| Highway maintenance would take up limited space resource, and result in highway capacity dropping, even traffic congestion and accidents. So safety study of work zone should be taken seriously. Moreover, work zone might, conceivably, be traffic bottleneck or the black spot of the highway network, which could directly reduce the whole services level. With microscopic simulation system and statistical analysis of field data, this paper systematically analyzed the work zone safety of classified highway and studied various measures to improve the work zone safety.Firstly, the papers systemtatically summerized characteristics of work zone and formed the complete understanding of work zone safety. Moreover, by analyzing the field data (traffic volume, driving speed, traffic composition, headway distribution, etc.) of classified highways, the paper also identified the difference of work zone of classified highways. Then, work zone models with different parameters, which can demonstrate distinct classified highways, were established with VISSIM.Secondly, in order to reduce the risks caused by decreasing speed, this paper put forward two speed limit schemes:single speed limit scheme and continuous speed limit scheme. With minimum safety distance equation (MSDE) as the safety evaluation index, the two schemes were compared and evaluated in safety. Based on simulation results, the reasonable speed limited scheme and concrete limit speed value were recommended according to highway grade and traffic flow condition.Finally, aimed at optimizing spatial layout of work zone, microscopic simulation system and other traffic analysis technologies, such as traffic conflict analysis and queue theory, were adopted to identify the length of each part, including warning area, upstream transition area, buffer space, activityarea and termination area. Based on the analysis above, this paper offered resonable traffic control and management measures as the reference of work zone safety. |
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