User:Math Teacher/Average highway speed

Average highway speed, the speed most cars are driven at on a highway, is largely independent of the posted limits. Experiments have shown that changing the limits by as much as 20 MPH lower or 10 MPH higher has little or no effect on resulting speeds. 

is used in calculations to find the fastest route (see Automotive navigation system). Conventional route-finding software depends on estimated speeds.

Bill Howard wrote in PC Magazine:
 * Seybold ... thinks cellular navigation will be more compelling to around-town users who know where they're going, when they can get real-time traffic information as well and see alternate routes around a jam. That could happen in as little as a year, as transportation departments switch away from the few embedded roadway sensors in use ($1 million a mile to build) to reporting services such as IntelliOne of Atlanta that measures how quickly (or slowly) cell phones move from cell tower to cell tower, strips out personal information (phone numbers), and reports it as average highway speed.