Research On Transit Service Design Under The Effect Of Multi-Type Travel Demand Characteristics

With the rapid expansion of urban city boundary and economic development,the travel demand has demonstrated its fast growth as well,which correspondingly leads to the deteriorated condition of urban traffic congestion.In order to mitigate the issue between the increasing travel demand and the delayed expansion of road network capacity,the city officials not only strive to increase the operational efficiency of the roadway network,but improve the quality of public transit service.The latter measure can help shift the travelers to transfer from the private cars(with low occupancy)to the public transit(with high occupancy)in terms of travel mode.Public transit system plays an important role in the passenger travel which has complex and various characteristics,such as the diversity of travel purposes and travel modes,the heterogeneity of spatial distribution,and the substitutability of travel behavior.Correspondingly,transit demand also has the characteristics of heterogeneity,elasticity,and randomness.Therefore,we propose the transit service design models with considering multitype of travel demand characteristics,and evaluate their impacts on the service design of public transit corridors.The main contents of the dissertation include:(1)Transit service design of a bi-centric corridor under elastic demand.In order to account for the elasticity of travel demand,the study attempts to construct and optimize a transit service design model(while considering heterogeneous housing choices)for a bicentric corridor based on the interaction between the land use and transit system.The bi-centric corridor allows multi worker of a household chose different commute destinations.According to the heterogeneity of travel destinations between two centers,the study proposes the operational strategy for the transit system with multiple lines and incorporates the optimal line combination into the design model.Numerical experiments unveil the unique features of the city size,housing market,and transit design in bicentric cities compared to monocentric ones and how they are affected by key operating factors(e.g.,the transit mode).Results also show that the optimal transit station density increases near the city centers,which disagrees with the findings in the literature under the uniform demand assumption.Lastly,we apply our models to a case study in the Chengdu Metropolitan Area of China,showing the impacts of the fastexpanding metro network.(2)Transit service design considering reliability under stochastic demand.According to travel demand randomness and the fluctuation as a result,we account for a headway-related constraint for the sufficient transit capability to ensure the reliability of the transit service.Then,we introduce a penalty cost when the service does not meet the demand and construct the stochastic design model where the expected system cost reaches the minimum.In the numerical experiment,the proposed model is applied in the impact analyses of the servicereliability constraint,as well as the sensitivity analyses of the household numbers and value of time.The impact analyses indicate that the transit service design integrated with the effect of housing location choice is necessary under the stochastic demand.The sensitivity analyses show that the number of households and the value of time play a significant role in the performance of transit systems accounting for service reliability.The proposed model and findings serve to improve the design of the transit system under the stochastic demand.(3)Phased transit service design model under fixedly growth demand.With the rapid expansion of city size,the demand is growing and heterogeneous at the temporal dimension.Due to high construction,operation,and maintenance costs of transit system,the growth and extension of transit demand should be considered in the planning stage of the transit system.Thus,based on the transit service optimization model considering the residential location,we assume the transit line is scalable and proposed the corresponding phased design model under fixedly growth demand.The proposed model is to determine the extended length of the transit line and its implement time,as well as the station location and headway at each period.In the numerical analysis,we firstly compare and analyze the result of the proposed continuum approximation model(CA)with the recalculated results under specific station location(i.e.,the discretized result of the CA solution)to verify the accuracy of the proposed CA model.Then,we illustrate the effectiveness of the multi-phase design via comparing the transit service design under different design strategies(full-coverage design,building-in-once design,and phased design);finally,we compare the difference of pashed transit service design under different transit mode,such as rail,Bus Rapid Transit(BRT),and traditional transit(or bus).(4)Phased transit service design under stochastic growth demand.In order to integrate the effects of the elasticity,heterogeneity,and randomness of travel demand,we firstly propose the phased transit service design model under random growth demand on the basis of the previous model(3).The proposed model is implemented under three risk-decision scenarios,including the neutral-risk,risk-avoidance,and risk-seeking attitudes.Then,the local decomposition method and optimization theory are adopted to find the analytical solution.Finally,the study compares the transit corridor designs with different design strategies(i.e.,full-covered,once-and-done,and phased designs of the transit line)and risk decision-making attitudes.The results indicate: 1)the phased design has a lower expected system cost than the full-covered and the once-and-done designs,and a more robust scheme than the once-anddone design;and 2)risk decision-making attitudes substantially affect the parameters(i.e.,the transit length,station location,and headway)of transit system under different design strategies;for example,the risk-averse decision-makers tend to seek denser station locations in the fullcovered design,but relatively lower station density in the once-and-done design in phased design.The issue becomes more complex in the phased transit design.From the theoretical perspective,the research serves to explore the influences and coupling effects of different transit demand on the transit service design.From the practical aspect,the findings may help provide guidance for transit system design aiming to promote a higher level of service,more applicable,and reliable transit service schemes.