How Traffic Calming Works

HOW TRAFFIC CALMING WORKS

What is Traffic Calming?

Traffic calming is the use of physical solutions to reduce traffic speeds and/or cut-through traffic with the goal of making streets safer and more accessible for motorists, bicyclists, and pedestrians. It has been proven as an effective way to reduce speeding on residential streets, avoid traffic crashes, and prevent needless fatalities. By implementing proper traffic management devices, we can increase the safety of pedestrians and cyclists as well as decrease vehicular collisions in those areas.

One of the historically reliable methods for traffic calming is vertical deflection, which adds a height variation to the road, causing motor vehicles to slow when approaching. Horizontal shifts and roadway narrowing are another way to implement calming measures. As with vertical deflection, traffic volume itself is relatively unaffected. These techniques will reduce vehicle speed and enhance streetscapes with minimal impact on traffic volume.

Traffic engineers, public works officials, and urban planners have many strategies for traffic calming including speed humps or tables, emergency-friendly speed cushions, lane narrowing, traffic circles, and improved bicycle access with designated bike lanes. These solutions are used to create more complete streets that offer safe access to all users.

Improving the streetscape will lead to a more walkable and bikeable area and allow for healthier lifestyles in the surrounding community.

Traffic calming has been shown to:

Reduce speeding
Improve speed limit compliance
Decrease injury severity when crashes occur
Lower fatality rates
Encourage varied transportation modes
Improve street aesthetics
Increase property value
Reduce crime

While solutions can be instituted at the street, neighborhood, or city-wide level, traffic calming is most effective when it is part of a proactive program to improve street safety based on highest need. This is often ascertained with a points program to determine where risk is highest.

Does it work?

Does traffic calming really slow cars down? Study after study has reached the same conclusion. Traffic calming solutions improve safety, reduce speeds, and prevent crashes every day.

An FHWA study on speed reduction found that the 85^th percentile speed was reduced by an average of 18% with speed humps, 19% with speed cushions, and 18% with speed tables.

Research abounds on the effectiveness of speed humps and other traffic calming methods in reducing speed and improving safety. The American Journal of Public Health found that children who live within a block of a speed hump have significantly lower odds of being struck by a vehicle. The Journal also found a 53-60% reduction in the odds of injury or death for children with traffic calming in their neighborhoods.

Slower cars save lives

Does slowing cars just a few miles an hour really make a difference? View the survival chance (%) of pedestrians when a vehicle is travelling at the following speeds:

Vehicle Travelling at 20 mph 90%

Vehicle Travelling at 30 mph 50%

Vehicle Travelling at 40 mph 10%

Speed Humps
Speed Cushions
Speed Tables

Radar Sign Effectiveness

They’re easy to install, brightly lit, and can flash at drivers who speed. But do they work? In short, yes. Radar speed signs really do slow cars down. And slower cars have been proven to reduce accidents and decrease impact when accidents happen.

When cities use speed display signs they can expect to see reduction in average speeds, better speed limit compliance, and even long term reduction in speeding drivers and average speeds.

Here’s some sample data of the way speeds were affected after SafePace signs were installed on a local roadways.

Some studies that prove just how effective driver feedback signs are include:

A landmark study from Bellevue, WA which concluded that “At the majority of radar sign locations, results show an overall reduction of vehicle speeds between 1 and 6 mph, even up to 8 years after the signs were installed. Due to this level of effectiveness, the City will continue to use stationary radar signs….. to address vehicles speeds and/or….. motorist’s attention…..”

A report on speed sign effectiveness compiled by the Western Transportation Institute on behalf of the US DOT and the State of California found that:

•In South Dakota the percentage of speeding vehicles was reduced by 20-25%
•In Riverside, CA, drivers slowed by approximately 6 mph near speed trailer
•In South Korea, speeders were reduced from 27% to 10% with speed signs
•In Santa Barbara, CA average speeds were reduced by 10%
•In work zones, signs reduced the number of speeding truck drivers by 24%

An evaluation by the Texas Transportation Institute of speed display trailer use in work zones found that the signs reduced average speeds by around 5 mph and were well liked by construction workers who felt that they “increased awareness of the work zone and significantly lowered speeds in the activity area.”

Speed display trailer reduces speeds in work zones

A study by the Texas Transportation Institute found that driver feedback signs “significantly reduced vehicle speeds at a school zone.…the average speed decreased more than 9 mph… [even] four months after installation.”

Driver feedback signs reduce average driver speed

Research quoted in Wired Magazine found that radar speed signs “have proven to be consistently effective at getting drivers to slow down- reducing speeds by about 10%, an effect that lasts for several miles down the road.”

A study conducted by the Maryland State Highway Administration of speed signs in work zones found that the display trailers reduced average speeds by 2-7 mph and increased speed limit compliance by 10-40%.

Effectiveness of speed signs in work zones

Want to read more about how SafePace signs will change the way people drive on your streets? Take a look at some success stories here.

View Success Stories

Some eye-opening traffic calming statistics:

Most traffic fatalities occur during daylight hours, by motorists driving straight ahead, and in normal weather conditions.

NHTSA, FARS Data

Traffic fatalities during daytime and normal conditions

Road traffic crashes are one of the top 10 causes of death worldwide, claiming approximately 1,300,000 people each year.

World Health Organization

Traffic accidents are the only one of the top ten causes of death that are self inflicted.

World Health Organization

Traffic accidents among top ten causes of death

Of all unintentional injury deaths among children 0-19 years old, car accidents were the leading cause of death.

CDC Child Injury Data

Car accidents are a leading cause of death

Teen drivers ages 16-19 are nearly three times more likely to be in a fatal crash than older drivers.

Center for Disease Control

Teen drivers at higher risk for fatal crashes

50% of people who die on the roads are “vulnerable users,” ie pedestrians, cyclists, and motorcylists.

World Health Organization

1 in 4 car accidents involves cell phone use.

NSC

At any given daylight moment in America, approximately 660,000 drivers are using cell phones or electronic devices.

NHTSA Driver Electronic Device Use

Speed kills. Speeding contributes to a third of all fatal crashes.

NHTSA Speeding Traffic Facts

A pedestrian was killed every two hours and injured every 8 minutes in traffic crashes in 2014.

NHTSA Pedestrian Traffic Safety

17% of traffic fatalities and 10% of traffic injuries were among the elderly, aged 65 and over.

NHTSA Older Population Traffic Safety

Of children killed in traffic accidents in 2014, 72% were passengers, 20% were pedestrians, and 5% were bicyclists.

NHTSA Child Traffic Safety

A study of 43 international traffic calming programs found that traffic calming solutions decreased traffic accidents by 8-100%

ITE Traffic Calming: State of the Practice

Children who live within a block of a speed hump have significantly lower odds of being struck and injured by a vehicle in their neighborhoods.

American Journal of Public Health

Speed humps lower odds of being struck by vehicles

Traffic calming has proven far more effective in preventing child pedestrian injuries than road safety education, which has been “unable to exert meaningful changes in the behavior of children”

American Journal of Public Health

Traffic calming helps prevent child pedestrian injuries

Speed humps [and similar devices] were found to have a 53-60% reduction in the odds of injury or death among children struck by vehicles in their neighborhoods.

American Journal of Public Health

Speed humps reduce odds of injury or death

Unintentional injuries, including road crashes, are among the top 10 leading causes of death.

CDC Leading Causes of Death

Road crashes among leading causes of death

Traffic calming reduces severity of childhood injuries in the event of collision and makes it easier for drivers to avoid accidents in the first place.

National Children’s Bureau

Traffic calming reduces severity of injuries

Speed management offers the best prevention against injuries from traffic accidents.

American Journal of Public Health

The faster a vehicle is traveling, the more damage is done to a struck pedestrian. 5% of pedestrians would be killed if struck by a vehicle traveling 20 mph, 40% at 30 mph and nearly 100% at speeds over 50 mph.

NHTSA Vehicle Travel Speeds and Pedestrian Injuries

TRAFFIC CALMING SOLUTIONS

SafePace 475

SafePace 800

Guardian Cam

Speed Humps

“Not only are the products well engineered and industry leading, but their customer service is just outstanding.”

ME, Greenwich, CT

“We can…. control the signs (at the port) right from our offices….. via the SafePace Cloud.”

RM, Charleston, SC

“It (the SafePace radar sign) is a neat little system that gets fantastic results.”

GL, Clearview, ON

“We love it (the SafePace radar sign)….. You’ll notice drivers instantly slow down. It really grabs their attention.”

SR, Greenburgh,

“People really slow down and they don’t speed up afterward. It (the speed hump) is a reminder to observe the speed limit and it actually seems to work.”

JM, Baltimore, MD

“It’s really great how we can download the data and share it with team members….. The response to the signs has been excellent.”

CL, Leading car manufacturing plant, Canada