Thursday, January 25, 2007

Ignorant lights create up to 10% of all traffic congestion

Getting stuck in bumper-to-bumper traffic isn't inevitable, at least not to the degree that it currently occurs. Fat Knowledge reports that the Federal Highway Administration has found that 5%-10% of delays on the nation's highways are a direct result of poorly-timed traffic signals, translating into an extra 295.8 million traffic hours (per year, presumably).

That's a substantial deadweight loss--if those stuck in traffic suffered only a minimum wage opportunity, that comes to an accounting cost of over $1.5 billion. Of course, many of those facing vehicular stagnation during normal business hours, when traffic congestion is the worst, are white collar professionals whose work is worth significantly more than five bucks an hour.

The congestion also surely accentuates the problem of drivers with 'intermittent explosive disorder', the subset of the population most likely to engage in road rage (up to 16 million Americans depending on how it's defined).

Then there is the squandered gasoline. While idling, your engine is consuming about as much gas as it would be if you were driving 25 mph. So if 7.5% (using the middle of the estimated range) of the slowdown is due to unnecessary congestion, and being stuck costs about half as much in gas per minute as cruising down the highway does, about 5.25 billion gallons of gas are wasted in the US due to sub-optimal traffic signals. At 19.5 gallons of gas per barrel of oil, that's 270 million barrels of squandered oil, or about 750,000 barrels per day (very roughly), saving over half as much oil as opening up drilling in ANWR would add.

Without being a city planner, a few common sense improvements, in addition to simply re-timing older intersections and installing traffic control automation in antiquated intersections that are not equipped with it, are not difficult to come up with:

- Minimize the number of signal changes. Each time one occurs, there is an interregnum in which the signals for all directions must be red.

- Building on this, give increased priority to main thoroughfares. It is senseless to stop twenty cars to let a single one pull out of a neighborhood rivulet onto a main drag. Doing thus forces forty tons to be brought from cruising speed to a complete stop over a few hundred feet. If there were quasi-highways every few miles going east-west or north-south (concentrated in juxtaposition to the area's major freeways), in which drivers entering them from side streets would be required to wait a couple of minutes to get on them, massive deadweight loss would be reduced. Yes, drivers would be required to wait a couple of minutes early in their commutes, but after that they'd be able to cruise without stop for most of the remaining drive.

- Install countdown systems in all electronic crosswalk signal devices. These serve as enduring yellow lights that will increase traffic flow and save fuel.

As an aside, required drive around the metro area for work purposes, but living on its outskirts, I've become a bit obsessed with trying to optimize the fuel economy of my vehicle. The EPA lists my vehicle (a Taurus) as getting an average of about 23 mpg, but I get just under 32 thanks to a combination of efficient driving tactics.

1 comment:

Anonymous said...

Good points. People who set the programs for the lights are being hired for their gender and ethnicity, so don't expect much improvement. Traffic flow logic and traffic light logic changes with time of day, days of the week, holidays ...........
Not for your typical affirmative action hire.