Thursday, March 28, 2019, 12:00PM (ET)

Urban Roadway Facility Conversion with The Predictive Safety Assessment Tool: An Application of Highway Safety Manual

The impact of predictive safety assessment based on quantitative methodology of the Highway Safety Manual (HSM) is significant, particularly in urban roadway facilities. Realizing this significance, the responsibilities of safety professionals, transportation planners, and decisionmakers are critical for safe and efficient transportation in the ever-increasing travel demand in the urban areas. The purpose of this study was to develop a predictive safety assessment tool (PSAT) for converting one urban roadway facility type to another with the application of predictive methodology and principles from the HSM. This tool (PSAT) is intended to help safety professionals, transportation planners, and decisionmakers to evaluate safety effects considering the local conditions to make informed decisions in the planning process from the traffic safety perspective. This study focused on developing a proof-of-concept framework of PSAT for converting one facility to another with improvements to specific geometric elements in urban settings. By considering traffic exposure, existing geometric conditions, and unit length of corridor (i.e., one mile of corridor length), PSAT (MS Excel spreadsheet) enables the safety analysts to evaluate existing and proposed facilities and covers a wide range of urban roadway segments. Some examples include 2-lane undivided roadway; 2 lane roadway with two-way left-turn lane; 4-lane undivided and 4-lane divided roadway; 4-lane undivided roadway with two-way left-turn lane, 6-lane undivided lane, and 6-lane divided roadway; 6-lane undivided roadway with two left-turn lanes; and 8-lane divided roadway. The PSAT was developed with user-friendliness to help the safety analysts input values in color-coded areas within the recommended ranges for the parameters from the HSM. The output of the crash prediction and sensitivity analysis (i.e., impact of traffic volume on predicted crashes in comparison facilities of interest) were graphically displayed. Thus, PSAT displays a user-friendly dashboard for the safety analysts with a conversion factor and predicted crash frequency, distribution of collision types (i.e., single- and multi-vehicle collisions) by injury severity levels and impact of traffic volume as part of a sensitivity analysis based on the well-researched HSM methodology. Download Handout

Presenter: Mouyid Islam, Ph.D. CUTR

Dr. Mouyid Islam is a Research Faculty at Center for Urban Transportation Research (CUTR) at University of South Florida (USF). His research interest includes safety data, data analytics, and statistical modeling dealing with data linkage process for different safety and related data sources. He brings the experiences from private sector working in safety projects in different states with implementation of Highway Safety Manual (HSM). He has been actively involved in predictive safety analysis of Highway Safety Manual as well as safety data analysis for Strategic Highway Safety Plan (SHSP) utilizing state level crash, roadway inventory, census data, vehicle registration and endorsement data for different emphasis areas (e.g., roadway departure crash, motorcycles, large trucks). Moreover, He is an actively involved with TRB safety committee for Highway Safety Performance (ANB25) and Safety Data, Analysis and Evaluation (ANB20) and Moped and Motorcycle Safety Committee (ANF30). He has published more than 15 research reports and peer reviewed journal papers and presented 25 presentations at several national and international conferences.


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  1. Thanks for this information about Highway safety.

  2. Nice work. It explains nicely about Highway safety.

  3. It’s Great !

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