Mobile is the largest Alabama city without the latest in traffic signal technology, but with new capital money available, it is looking to innovate.
Huntsville, Montgomery and Birmingham participated in a pilot program that brought adaptive traffic signal technology to some of their busiest intersections, while Gulf Shores recently added the technology to intersections along State Highway 59, Gulf Shores Public Works Director Mark Acreman said.
The new adaptive systems — which are the first in southwest Alabama — have been installed on 59 between Baldwin County 8 and State Highway 182. They allow signals to communicate with one another and react based on real-time traffic issues, Acreman said. The results have been visible.
The signals, which were installed just before the 2015 Hangout Festival, led to improvements in traffic the week before Memorial Day. Acreman said the technology resulted in a reduction in the traffic load following the festival. He said the highway cleared about an hour sooner than the year before. For example, where traffic had been heavy from about 10 p.m. to 12:30 a.m. in 2014, traffic this year cleared after about 11:30 p.m.
“We’re still collecting data on Memorial Day, but we’re expecting a 14 percent increase in efficiency,” he said. “It equates to more capacity.”
The new signal systems detect vehicles using radar, and account for traffic in all directions while being immune to fog, rain or sun glare, like older camera systems, Acreman said. The radar is not used to monitor speed, he said.
The information gathered by the system, which has been installed in 15 signals, is shared with all the signals in the system and can adjust cycle lengths based on the feedback, Acreman said.
The conversion to the adaptive systems was a 10-year process in partnership with the Alabama Department of Transportation, Acreman said, with Gulf Shores spending about $2 million so far.
Mobile is beginning to come out of a long drought in capital funding for signals, Traffic Engineer Jennifer White said. The city used $200,000 this fiscal year on detection and camera system parts and plans for more upgrades.
“We spent about $200,000 just on buying either spare parts — in case an accident happens we’ll have something on the shelf we can pull out, put in a cabinet and put on the street quickly and won’t have to order it,” she said. “Then we bought stuff for upgrades to existing signals we know need new detection systems.”
The capital money was a change from years past, White said, when maintenance was all they could do.
“A couple of years ago there were no capital funds available to departments and the budgets were real tight,” she said. “The city was basically doing whatever needed to be maintained.”
White said the city also used stimulus money a few years ago to upgrade to newer systems in many of the signals, although the manufacturer is “trying to phase them out” now.
Many of the current signals are older and out of production, but White stopped short of calling them obsolete because they still work as intended.
Even without upgrades, all of the city’s signals are on some sort of detection system, White said, and don’t rely solely on timers. The city currently uses camera systems and in-ground magnetic loops as forms of detection.
The problem is that loops, which are embedded in the asphalt, can be disrupted by road work or degradation of the asphalt surface, White said.
“Utility work goes on and they cut them by accident,” she said. “You know, any number of things can cause a loop to go bad. We know where they’re at and we’ve bought material for them and we’re in the process of getting a new loop-cutting saw. We’ll start some of that repair work this summer.”
Some of Mobile’s busiest intersections are linked together, but many of those links are made with copper wiring. White said a future upgrade would include switching all the links to fiber optic cables. The oldest coordinated system in the city dates back to the 1970s, Electrical Supervisor Billy Smith said.
Many signals in major intersections across the city are given peak times in which they react to increased traffic, for example, during rush hour. This is different from the newer adaptive systems because they operate on the same schedule no matter the day of week or time of day.
Mobile is a little behind the curve because the city’s signals work off time-based progression, ALDOT Area Traffic Engineer Daniel Driskell said.
Under the current system, Driskell said, Mobile drivers constantly “go and then stop,” but under an adaptive system drivers would be able to move through the city more efficiently.
“The adaptive technology is designed to optimize the system,” he said. “What we’ve got now, we’re just living with.”
To begin with, Driskell said, Airport Boulevard from Interstate 65 to University Boulevard would greatly be enhanced by an adaptive system. Driskell said while needed upgrades vary, it could cost between $60,000 to $100,000 per signal to accomplish it. But the cost benefit for the new system is much greater than an upgrade such as adding a lane of traffic, he suggested.
Hannah Pritchard, a traffic engineer with Toole Design Group, was part of team that recommended a plan for transportation improvements in downtown. At a recent presentation, Pritchard said many of the signals downtown could be scrapped for stop signs and could save the city money. Pritchard added that cycles at some of the downtown intersections were too long and could be improved.
One problem intersection for the city is at Cottage Hill and Hillcrest roads, White said. The issue at the standalone, eight-phase intersection is the number of vehicles that hit it at the same time, between 5:15 and 5:30 p.m. on weekday evenings, White said.
“The problem is everyone meets at the exact same time,” she said. “It’s like, whatever their route is from wherever their jobs are they all meet, but they’re all usually going west (and) going out further down Cottage Hill.”
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