convert the two signalized intersections into the SPI. Without a relevant CMF, INDOT has 
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SAFETY DATA CASE STUDY FHWA-SA-21-019

limited confidence in these results, but their impact is negligible on the total project (i.e., 205 total 

crashes in the Build alternative, as opposed to 201 total crashes in the No-Build alternative). 

Finally, due to the major changes proposed under the Build design, INDOT was not able to effectively 

use the EB method to compare both alternatives. The EB method provides greater confidence in the 

reliability of estimates of expected future crashes; however, the HSM recommends against applying the 

EB method to major redesigns that completely reshape the operational performance of a corridor. 

INDOT relied on the Indiana-specific CMF-derived predicted crash values to provide insights into future 

crashes. 

Conclusions and Lessons Learned

INDOT took guidance from several chapters of the HSM and used detailed geometric design elements 

to analyze significant differences between the Build and No-Build options. Analysts investigated each 

facility type independently, and the cumulative impacts of each design component predicted the total 

impact of the SR 37 freeway conversion. INDOT’s SR 37 Predictive Safety Report (INDOT, 2018)

provides an example of how the HSM and IHSDM can be used to demonstrate a safety benefit for 

projects originally developed for other transportation needs (e.g., operational performance). 

Operational LOS and capacity needs identified teardrop roundabouts as the preferred interchange 

improvements; however, the HSM and supporting predictive safety analysis provide transportation 

planners and engineers confidence that these operational improvements will not come at the expense of 

safety.
11

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/Tools.aspx.

 American Association of State Highway and Transportation Officials. (2014). Highway Safety 

Manual: 1st Edition, Supplement, Washington, D.C.

 Federal Highway Administration. (2020). “CMF Clearinghouse” (website). Available online: 

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

 Indiana Department of Transportation. (2018). SR 37 Predictive Safety Report, Fishers, IN.

 Tarko, A. P., and Romero, M. (2016). Guidelines for Roadway Safety Improvements. INDOT Final 

Report. West Lafayette, IN: Purdue University.

 Tarko, A. P., Romero, M., Hall, T., & Sultana, A. (2018). Updating the crash modification factors 

and calibrating the IHSDM for Indiana. INDOT Final Report. West Lafayette, IN: Purdue 

University.

Contact

Indiana Department of Transportation

Abell Gelaye, Senior Highway Engineer

agelaye@indot.in.gov