The Effects Of Pre-trip Information On Travel Decisions And Travel Costs

Traffic congestion caused by the imbalance between supply and demand has become a formidable problem impeding the sustainable development of society.The reasons causing traffic congestion include the increase of vehicles,inadequate road transport system,and improper allocations of resources among different regions.Furthermore,the uncertainty in transportation systems make traffic congestion become worse.One nonnegligible reason causing uncertainty in transportation systems is unpredictable events,such as adverse weather,unannounced road work,and traffic accidents.These unpredictable events reduce road capacity,thereby decreasing traffic supply and affecting travelers' choice behavior.Unilaterally increasing traffic supply,such as widening roads,is usually unable to solve traffic congestion caused by uncertainty efficiently.Under the circumstances,guiding travelers' choice behavior through traffic management has become especially important.One way to reduce the negative effects caused by uncertainty is to provide information to travelers.Thanks to the development of advanced traveler information system(ATIS),it is possible for traveler to obtain pre-trip information before traveling.According to the pre-trip information,travelers can adjust their choices,such as route,departure time and travel mode,and such adjustments may ease traffic congestion and reduce travel costs.Nevertheless,what factors related to the effects of pre-trip information and how pre-trip information affects travelers' choice behavior have not fully addressed.In this thesis,we investigate what factors influence the value of pre-trip information and how these factors affect travelers' choice behavior and travel costs through user equilibrium analysis.In our models,the road capacity is assumed to vary from day to day because of unpredictable events.When no information is provided,travelers only know the probability distribution of road capacity(zero-information scenario);when pre-trip information is provided,travelers can obtain the road capacity before their trips each day(full-information scenario).The welfare effects of pre-trip information are measured by the travel cost differences between the zero-information scenario and the full-information scenario.Pre-trip information is welfare-improving if the expected travel costs decrease after providing pre-trip information;otherwise,pre-trip information is welfare-neutral or even welfare-reducing.This thesis has the following four research parts,and their main findings are summarized as:(1)Equilibrium analysis of travel choices under zero-information scenario.In the spatial dimension,an overview of route choice equilibrium model based on the classic two-route network is examined.In the time dimension,the equilibrium mechanism of the classical bottleneck model is reviewed.On this basis,we study a morning commute model by assuming the stochastic bottleneck capacity following Bernoulli distribution.The theoretical solutions of all critical time points and expected travel costs under user equilibrium(UE)are derived.The results show that the departure rate under UE gradually decreases with respect to departure times,and the latest departure time at UE is never earlier than the work start time.(2)Effect of inaccurate pre-trip information on departure time choice.To explore the effect of pre-trip information quality on travelers' choices as well as system efficiency,we study a morning commute model in which the bottleneck capacity is assumed to follow Bernoulli distribution.Two types of traveler's behavior response to inaccurate information,namely information compliance behavior and information noncompliance behavior,are defined.Three cases concerning travelers' behavior in response to inaccurate pretrip information,namely compliance,noncompliance,and co-existence,are studied.All theoretical solutions in the compliance and noncompliance cases have been derived,and an iterative algorithm is adopted to obtain the travel costs in co-existence case.We find that the welfare effects of inaccurate information depend on information quality,travelers' response and heterogeneity,and the frequency and severity of bottleneck capacity reductions.The results reveal that the welfare effects of accurate information are always better than that of inaccurate information in the noncompliance case;however,the welfare effects of inaccurate information may be better than that of accurate information when enough travelers comply with the provided inaccurate information.(3)Effect of travelers' risk attitudes on route choice under accurate pre-trip information.To depict the choice preferences of travelers,we study a route choice model based on the classical two-route network in consideration of traveler's risk attitudes.In the model,the road capacity is assumed to follow Bernoulli distribution.We consider two information scenarios,i.e.,the zero-information scenario and the full-information scenario.We first derive all theoretical solutions by assuming linear travel time functions,and then extend the findings to nonlinear travel time functions.The impacts of free-flow travel time,travelers' risk attitudes,and structure of travel time function on the benefits of accurate information are analyzed under UE.Our findings indicate that the assumption that travelers are risk-neutral may underestimate or overestimate the benefit effect of the information,and the welfare effect of choosing one route may decrease although the overall welfare of all travelers improve.(4)Effect of pre-trip information on simultaneous route and departure time choices.To explore the effect of information quality on multi-dimensional travel choice under uncertainty,we propose a simultaneous route and departure time choice model by assuming the bottleneck capacity and free-flow travel time are both stochastic.We derive the expected travel costs at user equilibrium(UE)under stochastic conditions without and with pre-trip information first on one route,and later on two routes.Our results show that the degree of correlation between route conditions,the frequency and severity of capacity reduction,and the relationship between free-flow travel time and capacity significantly affect the welfare effects of pre-trip information.We find that full and accurate information is welfare-improving when the capacity is stochastic and the free-flow travel time is deterministic;when bottleneck capacity and free-flow travel time are both stochastic,full and accurate information can be welfare-reducing;when bottleneck capacity severely drops,full information is more likely to be welfare-improving,even if the information provided is not completely accurate.