Who Sets The Speed Limit?

ST. PAUL, Minn. (WCCO) -- Good news if you've got a lead foot. Two major Twin Cities highways will get a bump in their speed limit.

Parts of Highway 62 and Interstate 394 will go from 55 to 60 miles per hour this summer, according to a Minnesota Department of Transportation spokesman.

The change had us wondering: Who sets the speed limit? Good Question. Jeff Wagner learned no matter if it goes higher or lower, safety is at the core.

When asked how speed limit is determined, Diane from Minneapolis said, "I would assume the city."

As of a few years ago, she's correct. State law sets the baseline for speed limits.

It's 70 miles per hour on rural interstates, 65 mph on expressways and urban interstates, 55 mph on rural roads and 30 mph on urban streets.

"I prefer the higher speeds on the highway," added Nancy from St. Paul.

If a city or county wanted to change the speed on a road, it needed to request MnDOT do a speed study. That means taking into account the surrounding environment, pedestrian activity, crash records and average speed of drivers.

"A big change that happened in 2019 was the cities were allowed to set speed limits on their own roadways," said Randy Newton, city traffic engineer for the City of St. Paul. "The guidance that's in the state statute basically indicated that we needed to do a study."

Which the city did in conjunction with Minneapolis.

"We're obviously two major cities adjacent to each other and doing something different I think would have been hurt both of us and hurt the general public, so think from the beginning we thought it was imperative to work together," he said.

The study led to a speed limit drop in both cities last year, most notably taking residential streets down to 20 miles per hour unless otherwise posted.

Do slower speeds mean safer streets? Many neighbors living in St. Paul believe that to be the case.

"When cars are traveling slower, if a pedestrian or bicyclist was hit, that crash is less likely to be severe," said Newton.

According to AAA, 13% of pedestrians will die or suffer severe injury if a vehicle hits them at 20 miles per hour. It jumps to 40% at 30 miles per hour.

Slower speeds also help drivers better prevent accidents. Their reaction time is quicker and coming to a complete stop requires a shorter distance. Putting up a slower speed limit sign doesn't always change a driver's behavior, added Newton. Cities, counties and the state will change the roadway itself or surrounding area to make a driver travel slower.

"One of the things we're doing on different roads is adding bump outs or other things at intersections to make pedestrians more visible and visibly narrow the road," he said.

Adding light poles, foliage, sidewalks and trails next to a road can also cause a driver to slow down.

"We're hoping to change the culture a little bit about what people think are acceptable speeds," he said.

Why does the speed limit sometimes increase?

"The safest speed isn't necessarily the slowest speed," said Derek Leuer, traffic safety engineer with MnDOT, adding that the safest speed can sometimes be the one that most drivers feel comfortable going.

"It's a metric that's called the '85th Percentile.' We try to figure out what speed about 85% of drivers are naturally driving at, and then we set the speed limit based on that," he said.

A change in speed limit, such as the one coming to I-394 this summer, can happen when there's too much variation between the fast and slow drivers using the roadway.

"The whole goal is really to get everybody to be going at about the same speed together so that those who are both operating on the roadway and trying to cross that roadway can accurately gauge what other drivers are going to be doing," said Leuer.

Does a 5 miles per hour change really make a difference? Newton believes it's true.

"Right now I don't know if we necessarily expect to see major difference in our average speed people are traveling but I think we're hopeful that high end speeds will definitely come down with what we've done," he said.

Leuer said if a 5 mph change helps more drivers fit a pace, or the 85th Percentile, it will ultimately make a difference. He added that enforcement of the speed limit change by police can also have an impact.

MnDOT conducts more than 100 speed studies per year. As for Minneapolis and St. Paul, both cities are planning awareness campaigns this spring to remind drivers of the speed limit change.