There is nothing more annoying than sitting in a traffic jam and watching the clock tick by.
But the days of being stuck in congestion could be a thing of the past – if only cities added a fourth color to their traffic lights.
That’s according to researchers at North Carolina State University, who found that crossing delays could be reduced by more than 25 percent by adding a “white” signal.
Instead of simply stopping or going, this signal would direct autonomous vehicles to find their own path to cross while human drivers simply follow the car in front.
Co-author Dr Ali Hajbabaie said: “This improves the travel time, fuel efficiency and safety of all cars on the road.”
Scientists have proposed adding a new traffic light color that uses autonomous vehicles to reduce traffic. When the light turns white, self-driving cars determine the optimal flow and humans only need to follow the car in front of them.
The idea of a white signal is based on the assumption that, one day, a large number of vehicles on the road will be autonomous.
Since autonomous vehicles (AVs) can communicate with each other and with traffic infrastructure, they should be able to work together to create the most efficient traffic flow.
However, given that autonomous vehicles are only in their infancy, it is likely that large numbers of vehicles will continue to be operated by humans for the foreseeable future.
To ensure that both human drivers and robots can reach their destination quickly and safely, researchers have proposed installing a fourth traffic light.
As it stands, our well-known traffic light can only tell people to stop, prepare for the light to change, or leave.
Under this new system, once the traffic light detects that there are enough AVs at the intersection, it will change to a white signal.
Dr. Hajbabaie says this “leverages the computing power of autonomous vehicles to speed up traffic at intersections.”
The new system “harnesses” the computing power of autonomous vehicles. As this diagram shows, cars communicate with each other and traffic lights to know when to go.
The autonomous cars themselves determine which lanes they should go in and guide “platoons” or humans through the intersection.
Once the light turns white, the humans simply follow the car in front of them, which is an AV or another human also following an AV higher up in the group.
Since the system only turns on when there are enough AVs at the intersection, no human should be stuck at the front of a group while the white light is active.
Importantly, this system only becomes more efficient as the number of AVs increases.
The concept of a fourth white signal is not entirely new, having been proposed in 2020, but this study is the first to consider whether it could work alongside pedestrian crossings.
Under the new system, pedestrians would cross the street normally following a red and green light system.
The only difference is that when the white light is active, the crosswalk would work as part of the autonomous vehicle network to produce the optimal flow.
Traffic simulations show the new light color can reduce traffic by up to 25 percent when autonomous vehicles are widely adopted (file image)
By simulating a four-way crossing, the researchers found that wait times could be reduced by 27 percent, even taking pedestrians into account.
This figure is calculated for a near-universal AV adoption scenario, but Dr. Hajbabaie says there would still be “significant improvements” with lower AV adoption.
Dr Hajbabaie says: “We found that when pedestrians are added to the mix, the white phase concept continues to improve traffic efficiency for everyone.
“And, again, the greater the percentage of traffic made up of autonomous vehicles, the more efficiently traffic moves through intersections.”
This advancement would not only make travel faster, but could also make cities less polluted.
Exposure to nitrogen dioxide, largely from road transport, is thought to be behind 38,000 new cases of asthma in the UK and 240,000 in the US each year.
By reducing the time cars spend waiting in traffic, cities could save drivers time and reduce air pollution in congested areas (file photo)
And studies have found that motorists breathe in 40 percent more pollutants while sitting at traffic lights.
By reducing the amount of time spent idling at lights, cities could reduce emissions by easing congestion.
However, it’s unlikely that a fourth traffic light color will be coming to your city anytime soon.
Researchers say they are aware that governments will not implement these technologies in the near future.
However, they say they are already taking steps to ensure any future testing is effective and safe.
Dr. Hajbabaie says the team has already created a physical model to test their theory, although the cars in this model are small enough to hold in your hands.
“This will help us identify challenges in implementation without the expense (and security risk) of using large-scale vehicles,” he added.
“In the meantime, we are open to working with industrial and research partners to explore ways to advance these technologies.”