National statistics indicate that fatality rates on rural Federal-aid primary highways have been significantly higher compared to those for urban and rural Interstate highways and urban primary highways. Although this group of highways includes two-lane rural roads, an important component of the rural Federal-aid primary highways are multilane rural highways. More than 56 000 km of arterial highways in the United States are multilane, non-Interstate roads in rural areas. Many previous studies have been conducted regarding the safety effects of various traffic and geometric roadway features. The majority of these studies were concentrated on rural two-lane roads. There have also been a few notable studies that investigated roadway crosssection design elements for suburban highways and urban streets. However, there has been limited research on the safety effects of geometric design features on rural, multilane, nonfreeway highways. This study examined the effects of various cross-section-related design elements on accident frequency and developed an accident prediction model for rural, multilane, nonfreeway highways.

This study was intended to quantify the benefits and costs resulting from lane widening, shoulder widening, shoulder surfacing, sideslope flattening, and roadside improvements. Detailed traffic, accident, and roadway data were collected on 4,951 miles of two lane roads in seven states. An accident predictive model and statistical tests were used to determine expected accident reductions related to various geometric improvements. Construction cost data from several states were used to develop a cost model for numerous types of roadway and roadside projects. This volume contains the final report and four appendixes. The final report contains detailed information on data collection and data analysis and conclusions and recommendations. The appendixes contain detailed information on the literature review, photographs used for the rural and urban roadside hazard scales, and economic analysis inputs.