Development of a systematic approach for the inclusion of accident risk factors in the calculation of road user costs for construction zones

Construction sites or work zones create serious disruptions in the normal flow of traffic resulting in major inconveniences for the traveling public. These traffic problems affect the motorists by considerably increasing their travel time because of delays, and even their travel distances in the case of forced detours. The speed changes and detours also impact the operating expenses of the vehicles. Furthermore, and most importantly, these work zones create safety hazards that require special consideration. Reducing construction time, and therefore reducing the amount of extra costs generated, has become a major issue for state highway agencies throughout the United States. Most of the innovative contracting practices for highway construction projects specifically address the reduction in construction time as a means to minimize the negative effect that road work areas have on the motorists and on the general public. Additionally, current legislation and programs, at both state and national levels, are continually emphasizing the need for a better understanding of work zone problems as a means to address the issue of work zone safety. This reality, coupled with the fact that every year more miles of highway are being temporarily closed for rehabilitation and maintenance purposes, makes the analysis of safety at construction sites a very serious matter. This research endeavor represents a comprehensive study of the different problems and variables associated with the development of a new practical approach to address the issue of highway safety in construction zones. Since empirical models require sample sizes which are rather unattainable due to the intrinsic scarcity of construction zone accident data, the problem was studied from the point of view of risk analysis. Monte Carlo simulations were used to develop risk factors. These factors are meant to be included in the calculations of additional user costs originated at work zones, in an effort to optimize length and duration of closures for highway reconstruction/rehabilitation projects. In this way, it will be possible to effectively assess the danger that work zones represent for the traveling public, and therefore, help to minimize their adverse effect on highway safety.