| Insights into the nature of large truck-passenger car interactions and the understanding of safety corridors can lead to improvements in the safety and efficiency of freeway operations. One main contribution of this thesis is the analysis of truck-passenger car interactions on Missouri urban and rural freeways. The analysis consisted of: (1) comparison of mean, 85 th, and 95th percentile speeds, (2) investigation of large truck lane usage and (3) comparison of at-fault crashes. Contrary to some public perception, there was no evidence that, on the average, trucks were traveling faster than passenger cars. In terms of lane usage in general, trucks concentrated mainly in the middle lanes and avoided the right-most and left-most (median) lanes. In terms of at-fault in crashes, a new method of analysis was developed using the ratio of truck at-fault crash rates versus passenger vehicle at-fault crash rates, or RSEC ratios. The results show that in fatal and disabling injury rural interstate crashes, the passenger vehicle is more at fault. Trucks are more at fault in fatal and disabling injury urban interstate crashes as well as all minor injury rural and urban interstate crashes. The at-fault crash analysis is especially significant since previous studies have shown a different result.;Another main contribution of this thesis is the development of a synthesis of safety corridor programs conducted throughout the country and identifying the most promising practices and programs to disseminate among other state departments of transportation. Several states have developed safety corridor programs for identified corridors with safety issues, including but not limited to high crash frequencies or rates, and use a multi-disciplinary team of engineering, education, enforcement, and emergency medical services (4E) to identify treatments and strategies to improve the safety of the corridor. The purpose of this part of the thesis is to contribute to the safety management programs of the states so as to facilitate implementation of the best practices. Definitions of a safety corridor, possible criterion for selection, measures of effectiveness (MOE's), and other facets of a safety corridor program such as legislation were identified for states which currently have safety corridors. Finally, the thesis will provide a comprehensive list of characteristics and good practices found in safety corridor programs. |
