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Title:Calibration of HSM Predictive Methods on State and Local Rural Highways
Authors:Xiao Qin, Zhi Chen, and Mohammad Razuar Shaon
University:South Dakota State University
Publication Date:Aug 2020
Report #:MPC-20-416
Project #:MPC-438
TRID #:01751955
Keywords:calibration, crash modification factors, injury severity, rural highways
Type:Research Report – MPC Publications



This study presents the application of the Highway Safety Manual (HSM) to rural state highways in South Dakota and provides important guidance and empirical results regarding how to calibrate HSM models. Calibration guidelines have been developed to facilitate future calibration activities. The calibration was based on crash data from three roadway segment types and five highway intersection types during a five-year period (2008-2012). The calibration process includes establishing new base conditions, developing safety performance functions (SPFs), converting CMFs to base conditions, and deriving calibration factors. Considering the sample size, base conditions, and prediction accuracy, four state-specific SPF models have been developed for two segment types (two-way two-lane and multilane divided) and two intersection types (two-way two-lane three-leg STOP and two-way two-lane four-leg STOP), respectively. The HSM SPFs are retained for other highway facility types. The values of calibration factors for crashes are derived by injury severity scale (i.e., killed, type A, B, or C injury, and property-damage-only crashes). Results show that the number of crashes observed in South Dakota can be drastically different from those predicted by the HSM.

How to Cite

Qin, Xiao, Zhi Chen, and Mohammad Razuar Shaon. Calibration of HSM Predictive Methods on State and Local Rural Highways, MPC-20-416. North Dakota State University - Upper Great Plains Transportation Institute, Fargo: Mountain-Plains Consortium, 2020.

NDSU Dept 2880P.O. Box 6050Fargo, ND 58108-6050