Destination Choice: the Underestimated Dimension in Sustainable Travel Behaviour
P Goodwin, Centre for Transport and Society, UWE Bristol, UK
In recent years, there have been two main tools used for assessing the role of behavioural change in transport in helping to achieve large scale carbon reductions, such as the 80% reduction by 2050 discussed in the UK, USA and other countries. These tools are (a) extrapolation from evidence on demand elasticities and case studies on public transport, 'smart' measures and demand management; and (b) a new generation of multi-modal 'strategic' transport models, often operating at national level and containing many of the best features of local network based models. Both approaches have been dominated by consideration of mode switching - so much so, that in much of the discussion 'behavioural change' and 'mode switching' are treated as meaning the same thing, marked - for example - by judgements that only very short car trips can be transferred to walk or cycle, and only car trips on main public transport corridors can be transferred to public transport.
The result has been an unintended understimation of the scope for behavioural change, because a whole dimension of choice is omitted, namely destination choice. Land-use/transport interactions are rarely considered,so land use changes are taken as exogenous rather than responding to transport conditions. In addition the absence of a specific network and specific geography in strategic models, means that destination choice becomes invisible even within a fixed land-use pattern. The result is in effect to treat the trip pattern, or distribution of trip distances, as fixed or exogenous.
Yet in models which do allow both mode and destination choices to vary, it is often found that destination choice is the more variable, and indeed is sometimes the necessary pre-condition to mode switching: a car trip to an out-of-town shopping centre can change to walk if the destination is shifted to local, or to public transport if the destination is shifted to a town centre.
The paper reviews the evidence on this topic, including local studies and aggregate trends in trips and average distances, and argues that the tools and assumptions used are unnecessarily making a challenging task seem even more difficult than it need be. The difference could be as much as a facyor of two.
(Note: if this paper is accepted it will need to be programmed to avoid the special theme on road pricing, which I am chairing).
Association for European Transport