There’s a certain magic to a vehicle-activated traffic signal. You’re driving along a lonely road and pull up to a red light when — boom — seconds later the light turns green and you’re on your way. But while the results are certainly valuable, the technology that’s long been behind the magic is notoriously problematic.
Like most cities throughout the United States, the City of Greenville, North Carolina has experienced its fair share of problems with vehicle-activated — or actuated — traffic signals. The growing college town with a population of 85,000 is responsible for maintaining 265 miles of roadway and 125 signalized intersections — 115 of which are vehicle-activated. For many years, the City of Greenville has relied on inductive-loop vehicle detections to activate these signals, and city officials are very familiar with the high failure rates of loops, as well as the costs associated with their installation and maintenance.
In an effort to find a more cost-effective and reliable solution to vehicle-activated traffic signals, the City of Greenville has discovered SmartSensor Matrix and the benefits of high-definition radar. The sensor, designed and manufactured by Wavetronix, uses radar to detect vehicles at the intersection stop bar. Working with Transportation Equipment and Services, a local intelligent transportation system equipment vendor, the City of Greenville has begun to deploy Matrix as a replacement for failing loops; TES represents Wavetronix in the state as an authorized channel partner.
Since the 1970s, loops embedded in the pavement have been used at vehicle-activated signals. Typically, each traffic lane gets its own loop, which is connected to adjacent lanes with a lead wire; the lead wire is then connected by cable to the intersection’s control cabinet. Loops use electrical currents to detect the presence of vehicles; when a vehicle arrives at the light, the loop recognizes the vehicle and sends a message to the control cabinet, where the request is fulfilled based on the signal’s preprogrammed rules and logic.
But roads are a harsh environment, and loops require frequent repair or replacement. For example, the City of Greenville estimates it will replace approximately 50 of its 900 detection loops each year. “There are many reasons why loops fail,” says Greenville City traffic engineer Richard DiCesare. “Pavement can shift and affect the loops, especially on a downgrade. New construction on adjacent lots can easily take out the lead wire along with all the loops it connects. And every time you need to mill and resurface a road, the loops typically need to be replaced.”
In the past, when one of Greenville’s detection loops inevitably failed, a costly and labor-intensive replacement would follow. “Typically, three loops are knocked out at one time. The cost to replace all three loops and accompanying cabling is about $5000,” says DiCesare. “In addition, we tie up the resources of an entire work crew for one or two days. Plus, the installation requires temporary lane closures, which decrease safety and mobility for our motorists and pose a risk to our workers.”
According to DiCesare, temporary lane closures like those needed for loop replacements are especially troublesome for the city’s motorists. “Our major construction projects are publicized by the local media so motorists can plan their trips accordingly, but it’s impossible to get the word out about every temporary lane closure. As a result, the safety risks associated with road construction increase and motorists often arrive late to their destinations, decreasing their satisfaction with our public works department.”
Throughout his 30-year career in traffic engineering, DiCesare has seen traffic technology come, go and evolve. “Because of my experience, I’m always on the lookout for effective new solutions that can contribute to the safety and mobility of the motoring public and help us use valuable tax dollars wisely,” says DiCesare, who previously worked at engineering consulting firms in New York and Florida and also served as acting city traffic engineer in Lauderhill, Florida.
“We instantly recognized…the technological, safety and cost-saving advantages offered by Wavetronix.”—MARK HOLLAND, TES
Shortly after taking the reins in Greenville, DiCesare spoke with Mark Holland from TES about advancements in high-definition radar detectors for vehicle-activated traffic signals. Recognizing the potential for time and cost savings as well as safety improvements, DiCesare began investigating potential applications for the innovative technology in Greenville.
Working together, Holland and DiCesare identified the SmartSensor Matrix as the most likely solution for the city’s needs. Instead of loops buried in the pavement, the Matrix solution relies on a single radar-emitting unit mounted above each intersection approach. Each Matrix uses 16 separate radar beams to achieve a 90-degree, 140-foot field of view that detects vehicles in all weather and lighting conditions. “We instantly recognized that the technological, safety and cost-saving advantages offered by Wavetronix could be an excellent fit for the City of Greenville’s progressive approach to transportation solutions,” says Holland.
At DiCesare’s request, Holland arranged a field test of the Wavetronix solution in Greenville; the demonstration was attended by DiCesare along with Greenville’s three traffic signal technicians and representatives from the North Carolina Department of Transportation. “What impressed us most was how fast and easy the installation was,” says DiCesare. “In the past, an entire crew would be working in the road for hours, if not days, to install detection loops. With Matrix, the unit was mounted and programmed in less than two hours with absolutely no traffic disruption.”
“What impressed us most was how fast and easy the installation was.”—RICHARD DICESARE, GREENVILLE CITY TRAFFIC ENGINEER
DiCesare was also impressed with the ease of programming the Wavetronix detector. “It’s so much simpler than other similar solutions I’ve seen,” he says. “The sensor’s software includes a graphical interface you use to draw each virtual detection zone. The whole process is extremely intuitive.”
Though the city officials quickly realized that Matrix would be a good fit for Greenville, the costs needed to be carefully considered before moving forward. “When I did the cost analysis, I was surprised and pleased to find the costs of the Wavetronix solution were very comparable to a loop detection system,” says DiCesare. “Installing a loop detection system at a typical four-way intersection can cost about $24,000, while adding Wavetronix to the same intersection costs just a few thousand more.”
The analysis also demonstrated the City of Greenville would get more for its money with Matrix over the long haul. “For a similar price you gain significant benefits,” says DiCesare. “We’ll lower long-term maintenance costs by avoiding the ongoing cycle of loop replacement, save time and improve productivity with rapid installations, avoid the pavement degradation caused by the saw cuts needed for loop detectors, improve mobility and safety because we won’t need to shut down lanes to install the detectors, and add the capability to detect in-lane bicycles and count vehicles.”
In addition to these many benefits, DiCesare discovered he could leverage outside funding sources to save the city additional money. “Because the Wavetronix sensors can collect traffic data, our local Metropolitan Planning Organization will reimburse us for 80 percent of the cost,” he says.
With the clear advantages demonstrated by the cost-benefit analysis, DiCesare purchased the city’s first Matrix unit to have on hand when a loop detector failed; it was put to good use almost immediately. “A developer wanted fast installation of a vehicle sensor for their driveway at an existing signal-controlled intersection,” says DiCesare. “We were able to quickly adapt the signal along Greenville Boulevard using Matrix for traffic detection at the driveway and inbound left-turn lane, and the developer reimbursed the city for the cost.”
“Because the Wavetronix sensors can collect traffic data, our local Metropolitan Planning Organization will reimburse us for 80 percent of the cost.”—RICHARD DICESARE
Moving forward, DiCesare plans to keep Matrix sensors on hand and begin a gradual transition away from loop detection. “When we experience a loop detection failure or we need to pull out loop detectors due to a paving project, we will look closely at replacing those loops with Wavetronix detectors,” says DiCesare.“If the costs and benefits of this technology remain the same, eventually the City of Greenville will phase out loop detection in favor of the Wavetronix technology.”
In addition to the cost, safety and mobility benefits gained with every Matrix installation, city officials believe a more widespread deployment of the technology will provide even greater systemic benefits. “Because the Wavetronix units offer data collection, we’ll have much greater access to real-time traffic data,” says DiCesare. “We can use that data to make better decisions about where our city’s greatest transportation needs lie and determine how to spend our limited funds most effectively. Plus, there are many sources of state and federal funding available through an application process — having data available to support any funding applications our city pursues increases our chances of receiving those funds.”
Overall, DiCesare says partnering with TES to deploy SmartSensor Matrix in Greenville will help fulfill the city’s mission of providing safe, efficient and cost-effective transportation. “Especially in these economic times, we’re always looking for ways to do things better and more cost-effectively, and Wavetronix makes that possible. With SmartSensor Matrix, we really are getting more for each taxpayer dollar by leveraging the additional safety, mobility, data-collection and time-saving benefits it provides.”
