ACCIDENT PREDICTION MODELS FOR TWO-LANE ROADS IN FINLAND

Accident models were used in evaluating traffic safety of existing road sections, and also of roads currently in the planning phase. The models were based on the hypothesis that the safety of a road section depends on general factors having the same universal effect, and on local factors characteristic of the studied road section, or some sections only. The models were based on police reported traffic accidents, excluding accidents at junctions, on main and secondary two-lane roads in the years 1978-1983, and the road and traffic data of corresponding roads obtained from the road register of the roads and waterways administration. The studied road network was divided into road sections that were homogenous according to their road environment. The theory of general linear interactive modelling enabled us to study the effects of different factors and their interactions. Specific models were formed for various traffic volume categories according to the speed limit (80 or 100 km per hour) of the road section. The models applied only to road sections outside built-up areas. The models can predict the number of traffic accidents resulting in personal injury on a road section on the basis of the section's vehicle mileage, the percentage of heavy vehicles, pavement width, and the value of the variable or variables describing the section's longitudinal design. (TRRL)