Induced Travel: a Review of Recent Literature and the Implications for Transportation and Environmental Policy
NOLAND R B, Centre for Transport Studies, Imperial College, UK and LEM L L, Environmental Protection Agency, US
Transportation policy has normally been influenced by the desire to provide mobility and efficient access to alternative destinations primarily by alleviating traffic congestion. In the US this has focused around construction of the Interstate Highway Sys
Transportation policy has normally been influenced by the desire to provide mobility and efficient access to alternative destinations primarily by alleviating traffic congestion. In the US this has focused around construction of the Interstate Highway System and provision of capital assistance for public transport systems primarily in urbanized areas. The UK has followed a similar approach with a large expansion of the Trunk Road system. ~ Historically the UK has placed great emphasis on cost benefit assessment of road projects to help prioritize projects. Over the last 30-40 years both countries have seen a reduction in public transport usage despite maintaining very different land use planning systems.
Recently both countries have attempted to move towards more integrated transport policies. This began in the US with enactment of the Intermodal Surface Transportation Efficiency Act (ISTEA) of 1991 and subsequent reauthorization as the Transportation Equity Act for the 21st Century (TEA-21) in 1998. In the UK the central government issued a White Paper in 1998 laying out a strategic direction for transport policy (DETR, 1998). The latter was issued partly in response to research conducted by SACTRA (1994) on the impacts of induced travel as well as environmental concerns with forecasted growth in travel (Goodwin, 1999). In the US capacity enhancing projects are increasingly being challenged as either ineffective at reducing congestion or as likely to result in the continuation of sprawl development patterns and inefficient land use.
This paper analyzes the policy changes that are occurring due to the increased recognition among the public and policy makers that new or expanded roads are not as likely to relieve congestion as once was believed. We begin with a review ofthe behavioral relationships underlying the theory of induced travel and review recent research that documents and empirically measures induced travel effects.
We then examine how transportation and environmental policy is changing in response to the empirical findings both in the US and the UK We suggest areas of improvement in the decision making process to fully recognize the consequences of induced travel behavior on both transportation and environmental policy.
Association for European Transport