A Conceptually Innovative and Practical Approach to the Modelling of Household Activities and Travel Behaviour
Siamak Khorgami, AECOM, Peter Jones, University College London, Helena Titheridge, University College London
This research proposes an approach for the analysis and modelling of people's activities which addresses some of the existing shortcomings of activity-based models, using individual daily activities as the basic unit and starting point.
Activity based travel analysis has received much attention in the academic literature since the 1980s and has seen several practical applications in recent decades. Operational models have been developed, and are being used, in North America and some mainland European cities, for policy analysis; in the UK the practical application of activity-based modelling is much more limited, despite the fact that available sources of travel and activity data enable such models to be developed. An extensive review of the literature reveals that most operational models do not fully embody the principles of an activity-based approach. In particular, (i) the models mainly concentrate on out-of-home activities, (ii) there is no explicit trade-off between taking part in an activity in home or out of home, (iii) they assume that only one activity takes place at each non-home location, and (iv) the basic unit of analysis in these models is the trip tour or the activity pattern, rather than using individual activities as the basic building blocks.
This research proposes an approach for the analysis and modelling of activities which addresses these shortcomings, using individual daily activities as the basic unit and starting point. The approach recognises that activity participation is influenced by physiological constraints (e.g. the need to sleep and to eat), as well as socio-economic characteristics (e.g. employment status). Also, it considers time availability and overall time budget as further constraining factors. Inter-personal linkages and the trade-off between in-home and out-of-home activity time allocation are also incorporated in the proposed activity based modelling framework. The model has two major sequential components: (1) an activity generation and household allocation model system, developed in depth, followed by (2) an outline activity/travel scheduling model system.
The proposed modelling framework incorporates the possibility of engaging in multiple activities per non-home stop, and allows for trade-offs between in-home and out-of-home discretionary activity participation. The framework also allows for the joint engagement of household members in out-of-home activities.
The research focuses on the activity generation-allocation system modelling as less previous work on this can be found in the literature, both from the theoretical perspective and in terms of empirical model development. Statistical analysis modelling techniques are used to develop activity generation-allocation sub-models, using 2001 UK Time Use Survey (TUS) data. A simplified activity-travel scheduling model system is then outlined in order to demonstrate how the activity generation-allocation model outputs impact on patterns of travel behaviour (trip rates, tours, etc.), using mathematical programming techniques.
This proposed activity-travel system model allows for a range of policy sensitivity testing including:
• Encouraging activity densification and mixed land uses;
• Affecting work hours (e.g., changes in working hours or flexibility in working hours); and
• Changing population composition
Association for European Transport