Tuesday, October 6, 2015

New Report on Quantifying the Relationship between GHG Emissions and Land Use

The Federal Transit Administration's Transit Cooperative Research Program recently released its report, "Quantifying Transit’s Impact on GHG Emissions and Energy Use— The Land Use Component," which will be of great interest to lawyers and planners working in states intent on reducing GHG emissions and VMT.  Here is the report's summary:

Key findings of the research include the following:

• Effect on population densities. Taking the entire U.S. urban population in aggregate, gross population densities would be lower by 27% without transit systems to support compact development. In other words, U.S. cities would consume 37% more land area in order to house their current populations. The land use effect of existing transit makes U.S. cities more compact.

• Effect on VMT, fuel use, and transportation GHG. By providing more walking and biking opportunities and making some journeys by car shorter, the land use effect of transit produces land use benefits: an aggregate 8% decrease in VMT, transportation fuel use, and transportation GHG emissions in U.S. cities.

• Effect of transit trips replacing automobile trips. By transporting people on buses and trains who would otherwise travel by automobile, transit systems also produce a complementary ridership effect. In aggregate across U.S. cities, transit ridership reduces VMT, transportation fuel use, and transportation GHG emissions by 2%. This is a substantial change given that only 4% of passenger trips are currently made by transit in U.S. metropolitan areas.

• The land use benefit of transit. The land use benefit of transit varies across urban areas, ranging from a 1% to 21% reduction in VMT, transportation fuel use, and transportation GHG emissions compared to a hypothetical scenario without transit. Urban areas with higher route densities of transit, service frequencies of transit, and availability of light rail have higher land use benefits. Not surprisingly, higher land use benefits of transit are generally found in more densely developed areas.

• The land use effect of transit in a given region typically reduces GHG emissions more than the ridership effect. The average ratio of land use benefits to ridership benefits across all U.S. cities is 4:1, but the ratio varies substantially across different urban areas.1

• Adding a rail station to a neighborhood that did not previously have rail access is associated with a 9% increase in activity density (combined population and employment density) within a 1-mile radius of the rail station. The corresponding land use benefit is a 2% reduction in VMT (for households within the 1-mile radius), transportation fuel use, and transportation GHG emissions.

• Improving employment accessibility, by clustering new jobs around transit nodes or improving the bus and rail network in individual neighborhoods, can also have potent land use effects.

• An analysis of the Portland Westside light-rail extension found that the land use effect increased densities by 24% in the corridor area between 1994 and 2011. These changes correspond to a 6% household VMT reduction due to the land use effect and an additional 8% VMT reduction due to the ridership effect.


| Permalink