This research projects is aiming at the analysis of basic accident cost rates and the quantification of surcharges for cross-sections of rural roads. The results will present a valuation basis in the German manual on the assessment of road traffic safety (HVS). The research collective is based on 3,600 km rural roads from six federal states. In addition to perennial accident occurrences, data of the road information bases (SIB) and surveys from road inspections are the data set of the research. Road sections were allocated according to the guidelines for the construction of rural roads (RAL) in five different (typical) groups of cross-sections. The mathematical basis of the analysis are multivariate models to describe accident frequency. Compared to monocausal considerations, they have the advantage to gather a multiplicity of actuating variables as well as to take into account possible dependencies between different variables. For different cross-sections and t-junctions regulated by traffic signs, three models had respectively been developed according to accident severity. Underlying parameters were analyzed on the basis of their significance of clarification when describing the accident frequency and in the model accordingly taken into account as surcharge. On the basis of these results, functions were generated on the course of the accident rate and accident cost rate. Basic accident cost rates describe the accident cost level dependent on the vehicle mileage of a network element which can be achieved when sections are constructed compliant to rules. Since parameters which do actually not represent a deficit are also considered in the models, the rate of the accident cost rate without any surcharges equates a base level. Surcharges, divided into 4 deficits and properties describing characteristics of sections are to be allocated to this base level. On the basis of the models can be demonstrated that different cross-sections of roads show a different basic safety level. There is a non-linear correlation between accident frequency and the average daily traffic volume. The accident rate or accident cost rate thus represents an index dependent on the average daily traffic volume. Dependent on the cross-section, different parameters influence traffic safety. The magnitude of surcharges can be described as an accident cost rate ratio of the base level. If necessary, the determined surcharges were examined in comparative way and adapted as part of a plausible assessment of the crosssections. The calculation for basic accident cost rates and its surcharges for cross-sections of rural roads are illustrated according to the HVS. Thus, two different approaches will be presented. The results for t-junctions regulated by traffic signs are of advisory nature. (Author/publisher)
Abstract