Tear up I-5 in Seattle, start over, DOT says

First we learned the Alaskan Way Viaduct might collapse in an earthquake. Then we found out the Highway 520 bridge might sink in a big storm.

Now this.

The state Department of Transportation says the 40-year-old pavement on Interstate 5 through Seattle and Shoreline — the busiest stretch of freeway in the state — has deteriorated so badly that it needs to be torn out and rebuilt.

Not just resurfaced, but replaced. Not just the freeway's skin, but its muscles and its bones.

That includes the concrete, the steel rebar, the asphalt base — almost everything down to the dirt — on all the non-elevated stretches of the freeway from Boeing Field through downtown Seattle to the King-Snohomish county line.

It could take decades to complete work on all 18 miles. Construction could affect traffic for years. Project director Maureen Sullivan says the project could cost $2 billion or more.

She likens it to putting a new roof on your house: You can keep patching it and delaying the inevitable, Sullivan says, "but after a while you just have to take the whole thing off and put a new one on."

The sorry state of I-5 isn't a recent discovery. The Transportation Department conducted a study of the pavement's condition four years ago, concluded it was nearing the end of its useful life and recommended it be replaced. The agency's Web site has devoted a page (now outdated) to the project for at least a year.

But nothing has happened and it has gone mostly unnoticed, because the Legislature hasn't provided any money.

That could change soon. Gov. Gary Locke and House and Senate leaders are negotiating a new transportation package, to be financed mostly by a gas-tax increase, and I-5 is one of the projects in play.

Senate transportation leaders have proposed $144 million. Locke and the House have proposed nothing. That's fine with Seattle Mayor Greg Nickels and environmentalists, who say other projects — the viaduct, for instance — are higher priorities, considering limited funding.

But there's another issue lurking here. State Sen. Jim Horn, R-Mercer Island, who chairs the Senate Highways and Transportation Committee, wants the Transportation Department to spend some of the I-5 money to study ways to increase the freeway's capacity, perhaps by adding lanes.

"Nine percent of the congestion in the whole state of Washington occurs on I-5 in Seattle," he said this week. "We ought to look at doing something about it."

But the notion of expanding capacity raises red flags for environmentalists, who say adding more lanes for cars won't really solve congestion.

Nickels doesn't like the idea either, said spokeswoman Marianne Bichsel.

"Greg has said over and over again that we're not going to double-deck I-5," she said. "Giving people more options, like light rail and the monorail — that's what's really going to solve our transportation problems."

Tires and ice

"The greatest transportation improvement in the history of our state." That's what the director of the state Highway Department called Interstate 5 at a ribbon-cutting ceremony Jan. 31, 1967, the day the freeway first carried cars through Seattle.

The pavement had been poured in stages, starting in 1960. At the time, engineers expected it would need to be replaced in about 20 years.

Since 1967, 36 winters and billions of tires — especially the studded ones — have taken their toll on the pavement, Sullivan says. It's cracked, rutted, pocked with potholes. It's been patched in places over the years, "but that's never as strong as the original," she says.

The pavement on the elevated stretches of the freeway has mostly been replaced already, Sullivan says. If the same isn't done for the surface stretches, she says, the freeway will just get worse — rougher, slicker, less safe.

Only there's no money. The project's enormous price tag dwarfs the Transportation Department's current two-year budget of $558 million for highway preservation statewide, spokeswoman Linda Mullen says.

If the Legislature provides money for I-5, the department plans to pour 21 inches of new material: 13 inches of concrete atop 4 inches of an asphalt-concrete mix atop 4 inches of asphalt base.

Overpasses, sign supports, wiring and lights all would be replaced. Where possible, lanes and shoulders would be widened. The storm-water-drainage system would be retrofitted to meet today's environmental standards.

Thirty-six years of growth since 1967 also have exposed the freeway's design flaws. Lanes appear and disappear — there are just two through lanes in each direction through the downtown core. Left-hand on- and offramps have helped create such infamous bottlenecks as the Mercer and Ship Canal "weaves."

Department planners are exploring ways to address those problems as part of the repaving project. A study should be completed in about a month, Sullivan says.

Among the possibilities: Adding short lanes in places. Reconfiguring existing lanes so they appear and disappear more logically. Moving the southbound Ravenna onramp from the left side of the freeway to the right. Removing the northbound Seneca Street offramp. Separating traffic bound for northbound I-5 from I-90 from traffic leaving northbound I-5 for the James and Madison street exits.

Nothing has been decided, Sullivan stresses.

Sydney Elmer of the anti-sprawl group 1000 Friends of Washington says she has no problem with improvements that would allow I-5 to operate more efficiently. But increasing the freeway's car-carrying capacity would be a big mistake, she contends.

"New capacity brings new drivers," Elmer says. "Pretty soon you're right back at your previous level of congestion."

Horn disagrees. I-5 through downtown Seattle is a bottleneck that affects traffic throughout the region, he said.

Several months ago, for instance, the Transportation Department announced a possible eight-lane bridge across Lake Washington to replace the existing, four-lane 520 span wasn't feasible because a bridge that big would dump more traffic onto southbound I-5 than the freeway could handle.

"They dropped it not because the (eight-lane) bridge wasn't workable, but because of that bottleneck in downtown Seattle," Horn said. "It highlights the problem."

A third lane

Adding a third through lane in each direction to I-5 through downtown would help a lot, Horn said. He said he doesn't know if that's possible, but it should at least be investigated.

His top priority for I-5 funding, Horn said, is $10 million for an environmental-impact statement that would cover capacity expansion as well as pavement replacement.

"We don't like it," said Bichsel, Nickels' spokeswoman. "This is Jim Horn's idea for expanding I-5. The money needs to go into the viaduct."

The Senate package proposes just $45 million for Alaskan Way Viaduct work, compared with $100 million in the House package and $95 million in Locke's.

Sullivan says it might be possible to increase I-5's capacity without providing more lanes for single-occupant cars: Additional capacity for buses, car pools and freight also would be studied if the impact statement is funded.

Any construction on I-5 is years away, Sullivan says, but the department is thinking about ways to reduce its impact on traffic.

The reversible express lanes might be operated differently, she says. Or the department might close all lanes in one direction on a stretch of freeway on weekends, as it did on Interstate 405 during a repaving project in 1997.

Eric Pryne: 206-464-2231 or epryne@seattletimes.com