Abstract
Traffic accidents are frequent although various countermeasures are introduced. Traffic safety cannot be fundamentally improved if it is not considered in the transportation network design stage. Although it is well known that traffic safety is one of the most important concerns of the public, traffic safety is not adequately accommodated in transportation planning. This paper considers traffic safety as a major criterion in designing a transportation network. It is a kind of proactive measure rather than reactive measure. A bilevel programming model system is proposed where the upper level is the urban planners’ decision to minimize the estimated total number of traffic accidents, and the lower level is the travelers’ response behaviors to achieve transportation system equilibrium. A genetic algorithm (GA) with elite strategy is proposed to solve the bilevel model. The method of successive averages (MSA) is embedded for the lower level model, which is a feedback procedure between destination choice and traffic assignment. To demonstrate the effectiveness of the proposed method and algorithm, an experimental study is carried out. The results show that these methods can be a valuable tool to design a safer transportation network although efficiency, in terms of system total travel time, is slightly sacrificed.
Highlights
Traffic accidents are frequent various countermeasures are introduced
Because the reactive measures are mostly limited to the means of traffic engineering, they are not effective in case of many traffic accidents resulting from transportation planning. erefore, the problem of frequent traffic accidents cannot be fundamentally solved
Yang et al [3] proposed a three-objective bilevel programming model for optimizing variable speed limits to achieve better road network performance in terms of environment, efficiency, and safety. It is a kind of transportation operations for built road network, where the decision variables are variable speed limits. e link traffic safety is measured by the number of expected road accidents that is a power function of link traffic volume. e parameters are assumed to be the same for all links for Complexity simplification. e simplified safety performance function is used to demonstrate the proposed method, and it is suggested to be replaced by another realistic form. e lower level model is a deterministic user equilibrium model for traffic assignment, while trip distribution is not considered
Summary
Received 6 January 2021; Revised 20 June 2021; Accepted 14 November 2021; Published 26 November 2021. A bilevel programming model system is proposed where the upper level is the urban planners’ decision to minimize the estimated total number of traffic accidents, and the lower level is the travelers’ response behaviors to achieve transportation system equilibrium. Haas and Bekhor [6] proposed a biobjective bilevel programming model for the network design problem to achieve travel time minimization and road safety maximization. A nonlinear integer programming is formulated for mixed transportation network design in the upper level It is the decision of expanded location and lane numbers. It is a bilevel model system where the upper level is to minimize the total number of traffic accidents given investment budget, and the lower level is traveler response behaviors to the upper level decisions.
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