Study On Threshold For Urban Taffic Impact Analysis

The improvement of urban traffic condition essencially depends on the correspondence between land use and traffic.The correspondence macroscopically depends on the corporation of general planning of land use and urban comprehensive traffic plan,microscopically it depends on traffic impact analysis (TIA)of site development .However,in the traffic impact analysis, threshold identifying is always a critical problem and a difficult one ,this paper has a research on the threshold identifying of urban TIA in our country.Based on the comprehensive analysis of overseas and domestic urban TIA threshold,the paper expatiates the method for urban TIA threshold identifying of our country and builds the threshold index system.Then,the paper put forward method of threshold index identifying,namely,via the one grade dropping of LOS of critical sign intersection,we can confirm threshold lower limit;via the caculating of the rest capacity of the critical sign intersection in future when the LOS is given,we can confirm threshold upper limit,accordingly we get a range for threshold.Based on this it builts a non-linear programming model which is to get the largest serving flow of sign intersection in specific LOS and puts forward a series scientific and usful method and program to solve the model.Last,it chooses a representative intersection,using Nanjing TIA threshold identifying as an example,putting forward its peak-hour traffic threshold,day traffic threshold and scale threshold.