Bicycle System Performance Measures: the Interaction Hazard and Latent Demand Score Models

The Interaction Hazard Score (IHS) and Latent Demand Score (LDS) Models are prioritization tools for bicycle system planning and implementation. The IHS Model rates the on-road bicycling environment and interprets the rating as a level-of-service classification. The model uses existing roadway and traffic variables to estimate perceived hazards from the bicyclists' perspective. The LDS Model provides an estimate of latent bicycle travel demand, that is, the expected amount of bicycle travel that would occur on a given road segment if there were no bicycle travel inhibitions from motor vehicle traffic. The model is based on a probabilistic gravity model, which quantifies the proximity and magnitude of bicycle trip attractors/generators. This article provides comprehensive descriptions of each model and discusses their applications.