Publication Detail

Travel Behaviour-Land Use Interactions: An Overview and Assessment of the Research

UCD-ITS-RP-02-17

Reprint

The link between land use and travel behaviour has been of interest to transportation researchers for many decades. Mitchell and Rapkin's oft-cited Urban Traffic: A Function of Land Use, published in 1954, reflected the emerging interest in forecasting travel demand and stated that "more knowledge is needed about the precise nature of the relationship between land use and movement and about the extent of their mutual effects" (pg. 3). That statement is as true today as it was then.

In the intervening time, our knowledge of the nature of the relationship between land use and movement has certainly increased, thanks to a long series of studies on the topic. Early studies on the link between land use and travel focused maximizing the efficiency of the transportation system and determining transportation needs. Studies from the late 1960s and early 1970s often focused on energy consumption, reflecting the growing concern over resource limitations at the time. Studies from the 1980s reflected a shift towards concerns over congestion and the impact on the individual commuter, although energy and air quality concerns also played a role. Most of these studies characterized land use – or urban form more generally – using relatively "macro" measures such as density, activity mix, job decentralization, overall structure (e.g. monocentric vs. polycentric), or city size.

The movement towards micro-simulation as a tool for forecasting travel demand has also created a need for a better understanding of how the micro elements of urban form influence travel behaviour. Some agencies have succeeded in incorporating more and better land use variables in their traditional forecasting models, thereby increasing the sensitivity of these models to land use policies. But the coarseness of these traditional models means that there is limited benefit to worrying about urban form at a very detailed level. With micro-simulation models, however, it now becomes both important and profitable to incorporate specific aspects of urban form that influence individual decisions about travel. The question is how "micro" elements as well as "macro" elements of urban form influence travel choices.

The need for more knowledge today is partly driven by the fact that the questions have changed as the policy focus has changed. ISTEA, for one thing, has put renewed emphasis on planning for non-motorized modes such as walking and biking and has generated projects designed to increase use of these modes. In addition, as the new urbanism movement has grown, communities throughout the U.S. have taken a new look at their land development policies and considered or even adopted changes to these policies that enable or even encourage forms of development more supportive of pedestrians and transit users. The hope, supported by the claims of new urbanism proponents but not much else, is that pedestrian- and transit-oriented development will lead to a reduction in automobile dependence and thus automobile travel. In both cases, the question is much different than before: how "micro" elements of the environment influence travel choices.

Although the questions have changed, the research methodologies have not, or are at least changing slowly. For the most part, research-to-date demonstrates correlations between travel patterns and characteristics of urban form, with urban form accounting for a limited but statistically-significant share of the variation in travel patterns. But it has shed very little light on the behaviour underlying these correlations and thus on causal relationships – the kind of knowlegdge needed to predict the impact of new urbanist policies or to build more accurate micro-simulation models. Although some progress has been made, this body of research is sorely in need of more theoretically-based, exploratory approaches. In this chapter I first review the types of research approaches that have been used, then discuss a long list of issues that have yet to be adequately addressed.
Published in Perpetual Motion: Travel Behavior Research Opportunities and Application Challenges, ed. H.S. Mahmassani, Elsevier Science Ltd., chapter 10.