Research On Speed Limit Signs Of Operating Expressway

The role of the highway is to provide a safe, fast, convenient travel services for roadusers, so drawing up a reasonable sign speed is important to ensure the effective operation ofthe Highway Safety. How to set the value of the sign speed to handle the relationship betweentransport efficiency and safety, is the problem the society in general concerns and to be solved.But our country still does not have the unified sign speed setting methods and standards. Inthis paper, on the basis of analyzing the speed limit study at home and abroad, as the goal ofefficient and safe, we study the reasonable sign speed of in-service highway, providing thebasis for the management of highway speeds.By investigating and analysising of the design speed, signing speed and measured speedof the experimental sections, combined with the problems existing in our country in the signspeed of highway, and related research results at home and broad, we proposed the dividedsections based on the measured speed and the determined method of the value of speed limit.Through the analysis of the road linear condition of the existing highway, special sections incharacteristics, traffic conditions and traffic accidents, we proposed the linear control targetsby adjusting limited sign speed: central median lateral safety clearance, line of sight inhighway, the curve lateral force coefficient, the gradient and slope length, radius of verticalcurve, the length of changed speed lane; and also proposed the adjustment of sign speed to beconsidered the special sections containing the sections of tunnel and the tunnel group, longand large downhill section, long and large uphill section, the space of nearly sections betweeninterchanges (service area, parking area), nearly sections of the tunnel and the interchangeexport, accident-prone sections. Finally we made control conditions in these sections whilethe sign speed adjust.This thesis proposed one classification and optimization method of vehicle speed onsigns and the process to determine it based on the operating speed of different vehiclescombined with the location of interchange、alignment control parameters、special sections andtraffic crashes distribution as well as traffic volume and composition、highway road laws andregulations and the number of lanes. It is confirmed that the research proposed in this thesis is promising and experimental according to its benefits in operationa efficiency、security andsociety when implied in Shenjia-Shegan section of Hangjinqu expressway.