The dominant paradigm of transportation planning in the U.S. (a la MPOs) now consists of a hierarchy of activity centers connected by high-quality transportation facilities. Yet, there is a dearth of studies demonstrating the benefits of this pattern of development. Instead, the emphasis in the travel behavior literature has been on the benefits of compact, mixed-use, neighborhood developments.
The fundamental idea of this proposal is that polycentric development, with good destination accessibility within centers, is a partial antidote to urban sprawl. Even in a low-density residential environment, vehicular travel and VMT may be minimized, and walking and biking may be maximized, with efficient trip chaining made possible by polycentric development. Residents of surrounding neighborhoods may make auto trips from their homes to centers and back, but once in centers, they can make short trips, usually on foot, from one destination to the next in multipurpose trip chains.
Despite the negative effects, urban sprawl continues and policies to promote compact development run into political resistance. Instead of putting the emphasis of anti-sprawl policies on residential accessibility (placing attractions within walking distance of homes), this proposal explores the benefits of destination accessibility (placing attractions close to one another in centers).
The database we use consists of 931,479 trips by 94,620 households in 34 metropolitan areas in the U.S. This is the largest collection of household travel data with precise locational geocodes ever assembled. Based on precise XY coordinates, trip purpose and travel mode, we will identify trip chains and non-home-based trips within centers, and can relate trip frequency, trip distance, mode choice, and VMT to the D variables (density, diversity, design, distance to transit, and destination accessibility) for the centers. We would expect to find that households working and shopping in dense, diverse, well-designed, and transit-served centers generate less VMT on non-home-based trips, and make more non-home-based walk and bike trips, than those working and shopping in suburban sprawl.
If our expectations are correct, this would be the strongest evidence yet produced on the benefits of polycentric development through efficient trip chaining. This study has important policy implications by promoting polycentric and smart development as a more effective way to deal with urban sprawl and promote active transportation. Our quantitative analysis will be complemented by detailed case studies of ten regions among our 34 that have promoted polycentric development. The case studies will explore how and why each of the ten regions have promoted polycentric development patterns.