Sunday, November 9, 2008

Physicists: "It is Better to Close" West Houston Street

Some physicists in Korea and New Mexico have been making computer models of road use. They say that, counterintuitively, we've got a bunch of streets that actually cause congestion, and removing them (e.g. turning them into greenways) would reduce congestion on surrounding streets.

From this map (helpfully extracted in this post by The New Republic's Bradford Plummer) it looks like the dotted black lines are on West Houston Street, West Broadway, Kenmare Street, Grand Street west of Lafayette, and Canal Street west of Sixth Avenue. These lines show that if you made the streets unavailable to cars, congestion would improve on the rest of the grid.

This is due to something called Braess's Paradox, based on models worked out by John Nash. The paper (PDF) by Youn, Jeong and Gastner was discussed in a Christian Science Monitor article and WorldChanging; I found it by a brief link from The Overhead Wire.

Their model seems to be based only on trips from Washington Market Park in Tribeca to the Queensboro Bridge. It's not clear to me whether it would hold if you take into account all the other origin/destination pairs.


NYC taxi photo said...

ugh, I'm getting a stomach ache just thinking about this scenario. I believe light patterns, and the measure of all destinations need to be accounted for. kenmare and Delancey run really well in both directions despite their congestion, because the traffic lights have a good timing. Houston street runs well in the west directions. I think research should show that congestion exists where ever motorists believe their shortest distances combined with fastest travel times exist. sometimes despite extensive congestion, traffic actually flows efficiently.

But I do agree that something needs to be done to minimize traffic density and encourage a better space to live in.

Cap'n Transit said...

Taxi Photo, the point of the article is that if you closed those streets traffic would improve on other streets. That suggests that Kenmare, West Houston and the others are redundant and generate more traffic than they reduce.

The main thing I take away from this is that the DOT's opposition to a bike lane on Houston was wrong, and they should install a two-way cycle track there to improve traffic on other streets.