- This study describes relationships between travel for different transportation modes and aspects of the built environment. These relationships can be used to forecast changes in driving, walking, or transit use and estimate impacts of policy changes that influence the built environment on greenhouse gas emissions and health.
Results:
- This study defines a framework of “5 D’s” used in transportation research literature, which classifies changes in the built environment that can influence travel choices using the following categories:
- Density: measures a variable of interest per unit area (e.g. household/population density and job density)
- Diversity: measures the mix of land uses in an area (e.g. land use mix and jobs-housing balance)
- Design: measures street network characteristics (e.g., intersection/street density and percent of 4-way intersections)
- Destination accessibility: measures ease of access to trip destinations (e.g., job accessibility by auto or transit; distance to downtown)
- Distance to transit: measures street routes from home or work to the nearest rail or bus stop (e.g., distance to nearest transit stop)
- Overall, the relationship between individual built environment variables and travel choices was relatively inelastic (no more than 0.39, meaning that a 10% in a factor of the built environment only changes travel choices by 3.9%), but combining multiple built environment changes could have a greater effect.
- Measures of destination accessibility was most strongly associated with both motorized and nonmotorized travel, and population and job densities had the weakest association with travel choices.
- Walking was most strongly related to land use diversity, intersection density, and destinations within walking distance.
Methods:
- This meta-analysis synthesizes effects of the built environment on travel choices from 50 research studies. To create a common metric to compare outcomes across studies, the researchers calculated elasticities, which represent the percent change in choosing a travel mode relative to a 1% change in a specific aspect of the built environment.
Ewing, R., and Cervero, R. (2010). Travel and the Built Environment. Journal of the American Planning Association, 76(3).
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