With the occasion of accidence,the stochastic and time-dependent traffic flow causes the uncertainty of travel time in urban traffic, which decides that there only exists dynamic stochastic shortest route.The paper presents a conclusion that vehicle routing choice is context-dependent and varies with traffic importance,time to be used for route,the range of travel time and traveler′s acquaintance to the route,which is different from the existed hypothesis.Based on the empirical study,the paper gives a concl...