Speeds on the 88th Street NE overpass over I-5 have dropped to a crawl thanks to a crush of new big-box stores, the Tulalip Casino and outlet mall, and hundreds of new homes in the area.

Knowing that plans to rebuild the interchange are years away and are not guaranteed to receive funding, Tulalip Tribes officials have taken matters into their own hands.

Owners of many new businesses that lure the drivers who help clog 88th Street, the tribe is spending $1.5 million to squeeze one extra westbound lane onto the overpass.

The project, which just started, will also add a second left-turn lane onto 88th Street from the northbound I-5 exit.

“We’re looking at it as a pure safety issue,” said John McCoy, general manager of Quil Ceda Village. “We need to get traffic off of I-5 as quickly as possible.”

Quil Ceda Village is the economic development arm of the Tulalip Tribes. It operates Tulalip Casino and Seattle Premium Outlets. McCoy is also a state representative from Tulalip.

A little-used sidewalk on the south side of the overpass is being removed, giving state engineers room to add one extra lane. Pedestrians can still use a sidewalk on the north side of the overpass.

Adding a fourth westbound lane to the bridge will allow westbound traffic to keep moving during the afternoons, when exiting traffic often backs up onto northbound I-5, said Travis Phelps, a spokesman for the state Department of Transportation.

When the work finishes in October, there will be two westbound through lanes and two lanes for turning onto southbound I-5, Phelps said.

Now there are only three westbound lanes, with the middle lane alternating between a through lane and a left-turn lane.

Traffic exiting at 88th Street climbed 40 percent from 2002 to 2006, Phelps said.

According to state data, 9,500 cars exited northbound I-5 per day at 88th Street in 2002. By 2006, that number had climbed to 13,280 cars per day.

Westbound traffic across 88th Street has grown heavier, increasing from an average of 400 vehicles during the peak afternoon commute period in 1999 to 1,095 vehicles during that same period in 2006. That’s an increase of 178 percent.

McCoy said the tribes want to do their part to help solve north Snohomish County’s growing traffic congestion problem.

He said the problem remains a regional one, pointing out that traffic counts show that 70 percent of the traffic exiting the freeway heads east, away from the Tulalip Reservation.

Money to rebuild the 88th Street overpass is included in a road and transit tax package set to go to voters in November. The project cost $38 million.