Researchers are proposing a significant overhaul to the century-old traffic signal system, potentially adding a fourth signal—white—to accommodate the rise of autonomous vehicles (AVs). This change could enhance traffic flow and safety as self-driving cars become more prevalent on the roads.
University of Michigan’s Pilot Program
The innovative idea comes from a team of researchers led by Henry Liu, a civil engineering professor at the University of Michigan. Liu’s team has been experimenting with this concept in a pilot program conducted in Birmingham, a suburb of Detroit. The program leverages speed and location data from General Motors vehicles to adjust the timing of traffic lights, optimizing traffic flow without the need for costly infrastructure changes.
“Using data from the car companies, rather than relying on traditional traffic infrastructure, allows for more efficient and cost-effective traffic management,” Liu explained. The pilot program has shown promising results even with just 6% of vehicles in Birmingham connected to the GM system.
GPS-Driven Traffic Control
The potential of this new traffic management system has caught the attention of the US Department of Transportation, which has provided a grant under the bipartisan infrastructure law to further test real-time traffic light modifications.
In Birmingham, 34 traffic signals currently run on fixed schedules without cameras or sensors to monitor traffic. However, the data-driven approach from the University of Michigan aims to make these signals more responsive to actual traffic conditions, potentially reducing congestion and improving safety.
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“The beauty of this is you don’t have to do anything to the infrastructure,” Liu said, adding that “the data is not coming from the infrastructure, but from the car companies.”
Danielle Deneau, traffic safety director at the Road Commission in Oakland County, Michigan, noted that even slight adjustments to green light timings have already shown a reduction in congestion. “With the upcoming grant-funded research, we plan to automate traffic lights at another location in the county, which could lead to even bigger improvements,” she said.
The Fourth Light: White Signal Concept
At North Carolina State University, another team led by associate engineering professor Ali Hajbabaie is exploring a different approach. They propose adding a fourth traffic light, possibly white, to indicate when there are enough autonomous vehicles on the road to guide traffic.
“When we get to the intersection, we stop if it’s red, and we go if it’s green,” Hajbabaie told The Associated Press. “But if the white light is active, you just follow the vehicle in front of you.” This concept, termed the “white phase,” could leverage the computing power of autonomous vehicles to coordinate traffic more efficiently than traditional signals. Alternatively, existing lights could be modified to flash red and green simultaneously, signaling that autonomous vehicles are in control.
While this approach could dramatically improve traffic flow, Hajbabaie acknowledges that it requires a significant percentage of vehicles—around 40% to 50%—to be self-driving. “Implementing such a system is years away, but the rapid pace of AI and autonomous vehicle development suggests it could happen sooner than we think,” he said.
Challenges and Considerations
Despite the potential benefits, there are challenges to consider. Sandy Karp, a spokesperson for Waymo, Google’s self-driving car subsidiary, cautions against premature investment in AV-specific infrastructure. “It’s important to think creatively about facilitating the safe deployment of AVs, but policymakers should be careful about jumping too soon on investments that might be unnecessary,” Karp said.
“While it is good at this early stage of AV development that people are thinking creatively about how to facilitate the safe deployment of AVs, policymakers and infrastructure owners should be careful about jumping too soon on AV-specific investments that may turn out to be premature or even unnecessary,” Waymo spokesperson Sandy Karp told FOX Business.
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Waymo has successfully launched fully autonomous ride-sharing services in cities like Los Angeles and Austin without the need for a fourth traffic signal. This highlights the need for flexible and adaptable solutions that can evolve with the technology.
Historical Context
Traffic lights have seen little change since their inception in 1914 in Cleveland, where the first municipal traffic control system was installed. Initially featuring only red and green lights, the yellow light was added later to manage transitions. The introduction of a white signal or a similar modification represents a significant evolution in traffic management.
The future of traffic control could see intersections becoming more efficient and safer as the adoption of autonomous vehicles increases. Pilot programs like those in Birmingham and research at institutions like North Carolina State University are paving the way for these advancements.
As companies like Tesla, Mercedes, GM, Ford, and Waymo continue to develop and refine autonomous driving technologies, the integration of AVs into everyday traffic management systems becomes increasingly plausible. With further research and real-world testing, the vision of a more efficient and responsive traffic signal system could soon become a reality, transforming how we navigate our roads and cities.
