An effective way to optimize traffic structures is by changing travel costs, thereby moving travelers from private transportation to public transportation. However, according to the existing studies, the traveler will not transfer from one mode to another unless the change in travel utility is greater than the indifference threshold. Therefore, the “indifference threshold” is one of the most important factors influencing a traveler’s choice of behavior. This study defines the “indifference threshold” as the traveler’s sensitivity to changes in travel utilities. In the framework of the theory of planned behavior (TPB), a structural equation model (SEM) considering the indifference threshold is established to analyze a traveler’s mode choice behavior. The analysis results showed that a travelers’ sensitivity to changes in travel utilities has the greatest impact on mode-choice behavior intentions and mode choice behavior. Perceptual behavior control has the strongest influence on travel choice behavior. In addition, in order to further explore the heterogeneity of a traveler’s behavior, the travelers were subdivided into four types, by establishing a latent class model (LCM) considering the indifference threshold. Finally, different traffic management suggestions are proposed for different types of travelers.

In order to improve the mode share of public transportation, an evolutionary game model based on the indifference threshold is established to analyze the travelers' mode choice behavior. The model supposes that the travelers' behavioral adjustment of decision-making of travelers follows the principle of random utility maximization only when the perceived difference in utility between modes is greater than the indifference threshold; otherwise, travelers choose randomly. A transportation network that includes private and public transportation is presented as an example to show how travelers adjust their mode choice when traffic management policy is changed. We divided the travelers into three categories based on the online survey data: high sensitivity, neutral sensitivity and low sensitivity to cost difference. The results show that, the proposed-logit evolutionary game model has a unique stable equilibrium point and the point is the choice probability of the-logit stochastic user equilibrium. Moreover, compared with the logit evolutionary game model, the-logit evolutionary game model can predict the implementation effect of traffic policy and the time it takes for the traffic system to stabilize more accurately. In addition, the degree of sensitivity of travelers to cost difference affect the implementation effect of the policy. INDEX TERMS Travel mode choice, evolutionary game theory, indifference threshold, traffic management policy, evolutionary stable strategy.