Harmonize Speeds, Save Lives

November 11, 2021

Harmonize Speeds, Save Lives

Noam Maital

Noam Maital

Executive Director, ITS

Our world is becoming faster and more efficient than ever, and so are our vehicles. New cars on the market today offer significantly better performance while maintaining greater efficiency than just ten years ago, and this trend will undoubtedly continue.

For example, Tesla’s new Model S Plaid can reach 60 Miles per Hour in under 2.0 seconds - the fastest ever for any series-production car. Fast cars may be fun to drive, but excessive speed is a major factor in crashes, especially fatal ones. The higher the speed of the vehicle, the more catastrophic the crash.

Speeding causes injuries and death, but narrowing our focus on decreasing vehicle speed alone is not enough to improve road safety. In doing so, we are overlooking another crucial factor: speed harmony.

Objects in motion have variations in speed, and these variations can be very dangerous on the roads. This is known as speed variability. Sudden transitions from high-speed to low-speed will often lead drivers to slam on their brakes abruptly, whereas steady speeds are safer, even if they are slower. Part of the path to reducing crashes is tackling speed variability. In a recent program called “Road to Zero,” Rekor worked with agencies to do just that.

During the program, we used artificial intelligence algorithms to detect key areas along Las Vegas interstates where preventative activities could significantly reduce crashes. Based on this information, the Nevada Highway Patrol (NHP) and the Regional Transportation Commission of Southern Nevada (RTC) deployed proactive measures such as strategic police positioning and the coordination of Dynamic Message Signs (DMS) to help mitigate traffic crashes in these regions. On May 20, 2021, we reported on the results of this program during RTC’s public board meeting (see minutes 06:43 - 18:00).

When vehicles are moving at different speeds, our ability to react and prevent a crash is weakened. Therefore the program highlighted both speed reduction and speed variation. We wanted to reduce the standard deviation in vehicle speeds to promote greater speed harmony. The program not only managed to reduce the average number of drivers going above the speed limit, but it reduced the standard deviation of speeds by 9%.

Speed harmonization is a method designed to decrease speed variability, effectively improving our road safety. In an ideal world, every vehicle would travel at the same speed. There would be very little cutting in, dangerous lane changing, road rage, and emergency braking.

In the future, speed harmonization may be easier to accomplish with the advent of connected and autonomous vehicles. Perhaps your car will be able to calculate the speed of vehicles in your immediate vicinity and then react accordingly.

Cities like Chicago, Los Angeles, Seattle, Atlanta, San Francisco, New York, and Miami have also taken steps to promote speed harmonization. These cities are utilizing a technique called “ramp metering” to break up groups of vehicles entering the highway. They have installed traffic lights at entrance ramps to reduce the stop-and-go speed variability that often leads to crashes.

An independent study based in the Minneapolis-St. Paul area evaluated the safety impacts of turning off all 430 ramp meters for six weeks. In those six weeks, researchers found a 26% increase in crashes, including a 14.6% increase in rear-end collisions and a 200% increase in side-swipe crashes.

Although there has been some progress within these major cities to address the problem of speed variability, there is still room for improvement across the world. Cities must begin taking this problem seriously and focus more on ways to improve harmonization of speeds - this initiative has proven successful and will lead to safer roads across the world.