Managing traffic flow on seven-lane Rainier Avenue corridor through the middle of Renton can be tough enough on its own. Toss in construction, causing the number and positions of lanes to change, and it can be nearly impossible.

Fortunately Renton brought in some help in the form of ACS Lite. By improving the efficiency of traffic lights, the new software will ease traffic for drivers through one of the most congested areas of Renton.

ACS Lite, from Siemens, is an adaptive traffic-management program. The software uses video to determine “loops” in an intersection instead of the common induction loop system, where an electrically conducting loop is installed in the pavement. When a car pulls over the loop, it changes the current in the loop and triggers the system.

That is a huge bonus during the construction on Rainier, since work crews often have to modify the number and locations of lanes. Such changes would likely result in a frustrating mess for induction loops, but the video system can handle them in stride.

The software has been perfected since 2002 and became available for purchase in 2006. Transportations operations manager Chris Barnes said it might be the first use of this software in the state.

“The adaptive traffic management system that is in place, it is where the evolution of traffic signal controls is going,” said Doug Jacobson, deputy public works administrator for transportation. “We’ve been looking for an appropriate opportunity to use it and the Rainier corridor, with things changing during construction, was that opportunity.”

While the Rainier construction provides a good opportunity to showcase the video loop method, the software goes far beyond that. It also adjusts the amount of green time each movement in an intersection has to try to interactively meet the demand.

For example, if 30 seconds of green isn’t clearing all the cars trying to make a left turn, the software will add green time to make the intersection flow better. Jacobson said the software usually adds time in one- or two-second increments.

The software adapts and make changes every five minutes. Under the old system, the staff would make changes if a problem arose or for special occasions, but the only regular meeting to make adjustments to flow and timing would be roughly once a year. During an average week, there is only a staff member in the control room monitoring traffic about four to eight hours a week.

“The software is essentially allowing us to be more proactive, because we don’t have the staff to have a person in here regularly,” Jacobson said.

So far it’s worked out very well, having a positive effect on traffic.

“Even with the construction, we are trying to keep the traffic flowing as well as before,” said Barnes.

The catalyst for installing the software was the Rainier construction project, but that one street won’t necessarily be the end of the new system.

“It gave us an opportunity to give this a try,” Jacobson said. “We will evaluate it over the next couple of years and decide whether or not we want to expand into other parts of the city.”

The new software is running in addition to the existing system, which establishes a pattern and changes it for different times of day.

The new software will also completely erase an occasional, and frustrating issue, with induction loops: Sometimes they don’t detect the car if it’s not pulled into the lane correctly.

“With the visual loops, there’s no likelihood of someone missing a loop,” Barnes said.

Jacobson said the Rainier corridor is specially suited for this software because it has to many dynamic features, including Boeing, Renton High School, Renton Memorial Stadium, even traffic runoff from 405.