What would happen if . . . we raised highway speed limits?

Frank Navin and Michael Cain
The Next City
March 21, 1998


We asked Frank Navin, professor of civil engineering, and Michael Cain, director of research at Saftey by Education (Not Speed Enforcement),to comment

We would be flouting science. It doesn’t take a rocket scientist to realize the faster you hit a solid object the more severe your injuries. It does, however, take a high level of science to measure the effects of increased highway speeds on our safety. Most modern vehicles are built to allow a belted occupant to survive, with little injury, a 50 km/h head-on impact into a solid object. Although expressways are usually driven at 100 km/h or more, depending on the posted speed limit and the level of police enforcement, engineered roadside objects have protective outer barriers that can be hit at the highway’s designed speed — usually within 10 km/h of the posted speed. But the faster a driver is travelling before crashing, the worse the impact. While a 50 km/h impact is equivalent to dropping a car from the top of a two-storey building, a 100 km/h impact is equivalent to dropping 11 storeys, and a 150 km/h crash to almost 30 storeys.

The number and severity of crashes would increase. Canadian studies show that increased speed increases the chance of crashing, and a Finnish study observed that for every one km/h speed increase, the number of injuries increased by three per cent and the injury costs doubled. These negative effects come about because of the shorter time for the driver’s observation, decision making, and action, made worse by the shortened distance available for braking and steering.

Actually, we need increased enforcement and reduced speeds. The combination of reasonable speed limits and vigorous police enforcement effectively reduces the number and severity of injuries and fatalities on our highways. Electronic police enforcement by photo radar cameras can be one useful tool. For example, Victoria, Australia, claims that photo radar has reduced its road fatalities by about 11 per cent.

We’d be recognizing the speed at which most motorists already drive. Decades of research around the world proves that the upper end of average traffic speeds are safest for our highways and major roads. This reduces variations in speed among vehicles, which has long been identified as a far greater cause of accidents than absolute speed.

There wouldn’t be more accidents. Contrary to aggregated statistics produced by governments, mere speed is rarely the sole contributing factor in a crash; in fact, research shows that two-thirds of speed-related fatalities involve either drugs, alcohol, or both. Of the remainder, about two-thirds occur below the speed limit and are related to road conditions. In late 1995, the U.S. Congress allowed states to set their own maximum speed limits. The safety lobby predicted that fatalities would increase by 6,400 or about 15 per cent. Results now confirm that fatalities were within a statistically insignificant 0.2 per cent.

Government and insurance companies would stop gouging us. These bodies may appear safety conscious when they push for lower speed limits, but the desire for revenue underlies their motives. Since motorists frequently face 50 per cent increases in basic insurance for just two speeding tickets, it’s not surprising that the Insurance Institute for Highway Safety is the largest group lobbying against raising American speed limits. In fact, insurance companies frequently supply speed enforcement equipment for police departments.

Police could concentrate on important issues rather than on revenue and photo radar. Citizens suffer as police focus more on activities that return revenue (speed enforcement) and less on traffic activities that, while time intensive to enforce, reduce both accidents and driver frustration (red light running, failing to yield, and impaired driving).

Michael Cain

Frank Navin

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