Big Bridges
Local Spans Expanding and Receiving Facelift

Multi-million dollar bridge projects in Oregon and Washington dominate DOT budgets.

by George Bukota

Getting vehicles across waterways has never been easy. It isn't cheap, either.
Not only is it a difficult task to levitate huge concrete deck sections - and to keep them in place under load - but the damp environment constantly attacks all construction materials.

It's little wonder, then, that six of the top 10 infrastructure projects in Oregon and Washington this year are bridges.

The largest is Washington's new Tacoma Narrows Bridge on State Route 16, a six-year, $849 million project so large that general contractors Bechtel and Kiewit Pacific named their joint venture for the project. It's called Tacoma Narrows Constructors and is headquartered in Gig Harbor.

Oregon's largest bridge project, St. Johns Bridge at $30.98 million, seeks to rehab a bridge that has been exposed to the elements for nearly three quarters of a century.

Tacoma Narrows

Every transportation engineer in the Northwest has seen the infamous "Galloping Gertie" film, about 10 to 15 seconds of the first Tacoma Narrows Bridge whipping itself to pieces under high winds in 1940. It was the end of a nearly 50-year era of building lighter, graceful and flexible bridges.

But its death wasn't a complete loss. The tons of material that settled beneath about 100 to 150 ft. of water is the largest man-made structure ever lost at sea and has become the largest single man-made reef sheltering abundant marine life.

"Bridge engineers have learned a lot since Gertie's demise," said Craig McDaniel, Washington Department of Transportation's chief engineer on the current Tacoma Narrows Bridge project.

The second Narrows Bridge was tested in University of Washington wind tunnels before the design was approved and construction began in 1948. That bridge opened to traffic in 1950 and all components were completed a year later.

Among the changes in bridge design were an increase in total superstructure weight by 1.6 times per lin. ft. and a reinforced roadway deck design that included open steel gratings between each traffic lane and at both curbs to reduce wind forces on the deck.

Bridge length was extended 40 ft. to 5,979 ft., with a main span of 2,800 ft., making the current bridge the fifth longest in the United States. It was designed to carry 60,000 cars per day and now carries some 90,000 per day.

Work began on the latest Narrows Bridge in October 2002 and should be completed in 2007. The new bridge will maintain the existing bridge's overall length of about 5,400 ft. Its 510-ft. towers, each made with 23,000 cu. yds. of concrete, will be within 5 ft. of the current bridge towers.

The suspended superstructure being built south of the existing bridge will include three standard-width 12-ft. eastbound traffic lanes, two 10-ft.-wide shoulders and a 10-ft.-wide bicycle/pedestrian path separated from the shoulder with a barrier.

One traffic lane in each direction will be restricted to high-occupancy-vehicles and will connect with other HOV segments under construction along the SR-16 corridor.

A second deck can be added later to carry more cars or light rail traffic as needed. When the new bridge opens, the existing Narrows bridge will be refurbished and reconfigured for three full-size westbound lanes and shoulders, and surface grates will be removed from the existing deck.

One of the biggest jobs in this project is placing two 56,000-ton caissons - or tower foundations - into the seabed. Simply getting structures that large precisely positioned beneath as much as 150 ft. of water is complicated by the tides - which can change sea level by 15 ft. - and by strong currents flowing north or south.

Caissons are placed precisely with the help of electronic distance meters, global positioning systems and laser beams to align the caisson.

The project includes adding an HOV lane in each direction on a 3.4-mi. segment of SR-16 from Tacoma's Jackson Avenue interchange to west of a new interchange at 36th Street NW. It also includes a new underpass at 24th Street NW that opened to traffic in September.

Meanwhile, in Oregon

Oregon's St. Johns Bridge is being rehabilitated after being exposed to the elements for more than 70 years.

General contractor Max J. Kuney Construction of Spokane, Wash., is replacing deck and sidewalks, refurbishing railing, replacing deck joints and frozen bearings, removing loose lead-base paint and repainting metal surfaces, and improving Bridge Avenue ramps on the Willamette River's west side, according to Greg Waugh, Max J. Kuney project manager.

Portland's northernmost bridge over the Willamette River was opened in 1931 to replace the city's last ferry, which linked St. Johns with Linnton, a community just north of today's bridge access in Fairmont. At the time, it was the longest suspension bridge west of the Mississippi River.

It is still the only major highway suspension bridge in the Willamette Valley and one of only three major highway suspension bridges in Oregon.

The four-lane bridge features steel Gothic arch towers, Gothic-inspired reinforced concrete piers for the steel frames and the longest prestressed steel cables designed in the 1930s.

The St. Johns bridge rehab began in March 2003 and is scheduled for completion in 2005.

The second of three construction stages should begin in April, Waugh said.

"We completed the first stage of rehabbing the north-side lanes," he said. "Now we'll work on the center section and, finally, we'll rehab the south side."

Waugh said the north-side rehab work uncovered and replaced more "substandard" cables than originally forecast. The extra cables are covered in the contract's "quantity overrun" clause and shouldn't impact the overall project timetable, he added.

Waugh said work on the bridge has given him a better appreciation for the creativity and engineering ability of the people who built it in the 1920s and 30s.

"We'd dig into some part of the bridge and uncover something that would stop us and make us think, 'Why'd they do it that way?'" he added.

"Then we'd run into a problem and realize that those old-timers had the same problem and that's how they fixed it.

"Sometimes we don't have a better solution, so we do it the same way they did back then."