A case study of induced trips at mixed-use developments

Conventional thinking suggests that pedestrian-friendly, mixed-land-use developments will contribute to an overall reduction in travel by providing an alternative to automobile travel. However, these elements may serve to increase travel demand by reducing the overall cost of travel-a phenomenon generally known as 'induced' travel. To date, most studies of induced travel have focused on aggregate travel patterns, without examining how development patterns may influence people's trip-making decisions. To fill a void in the empirical research, we examine the potential for induced trip making at mixed-use developments by analyzing data obtained from a survey of travelers at a typical mixed-use site in suburban Dallas, Texas, USA. Our analysis found that during both the morning and afternoon study periods, at least some percentage of internal trips at the case-study site were induced, and not 'captured' from the external street network as is typically assumed. Induced trips by land-use pair and travel mode are also reported. Even with the induced trips, a reduction in regional vehicle-miles traveled can still be realized at mixed-use developments sites due to the propensity for those trips to be made on foot. Induced travel also has implications for the development of traffic-impact studies for proposed mixed-use sites, which generally assume that all internal trips are replacing external trips. Planners, policy makers, politicians, and other stakeholders exploring mixed-use developments as a land-use solution to urban traffic congestion and air-quality issues are encouraged to consider the implications of induced travel in the mixed-use environment.