Cost-effective safety treatments for low-volume roads.

The majority of roadside safety guidance pertains to high-volume roads.Very little guidance exists to assist engineers in treating common obstacles found alongside low-volume roads.In general, it is assumed that low traffic volumes can effectively mitigate the risks associated with vehicle impacts into fixed objects and other geometric features to a point where they do not significantly increase the accident costs relative to high-volume roads.However, a single crash on a low-volume road may result in a fatality or a severe injury, effectively making low-volume roads competitive in severity scale with high-volume roads.As a result, the possibility of a fatal or severe injury crash needs to be mitigated on low-volume roads.Common roadside features were observed in a field study and included culverts, trees, slopes, ditches, and bridges.A probability-based encroachment tool, known as the Roadside Safety Analysis Program (RSAP), was used to determine impact frequencies and severities for each feature.Treatment options, like removing the fixed object or installing W-beam guardrail, were considered for each feature.Finally, acceptable ranges in traffic volume were recommended for each safety treatment option.In these recommendations, the "do nothing" option was often considered to be the most cost-effective safety treatment for the existing configuration.However, this was not always the case.17.