smart growth

the transportation perspective

Smart Growth is an integrated, environmentally-sensitive approach to land use and transportation planning. Smart Growth transportation strategies include:

  • Transit enhancements and transit-oriented development (TOD)
  • Visionary community and regional policies and land use plans that reduce the need to travel and minimize impacts.
  • Streets that provide context-sensitive, multi-modal mobility for traffic, transit, pedestrians, and bicyclists … (full text Homepage).

Livable Streets; Strategies; Mesuring performance; Case Studies; Community Vision; FAQs; Links;

Typical effects, Matching transit investment to context: There are commonly-accepted residential density thresholds for various transit modes.  

Minimal local bus service (operating on 60 minute headways) requires at least 4 dwelling units per acre (du/acre), while more frequent bus service requires a minimum of between 7 and 15 du/acre. Express bus service requires at least 15 du/acre over a two square mile area, and is effective at serving large downtowns 10-15 miles away.  Light rail requires an average of 9 du/acre over a 25-100 square mile corridor, and is appropriate to serve downtowns with 20-50 million square feet of non-residential floor space.  Rail transit can operate with densities of 12 du/acre over a 100-150 square mile corridor, but is best for serving a downtown with more than 50 million square feet of non-residential floor space.  Commuter rail can operate with residential densities as low as 1-2 du/acre, but only when serving very large downtowns.

Transit service improvements: Increasing bus frequencies (decreasing headways) has been found to increase ridership with an elasticity of between -0.4 and -0.6.  Thus, a 10% decrease in headway would increase bus ridership by 4% to 6%.  These effects vary by time of day; ridership during off-peak hours is more sensitive to headway than ridership during peak hours or weekends.

Increasing transit speed: … (full text).

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