Analyzing On The Vehicle's Running Characteristics And Delay At The Signalized Intersection In Mountainous City

With the rapid economic developing,the level of urbanization of China has entered a new level.The substantial increase of vehicle numbers has brought great convenience to people's travel,but also caused a series of negative effects to the city development,such as aggravating environmental pollution,serious traffic congestion,frequent traffic accidents,extremely shortage of energy supply et al.Limited by terrain,the traffic environment of mountain cities are more complex,and its various traffic parameters show great difference from that of other plain cities.So,it is necessary to study the vehicle's operational characteristic and delay in mountainous cities,which has more practical significance to the intersection planning and design,and the same to the intersection management and application of intelligent transportation systems.Firstly,the research status of vehicles' delay extraction was introduced at signalized intersection,including field investigation,analytical approach,delay acquisition method based on video and GPS,and assessed these above methods.Based on a detailed analysis of classical delay theory and a good deal of field research,the delay value of the import lane of one mountainous urban intersection was calculate by four classical models(Webster,Miller,Akcelik and HCM2010),and was compared with measured value of it.The following phenomenon was found that these model precision were 77.47%%,74.52%,72.98%,and 77.54% respectively in the import lane with no gradient,but they were 55.56%%,40.89%,40.97%,and 57.14% respectively in the import lane with-4.5% gradient.Vehicles' running speed and saturated flow of import lane et al.,which may cause calculation error of the delay models were discussed.The velocity characteristics of buses and cars running on the typical longitudinal sections with different slope of 0%,±2.4%,±3.3%,±4.5% and ±5.2% was also measurement artificially and studied.The forecast models of the vehicle speed on the corresponding slope and different radius of curve were given as well.In addition,the basic saturated flow of the import lane in mountainous cities represented by Chongqing was calibrated by means of measuring the saturated headway data.Meanwhile,the suggestion of choosing modified formula about road slope and large vehicle ratio was given too.Finally,the corrected delay extraction model for signalized intersection in mountainous cities was proposed,through modifying the vehicle arrival rate and import lane saturated flow.Then,the proposed model was tested and verified by actual data,which results showed that the corrected model could improve the accuracy of vehicles' delay calculating for mountainous cities.The research outcome of paper can establish a basis for the analysis of intersection parameters in the mountainous cities.