The US EPA’s smart growth office released a new study (5 mb pdf) examining the impact that good infill development can have on reducing transportation demand and lowering emissions. In some ways, this study picks up at the point where EPA left off in studying Atlantic Station in Atlanta — where they found that residents drive 2/3 less compared to putting the same amount of development in the suburbs. (More about Atlantic Station here)
While it may seem obvious to conclude that reusing vacant or underutilized land near existing roadways, transit lines, and existing infrastructure would result in fewer auto trips, quantifying those benefits will help metro planning groups make a solid case for steering development into existing areas — which Americans overwhelmingly support.
This particular report looked at three metropolitan areas as case studies: Charlotte, Boston, and Denver:
Fundamentally, well designed neighborhoods in more accessible places make walking, biking and transit more convenient options. Therefore, policies that increase the amount of urban and suburban infill development can help more people meet their everyday needs with less driving. In turn, this can reduce traffic and contribute to better regional air quality.
…Across the three case studies, redirecting jobs and households to brownfield and other infill sites reduces overall travel, congestion and emissions from cars. For example, if just 8 percent of Denver’s jobs and households were shifted over time toward 10 regional centers, congestion would be reduced by over 6 percent and emissions would be reduced by about 4 percent. This would be equivalent to removing nearly half a million trips per day from the region’s roads, a significant share of the daily average (12.7 million miles)
In Charlotte, NC., where a newly-opened transit line has been exceeding ridership projections since opening late last year, the study looked at the transit corridor very specifically. According to the study, you can see that if Charlotte is successful at steering new growth into the transit corridor — leveraging their hefty investment in the system — they can add housing and jobs in such a way that doesn’t contribute to overall emissions or burden already congested roads circling the city.
The Charlotte case study evaluated the impact of increased infill development in a single corridor. Although, a much smaller number of jobs and homes were relocated to infill sites, the analysis demonstrates the benefits of focused development around transit. While the new rail service alone did reduce congestion in the corridor, it had a minimal impact on the region’s emissions. However, when 16,000 households and 10,000 jobs are relocated near the South Corridor stations, the reduction in emissions was 10 times greater and transit ridership increased by more than 6,000 trips each day.
Check out the other studies and valuable resources from the EPA’s smart growth office. And help save their funding! Hard copies are available from EPA by calling (800) 490-9198 or emailing [email protected] and requesting EPA 231-R-07-001.