The world's longest floating bridge - the Evergreen Point Bridge (or SR 520) - rests atop Lake Washington in Seattle. The bridge has had an important impact on the development of the Seattle metropolitan area, providing commuters easy access between Seattle and communities east of Lake Washington. As the bridge hovered around its 50th birthday, it was deemed time for an upgrade, and so it was approved that a new SR 520 would be built alongside the existing bridge, becoming the "new" longest floating bridge in the world.

The new bridge is a component of a $4.6 billion project that includes the SR 520 replacement with high occupancy vehicle (HOV) lanes, bicycle/pedestrian paths, and the potential for a future light rail.

Water Work Poses Challenges

Pacific Pile and Marine, a heavy civil and marine contractor, has experience with end-over-end construction and marine-based trestle installations. The company was subcontracted to install the wooden access trestle that will make it possible to build the West Approach Bridge North - a portion of the SR 520 project that will eventually connect to the new floating bridge over Lake Washington. When your worksite is on waves, however, it can bring some unique challenges.

"Access is a major obstacle on a project like this. We need a work platform to get the materials and supplies out on the water," says Mark Steen, Logistics Superintendent and Yard Manager, Pacific Pile and Marine. "We build a bridge to be able to build a bridge." The wooden trestle will also provide access points for Pacific Pile and Marine to install 99 steel casings that will form the concrete columns that support the roadway of the floating bridge.

With future progress relying on the work trestle, Pacific Pile and Marine couldn't afford to lose any time. "We had a day shift and night shift working around the clock," says Brian Clark, Superintendent, Pacific Pile and Marine. The project also had to contend with the state mandated freshwater work window, which prohibits "in-water" construction during certain times of the year in order to protect spawning and incubating fish populations. 

Insuring Less Downtime

Renting equipment helps ensure equipment problems won't hinder productivity, causing a delay that compromises the entire project timeline. "On a project like this, if one part falls behind, it's a chain reaction," says Clark.  "We like to rent equipment so in case it goes down, we can get it replaced immediately and keep up with our schedule. We don't have to deal with maintenance headaches."

Papé Material Handling is the primary equipment supplier for Pacific Pile and Marine. The relationship between Pacific Pile and Marine and Papé Rents goes back more than a decade. Papé Territory Manager Erik Strecker plays an integral role in ensuring Pacific Pile and Marine has the equipment to get the job done. "We depend on Papé Rents to make sure we have quality equipment and good service," says Clark. "Erik understands that if the rental equipment fails, we fail to stay on schedule." 

Strecker in turn relies on Doosan Portable Power to deliver reliable performance. "For me it all comes down to quality," he says. "Any equipment I recommend is going to be a premium, competitive product. And in my experience, Doosan Portable Power is superior to the competition."

The timeline crunch made around-the-clock work a must. Light towers made it possible to continue work overnight, while also providing auxiliary power for tools like electric drills and battery chargers. "Those light towers ran 24/7," says Clark. "It was dark from 5 p.m. until 8 a.m. every day, and we needed a piece of equipment that was going to stay up and running."

Protecting the Wildlife

Another unique challenge of marine construction is the EPA regulations associated with water life protection. As part of the pile driving activity necessary to build the work trestle, the state requires the use of oil-free air compressors to create mandatory bubble curtains.

A bubble curtain is designed to protect fish from the noise and pressure waves generated by the impact of pile driving. It's created by placing a ring with small holes around the pile, and using an air compressor to produce the necessary swell of bubbles in the water around the pile. Because the air is dispersed into the water, the air compressor must meet oil-free regulations.

 "The Doosan Portable Power compressors were some of the only air compressors that had it," says Steen, referring to the IQ System technology unique to Doosan Portable Power air compressors, which removes residual oil from the compressed air.

By the time the fishing window took effect, Pacific Pile and Marine had installed 657 piles, completing a 1-mile span of the work trestle. Work began again last month when in-water work restrictions were lifted and the three HP935 air compressors with the IQ system, 13 LSC light towers, G70 generator and G25 generator - all Doosan Portable Power products - were back on the job.

As the trestle extends, so does Pacific Pile and Marine's progress on installing steel casings - 99 in all once the West Approach Bridge North and the floating bridge connect over the waters of Lake Washington.

The SR 520 project is expected to be completed in summer 2017, when the old Evergreen Point Bridge will pass on its crown for "world's longest floating bridge" to the new bridge in town.