Roads
The whirlpool of induced demand
Each of our transportation choices, no matter how small, have far-reaching effects. Every day, people make the decision to drive, take transit, bike or walk. And every day, some people move to a new home, and choose the location of that home based on the transportation choices available to them.
When we reconfigure an intersection to become more walkable, we push the balance toward walkability. When we add freeway ramps or parking lots, we push the balance toward driving. And these decisions feed upon themselves in a cycle.
The more appealing walking is, the more likely people will choose places to live based on walking, which creates political pressure to make streets safer and more appealing to walk. The easier driving is, the more people will live great distances from work, creating more traffic and pressure for more roads which make walking impossible.
This cycle has its own inertia, like water moving in a whirlpool. The faster we move in one direction, the harder it is to move the other way. Some cities, like San Francisco, are circling in a more transit-friendly direction. Others, like Atlanta, are still circling the other way, though slower. DC is like turbulent water, not moving one way or the other. Some days, we push a little bit one way, by traffic calming an intersection or turning a superblock into a regular street grid. Other days, we push the other way, widening a freeway bridge or turning a bit more park into parking.
I care about, and harp on, the little things because each small push in the car-centric direction speeds up the whirlpool that way, and the decisions we make will last for decades. DC was moving rapidly in the direction of more freeways and more traffic until activists blocked many of the freeways and Presidents Kennedy and Johnson make Metro possible and saved DC as a walkable city. Without vigilance, we may gradually start circling the drain once again.
 | David Alpert is the Founder and Editor-in-Chief of Greater Greater Washington and Greater Greater Education. He worked as a Product Manager for Google for six years and has lived in the Boston, San Francisco, and New York metro areas in addition to Washington, DC. He loves the area which is, in many ways, greater than those others, and wants to see it become even greater.   |
Comments
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One aspect of transit that I'd like to see addressed more is frequency of service. Building new Metro lines all over the place is all well and good, but if you have to make a journey at an off-peak time that involves changing lines, you could be stuck spending 30 minutes or more just waiting for the trains. And I could live quite happily without the Metrorail extension to Dulles, if only the 5A bus ran more frequently. (On Memorial Day - a peak time for travel to and from the airport if there ever was one - the bus ran on a regular Sunday schedule, with service only once an hour.) Is anyone pushing in that direction?
by Johanna on Jun 2, 2008 11:07 am • link • report
As Fred Kent, head of Project for Public Spaces has said, when you design for people and places you get people and places but when you design for cars and parking you just get more cars and parking.
by Steve P on Jun 2, 2008 12:45 pm • link • report
by Bianchi on Jun 2, 2008 1:28 pm • link • report
by David Alpert on Jun 2, 2008 1:37 pm • link • report
I agree that a train every 14-15 minutes on Sunday afternoon makes it more likely that I'll drive than take the train. Should be closer to 10 minutes. Our car had ~85 people in it at Ballston going in, and the WMATA standard (I believe) is 120. I think it would be unreasonable to expect a train car on a Sunday to get to 120 people before they add service. Because they're competing with less clogged roads and cheaper parking, the standard on the weekend should be lower, somewhere around 80-90.
Up to this point, the only response I've gotten from WMATA is that they periodically take surveys to see how crowded the cars are and add service (by lengthening trains) accordingly. I've mentioned to them that lengthening trains doesn't actually improve service as far as the rider is concerned (you only get a less crowded train, not a more frequent train), but the fact is that it's more expensive to pay more operators to run trains more frequently than just lengthening the trains.
When I filed a PARP (like FOIA) request for the train crowding data collected, I received only aggregated faregate data (entry/exit for the whole month) because releasing more detailed data would be a threat to security. It took three months for WMATA to discuss whether to release the data.
by Michael Perkins on Jun 2, 2008 1:43 pm • link • report
by Bianchi on Jun 2, 2008 1:49 pm • link • report
Great site--please keep up the hard work.
I wondered if you've seen this video on cycling given by a Rutgers professor of public policy on "lessons learned" from Denmark, Germany and the Netherlands and their promotion of cycling as a viable transportation mode. It is a bit long but I thought you might find it interesting: http://www.sfu.ca/city/city_pgm_video020.htm
by MWDC on Jun 2, 2008 5:04 pm • link • report
by Richard Layman on Jun 2, 2008 10:34 pm • link • report
Keep up the good work!
by PJ on Jun 2, 2008 11:20 pm • link • report
by NikolasM on Jun 3, 2008 10:57 am • link • report
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