Declining Traffic: How Will It Affect U.S. Transportation?

Several Streetsblog Network members, including the Bicycle Coalition of Philadelphia and Decatur Metro, have blogged about the latest numbers from traffic information firm INRIX, which show declining congestion in 2008 vs. 2007 in nearly every metro area surveyed (Baton Rouge, LA, bucks the trend; go figure). INRIX reports "peak hour congestion on the major roads in urban America decreased nearly 30% in 2008 versus 2007."

us_ave_annual_vehicle_miles_projection_to2032_2009_01.png Missouri Bicycle News digs into a related set of data, the traffic volume trends from the Federal Highway Administration:

The December 2008 figures (the latest available) show that motor vehicle miles traveled were down about 3.6% for 2008 as compared with 2007.

Three thoughts:

1. It is remarkable that miles traveled continued to decline quite sharply even in the last part of 2008. During that period, gas prices were declining dramatically — which creates a strong incentive to drive more…

2. This continued drop in miles driven dramatically upsets transportation planning as it has been done over the past 50 years in the U.S. All road and highway planning is done on the assumption that travel miles will continue to increase at a 2-4% annual rate as they have done (on average) through the entire 20th century.

Now — even after the U.S. recovers from the current economic difficulties — predictions are for miles driven to grow less than 1% annually.

Most
road projects are planned using 10, 20, and 50-year traffic forecasts. Even just 10 years out, the difference between 1% and 3% annual growth rate is very large. Twenty years out it’s a 2:1 difference.

Are we planning our roads for twice the traffic that will really exist in 20 years?

Give us your thoughts on the data in the comments.

Elsewhere around the network, Trains for America posts about an engine shortage on Amtrak (need a place to spend some capital, Mr. President?), Lightrailblogger has a report from a light rail pub crawl to benefit Phoenix businesses and charities, and Fifty Car Pileup gets doored in Soho (no serious injury sustained, thankfully) and attracts the attention of the paparazzi in the process.

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