ADDING NEW ROAD CAPACITY DOESNT IMPROVE CONGESTION

-> 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 (405 Commutes Now a Minute Worse Than Before Carpool Lane: http://bit.ly/1AcBVLL), 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 (The Fundamental Law of Road Congestion: Evidence from US cities: http://bit.ly/1Hevghc): adding road capacity just increases the total number of miles traveled by all vehicles.
In an influential 2011 paper, they looked at the total capacity of highways in each metropolitan area in the US and compared it with the total number of vehicle miles traveled. They found a one-to-one correlation: the more highway capacity a metro area had, the more miles its vehicles traveled on them. A 10 percent increase in capacity, for instance, meant a 10 percent increase in vehicle miles, on average. [http://bit.ly/1S6NEBa]

from CenterLines, the e-newsletter of the National Center for Bicycling & Walking.



[B' Spokes: What ever mode of transportation gets the most support gets used the most. That should be fairly obvious by now.]