The shortest path or not? Analyzing the ambiguity of path selection in China's toll highway networks

The highway toll road system in many countries is incapable of providing the detailed route information of users, and drivers may choose alternative paths rather than the shortest path in the hope of saving the travel cost. Existing ambiguous path identification research is heavily dependent on vehicle detection sensors, and traffic assignment models using simulations. In this paper, we present a new approach to reveal an important fact: for the majority of traffic, compared with selecting shortest , the distance travel cost of selecting the alternative path is far from the acceptable level in reality. We define a new index that measures the path selection ambiguity that represents the ratio of cost difference. With the real-world O-D (origin-destination) tollgate data, we examine the overall path selection ambiguity problem from both topological and traffic demand perspectives across three major highway networks in China. As a whole, only a small minority of the traffic demand is distributed on the O-D pairs with a great uncertainty concerning route selection. Hence, this paper suggests the shortest path should be considered as the acceptable route taken by individuals in a highway analysis when only O-D data is available. Moreover, a more in-depth study is conducted to explain the reasons behind this observation.