Raising speed limits doesn’t lead to faster driving

I’ve seen several articles about this lately as several states consider raising highway speed limits: raising the speed limits does not lead more people to drive faster.

Traffic experts say that motorists tend to drive at a speed they feel comfortable, regardless of the posted speed limit. And according to Michigan Department of Transportation spokesman Rob Morosi, comfortable drivers generally make for safe roads.

“There’s a misconception that the faster the speed limit, the more dangerous the road,” said Morosi, “and that’s not necessarily true. Speed limits are most effective when the majority of people driving are comfortable at that speed.”…

Common sense, then, would suggest that increasing a speed limit would lead those motorists to increase their speed at a similar rate. But Megge, pointing to I-96 in Flint as a striking example, says that belief is not supported by the research.

Before 2005, traffic studies indicated that most motorists were traveling the Interstate at roughly 73 mph, he said. After the speed limit was increased, most motorists still traveled the Interstate at roughly 73 mph.

“When we raise a speed limit, traffic speed does not automatically increase. That’s a myth,” Megge said. “I’ve been doing this 15 years and raised 300 speed limits, and never have we seen or observed a wholesale increase in traffic speeds. It’s a very counter-intuitive idea. But the science and engineering works. We want to ensure it’s safe and fair to the public.”

Common sense approaches often don’t apply to traffic. This finding about speed limits fits with another finding about traffic signs: drivers don’t necessarily pay attention. Read about several places in Europe that have no traffic signs and few traffic markers and safety improves. In the case of driving speed, drivers seem to pay more attention to nearby drivers rather than the official speed limit. So even as people often drive solo and might argue their actions on the road are the result of their own individual choices, driving is indeed a social activity.

Here is a second good example regarding traffic that counters “common sense” or common behavior: using all possible lane space to merge is more efficient for everyone rather than having drivers block off lanes that will soon close.


0 thoughts on “Raising speed limits doesn’t lead to faster driving

  1. Pingback: Chicago area highway drivers going faster: 85th percentile between 71 and 75 mph | Legally Sociable

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