Developing Crash Modification Factors for Urban Highway with Substandard Wide Curb Lane

Across the United States, a great deal of attention is being focused on promoting energy efficient and environmental friendly modes of transportation. Bicycling is an integral part of a sustainable transportation system that is one of the most efficient. The growing use of bicycles for commuting and leisure activities is creating conflicts with motorized traffic mainly due to deficient roadway facilities that were in the past designed to primarily accommodate motorized traffic.In 2008, 716 bicyclists were killed in the USA which corresponds to 2 percent of total traffic fatalities reported. In the same year, over 52,000 bicyclists were also reported to have been injured in traffic crashes. When the data is broken down state by state, Florida ranked second with 6.82 bicyclist fatalities per million population. These statistics provide a grim reminder of the dangers faced by bicyclist riding on urban and rural highways.This study developed lane width crash modification factors (CMFs) for roads with wider outside lane narrower or equal to 14 ft, and inside lanes narrower or equal to 11 ft that were minimum recommended by the Florida Department of Transportation (FDOT) for arterial roadways in the state of Florida. The road segments used were urban four-lane with a divided median and four-lane two-way left turn lane (TWLT). Data used in the evaluation included 25 centerline miles of urban four-lane (TWLT) roads and 75 centerline miles of four-lane with a divided median roads. Two main types of crash modification factors and safety performance functions were developed in this study. The first type is crash modification factors and safety performance functions for all types of crashes, and the second is crash modification factors and safety performance functions for motor vehicle-bicyclist crashes only.In sum the results obtained from this study suggest that, maintaining of inside lane width to 11.5ft and outside lane width to 13 ft for 4D and 5T could results in less number of all types of crashes. Additionally, the decreases in motor vehicle-bicyclist crashes will also be achieved by outside lane width of 13 ft as the inside lane width was not found to contribute to the increase or decrease in motor vehicle-bicyclist crashes.