COST EFFECTIVE 3R ROADSIDE SAFETY POLICY FOR TWO-LANE RURAL HIGHWAYS.

The purpose of this research was to investigate the effect of clear zone widths on accidents and to determine the "break-even" traffic volumes and clear zone widths where accident savings equalled roadside improvement costs. Although sufficient data was not available to determine the statistically significant combined effects of clear zone widths and traffic volumes on accident frequency, some very logical trends were observed which provided the basis for accident prediction models and cost-safety-effective analyses. The cost of clearing the roadside of fixed objects (trees, culvert headwalls and entrances) was generally greater than the present worth of the cost of all collisions involving these objects for most highway segments. For those segments whose accident costs were higher, remedial action should be considered. Generally, these segments have higher ADTs than other segments. In contrast, for all segments examined the cost of flattening the side slopes and removing all fixed objects exceeded the present worth of the savings from the predicted reduction in run-off-road accidents.