Launch Slideshow


Can your community afford adaptive traffic control?

Can your community afford adaptive traffic control?

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    There's more to adaptive traffic control than artificial-intelligence software.

    In addition to traffic volumes and variability and roadway geometry, how well adaptive signals ease congestion depends on how well the signals worked before the solution was implemented, scope of deployment, an agency's objectives (i.e., minimize aggregate delay, minimize extreme delays, progression, etc.), and weather conditions.
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    Most vendors roll the first two years of service and support into the purchase price, so make sure you ask customers for both initial and annual operating costs. Use your research on costs and in-field performance to develop best-, average-, and worst-case scenarios for each product. This method puts the initial cost in terms of an investment. Thus, Product A is the least expensive option but represents the worst long-term investment. Depending on your risk tolerance, you might decide that the most important consideration is to avoid failure on the magnitude of the worst-case scenarios below (especially Product A). You might strive for the best-case performance (Product C), but be willing to accept that a consistently strong performance (Product B) is the best of both worlds: maximum results with minimal downside risk.

Benefits and pricing/what to ask vendors

Measurable benefits will vary depending on your operation's previous signal optimization efforts (i.e., how well the signals operated before the solution was implemented), traffic volumes, level of variability, roadway geometry, scope of deployment, objectives (i.e., minimize aggregate delay, minimize extreme delays, progression, etc.), weather conditions, and the community's expectations.

More dynamic = more benefit. The more often and quickly the solution makes changes, the better it adapts to traffic demands. Some adjust each second while others wait a “cycle” or several minutes. Some provide a few extra seconds of green light time to a needy approach.

Results of similar deployments. Be sure to ask for actual field results measured by the deploying agency or a third-party such as an engineering firm.

Total deployment cost. Different vendors construct their pricing differently. Some include training and software licenses; others don't. Some solutions require upgrading controller hardware or firmware; others won't.

Require a written proposal that addresses everything — components, configuration, installation, recommended options, licenses, hardware, equipment, integration, and training — required to deploy and maintain the solution. Most vendors roll the first two years of service and support into the purchase price. Beyond that, some solutions require the attention of one or more full-time employees; others require much less staff time and ongoing financial expense.

Availability and extent of self-help and live support. Ask to be shown all user documentation and tools. Call each vendor's support phone number to find out how quickly you reach someone who can help with a significant problem.

Standard and optional warranties and support plans. Review the standard and extended hardware and software warranties for each solution. Evaluate options for coverage and support after the end of the standard coverage.

Response to extraordinary circumstances such as product failure. Fair or not, your investment will be judged on a freak occurrence rather than less day-to-day congestion. When (not if) these scenarios play out in your community, how does the product and the vendor respond?

Assurances and guarantees. High-performing products are easy to guarantee. What assurances does the vendor give about how well the product improves traffic flow?

Performance/what to ask existing customers

It's time-consuming, yes. But given the relative youth of most of the products in this category — most are less than 10 years old — ask for a list of all customers. Talk to at least three that parallel your goals to find out why or why not the deployment and operation meets expectations.

What feedback have you received? If motorists, elected officials, business owners, the police department, the neighboring city, and the state DOT haven't noticed a drop in congestion or other benefit, what can you do differently to ensure your investment is impactful?

How easy is the solution to learn and use? The answer will help you plan how much time your team will need to get up to speed and to train new employees.

How quickly did the solution actually deploy versus promised? Ask about all the components — detection, controllers, communications, central server, etc. — and whether new timing plans had to be created.

Did the vendor respond as promised to an extraordinary circumstance? Why did the system go down, how long was it out, and how well did the solution respond?

—Chris Gregory ( is vice president of Rhythm Engineering, which introduced the InSync self-optimizing traffic control solution in 2008. The solution has been installed at 700 intersections in 19 states. For more information, visit


Several organizations report the growth in adoption and benefits of adaptive traffic control solutions (ATCS).


Challenge: Intersecting arterials
Owner: Columbia County DOT

Named in 2008 as one of Money magazine's 100 best small cities, Evans, Ga., is also where two major thoroughfares intersect along a 1-mile corridor.

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    Georgia's Columbia County DOTC installed Rhythm Engineering's InSync at 22 intersections and is scheduled to deploy 39 more. Contact Traffic Engineer Glen Bollinger at or 706-868-3 3356. Map: Rhythm E Engineering
Washington Road averages 40,000 vehicles daily; North Belair Road, 41,000. Optimizing traffic signals on intersecting arterials is particularly difficult. Both have heavy traffic volume and their need for progression is equal. If not perfectly engineered, a timing plan for one works against the other's.

In 1995, the Columbia County DOT coordinated signals on Washington Road and periodically updated the timing plan. But with the corridor experiencing heavy traffic during both on- and off-peak travel times, the system couldn't overcome congestion.

Rhythm Engineering installed its InSync adaptive traffic control product and fused the system's detection technology with the city's existing inductive loops to eliminate the possibility for false calls and ensure efficient traffic movement. The DOT's subsequent performance study showed the system cut travel time in half by:

  • Reducing stops by up to 100%
  • Increasing average speed by up to 93%.

Columbia County Board of Commissioners Director Matt Schlachter drives Washington Road daily. “I made it through the corridor, without stopping, once in five years,” he says. “We did it three times in a row within 30 minutes of activating the system.”

Total estimated economic benefit: $2.6 million annually in saved fuel, stops, and time.

Challenge: High pedestrian traffic
Owner: City of Salinas, Calif., Public Works Department

For years, Main Street in the City of Salinas bedeviled drivers with stop-and-go progress dictated by pedestrians crossing from Monterey Bay.


Salinas, Calif., installed InSync at five intersections to manage pedestrian and vehicle traffic along Main Street and is scheduled to deploy the system at seven more. Contact Junior Engineer Jose Saucedo at or 831-758-7197.

Public Works ran the corridor in free mode, delivering green time based on the presence of traffic without prioritizing movements on main or side streets or factoring in queue length at intersection approaches. With no coordination plan, the traffic control system served pedestrian movements upon request from pedestrian button pushes. Traffic along the corridor inevitably backed up.

Officials and traffic engineers for the city of 150,000 concluded that signal timing wouldn't solve the problem. Instead, they deployed Rhythm Engineering's InSync adaptive traffic control system at five intersections in part because the product could be used with the city's existing but outdated copper infrastructure that tied existing controllers together. The company saved the city the significant expense of installing new Ethernet wiring to connect the corridor's intersections by installing an Ethernet-over-copper device on the controllers.

InSync incorporates pedestrian calls in its local optimization and global coordination to ensure pedestrians cross safely without disrupting traffic. It does this by serving pedestrians crossing in the same direction during both green tunnels and in the periods between green tunnels. Instead of breaking traffic signal coordination along the corridor when a pedestrian arrives at an intersection, the product provides a wait time of 10 or 15 seconds — not long enough for anyone to notice — so dozens of vehicles driving at 30 mph or more don't have to stop for just one person.

“Other systems try to work this way, but a high volume of pedestrian calls can override vehicular calls and throw the signals out of coordination,” says Grant Niehus, a Rhythm engineer who worked on the deployment.