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Virginia Solved Their Traffic Congestion with Adaptive Traffic Control

The state of Virginia had a problem. Across multiple jurisdictions, traffic flow issues were rampant. Each corridor and signal was different, with unique structure, volume, speed limit and control need; but they needed a solution that would solve traffic congestion across the state. What could be done? The answer was simple: adaptive traffic control.

Between 2011 and 2013, Rhythm Engineering worked with the Virginia Department of Transportation (VDOT) and installed In|Sync adaptive traffic control at 111 intersections, comprising 13 corridors in 11 jurisdictions. The goal was for In|Sync to help reduce delay and improve overall traffic safety as compared to the existing static time of day plans that weren’t working for those backed-up intersections.

“We have a little over 3,000 traffic signals that we operate and maintain from VDOT,” said Michael Clements, PE, VDOT Traffic Signal and Arterial System Program Manager. “Most of our corridors in Virginia are running time-of-day plans, so they’re based off of historical traffic data.”

While historical data provides information about vehicles, often times traffic patterns change before time-of-day plans can be updated. In many jurisdictions, signal timing plans are only updated every five years, and traffic patterns can change a lot over that lengthy period of time. Instead of relying on outdated data, Virginia needed a system that could adapt to the changing traffic flows driving through their intersections. In|Sync was the answer.

As an adaptive traffic control system, In|Sync is programmed to respond to the actual demand at the intersection. This means, the system will prioritize movements based on the volume of vehicles. It does this by detecting vehicle presence and making real-time adjustments to phase sequencing to more efficiently serve demand.

The Problems Virginia Needed Solved

Many cities in the state of Virginia were having issues with increased traffic demand and backed up intersections. Before technological advances, the only answer to an increase in vehicle volume was expanding streets in order to accommodate traffic demand.

“We don’t have the option of expanding at all, so getting those facilities in is difficult,” said Justin Hall, Traffic Manager of Winchester, VA.

Due to an increased number of commuters to Winchester or out of Winchester to Washington D.C., peak volume times and increases in summer time traffic patterns, Winchester had a traffic volume their roads couldn’t handle. Winchester is full of historical buildings and was already tightly packed, so expanding roadways wasn’t an option.

Widening the roadways also wasn’t a favorable option in the County of Albemarle. While they had the space to widen, the budget was was creating another problem.

“With a lot of lane widenings you have to buy right of way and they can get very expensive,” said Dennis Rooker, Albemarle County Board of Supervisors (2001-2013), County of Albemarle. “You can expect to pay $10 million a mile for adding one lane, at least. Now we’re looking at a widening project on route 29 North that I think is a couple of miles long, and it’s projected to cost $30 million.”

Rather than invest in a long-term construction project, Rooker found In|Sync adaptive traffic control system to be a better option.

“I’m very much in favor of looking at ways to improve traffic flow and deal with capacity issues that don’t involve laying new pavement,” said Rooker.

In other areas of Virginia, sometimes the issue couldn’t possibly be solved with a widening project because it wasn’t the vehicles that were the problem.

“Our biggest challenges right now are with pedestrians,” said Gigi O’Donnell, Traffic Signal Supervisor in Charlottesville, VA. “Almost every single intersection has pedestrian signals.”

Cities Across Virginia Signed Up for In|Sync

VDOT approached several cities and asked them to join in on the In|Sync deployment, including Winchester, Albemarle County and Charlottesville, among many others. Each city did their own research and were all impressed with the results.

“I think I had a constituent send me some information on In|Sync,” Rooker added. “I looked at some of the third-party evaluations of the In|Sync system, and I became convinced that it would be something that would probably enhance the transportation here.”

“I looked into it and what attracted me most was that it was real-time coordination,” said O’Donnell of Charlottesville.

“We thought that we would partner with Virginia DOT and see if this system would work for us,” replied Don DeBerry, PE, a Transportation Engineer in Lynchburg, VA, whose community also deployed In|Sync with VDOT.

In|Sync Deployments Brought Immediate Results

Over the next three years, In|Sync adaptive traffic control system was deployed at all 111 intersections chosen by VDOT. During that time, extensive amounts of data were collected in order to judge how In|Sync had impacted the corridors it was deployed on. Michael Fontaine, PhD, PE, Associate Principal Research Scientist was one of the lead analysts from the Virginia Transportation Research Council who evaluated the impact of In|Sync adaptive traffic control.

“We definitely saw benefits on the corridors where we deployed, both in terms of moving people safer and faster,” said Fountaine.

All intersections were impacted by the installation and the results were noteworthy in terms of stops, average speed, travel time and accidents. Overall, there was up to a 67% decrease in stops, a 58% increase in average speed, a 36% decrease in travel time and a 17% decrease in total accidents collectively across Virginia. Compared to the previous time-of-day plans, In|Sync’s adaptive technology was positively impacting the state of Virginia.

“We certainly have enough experience to know that with the initial implementation and the corridors are operating much more efficiently than we could have timed them,” responded DeBerry of Lynchburg, VA.

The data clearly illustrated how drastic the improvements were once In|Sync was in place, but the comments from the community were even more telling.

“Citizens were very excited about it. I don’t think I had a single negative comment from a citizen,” noted Rooker of Albemarle County. “I had many people comment that they thought it was one of the better things we had tried to move forward in the county on the transportation side for years.”

The same went for Winchester: “Everything we’ve been hearing has been positive about In|Sync in the two corridors that we have,” said Hall.

Safety Improved Across the State

Beyond the improvements in traffic flow, the safety benefits of installing In|Sync were apparent across Virginia.

“On the safety side, we looked at 47 intersections around the state where we had at least one to two years of data after In|Sync was activated,” said Fountaine. “On average we saw a statistically significant reduction of about 17% in total crashes.”

Imagine what 17% fewer crashes looked like to every city involved in the Virginia deployment of In|Sync. That is countless lives saved and hundreds of thousands of dollars saved from the cost of car accidents.

“We’ve definitely seen an improvement in traffic flow, and it looks like we’re going to see a significant reduction in our crashes. So I’d say job well done, guys.” DeBerry of Lynchburg said.

Overall, the benefits of the system were numerous and better than VDOT could have expected. From constituents to traffic engineers and managers, the positive impacts successfully improved the traffic environment across Virginia.

“It’s just unbelievable,” said O’Donnell of Charlottesville about their In|Sync deployment. “I ride down that way every day now.”

After all the data was reviewed, the Virginia Transportation Research Council also determined the benefit/cost ratio of their entire In|Sync deployment. They found an average ratio of over 8 after just a year of deployment, meaning almost 8 times as many benefits were accrued on those corridors than the cost to install the system initially. That is in one year alone. Overall they found an annual benefit vs. cost of $34.6 million.

“We have quite positive results with the system,” said Clements of VDOT. “Positive enough that we continue to keep installing it.”