Model of urban link travel time under ice and snowfall conditions
To predict accurately urban road travel time under ice and snowfall conditions,link travel time model was established for ice and snowfall conditions.Based on link travel time model(BPR,Bureau of Public Roads) of Federal Highway Administration and introduced respectively corrective function of free travel time and road capacity under conditions of ice and snowfall,ISB-BPR(Ice and Snowfall Based Bureau of Public Roads) function was constructed.The correction function and BPR parameter were calibrated through a large number of field data.The results show that the function can predict link travel time at urban streets in conditions of ice and snowfall accurately,which can be used for theory basis on traffic flow characteristics research and traffic management under conditions of ice and snowfall.