This volume is the second of a three-volume final report that describes the relationships between intersection geometry and traffic and the motor-vehicle accident rates for groups of intersections sharing common design features. Detailed multidisciplinary investigations of a sample of accidents were studied. Volume II presents the details for the study area, sampling technique and data-collection methods, analysis methods and data processing, study results, and conclusions and recommendations. Volume I is an Executive Summary for managers, and Volume III contains supporting data in the form of Appendixes. A relatively detailed on-scene inventory of the geometry, design characteristics, and traffic counts at 558 intersections coupled with police reports of the 4372 accidents that occurred there during the past three years were used in the analysis. Forty-one accidents were investigated by a multidisciplinary team to provide causal factor evidence and to evaluate the effects of federal safety standards on intersection accident incidence and severity. The following six intersection design features were demonstrably accident related: (1) sight-distance obstruction, (2) street-name signs, (3) use of left-turn storage lanes, (4) use of raised marker delineation, (5) bus -loading zones and routing and (6) multiphase signilization. Accident countermeasures based on the influence of these six factors are recommended.
Samenvatting