Study on the road speed limit value of expressway reconstruction and expansion

Introduced and analyzed the related factors which influence the running speed in the construction section during the expressway reconstruction and expansion, such as the saturation of construction section, Lane width and the road shoulder width, pavement condition, composition of motorcycle type, type of segregation facility and other safety factors. Associating these main influence factors with the reduction factors of vehicle speed, calculating the corresponding weight of each factor by using AHP, and then the comprehensive speed limit value would be obtained. By comparing the obtained result with the minimal speed limit value influenced by other safety factors, the minimum speed limit value would be chose between them as the reference value. Finally the speed limit value was analyzed by putting the expressway reconstruction and expansion project from Beijing to Hong Kong and Macau (G4) as an example.