Tom Vanderbilt from Slate.com looks at the counter-intuitive nature of lowering speed limits to decrease travel times.
But one thing that tends to be lost on the individual driver, who through the proscenium of his windshield commands what he believes to be an empirically incontrovertible perspective on the ground truth of traffic, is that sometimes you have to go slower to go faster.
This is the thinking behind some recent trials on Colorado’s vital, increasingly congested I-70 mountain corridor. Once the number of cars on the road reached a certain level (initially, 1,100 vehicles per hour per direction), highway patrol vehicles, riding in tandem with lights ablaze, set an artificially low travel rate of 55 mph—on a highway where cars and trucks might travel 70 and 30 mph, respectively—“pacing” a series of vehicle platoons on a segment of the highway. Gone was the furious weaving, the sudden squalls of brake lights—this was a NASCAR pace lap.
Welcome to “rolling speed harmonization.” As one report describes it, speed harmonization “holds that by encouraging speed compliance and reducing speed differential between vehicles, volume throughput can be maximized without a physical increase in roadway dimensions.”
Illustration by Rob Donnelly
