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Develop Highway Safety Manual (HSM) Safety Performance Functions (SPFs) and Calibration Factors for Texas

What Was the Need?

Historically, safety was not a meaningful performance measure in design decisions compared to operational and environmental elements primarily due to the unavailability of safety analysis tools. HSM introduces a science-based approach for safety analysis. HSM provides predictive methods to support the project development process.This approach can be used to make informed decisions. The safety performance functions (SPFs) represent data from specific locations and times. SPFs are the basis for predictive models and were developed in HSM-related research from the available roadway and crash data sets. Because crash frequencies can vary significantly from one jurisdiction to another, it is important to either develop local SPFs or calibrate the HSM SPFs to a count for local variations. Local SPFs and calibration factors will provide certainty of reliable results. Most states have calibrated or developed agency-specific SPFs. Texas does not have local SPFs or calibration factors for these SPFs.

Project Summary

The research team will develop Texas-specific SPFs and calibration factors for various facility types, including freeways and interchanges per HSM recommendations. Depending upon the data analysis, separate calibration factors may need to be developed for each region (North, South, East & West). These will be developed using the data including crash, facility, and traffic volume for several facilities, including interstate highways from each region of Texas. TxDOT will use the findings of the study to improve safety on these facilities.

Project Number

0-7083

Status

Completed

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Project Details

Start Date

9/1/2020

End Date

8/31/2022

Performing Institution(s)

Texas A & M Transportation Institute (TTI)

Research Team

Srinivas Geedipally

Sponsor

Project Manager

Jade Adediwura

Contract Specialist

Tami Graham

TxDOT Advisor

Khalid Jamil, DES

Amount Funded

$309,754

Publications from this Project

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Functional Area

Safety and Operations

Index Terms

Calibration
Crash rates
Frontage roads
Ramps (Interchanges)

Lead University

TTI

Researcher

Geedipally, Srinivas Reddy

Geographic name

Texas

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Record Added:

2/23/2021

Record Updated:

7/22/2023 5:38 AM EDT

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