By
Ayse Guner
Arizona Daily Wildcat
The "smart" sensors project will be completed soon after a decade
About nine years ago, Pitu Mirchandani, a UA professor in systems and industrial engineering, had an idea that would decrease traffic congestion.
Today that idea turned into a major non-construction traffic proposal and the most innovative project that the city of Tucson has ever taken, said Tony Paez, director of City of Tucson's transportation department.
"One of the best directions in regards to expense and cost benefit," Paez said about the benefits of the project.
Mirchandani, along with several faculty members and 10 students, will soon complete a project on the traffic control systems called RHODES, which aims to place "smart" sensors on traffic or street lights on the busiest streets in Tucson.
RHODES stands for Real-time Hierarchical Optimized Distributed Effective System.
After completion in March, "smart" sensors will upgrade under-pavement magnetic loop detectors, which work on a predetermined time schedule.
"Loop detectors were only made to say that there is a car waiting for the signal," Paez said. "Right now we aren't able to monitor intersections."
The loop detectors are inefficient in estimating the number of vehicles waiting on intersections and could be easily damaged by construction or rain, Mirchandani said.
Rain could cause a shortage if there is damage to the wire inserted under the pavement and could melt a loop.
"It's sort of dumb," Mirchandani said.
Whereas the "smart" sensors are more technologically advanced using either video, sonar, radar or remote. The sensors can signal the number of vehicles approaching a traffic light and tell how far back the cars are.
Some of the sensors will even count the driving speed and estimate the direction headed, Mirchandani said. Then the sensors will send the measurement to a controller cabinet made up of computers to time the traffic light. If there is any traffic congestion, the controller will use algorithms to set the green light and adjust the queue.
Depending on the amount of the traffic, the waiting time at a traffic light could be minimized anywhere from 5 percent to 40 percent, Mirchandani said.
In addition, controllers on busy highway intersections like East Speedway Boulevard, could exchange information with one another through a cable system and "make the network of the whole city level minimal," said Wenji Wu, a doctoral student in systems and industrial engineering, who has been working on the project for a year.
Wu said the "smart" system will also reduce pollution and save from money that is spent on fuel.
"If you spend 10 or 20 minutes on an intersection, that's money," he said. "If you spend less time on the roads, everybody will be happier and more productive."
A total of $3 million has been spent on the RHODES project so far.
Last week an additional $1 million came from federal funding as a part of President Bill Clinton's approval of $5 million on transit-related projects for the Tucson area.
The funding will be spent on lab resources at the ATLAS Center - Advanced Traffic and Logistic Algorithms and Systems.
When completed, the University of Arizona researchers will pass the project to the city for the implementation process and the city will decide where to place the sensors.
Speedway Boulevard near the university has the most traffic congestion and several detectors could be implemented on the intersections, Paez said.
An estimated of 57,000 cars drive on Speedway Boulevard each day and there are about five traffic lights.
"We will observe from a traffic control center and have eyes out there," Paez said.
The biggest benefit of these sensors will come when there is an accident on the highway, Mirchandani said. The "smart" sensors will give priority to emergency vehicles like ambulances, fire vehicles and police cars.
However, because the whole system will depend on computers, disasters could cause software problems and result in delays. Paez said back-up systems for RHODES are being provided to prevent any system failure.
"Anything's possible," Paez said. "If it is down, we don't have a lot of police to be on traffic lights."
