Family-based Traveler's Daily Activities-travel Decision-making Behavior Research

With the deepening of urban traffic research,the solution of urban traffic problems has been transformed from urban road facilities planning to urban traffic management,which is guided by traffic management and traffic services.The focus of urban traffic research is focused on people's activities and travel behavior gradually.However,household is considered as the highest decision-making unit of individual activity-travel behavior.Because of the interdependence and mutual restriction among members in this decision-making process,there are joint decision-making behaviors such as companionship,substitution and mutual assistance in family activities.Then interweaving and nesting are produced.This is the key factor to be considered when studying the traveler's activity-travel decision-making problem.However,independent individuals are regarded as the basic unit of activity-travel decision-making.Minimum travel time or travel cost are regarded as decision-making objectives to simulate travelers' daily activity-travel plan arrangement in previous studies.This ignores that the traveler is a member of a household,and his/her activity-travel behavior is the result of decision-making under the interaction of multiple members of the family.Many of the activities and activities of travelers often come not from “where I am going and what I am going to do” directly,but from “where my family is going and what they are going to do” indirectly.Because of the existence of family relations,some limited activities in the family need to be transferred among members rather than disappear.Therefore,it is often impossible to explain the reasons for the change of travelers' activities and travel behavior when travelers are regarded as independent individuals,which leads to a big gap between the simulation of travelers' activities and travel behavior and their actual behavior.Based on the above analysis,the framework and simulation model of family activity-travel decision-making were constructed from the perspective of family.The interaction mechanism within the family was built into the travelers' daily activity-travel decision model.The interpretation and description of travelers' daily activity-travel behavior were improved,which helps to understand travelers' activity-travel behavior,and provides theoretical support for traffic management measures and traffic policy formulation.The main research work as follows:Firstly,starting with behavioral analysis,the characteristics of joint decision-making among family travelers were concerned,and the characteristics of joint activity and trips were extracted.Travel chains were used to deconstruct the interweaving and nesting phenomena of joint activity and trips.The differences between individual and family perspectives in describing travelers' activity-travel behavior were compared.Finally,the typical characteristics of household association activities and travel behavior were obtained.Typical patterns of joint activities,such as accompanying activities,pick-up activities and alternative activities,were extracted in the family.Space-time path was used to highlight the process expression of interactive decision-making between joint activity and individual travel chains.Secondly,the physical environment and objective constraints faced by travelers in the process of activity-travel and decision-making were constructed based on the theory of time geography;the relationship between the elements of family activity-travel was established from the perspective of family relations,family functions and family strategies,supported by the theory of family sociology.Including the relationship between travelers,activities,trips and the relationship between travelers and activities and trips,forming a complete family activity-travel decision-making system.Based on the optimization theory,a balanced family activity-travel decision-making model was established.Through the external equilibrium of travel utility and activity utility,and the internal equilibrium of individual activity-travel relaxation utility and joint utility,the interaction and restriction between family travelers in activities and trips,such as companionship and substitution,were placed in the decision-making model.Finally,we validate the applicability of the proposed framework and modeling method by establishing different family daily activity-travel decision scenarios.Children's pick-up and take-off activities,shopping activities and leisure activities were used to set different space-time scenes in the household.The interweaving of joint activities in the travel chain and the transfer of activities and travel needs between the travel chains were reproduced.The designed genetic algorithm was used to solve the model and simulated the family activity-travel behavior.The results show that the response mechanism of travelers to the change of decision-making environment through joint activities and trips is more complex from the perspective of family.The change of activities and trips at the individual level is the expression of the balance of family activities between space-time constraints and membership relations.