The Interactive Highway Safety Design Model (IHSDM) is a suite of software developed by the Federal Highway Administration (FHWA) for monitoring and analyzing two-lane rural highways in the United States. IHSDM consists of six modules: Policy Review Module (PRM), Crash Prediction Module (CPM), Design Consistency Module (DCM), Traffic Analysis Module (TAM), Intersection Review Module (IRM), and Driver/Vehicle Module (DVM). Among the six modules, CPM was selected for possible use in safety audits of two-lane ruralhighways. Many DOTs often do not have resources to calibrate the model’sfactors; hence, the module was tested to see if it can be used as is, without model calibration. Three two-lane rural highway sections in Utah were selected for a sample application of CPM to safety audits. The results of this evaluation show that the CPM can produce reasonably reliable crashpredictions if appropriate input data, especially alignment data, reflectexisting conditions with reasonable accuracy. Using crash records available from the multiyear crash database maintained by the Utah Department of Transportation (UDOT) and CPM’s crash prediction capability, UDOT’s traffic and safety engineers can locate “hot spots” for detailed safety audit, thus making the safety audit task more focused and effective. Based on the findings of the study, it is concluded that CPM could be useful for engineering decision making during safety audits of two-lane rural highways. Itshould be noted though that interpreting the outputs from CPM requires knowledge and experience in highway design.
Abstract