Tuesday, January 13, 2015
Federal traffic forecasting modified to reflect decline in drivingA recent blog post on BikePortland discusses how federal traffic forecasters have finally modified future traffic estimates that reflect the decline in driving nationwide: After a decade of less driving, federal forecast shifts to match reality. Traffic forecasts are important since they are used by state and local transportation departments to justify massive road projects, and to reject bike projects.
|U.S. VMT (in trillions) as tracked by FHWA's|
Travel Volume Trends ("Actual") and
as projected by U.S. DOT's C&P reports
(by year reports are dated).
For travel forecasters around the country, it’s been a very confusing decade, probably best summed up by this chart showing year after year of incorrect traffic projections from USDOT’s annual Conditions and Performance report, which aggregates projections from metro areas around the country.
How much traffic will increase is a debate that affects us in very practical ways here in Portland, where (for example) the Oregon Department of Transportation has cited future traffic increases as a reason not to improve bike lanes on Southwest Barbur even though its own data shows that auto traffic on Barbur peaked in 2003.
Andy Cotugno, the transportation planning director for regional planning agency Metro, said Wednesday that his organization won’t be affected by the federal change, in part because his team’s projections already reflect the plateau in miles driven per person.
“We’ve scaled our transportation plans down to be more realistic,” said Cotugno.
Cotugno often circulates a chart showing that in the Portland metro area, driving rates per person peaked in 1996, eight years before they did the same nationally.
But Cotugno said he worries that state DOTs and other agencies are too eager to circulate overestimates for future travel demand as a way to justify the need for more money.