| With the rapid development of socialization,China’s aging problem has becoming more and more serious.Population aging has put forward higher requirements for more convenient and aging friendly urban transportation system,urban resource distribution as well as other urban public services.Given environment conditions,such as traffic congestion during peak hours,travel time reliability and unbalance urban resource distribution,integrated with the increasingly diverse and personalized travel demands of the Chinese elders,it’s necessary for transportation planners to put forward policyrelated recommendations to improve the accessibilities of the out-of-home activities.Based on the above background,this paper focuses on measuring and evaluating the accessibility level of the urban traffic system,as well as analyzing the effects of accessibility on the elderly people’s daily activity time-use.Under the background of China’s aging society,this paper provides a utility-based accessibility method to analyze the elderly couple’s activity-travel behaviors by independent activity and jointly activity separately,where intra-household interactions between the elderly couples and multiple traffic modes network with uncertain travel time will be considered in the proposed model.Furthermore,by formulating a joint decision model of time use and destination for daily activities of elderly couples,the accessibility of different types of activities can be integrated in the same scale level,and the effects of accessibility on activity participation and its durations of elderly couples can be quantitatively analyzed.The main research points include the analysis of the activity-travel characteristics of elderly couples,utility-based accessibility measurement of the independent activities under the uncertain temporal-spatial constraints,utility-based accessibility measurement of the joint activities under the group decision-making mechanism,and the effects of accessibility on daily activities’ time use of elderly couples.1)The analysis of the activity-travel characteristics of elderly couples.Based on daily activity-travel survey data of residents in Beijing,2014,the different types of activities’ travel characteristics will be analyzed.According to ‘who are the decision makers’ in the household-level,all of the daily activities will be classified into independent activity and joint activity.According to the purpose of activities,activities can be classified into work,shopping,leisure,escorting,medical treatment and others.Travel characteristics of the different age-group elders and the comparison of travel characteristics between the elders and other age groups are statistically analyzed to show the elders’ particular characteristics.What’s more,in order to obtain the special characteristics of activity participation,different kinds of activities’ durations and its travel time as well as travel modes are analyzed either.2)A utility-based accessibility measurement approach of independent activities under uncertain temporal-spatial constraints is proposed.Different from the traditional temporal-spatial accessibility or utility-based accessibility method,which ignores the effects of uncertain conditions of multiple travel modes networks,this paper formulates a joint destination-travel modes means-standard deviation NL model for the elderly people.The proposed utility-based accessibility model constrained by uncertain spatial-temporal conditions will be applied in an empirical independent activity,medical treatment for the elderly people.3)A utility-based accessibility measurement approach of joint activities under group decision-making mechanism is innovatively proposed.In terms of the joint activities,the elderly couples’ destination choice is a group-decision process of negotiation.Therefore,this paper proposes a destination choice model for the elderly couples based on group-decision mechanism,which includes a simple MNL structure.Furthermore,considering the uncertain temporal-spatial constraints derived from multiple traffic modes network,a utility-based accessibility measurement model under group-decision making mechanism for joint activities is formulated.The proposed model will be applied in an empirical joint leisure activity for the elderly couples.4)The effects of accessibility on daily activities’ time-use of the elderly couples.Although the elderly couples arrange different out-of-home activities,they are still limited by multiple constrains derived from different household members.In order to analyze the effects of accessibility on time-use,this paper proposed a joint choice model of daily activity time use and destination under the groupdecision mechanism with consideration of multiple constrains,i.e.MDCEVMNL-MC model.This model makes destination choice endogenous nested in activity time-use under group-decision making.At last,the nested destination choice process ultimately affects activity time use in the form of accessibility.The proposed method has the following advantages: a.integration of individual decision-making and group decision-making;b.integration of incomplete substitution and complete substitution among alternatives;c.not only reveals the individual decision mechanism of time use and destination choice of the independent activity,but also reveals the group decision mechanism of the timeuse and destination choice of the joint activity;d.which activity will be participated and its duration,and which destination will be selected can be solved by the proposed model;e.this model unifies the accessibility indicators of various activities in the same framework,avoiding the scale difference of the utility-based accessibility indicators when they are estimated independently.By the proposed model,the accessibility indicators of various activities will be unified in a same scale,which is convenient for the comparison of different activities’ accessibility.By analyzing the impacts of accessibility on time-use of the elderly couples,it’s useful for the transportation planners to put forward policy suggestions that give some activities priority and balance different activities.Consequently,the proposed policy for improving accessibility can be more reasonable,more effective,more focused and prioritized. |
