[ad_1]
× closure
Traffic signal timing is re-adjusted based on vehicle trajectories. A Track points are scattered throughout Birmingham, Michigan, with a total of 34 signalized intersections, including 3 major corridors and some isolated intersections. Each dot represents the vehicle’s position at a certain timestamp, and the color of the dot changes with speed. Corridors and intersections identified as opportunities for traffic signal retiming are marked with different colors. Second Space-time (TS) graph and connected vehicle trajectories. The blue line shows the vehicle trajectory of the connected vehicle. Each blue dot represents a trajectory point. C Euler and Lagrangian traffic state representations. The Eulerian traffic state representation defines the traffic state as the density of each cell, while the Lagrangian tracks the movement of vehicles. d Comparison of current practice based on fixed position detector data with the proposed vehicle trajectory method. LWR models are often used to model traffic flow based on detector data, directly providing speed, density, and volume at certain locations. We utilize a stochastic point queuing model in Newell coordinates, where vehicle trajectory data directly providing delays and parking locations are the only inputs. e OSaaS system: an integrated closed-loop system that integrates performance evaluation, traffic status parameter estimation, diagnosis, optimization, and on-site implementation. Credit: nature communications (2024). DOI: 10.1038/s41467-024-45427-4
Researchers at the University of Michigan can use GPS data from just 6 percent of the vehicles on the road to recalibrate traffic signals to significantly reduce congestion and delays at intersections.
In an 18-month pilot study in Birmingham, Michigan, the team used connected vehicle data insights from General Motors to test its system, resulting in a 20 percent reduction in stops at signalized intersections. 30%. General Motors currently accounts for 6-10% of the cars on the road in the United States.
According to the official introduction, it is the world’s first large-scale, cloud-based traffic signal retiming system, which provides the community with a significant opportunity to recalibrate signal patterns at a reduced cost. The UM study appears in nature communications.
The UM system obtains GPS data from a proportion of vehicles on the road and infers traffic patterns. For example, a connected vehicle stopping approximately 100 feet from an intersection is a strong indication that it is lagging behind at least three to four other vehicles.
“While detectors at intersections can provide traffic counts and estimated speeds, even at lower penetrations, capturing vehicle trajectory information can provide more valuable data, including vehicle delays, number of stops and route choices. ” said Henry Liu, a professor in the Department of Civil Engineering at the University of Michigan. Director of Engineering, Mcity and Director of the Center for Connected and Automated Transportation.
There are approximately 320,000 traffic lights in the United States, and the direct and indirect congestion costs associated with these intersections amount to $22.9 billion annually. These costs include time spent waiting for signals and unnecessary energy consumption due to signal lighting times that could be improved.
Most traffic signals operate according to a time of day signal timing schedule, with preset patterns for morning, afternoon, evening and nighttime. Transportation planners try to coordinate these bikes with surrounding intersections, allowing cars to flow between intersections and minimizing stop-and-go trips.
“The reason these signs should be changed more frequently is that traffic is always changing,” Liu said. “A good example is the traffic patterns we saw a year before COVID-19 arrived and two years after. The morning rush hour changed dramatically because so many people were working from home. When you see that change, you need Retime these signals.”
Optimizing signals to keep up with changes in traffic flow is no simple task. The cost and time involved in conducting traffic counts and recalculations means most municipalities don’t reassess for two to five years or sometimes even decades.
Although adaptive traffic lights have been around since the 1970s and can detect vehicles at intersections and reprogram signals almost instantly, cost issues have prevented widespread use. Installing an adaptive system at a single intersection can cost up to $50,000 and require regular maintenance—a price not all communities can afford. The cost of an optimized UM system is a fraction of that of an adaptive system.
The UM system, called a probabilistic space-time graph, allows a smaller proportion of connected vehicle data to do the same workload as sensors at adaptive traffic signals. To test its effectiveness, researchers collected data from 34 signalized intersections in Birmingham over three weeks in March 2022, most of which are fixed-time systems.
“This really solves our data collection problem,” said Gary Piotrowicz, deputy general manager of the Oakland County Road Commission. “I can say this is going to be the practice for everyone in the country. Once they solidify With this system, there’s no reason to do it any other way.”
Liu’s team consists of several graduate students, including graduate research assistant Zachary Jerome, a member of the UM Transportation Laboratory who helped develop UM’s algorithm. Jerome works directly with the RCOC and hopes to work with industry partners to assist other cities in deploying this cost-saving technology.
“The opportunity to work with industry to bring this breakthrough technology to real-world applications is incredible,” said Jerome. “My vision is that this system will provide a revolutionary signal retiming solution to communities around the world, The solution is scalable, sustainable and efficient.”
More information:
Xingmin Wang et al., Traffic light optimization for low-penetration vehicle trajectory data, nature communications (2024). DOI: 10.1038/s41467-024-45427-4
[ad_2]
Source link