Twin Rivers Of Concrete -- New Hewitt Avenue Trestle Goes Up As 30, 000 Cars A Day Keep Flowing

On those rare occasions when Ebey Island is completely flooded, the Hewitt Avenue Trestle looks like a long pier cutting across an immense lake.

The trestle, after all, is a bridge, a 2 1/2-mile wood and concrete span that connects Everett to central Snohomish County towns across a fickle flood plain dominated by the mood swings of the Snohomish River.

There are two trestles, actually, and unlike the Snohomish, they are rigid rivers of concrete firmly attached to Ebey Island. Its pilings dig deep, an average of 90 to 100 feet before they touch solid ground.

One of the trestles, its foundation made of wood, dates to the 1930s. Some drivers claim to feel its timbers buckling underneath as they head east. It carried traffic both ways until the 1960s, when westbound traffic moved onto a new concrete and steel trestle built alongside.

The ongoing project to replace the old wooden structure is not easy or cheap: $100 million over 10 years. The first phase of the project is almost complete, at a cost of $19 million. Stage two will begin soon at a cost of $13 million.

The reasons for building a road across such fickle landscape were lost in history long ago. At one point, the road was at ground level, nothing more than wooden planks laid side by side. Later, concrete would cover the same spot.

At the turn of the century, wooden trestles were the most efficient way to connect roads across gullies, around hills and over creeks and rivers, historian David Dilgard said.

"That's basically what they used, a lot of wood," Dilgard said. Old Mukilteo Boulevard was built on a series of trestles before a modern road took over.

Today, the trestles have become major east-west routes, something the old wooden span wasn't designed for. As many as 30,000 vehicles per day cross the trestles, said Steve Miller, project engineer with the state Department of Transportation. He is in charge of construction of the new trestle.

It takes only one accident to back up traffic for hours on the old trestle, which doesn't even have shoulders. During rush hour, traffic waiting to cross it builds up on Interstate 5.

Building a new trestle will be tricky. The top 90 to 100 feet of the river valley is soft silt, deposited by the Snohomish over countless years.

Some of the roads built on Ebey Island show the damage left behind by shifting land. An access road to the trestle rides like a roller coaster, only rougher.

"Any weight you put on it, will make it settle," Miller said. "There are some artesian-type waters that have caused some problems with construction. It is very soft." ------------------------------------------------------------------- Construction is a 10-year project

It will take 10 years and $100 million to build a new trestle and demolish the old wooden one on Ebey Island, between Home Acres Road and Ebey Slough. The project is planned in five stages: -- Phase 1: Construction of a bridge over Ebey Slough and a new interchange at Highway 2 and Highway 204 at the eastern end; access to 20th Street Southwest. Cost: $19 million. Completion date: October. -- Phase 2: Construction of a temporary road while sections of old trestle are replaced; replacement of wetlands lost to construction. Cost: $13 million. Completion date: The two-year project begins after July 4. -- Phases 3-5: Underground utilities for Everett water constructed; Homes Acres Road moved farther east and new access to trestle built; continued replacement of trestle to the west; replacement of old steel drawbridge over Snohomish River with a high concrete bridge. Cost: $68 million. Completion date: 2001.