November 27, 2015
“It’s a theory called “induced travel,” basically the transportation version of the law of supply and demand. Adding capacity cuts travel time, thus lowering the “price” of driving and leading to an increase in driving. In the paper, UC Davis professor Susan Handy writes that increasing a road’s capacity by 10 percent is likely to increase vehicle miles traveled by 3 percent to 6 percent in the short run and 6 percent to 10 percent in the long term, basically offsetting any gains.”
Read more here.