The Highway Safety Software (HSS) performs Crash Prediction evaluations in roadway facilities based on the Highway Safety Manual (HSM). As presented in the HSM (©️ 2010 by the American Association of State Highway and Transportation Officials — AASHTO), the base model to predict crash frequency was built to consider the local infrastructure and operational characteristics. Safety Performance Functions (SPF) and the Crash Modification Factors (CMFs) are presented for the various facility types. An additional Calibration factor, Cr, can adjust the model for a condition other than the one for which it was developed.
The Highway Safety Software (HSS) faithfully implements the Predictive Method of AASHTO’s 1st Edition HSM and its supplement HSM 2014, allowing for local and state-level calibration for parameters. This release of the HSS includes updated modules to implement the Highway Safety Manual Predictive Models.