Almost any time of the day, traffic on Interstate 494 tends to slow to a crawl as it nears I-35W. That's when drivers tend to pull off and seek a faster east-west route on 76th Street in Richfield or American Boulevard in Bloomington.

But with so many stoplights on those roads, traffic congestion can be just as bad there as on the freeway.

Now the Minnesota Department of Transportation (MnDOT), Hennepin County and the two cities are getting together to try to better time the stoplights to improve the flow by the end of next year.

It's an unusual effort involving traffic signals that are separately owned by cities, the county and MnDOT. The project will count cars, analyze traffic patterns and try to devise a signal timing plan that will let groups of cars stop at a light and then move as a group through several green lights.

"This is more complex than usual," said Kevin Schwartz, a MnDOT signal optimization engineer for the metro area. "The difficulty is in communications, keeping all the different signals in sync. ... We need to hook up the signals so they talk to each other."

American Boulevard in Bloomington and 76th Street (which becomes 77th Street) in Richfield are two of the busier streets in those suburbs, carrying 17,000 to 20,000 vehicles per day at their peak. Both run parallel to I-494 and take spillover traffic from the freeway.

Schwartz said MnDOT has wanted for some time to better synchronize the lights on those roads and intersecting streets. The rebuilding of bridges and roads in the area delayed the signal project until construction eased and traffic patterns settled down.

"Our goal is to not have you stop at each signal as you go through there," Schwartz said. "If you get stopped at Penn, our hope is that we can take that platoon of cars and bring them through the rest of the signals going east. And then when they get close to Lyndale, having that light turn green."

The project is expected to cost at least $100,000, with MnDOT, the county and cities contributing to cover the cost.

Jeff Pearson, a transportation engineer with Richfield, said he knows from personal experience how the project could benefit drivers.

"I take it quite a bit from work and home and every once in a while I hit it right, but there can be numerous backups depending on the time of day," he said. "This would allow drivers to get through the city faster ... and it really maximizes [76th Street's] effectiveness as a reliever to the freeway."

Karl Keel, Bloomington's public works director, said the cities, county and MnDOT sometimes have different priorities for traffic lights, and the project should fix that. He said the project also should have energy and environmental benefits.

"From an energy point of view, cars are much less efficient when they're idling at lights rather than driving," he said.

Many streets will be affected

The project affects not only 3 1/2 miles of American Boulevard and 76th and 77th streets from France Avenue to 12th Avenue, but also mile-long spans of major north-south streets like Penn, Lyndale and Nicollet Avenues where they cross the freeway.

Exactly what will be done depends on variables like how many cars a left-turn lane can handle, Schwartz said. Traffic light timing could change depending on which direction most of the traffic flows at morning, noon and evening rush hours.

For drivers, improvements in traffic flow may be hard to spot if they're at the wrong intersection at the wrong time, Schwartz said. Green lights and left-turn lights may change more quickly than they did before to keep timing coordinated with nearby signals. Paradoxically, Schwartz said, complaints to MnDOT tend to come after signal timing has been changed because some green lights are shortened.

And the benefits of coordinated signals can be short-lived, Schwartz said. Drivers quickly find the fastest way, changing traffic patterns. MnDOT usually re-examines signal timing in busy areas a few years after reprogramming.

Bloomington is beginning a separate project, funded with $200,000 in federal stimulus money, to optimize traffic signal timing at 45 intersections in the city. Tom Bowlin, a civil engineer in traffic and transportation for the city, said the intersections were selected because their signal timing had not been refined for at least three years.

Included in that project are stoplights on streets around the Mall of America and on Old Shakopee Road, Lyndale Avenue, W. 98th Street and 84th Street near Normandale Boulevard.

Mary Jane Smetanka • 612-673-7380