The addition of a fourth color in traffic lights to manage the flow of autonomous vehicles is being evaluated in the United States through a series of tests led by the team at North Carolina State University.
The proposal includes adding a white light to traffic signals to facilitate the coexistence between autonomous cars and human drivers at urban intersections.
How this new phase works was developed by the team led by Dr. Ali Hajbabaie, associate professor of Civil Engineering at North Carolina State University.
As Hajbabaie explained in an interview, the white signal will serve as a visible indicator for traditional drivers that autonomous vehicles are taking control of traffic at the intersection. “The white light is the signal for human drivers to simply follow the flow of cars in front of them, as autonomous vehicles negotiate the crossing automatically,” the researcher emphasized.
The proposed technology does not aim to replace the traditional red, yellow, and green signals but to complement them. According to the described tests, the smart traffic light will activate the white phase only when it detects a high proportion of autonomous vehicles (AVs) approaching the intersection.
“The system will allow AVs to collaborate to cross intersections more smoothly, while human drivers will only need to follow the movement of traffic led by these vehicles,” Hajbabaie stated.
One of the main arguments in favor of this innovation is traffic optimization. Researchers claim that implementing the “white mode” will reduce delays by up to 94% at intersections with a high presence of AVs and that even at intersections with only 10% autonomous cars, wait times will decrease by 3%. AP noted that ongoing tests also aim to reduce stop-and-go traffic, which could lead to more efficient fuel use.
How It Would Work
The technical development relies on the ability of autonomous vehicles to communicate with each other and with road infrastructure. The proposal is based on distributed computing systems capable of coordinating AVs and traffic lights in real time.
When the white light is activated, autonomous cars determine the order of passage, and human-driven vehicles follow them through the intersection. “The automatic control of the white phase ensures that the transition of command between AVs and humans is clear and safe,” the university team explained.
When autonomous traffic decreases, the traffic light automatically reverts to the classic operation. This dynamic aims to provide confidence to traditional road users, minimizing interpretation errors.
“The system does not eliminate conventional colors but introduces this brief and specific white phase for moments with a high flow of autonomous technology,” Hajbabaie added.
The first implementations of the white light system will take place in areas with high AV traffic, such as industrial ports and university campuses, where fleets of driverless vehicles already operate. According to North Carolina State University, these areas are suitable for testing because they have repetitive traffic patterns and low pedestrian traffic. “Ports offer an ideal laboratory since variables are more controlled,” Hajbabaie explained.
The necessary infrastructure is already under development. Initial tests will be conducted in closed environments to evaluate the joint behavior of AVs and humans under supervision.
According to North Carolina State University, the choice of the white light is arbitrary; any other color could serve the same function as long as the message is standardized as an unequivocal alert for human drivers.
Image: Infobae
