• Studies of threshold population and employment densities to support alternatives to automobile travel: Studies of the threshold densities required to support rail and bus transit would help guide infrastructure investments as well as zoning and land use plans around stations. Current rules of thumb are based on outdated references. Similar threshold information is needed to determine what development densities and land use patterns are optimal to support walking and bicycling.

  • Studies of changing housing and travel preferences: Studies of the housing preferences and travel patterns of an aging population, new immigrant groups, and young adults are needed to help determine whether future trends will differ from those of the past.

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