The potential efficiency and success of various measures for eliminating or reducing traffic problems in metropolitan areas largely depend on how people will respond to them. Lack of public acceptance is an important issue that has been highlighted in recent years.
Whether and how travel actually changes is however an equally important issue that is far from settled.
As it has been pointed out in the past by leading travel-behaviour researchers, it has become increasingly evident that travel results from choices people make that are both interdependent and dependent on desires or obligations to participate in activities.
In the proposed approach travel choice is viewed as an adaptation to changes where people select different available choice options over time.
The project aims at investigating behavioural response to Travel Demand Management (TDM) policy measures. This has direct relevance on how to manage urban transport in the future.
In particular it will be possible to propose innovative solutions consisting of combinations of policy measures that promise to effectively manage demand for use of private cars in metropolitan areas.
- Specifying societal change goals (reduced driving distance and frequency of car trips) and feasible TDM measures. Interviews will be conducted with politicians and experts.
- Specifying how given TDM measures impact travel choice alternatives for different households. Available travel diary data will be used so that the effects on various prototypical trips can be evaluated (primarily in terms of time and costs).
- Conducting focus group interviews followed by surveys with three aims related to given TDM measures (selected in phases 1 and 2):
- to determine households' degree of acceptance;
- to determine households' commitment to and type of adjustment (e.g., car-use reduction) goals; and
- to determine households' general implementation strategies including what they perceive as feasible choice alternatives and what they define as travel options (attributes of subjectively defined trip chains, e.g., trip from home to work, trip from work to home, trip from home to store and back, or trip from home to stores, back home and again to stores and back home).
- Experimental simulations to determine how people develop and implement adjustment goals. A computerized laboratory at Department of Psychology, Göteborg University, will be used with university students as research participants. Some follow-ups on other groups are also planned using web-based questionnaires.
The empirical studies focused on how car users evaluate and respond to three TDM measures: individualised marketing, road pricing and prohibition.
The proposed hierarchy of adaptations was investigated in focus-group interviews and a web-survey (Loukopoulos et al., 2004), in another Web-survey (Loukopoulos, Jakobsson et al., 2005, 2006), in an experimental simulation (Horeni et al., 2007), and by analysing data of actual reported changes collected in Trondheim when road pricing was introduced (Loukopoulos, Gärling et al, 2005).
It was shown that acceptance and adaptations were less for the coercive measures and that the adaptations followed a psychological cost-minimisation principle. However, whether more efficient car use, using public transport, or changing activity patterns were more attractive depended on age of the car users, type of trip (work, shopping, leisure), and type of TDM measure. Additonal studies have been performed of car users' choices of driving at short distance showing a relation to differences in perceived physical exertion (Loukopoulos & Gärling, 2005).
In summary the results indicate that coercive TDM measures (prohibition and road pricing) need to be combined with non-coercive (information) to achieve public acceptance, effectiveness, and political feasibility (Gärling & Schuitema, 2007). Furthermore, how car users adapt needs to be forecasted so that more effective adaptations (e.g, public transport use) are also made less psychologically costsly.