from How We Drive, the Blog of Tom Vanderbilt’s Traffic by Tom Vanderbilt
My latest Slate column explores the concept of “rolling speed harmonization” on a Colorado highway.
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.”
The concept plays, in part, on one of traffic engineering’s core truths: Big speed differentials are dangerous. This is laid out in the “Green Book,” the bible of the American Association of Surface Highway Transportation Officials. “Crashes are not related as much to speed as to the range in speeds from the highest to lowest,” the book states. “Studies show that, regardless of the average speed on the highway, the more a vehicle deviates from the average speed, the greater its chances of becoming involved in a crash.”
https://www.howwedrive.com/2011/10/16/go-slow-to-go-fast/oldId.20111016154112266