October 8


FHWA’s Traffic Volume Trends report from June 2015 is quite surprising to all of us who have been in the transportation industry for more than five years.

12 Month Driving PatternTo the right is the chart of vehicle miles traveled in the United States.  It shows a five year stagnation from 2009 to 2014, but in the last year traffic has been growing at a rate similar to the 1991 to 2009 rate. Capping that growth rate is that we are now setting new records for total vehicle miles traveled in the U.S.

What does this mean to transportation professionals?

I think it means we need to start scenario planning for the future instead of planning for a magical, single forecast traffic volume.  To me, this would mean a more Bayesian approach to calculating low/medium/high scenarios and then performing planning exercises around these alternatives.

Given the major funding shortfalls our industry faces, I would preserve public right-of-way for the medium or high scenarios and plan construction around the low scenarios.

It is still quite possible that mass transit, telecommuting, drones, flying cars, etc. will mean we never reach the high forecasts.

The important take away from the latest traffic growth trend is that we need to be prepared for a range of possible future scenarios.

  • I’d expect the increase is driven not just by an improving economy but also by the combined energy boom + release of oil supplies that are keeping prices at the pump super low. With fracking slowing and if (cold)wartime energy policies should shift & prices rise: it’ll be interesting to see how that affects growth in VMT.

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    Mike Spack

    My mission is to help traffic engineers, transportation planners, and other transportation professionals improve our world.

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