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.

  • anonymous

    Just means more empty freeway lanes on which to build automated group rapid transit!

  • It means that state governments will be raising less moeny through the gas tax, which means less money for road maintenance, which will just force states to raise the moeny elsewhere, and raise taxes. Just because driving is down doesn’t mean that politicians won’t want to keep road building. Most politicians are a long way from thinking that other modes of transportation other than the car is worthy of investment. And just because miles driven is falling doesn’t necessarily mean that people are changing their behavior, it could just as easily represent people having less money to spend, or not having a job to commute to, and so are making less trips.

    Politicians are still of the mind set of buil, build, build when it comes to roads. The stimuls has a large amount of money for road projects and even a tax break for people that buy new cars. And look at all the moeny we spent bailing out the auto industry just so they could lay-off a substantial portion of their workforce.

    We are a long way from thinking that anything other than SOV transportation is the mainstream.

  • If we continue to build for 2 times the amount of predicted traffic we will end up with 2.5 times the amount of predicted traffic. Right miles driven is falling because gas prices were high and everyone still has their SUVs, once efficiency or a fuel source make all that precious driving economically feasible we will be right back on track for more and more traffic congestion. That is if we don’t change national policy on transportation.

  • Felix

    Baton Rouge received an influx of people after Katrina.

  • So with regards to the Tappan Zee Bridge, is Commissioner Glynn genuinely out of touch, or deliberately ignoring these important VMT trends?

  • Incredible numbers.

    Local reaction on New Haven’s new $757 million bridge:

    http://www.designnewhaven.com/2009/03/q-bridge-built-for-2x-necessary-traffic.html

  • Larry Littlefield

    I wonder how much road building has been going on over the past 30 years. My guess is a lot less than in the 30 before that.

    How much of this is just a recession, and how much is people choosing a new way of life? There aren’t a whole lot of folks who radically alter their preferences late in life — just listen to the local pols to hear those whose eyes are closed. To see where things are going, one has to measure trends among the young.

    Is that possible using VMT data? Auto ownership data? Or is it necessary to use one of the population surveys, with data on age that can be crossed by autos available and journey to work?

    I’d be interested to see the trend among those age 20 to 29 over the past 30 years. They are certainly earning less:

    http://www.gothamgazette.com/print/2208

    How about their vehicle choices?

  • garyg

    the latest numbers from traffic information firm INRIX, which show declining congestion in 2008 vs. 2007 in nearly every metro area surveyed

    And not just small declines in congestion, but dramatic ones. This dramatically lowers the congestion-reducing benefit attributed to transit, and severely undermines tha argument that we should spend more on transit to reduce road congestion.

  • Go away, troll.

  • garyg

    Er, is this your blog?

  • Grayg

    Those numbers are down because people were doing things other than drive. Like, I dunno, take the bus, walk, or even ride a little red wagon. How does this prove otherwise?

  • Rhywun

    Those numbers are down because people were doing things other than drive.

    You mean they didn’t just vanish into thin air? Gee, for second I thought he had something there.

  • garyg

    Those numbers are down because people were doing things other than drive. Like, I dunno, take the bus, walk, or even ride a little red wagon. How does this prove otherwise?

    It doesn’t. I wasn’t suggesting that it does. The point is that since road congestion has declined there’s less reason to expand transit to relieve congestion. Congestion in Los Angeles, for example, declined by 24% between 2007 and 2008. So there is now much less need for transit expansion in LA to reduce congestion than there was in 2007. The same is true in almost every other metropolitan area. In many of them, congestion is down by 40-50% or more.

    Of course, you might argue that the reduction is only temporary and that congestion will soon rise back to 2007 levels or higher, but you’d need to make a case for that with evidence.

  • Yeah as the population grows its most likely that people will leave their homes less on a daily basis. Especially when the economy begins growing again people will be even more likely to stay at home and not spend their money.

    That was sarcasm if you didn’t notice.

  • Gary Fisher, the red herring in Gary G’s argument is the idea that we’re building transit to reduce road congestion. There are plenty of reasons to build transit (for example, so that we can take trains where we want to go), and reducing congestion is pretty far down on the list.

  • Well that’s basically my point. If traffic continues to decrease for reasons it has in the past year i.e. economic downturn and fuel cost, then people will need the option of transit or preferably more walkable communities, if they want or need to go anywhere.

  • garyg,

    uhhh… while yeah road congestion is down, other reports show many transit systems bursting at the seems! While you might not be able to prove causation with 100% certainty, it sure seems there is a likely correlation.

    Plus the big reason to provide transit is that 30% of Americans can’t drive! And probably 10-20% of those that do probably shouldn’t (bad records, DWI, old age, other impairments). Things will only get more critical as the population ages.

    There are a ton of other reasons to provide transit that have been talked about ad nauseam on this blog. If someone else cares to elaborate further, please do.

  • garyg

    According to the Texas Transportation Institute’s 2007 Urban Mobility Report, in 2005 public transportation saved 541 million hours of congestion delay, and over $10 billion in congestion costs. Congestion relief is routinely cited in mass transit proposals as a “positive externality” benefit of transit to justify public subsidies. Less benefit from congestion relief means less public subsidy.

    uhhh… while yeah road congestion is down, other reports show many transit systems bursting at the seems! While you might not be able to prove causation with 100% certainty, it sure seems there is a likely correlation.

    The data shows that only a tiny share of the decline in driving was attributable to people substituting transit for driving. Here is a summary from Robert Dunphy, senior resident fellow in Transportation at the Urban Land Institute:

    The number of transit trips increased 174 million in the quarter, so the total miles traveled by those riders, using a standard 5 miles for the average trip distance, comes to an increase of 876 million – just under a billion passenger miles. The Vehicle Miles of Travel (VMT) for the same period, for all types of vehicles, including trucks, declined by 35.5 billion. That would put transit’s share of the decline in driving at a mere 2.5 percent.

    A July survey by NuStats in found that, indeed, two out of three respondents reported driving less, but largely by combining trips, eliminating trips altogether, and working from home. The use of public transit as a replacement for driving ranked behind combining and eliminating trips, using a more fuel efficient car, working from home, using toll roads to save gas, and car pooling. Even walking instead of driving was more common than public transit.

    http://thegroundfloor.typepad.com/the_ground_floor/2009/01/transits-up-drivings-down-have-we-reached-the-tipping-point-.html

  • And yes all of that may be true but it doesn’t justify un-funding of transit, particularly those systems that are running at max capacity.

    You original statement, “This dramatically lowers the congestion-reducing benefit attributed to transit, and severely undermines the argument that we should spend more on transit to reduce road congestion,” is just one of many reasons to provide transit.

    Your argument does make sense in sprawled, auto-centric cities (i.e. most of America) where it is inherently more difficult to make transit a more viable option. However, if the MTA stopped running in NYC, there would be so much congestion that the city would shut down as happens every time there is a transit strike.

    And when the oil supply slows to a trickle, transit powered by domestically produced electricity, is going to become the only game in town (I’m paraphrasing, I know.)

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