Shoup Critique Of ITE Parking, Traffic Generation Manuals

Long the bible for planners, the ITE standards are misleading and reinforce car dependence

In a more popular version of a forthcoming article in the Journal of Transportation and Statistics, Donald Shoup chronicles the problems with the ITE Parking Generation and Trip generation manuals that have become standards for planners and transport professionals in the U.S. and even abroad. He demonstrates that their ostensible accuracy is unmerited and misleading; that average rates are most often presented despite lack of statistical evidence for any relation between floor area and trips generated; and, more profoundly, that the tables are based on assumptions of car dependent land use that the manuals help become self-fulfilling, as follows. Rates are derived from studies of peak parking demand and number of trips in suburban sites with ample free parking--lacking transit, pedestrian facilities, or TDM; these are then used to mandate the design of new developments, thus ensuring that parking in these will be free, and densities low (so traffic generated at the predicted rates does not overwhelm roads.) When such sites are surveyed in the future, they will, indeed, validate these rates. Voila!

Thanks to Yaakov J. Garb, ITDP

Full Story: Roughly Right or Precisely Wrong, Page 20. [PDF 3.35MB, 44 pages]


Prepare for the AICP* Exam

Join the thousands of students who have utilized the Planetizen AICP* Exam Preparation Class to prepare for the American Planning Association's AICP* exam.
Starting at $245

Essential Readings in Urban Planning

Planning on taking the AICP* Exam? Register for Planetizen's AICP * Exam Preparation Course to save $25.
Rome grey gold tie

Tie one on to celebrate your city!

Choose from over 20 styles imprinted with detailed city or transit maps.

Stay thirsty, urbanists

These sturdy water bottles are eco-friendly and perfect for urbanists on the go.