'Fundamental rule': Widening a freeway does not reduce congestion | Arkansas Blog

'Fundamental rule': Widening a freeway does not reduce congestion

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From Vox this morning
yet another reminder of something that the freeway builders and power structure of Little Rock simply will not accept:

Decades of traffic data across the United States shows that adding new road capacity doesn't actually improve congestion. The latest example of this is the widening of Los Angeles' I-405 freeway, which was completed last May after five years of construction and a cost of over $1 billion. "The data shows that traffic is moving slightly slower now on 405 than before the widening," says Matthew Turner, a Brown University economist.

The main reason, Turner has found, is simple — adding road capacity spurs people to drive more miles, either by taking more trips by car or taking longer trips than they otherwise would have. He and University of Pennsylvania economist Gilles Duranton call this the "fundamental rule" of road congestion: adding road capacity just increases the total number of miles traveled by all vehicles.

This is because, for the most part, drivers aren't charged for using roads. So it's not surprising that a valuable resource, given away for free, leads people to use more of it. Economists see this phenomenon in a lot of places, and call it induced demand.
The article explains in detail the various studies that have reached the same conclusions. (And, no, sorry, public transportation is no panacea.)

I liked this analogy:

So why does traffic increase when new road capacity is added? Turner and Duranton attribute about half of the effect to people's driving decisions. "Think of it as if you made a bunch of hamburgers and then gave them all away," Turner says. "If you make hamburgers free, people will eat more of them."

By way of illustration, consider the following situation: there's a store where you know you can save $10 on something you need to buy, but it's 10 miles away. If you assume there will be terrible traffic and it'll take 30 minutes to get there, you'll just buy the product at a closer store. However, if a new lane gets added to a highway that will speed your journey there, you'll decide it's worth it.
Another analogy: Make it harder to drive to Cabot and Benton and maybe people will live in Little Rock. But don't tell that to Cabot Mayor (Hon.) Lance Hines, who nominally represents Little Rock on the City Board but seems determined to place commuters' needs first.

PS: The Democrat-Gazette wrote this morning on something we've reported before: All the plans to widen Interstate 30 in Little Rock to a 10- to 12-lane concrete canyon will take hundreds of parking places out of downtown. And yet City Director Dean Kumpuris, the father of the River Market, thinks this will be somehow a good thing. There ARE people we've quoted before who talk of the need to retain on-street parking on east-west arteries to offset the loss. But this, of course, will slow traffic moving east-west between I-30 and Cantrell Road (Highway 10). That's OK by me, but I'll bet the commuters to and from Riverdale won't like it much. The morning paper's description of moving traffic that now uses Highway 10 (La Harpe) to reach Interstate 30 with a high-speed ramp will now, when eastbound, have to turn south on Chester and then make a left turn at Fourth, where no protected turn lane currently exists. A series of traffic experts have warned repeatedly that a 12-lane Interstate 30 will provide a few minutes of rush hour speed in the early years, before induced demand catches up, but it is going to create huge problems and need for still more expensive work elsewhere, including hundreds of millions worth of widening of freeways that feed I-30 downtown

There is a better way (think boulevard and another bridge crossing), but don't tell it to the Arkansas Freeway Department, the Little Rock Chamber of Commerce or city directors like Lance Hines, Joan Adcock and Dean Kumpuris. The Arkansas way — grandpa's way — is the better way. How do you think we got to be a national leader in so many categories?

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