Three years after the project’s start, smart signs were activated for the first time along northbound I-5 from Boeing Field to the downtown area on Tuesday, providing a sneak peek into the system that is to come to I-90 in 2011.

With these signs up and running, Washington is one of the first states in the United States to have an Active Traffic Management system capable of assessing traffic speeds, warning of congestion ahead and directing drivers to change lanes. It’s expected to speed up commute times and reduce collisions in an area where space constraints make adding freeway lanes prohibitively expensive, according to Washington Department of Transportation officials.

“This type of thing has been in place in Europe for a couple of decades, and they’ve seen a 30 percent injury reduction rate,” said Patty Michaud, spokesperson for the Department of Transportation. “There’s this cyclical relationship where collisions lead to congestion, which leads to more collisions.”

By installing the signs, Michaud said, driving in the Seattle area should get safer and more efficient because drivers will be warned ahead of time about traffic slow-downs and lane closures, reducing rear-end collisions, and traffic engineers will be able to set aside lanes for emergency response vehicles to reduce the time that it takes for them to arrive on the scene of an accident.

Michaud said the I-90 sign system is currently undergoing its first phase of testing in Department of Transportation warehouses, but is on track to get up and running in spring 2011. When it does, she said, it will work just like the I-5 signs.

The smart sign system was particularly useful in the Seattle area because there is very little room to expand the freeways that run through the city, Michaud said. This was especially true of bridges such as I-90 and SR-520, where adding a lane could have serious environmental impacts and cost billions.

The sign project on I-90 and SR-520 is to cost about $42 million, and the I-5 system will cost about $24 million, according to the Department of Transportation Web site.

What will drivers need to do differently with smart signs in place? The answer, it seems, is fairly simple: “Pay attention and trust the system,” said Michaud. “It’s for your safety.”

For more information on WSDOT’s Smart Highway plan and I-90 Active Traffic Management, visit: www.wsdot.wa.gov/projects/lkwamgt/lkwaatm.