Those speed humps can be annoying, but do they make streets safer?

Chicago has relied on speed humps — yes, humps — for decades. While they’ve proven effective they’re not the only way to slow speeding drivers.

speed hump
Maggie Sivit / WBEZ
speed hump
Maggie Sivit / WBEZ

Those speed humps can be annoying, but do they make streets safer?

Chicago has relied on speed humps — yes, humps — for decades. While they’ve proven effective they’re not the only way to slow speeding drivers.

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Every driver in Chicago has probably encountered a speed hump (yep, they are officially known as humps, not bumps) at some point while traversing the city. It’s safe to say that no one particularly enjoys going over one, but these barriers meant to slow drivers certainly annoy some more than others. Recently, one Chicago resident destroyed a speed hump, resulting in a $500 fine.

And while Rob Cassidy, who wrote into Curious City with a series of questions about speed humps, hasn’t taken a pickaxe to one, he certainly finds them irritating and more importantly isn’t sure they’re effective.

“I think there’s really some question as to whether they do anything, “ Rob said.

So Rob wanted Curious City to find out more about why speed humps became a tool used for traffic safety, how and why they end up on certain streets in Chicago, and whether they make a difference when it comes to making our streets safer.

While speed humps aren’t unique to Chicago, the city has relied on them to slow down drivers for several decades. And while there’s evidence they are effective at reducing fatalities, many experts say they’re not necessarily a long-term solution, or at least not the only method that should be used to make city streets safer.

A brief history of speed humps

While it’s complicated to pin down exactly when the first speed hump appeared on American streets, the concept is well over a century old. There are references to something called “automobile teasers” appearing on the streets of New Jersey in the early 1900s.

And in the 1950s, Arthur Holly Compton, a Nobel Prize-winning physicist and professor at Washington University in St. Louis, was concerned about speeding around campus. So he designed some humps, referred to as “Holly Humps,” which were installed around campus (although they have since been removed).

Holly Humps Drawing
Compton produced two different variations on the same design: one with a single hump; one with a double hump. Both can be seen in the above drawing, which comes from Compton’s personal papers. (Compton’s Personal Papers, Series 04, Box 01, Notebook June - July, 1953). Julian Edison Department of Special Collections, Washington University in St. Louis Libraries

Holly had good reason to be concerned about speeding. Cars had become the dominant mode of transportation in the United States and streets transformed to suit motorists over pedestrians.

“By the 1950s, more cities had been converted to places where you didn’t see people using the street in a very free way. People were pushed to the side. And cars controlled most of the real estate,” says Dr. Norman Garrick, professor of transportation emeritus at the University of Connecticut.

During the 1950s, there was an average traffic-related fatality rate of 24.6 per 100,000 people in the United States. To put that in perspective, that rate in 2018 was 11.7, more than a 50% decrease.

This wasn’t just a problem in the U.S either. In the 1970s, many European countries saw similar fatality rates. However, beginning in the 1970s, activist groups in the Netherlands and elsewhere in Europe began to push for change.

“So part of what was going on then is this pushback that started governmental action. But you also saw activists developing ideas like what in English we call ‘home zones’, where they turn residential streets from mostly car use into places for kids to play and change the design,” says Dr. Garrick.

These new approaches to street design included things like bike lanes, narrowed streets, roundabouts, and of course, speed humps. With these new design methods, places like the Netherlands and other European countries saw a dramatic decrease in traffic fatality rates.

Car speed hump 1990s
A car passes over a speed hump in California in the late 1990s. Kevork Djansezian / Associated Press

Here in the United States, beginning in the mid-80s and ’90s, concern over traffic-related fatalities began to increase and we began to look at ways to address them. These measures would come to be known as “traffic calming.” But unlike the multi-faceted European approach, the solution in cities like Chicago, at least early on, tended to be speed humps, “because it’s the easiest thing to do. And it’s a fairly cheap way,” says Dr. Garrick.

According to Vig Krishnamurthy at the Chicago Department of Transportation (CDOT), the city installed speed humps in alleys in 1997 and began another pilot program to install them on side streets in 1998. Decades later they are all over Chicago, although CDOT does not have a map of where each of these speed humps is located.

How does a speed hump end up on a Chicago street?

For the most part, speed humps are installed at the behest of Chicago residents, according to CDOT’s Krishnamurthy.

If a Chicagoan feels there is excessive speeding on their block, they can petition their alderman to have a speed hump installed. Residents must get signatures from 70% of the units on their block, who agree a speed hump is needed. The alderman then submits the petition to CDOT for review. CDOT studies whether traffic calming would be effective in the area and if it’s approved, sends a work crew to install the speed hump.

On the one hand, this method “provides an element of buy-in for the neighborhood. So they feel that they have some control over how things are happening on their block,” says Dr. Joseph Schwieterman, transportation professor at DePaul University.

However, this is a very lengthy process that requires time and energy from residents, thus privileging those who have the resources to organize a petition. “We all know it can all devolve into the noisiest resident gets the speed bump [hump] where it’s perhaps not needed the most. And there are limits to that approach,” says Dr. Schwieterman.

So why not take a comprehensive study of the entire city and install speed humps everywhere it makes sense? Well, in recent years, the city has become more proactive in installing traffic calming measures across the city based on studies, in part because of the Vision Zero Chicago initiative that seeks to eliminate traffic-related fatalities. But there are budget and resource limitations. “With the vastness of our city, it’s really tough to figure out, given we have X dollars, where’s our investments best placed?” says Dr. Schwieterman.

Are there design standards for the speed humps around Chicago?

The Federal Highway Administration and the National Association of City Transportation Officials do outline specifications for the height and width of speed humps: generally speed humps should be 3-4 inches in height, 12 feet wide, and have a ramp length of 3-6 feet.

But speed hump design has changed over the years, so not all speed humps around Chicago have been installed to current modern standards.

There are also no regular audits of these traffic calming measures and it would cost the city somewhere between $2,000 and $8,000 dollars to remove speed humps that do not meet current design standards.

Do speed humps work?

The short answer is yes. Urban planners and civil engineers generally agree that speed humps slow down drivers and reduce traffic fatalities.

“They are very effective,” says Dr. P.S Sriraj, director of the Urban Transportation Center at University of Illinois at Chicago.

There have been hundreds of efficacy studies in a variety of cities and towns that have demonstrated that speed humps work. One recent study conducted by National Association of Transportation Officials found speed humps reduced speeds by an average of more than 7 mph.

And when it comes to reducing traffic fatalities, speed is one of the most important factors.

speed hump ahead sign
Maggie Sivit / WBEZ

“When you compare speed that is at 40 miles per hour with 20 miles an hour, at 40 miles an hour you have almost an 80% chance of a fatality versus 20 miles when the probability of a fatality just drastically reduces down to maybe 10% or 20%,” explains Dr. Sriraj.

And speed humps are effective when they are installed properly. The Federal Highway Authority says they should be used on roads with a speed limit of 30 mph or less which are not main arteries for general traffic and emergency vehicles. For example, a speed hump on Ashland would not be a useful application, but a residential street or alley that connects to it would be.

While they work, they are not without drawbacks. Speed humps have been criticized for their aesthetics and for causing trucks and larger vehicles to make more noise when traversing them. Some have also argued they slow the response of emergency vehicles, such as ambulances. But Dr. Sriraj says their benefits outweigh these issues.

Even if they work, are they the future?

While speed humps work, are they the most effective way to reduce fatalities? Maybe not.

“It’s a crude approach, because it’s really trying to retrofit in a very quick and easy and cheap way, a bad design… And the easiest solution is just to put in a speed hump, ” says transportation expert Dr. Garrick.

There are numerous alternatives, including things like residential roundabouts, curb extensions — called chicanes — that create curves in the street, dedicated bus lanes and protected bike lanes, among others. And in places like the Netherlands, which has a lower traffic fatality rate, speed humps are not nearly as common as in the U.S.

Bike lane and traffic circle
Left: A protected bike lane in Hyde Park. Right: A residential roundabout, or traffic circle. Active Transportation Alliance

But the reason that many European countries like the Netherlands have fewer speed humps is the result of decades of urban planning and design. They have created their streets to utilize a plethora of traffic calming solutions that inherently slow motorists and incentivize alternative forms of travel such as biking. These sorts of solutions are costly and require years to institute.

Sadly, traffic fatalities in Chicago have gone up dramatically over the last year, which many transportation officials think is a result of increased traffic and speeding in residential areas. And the city has announced new initiatives and allocated funds to try to address the problem.

As Dr. Garrick points out, speed humps raise larger questions about priorities in our city and what investments we’re willing to make.

“You say speed humps and sounds like a throwaway topic, but it really relates to what kind of place we want to live, what kind of place we want to build.”

Andrew Meriwether is a journalist living in Chicago. Follow him @ohsomeriwether