Research suggests that the Trip Generation Manual—a familiar tool for planners calculating the vehicle trips expected to be generated by developments of various sizes and uses—produces "phantom trips" and unneeded automobile infrastructure.
Eric Jaffe suggests that it might time to add the Trip Generation Manual from the Institute for Transportation Engineers to the list of questionable planning tools. Jaffe cites research by Adam Millard-Bell of the University of California, Santa Cruz, "who challenges the merits of the Trip Generation Manual in an upcoming research paper [pdf] (nicely summarized in ACCESS magazine)." See the video below of Millard-Bell describing his research.
In the study, "Millard-Ball reports that the ITE manual may overestimate the number of trips generated from a new development by as much as 55 percent," according to Jaffe. The result of these "phantom trips": "cities may build way more roads than necessary, perpetuating sprawl and leaving less street space for non-drivers in the process."
FULL STORY: A Widely Used Planning Manual Tends to Recommend Building Far More Roads Than Necessary
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