Today’s speed limits were born from studying rural roads in the 1930s and 1940s. Now states seek to change the directives

“What are you waiting for, someone is killed?” The 85-year-old reprimand officials in the northwest of Ohio, complaining that nothing was done on the motorcycles that run almost daily.

In the midst of increasing public pressure, the canton of Sylvania asked the county engineers in March to analyze if the displayed speed of Mitchaw Road was too high. The surprising answer: technically, it’s 5 mph too low.

The reason goes back to studies on rural roads in the 1930s and 1940s which still play a disproportionate role in the way speed limits are set in the United States – even in urban areas.

Born of this research was a widely accepted concept known as the rule of 85%, which suggests that a displayed speed of the road should be linked to the 15th fastest vehicle out of 100 which traversed it in free flow traffic, rounded up to 5 MPH closest.

But after decades of closely monitoring of the rule, certain states – with a boost from the federal government – seek to modify if not replace it when defining guidelines on how local engineers should decide on the speed limit to be published.

The drivers define the speed

The concept assumes that the surest speed of a road is the one that most vehicles travel – neither too high nor too low. If drivers think that the speed limit must be increased, they can simply walk on gas and “vote with their feet” because an old brochure from the Institute of Transport Engineers said it once.

“The problem with this approach is that he creates this feedback loop,” said Jenny O’Connell, director of members of the National Association of City Transportation Officers. “People accelerate, then the speed limits will be creeping to match this speed.”

The association has developed an alternative to the 85% rule known as “city limits”, which aims to minimize the risk of injury for all road users by fixing the speed limit according to a formula which facilitates the level of activity of a street and the probability of conflicts, such as collisions.

The report stresses that the 85% rule is based on dated research and that “these historical roads are far from the dynamic streets and arterial that characterize the streets of the city today.”

In the midst of a recent peak of death on the road across the country, the Federal Highway Administration sent a subtle but important message to the States that the 85% rule is not at all a rule and took too much weight to determine the local speed limits. In its first update since 2009 to a manual that establishes national directives for traffic signs, the agency said that communities should also consider things such as the way the road is used, the risk for pedestrians and the frequency of accidents.

Leah Shahum, who directs the Zero Network vision, a non -profit organization pleading for street safety, said that it wanted the manual to have gone further by minimizing the 85%rule, but recognizes that the change had already had an impact on the way some states have set speed limits. Others, however, always hang on to the simplicity and familiarity of the long-standing approach, she said.

“The 85th centile should not be the Holy Grail or the Bible, and yet again and again, it is accepted like that,” said Shahum.

Rethink the need for speed

As part of its “20 is Planty” campaign, the capital of the Madison Wisconsin has changed panels across the city this summer, reducing the speed limit of 25 mm to 20 mph in the local residential streets.

When Seattle took a similar step in a pilot program seven years ago, not only saw a significant drop in accidents of serious injuries, but also a 7% drop in the speed of the 85th centile, according to the Vision Zero network.

California kisses the 85% rule even more than most states as a basis for setting speed limits. But the legislators have slightly diverted the restrictions of local governments in recent years, allowing them to deviate from directives if they can cite a proven need for security. Defenders of pedestrians and cyclists say that change helps, but is not enough.

“We still have a long way to go in California in terms of value on all road users,” said Kendra Ramsey, executive director of California Bicycle Coalition. “There is still a very heavy state of mind that cars are the main travel method and they should have priority and bow.”

But Jay Beeber, Executive Director of Policy at the National Motorist Association, a plea organization for drivers, said that the rest of the 85% rule is generally the safest way to minimize the variation in speed between drivers who respect the displayed limit and those who have exceeded it.

“Regardless of the number you put on a panel,” said Beeber. “The average driver leads to the nature of the road. It would be clearly unfair for a government to build a road to encourage people to drive 45 MPH, to put a speed limit of 30 MPH, then to everyone to have done what they built the road to do. ”

80 is the new 55

The fears concerning oil prices prompted Congress in the 1970s to set a national speed limit of 55 MPH, which then relaxed at 65 MPH before repealing the law in 1995 and relying authority to the States. Since then, the speed limits have continued to climb, the Dakota of the North this summer becoming the ninth state to allow drivers to go to 80 mph on certain sections of the highway. There is even a 40 miles segment in Texas between Austin and San Antonio where 85 MPH is authorized.

Although high -speed highways outside the main population centers are not at the center of most efforts to facilitate the 85%rule, a 2019 study of the Road Safety Institute – A research arm funded by car insurers – illustrates the risks. Every 5 MPH increases at the maximum speed limit of a state increases the chances of death by 8.5% on interstate highways and 2.8% on other roads, the study revealed.

“Maybe when you drive a T model, you had a real idea of the speed at which you were going, but in modern vehicles, you don’t have an idea of what 80 mph. You are in a cocoon,” said Chuck Farmer, vice-president of the Institute’s research, which conducted the study.

The attempt to change a city

If elected officials in the canton of Sylvania, Ohio, had their way, the displayed speed limit of Mitchaw Road would be considerably reduced – from 55 MPH to 40 MPH or less. The county’s conclusion that the 85% rule in fact calls for the 60 MPH increase surprised the city leaders, but not the engineers who led the study.

“If we do not make decisions according to the data, it is very difficult to make good decisions,” said Lucas County engineer Mike PNIWSKI.

For the moment, the speed limit will remain as it is. Indeed, the Ohio law establishes maximum speeds for 15 different types of roads, regardless of the 85%rule.

And the directives of Ohio evolve. The State now gives more consideration to the context of roads and allows cities to reduce speed limits as a function of the lower standard of the 50th centile speed in the event of the significant presence of pedestrians and cyclists. The authorities recently hired a consultant to consider additional changes according to what other states do.

“The States have very slowly started to move away from the 85th centile as being in a way the gold stallion for decision-making,” said Michelle May, who manages the Ohio road safety program. “People travel and live differently that they did 40 years ago, and we want to put more security for attention.”

We do not know if one of these changes will ultimately have an impact on the speed displayed on Mitchaw Road. After years of futile calls and emails to state, county and canton officials, Hammond said that she did not hold her breath.

“I’m so discouraged,” she said.