Utility Analysis Of Representative Combined Travel Mode In Multimode Traffic Network

With the expansion of urban size and the significant acceleration of the average travel distance,the travel mode of travelers tends to be combined and diversified.In order to study the inner mechanism of travel mode selection under combined travel mode conditions,a series of Nested Logit models of combined travel mode utility were constructed based on travel survey data.Through analysis,the key influencing factors of preponderate mode and the threshold of the conversion of single mode to combined mode were determined,which will provide basis for improving bus connection conditions and adjusting the structure of commuter travel.First of all,focusing on the combined travel mode in multi-mode traffic network environment,this paper analyzed the travel speed,cost,punctuality,comfort and other traffic characteristics,and analyzed the influencing factors of combined travel mode utility based on stochastic utility theory.According to the preponderate trip distance,commuting situations were divided into three types,and the questionnaire was designed by means of uniform design.The analysis of the survey data showed that the comfort index of bicycle,car,bus and subway has a significant correlation with the congestion degree and physical exertion.Secondly,through RP&SP survey method,the data of choice of combined travel mode were collected,and Multinominal Logit models and Nested Logit models of travel utility under three kinds of scenario were constructed to carry out quantitative analysis of the impact of the individual's economic and social attributes,travel properties and transport characteristics on travel mode choice.The comparison of the MNL model and NL model showed that the NL model considering the relevance of alternative options by setting the nest hierarchical structure has better fitting degree and can get rid of the IIA features and randomness preference which MNL model usually has,and has more effective ability to study the choice behavior of combined travel mode under commuting travel conditions.The analysis results of NL model showed that travel expenses and travel time both have negative effects on travel utility under three types of travel scenarios,and travel cost is the most significant factor.The results also indicated that travelers between the age of 40 to 50 are more receptive to combined travel behavior,and female travelers are more receptive to the transfer to subway compared to male travelers.Last but not least,the critical state between the single mode and combined mode was determined by calculating the inequalities between the NL models of travel utility of two types of travel mode.After aggregating the characteristics of travelers and eliminating the collinearity of characteristics of travel mode and travel,threshold between single mode and combined mode was constructed in the methods of three-dimensional heat map by Matlab Software.The thresholds between single mode and combined travel mode are analyzed through three-dimension graph and two-dimension graph of utility threshold by Matlab software.It is indicated that under short-distance travel scenario,the threshold between bus and bicycle to bus is determined by the travel difference between two travel methods,travel distance,bicycle traveling expenses and bus waiting time;under middle-distance travel scenario,the threshold between of subway and bicycle to subway is determined by the travel difference between two travel methods,walking time during transformation,waiting time during transformation and bicycle traveling expenses;under long-distance travel scenario,the threshold between car and car to subway is determined by the travel difference between two travel methods,traveling time in car before transformation,walking time during transformation and traveling distance.