1122 Speed limits and traffic cushions

The news today is reporting that law enforcement is allowing a 10+ mph cushion above the 65 mph limit on most major highways, which is dangerous and inconsistent. It's been about 10 years since Congress increased the speed limit from 55 to 65 mph.

It's virtually impossible to find unbiased statistics on what all these limits, no-limits fiddling means (although I only spent 3 minutes looking through Google, it didn't take long to size up the politics of it). It's a real political football.

My recollection is the speed-limits were reduced to 55 mph not for safety, but to conserve gasoline back during the shortage in the later 1970s. As a parent with young children in the back seat I immediately noticed how much smoother and less traumatic driving to Indianapolis became. We had become so accustomed to seeing accidents and emergency vehicles and to long back-ups and traffic snarls that the amazing transformation after the 55 mph limits was very pleasant. Even congested urban areas smoothed out. The reduction in deaths on the highway was sort of by-product, at least that's how I remember it.

Now everyone is using statistics to try to prove a point--cars are safer, fewer deaths; more cell-phones so drivers are distracted at any speed; more miles travelled than 30 years ago, thus more deaths, and so on. You don't need to be a rocket scientist to figure out a drunk driver is more dangerous at 65 + a 10 mph cushion than he would be at 55 or that talking on your cell phone at 65 + a 10 mph cushion makes you even more likely to mess up.

We Americans are still killing more young people on the highways than "insurgents" are in Iraq. It wouldn't hurt, and might actually save some lives to go back to 55. Or at least enforce the 65. If he's your kid, the pain is the same.

Illinois: ". . .300 additional accidents per month in rural Illinois, with associated increases in deaths and injuries. This impact was apparent on both 65 and 55 mph roads. There is some evidence of traffic diversion from 55 to 65 mph highways plus traffic generation and speed spillover." Accid Anal Prev. 1995 Apr;27(2):207-14.

New Mexico: "The rate of fatal crashes in the 1 year after the speed limit was increased was 2.9 per 100 million vehicle-miles traveled, compared with a predicted rate of 1.5 per 100 million vehicle-miles based on the trend of the 5 previous years." JAMA Vol. 262 No. 16, October 27, 1989

Israel: "After the raise, speeds rose by 4.5%–9.1%. Over 5 years, there was a sustained increase in deaths (15%) and case fatality rates (38%) on all interurban roads. Corresponding increases in deaths (13%) and case fatality (24%) on urban roads indicated "speed spillover." " April 2004, Vol 94, No. 4, American Journal of Public Health 568-574

California: Death rates decreased with the change to higher limits, however in the first year the average mph only changed about one mile. In other areas, "In the first two years of higher limits, the number of fatal accidents increased 8.7 percent over the previous two years on the 2,317 miles of highway where limits were raised from 55 mph to 65 mph. Fatal accidents increased 9.7 percent on the 1,297 miles of highway where limits went from 65 mph to 70 mph. Relatively few people, however, are killed on freeways, with most dying on surface roads where hazards such as cross- traffic and the lack of center dividers raise the risk." SFGate