[DGthe3]

The only way it work is if there was a comprehensive approach, involving vehicle design, roadway design, and driver education. Neglect any one element and it falls apart. The first thing needed would be cars that are capable of doing those speeds safely and reliable. This isn't much of an issue for sports cars at the moment, but trucks, SUV's, and economy cars just aren't meant to go that fast. These cars would need to represent the vast majority of the market at least 15 years before the 150 mph roads are opened up, 20 would be better. More stringent licensing laws would be needed, unless the 150 mph cars are self driving while on the super highways ... which may be a necessity. Most highways would need to be rebuilt, or at least the on and off ramps/accel-decel lanes. It takes a pretty long time to go from a city speed of 35 mph up to 150 on a highway, especially if all you've got is a family sedan. Then there is the issue of slowing down. You would need tons of space to slow cars down without requiring each exit to be a panic stop. Firgure if the best sports cars can't go from 100-0 in much less than 100 yards using maximum effort, normal cars cars going 50% faster would need several hundred yards with moderate effort, possibly over a half mile.