Tuesday, April 8, 2008

Transportation Hierarchy

Most regions in North America have been trying (and failing) to building transportation systems and their communities around mobility instead of accessibility. What's the difference and why does this matter? The following quote from the Oregon Department of Transportation sums it up.
Cities and other major activity centers tend to have a relatively poor vehicle mobility (due to congestion), but are economically successful due to excellent accessibility (activities that are clustered together and many travel options). This indicates that in the game of economic competitiveness, accessibility trumps mobility.

This suggests that traffic congestion itself is not necessarily a major constraint on economic activity provided that land use patterns minimize the amount of driving needed to reach common activities and destinations, and that travelers have good transport options to choose from. Roadway level of service or average per-mile vehicle operating costs are less important indicators of transport system performance than average per-capita commute travel time and total per-capita transportation expenditures. Smart growth strategies that result in more accessible land use may be the best way to improve transport and increase economic productivity, because they reduce the average distance between destinations and therefore total travel costs, while a congestion reduction strategy may provide little or no economic benefit overall if it stimulates sprawl which reduces overall accessibility in a community.
Accessibility includes mobility like walking, cycling, public transit, ride-share, taxi, automobiles, trucks; mobility substitutes like telecommuting; connectivity like roads, paths; and land use. When we start building communities around accessibility, we can start building communities around people. At the end of the day, most people would rather live in a complete community (shop, offices, apartments, detached houses, etc.) than Stepford Wives Samesville.

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