Traffic Flow Modeling Based on the ISOHDM Study

The article deals with impacts of road capacity on traffic speed and road user costs. Calculation of free speeds and operating speeds in the Highway Design and Management HDM-4 model are explained. In a case study, decrease of traffic speeds and increase of road user costs are observed if free flow capacity, nominal capacity and ultimate capacity is changed. Methodology for Annual Average Daily Traffic recalculation into passenger car space equivalent/lane/hr is explained. The article gives an insight into traffic flow modeling based on the ISOHDM study.