The ongoing construction of the $29.37 million Holgate to King Street project — an h-shaped bridge (elevated bypass) in downtown Seattle, Wash. — is expected to be complete next March and is part of the ongoing work to build the Alaska Way Tunnel.
The 1,428-ft. (435 m) long bypass is being built by Guy F. Atkinson Construction LLC. Actual construction began on July 12, 2012 following several months of serious planning as the project crosses the busy SR 99 freeway, railroad tail track operated by the Burlington Northern and Santa Fe Railway (BNSF), and is adjacent to the Port of Seattle and its cargo container yard Terminal 46, the Century Link Stadium (home of the Seattle Seahawks), the Safeco - field (home of the Seattle Mariners), and the work site for the Alaska Way Tunnel.
“They call our job the gateway to the tunnel,” said Ma Ma, Atkinson's project manager. “When a train goes by, the whole area stops. When completed, the bypass will eliminate traffic interruptions for the public and the port. We're building a two-lane bridge with three approaches.”
The bypass, designed by the Washington State Department of Transportation (WSDOT) and built for WSDOT, is being integrated into the existing road infrastructure.
The challenges for the concrete bypass are many, including a combination of cast-in-place box girder and the installation of precast tub girders for the lengths of the “h,” which were spliced with top girders. When completed, 15,000 cu.
yds. (11,468 cu m) of concrete will have been used, along with 1,500 tons (1,361 t) of reinforcing steel, 530,000 linear ft. (161,544 m) of prestressing steel, and 2,200 linear ft. (671 m) of prestressed concrete tub girder.
“A big thing about cast-in-place box girders is that it requires a lot of falsework and a lot of heavy steel beams that have been placed over traffic,” said Ma. “Erecting them was not easy and the highway was closed for a few weekends in late October and early November to strip all the falsework.”
Coordination with railway, the Port of Seattle and WSDOT, the city of Seattle, and the consortium building the tunnel is crucial as the bypass provides a solution for multiple problems. This required serious pre-planning and coordination with all the stakeholders, including subcontractors for the project.
“We're not facing major challenges,” said Ma, “but just the daily small problems associated with major projects such as this one and everything is progressing smoothly. We spent a couple of months estimating the project, redesigning some of the elements and preparing a work schedule.”
While there is room for Atkinson and the subcontractors (around 22) to establish temporary offices, depots and parking for vehicles and equipment, it was still a tight fit and a pre-staging plan needed to be developed to determine where equipment such as cranes would be placed, how equipment would be moved about, where to place materials for immediate use and for delivery schedules.
“The subcontractors had to buy off on the plan before we could execute the plan,” said Ma. “We have a lot of big equipment moving around, especially for the subcontractors such as Malcolm Drilling, which brought in many big cranes at the start of the project. We not only had to ensure the installation of the cranes, but how long it would take to remove them so that we let other subcontractors know when they could move in. We have between four and five subcontractors on site at any given time.”
On a daily basis Atkinson has about 46 personnel on site and subcontractors have between 15 to 30 people.
Some of the major subcontractors include: Gary Merlino Construction CO (for PCCP), Gerdau (for rebar), John-Wayne Construction Company (for barrier and moment slab), Lakeside Industries Inc (for asphalt paving), Malcolm Drilling (for drill shafts), Pacific Pile & Marine LP (for falsework piles), Schwager Davis Inc (for post tensioning), and Totem Electric (for traffic signals and illumination).
When weekend work occurs, operations are 24/7 per-day — two 12-hour shifts, and during regular operations, standard day shifts are the norm.
“You tend to get more productivity when people work during the day,” said Ma. “Working at night interferes with a lot of peoples' family time and schedules. When we get opportunities on weekends and closures on holidays, we can accomplish quite a lot.”
The project includes some drainage work as well, which will entail the removal of about 27,000 tons (24,494 t) of contaminated soil which will be sent for processing at local yards to remove recyclables.
“This is an area where much of the soil is contaminated,” said Ma. “Every time we dig, we have archeological recovery people on hand because there are many artifacts in the area due to being next to the port and on the waterfront.”
The nature of the project requires Atkinson to submit updated work schedules in advance and to hold weekly meetings to let everyone know what is happening to ensure that railway operations and traffic closures can be properly anticipated and implemented.
“They know that they can contact us any time with concerns and that we will respond rapidly,” said Ma. “The BNSF and the Port of Seattle are helping us a lot. We are constantly trying to do a good job as everyone has the same goal — open the bridge as soon as possible, as was the case for the falsework removal operation.”
The Alaska Way (SR 99 Tunnel — Design-Build Project) being constructed by Seattle Tunnel Partners, a joint-venture of Dragados USA and Tutor-Perini Corp., requires road access for a variety of heavy vehicles to access the tunnel via the haul route and this meant passing through areas where the falsework was installed and removed.
“We planned the falsework to accommodate their trucks and drive by the bridge daily,” said Ma. “We meet with Tutor-Perini officials every two weeks and they know what we are doing at all times. We're in constant communication. As long as you let people know what is going on, there are no surprises. Open communication is the key.”
Atkinson did not purchase any equipment for this project. The company, based in Denver, maintains fleets of vehicles and equipment in several key centers. For the bypass, Atkinson has brought in several Link Belt rough terrain RTC8065 cranes, Manitowoc Model 2892C 28-ton (25.4 t) boom trucks, several Ingersoll Rand VR-1056C forklifts, several F-150 (vehicles), and several F-450 (vehicles).
Ma does not have any onsite mechanics, but has access to Atkinson mechanics who visit a number of area construction sites on a regular basis for scheduled maintenance and unexpected breakdowns. For the cranes, Ma has access to dealers for repairs and for the forklifts, various vehicles and machinery, the company's mechanics.
“They come in for the typical repairs,” he said. “The forklifts experience a lot of flat tires and hydraulic chords snap. Right now I have four forklifts on site and we recently had one down, but were able to continue on schedule. The stripping work can take its toll.”
He added that his superintendent handles equipment issues and deals with the operators, who each day must do a thorough inspection of the vehicles and equipment they use, which includes filling in a daily report and a 360 walk-around the equipment.
“This way defects and problems are reported and the superintendent can take care of it and call in the mechanics,” said Ma.
Atkinson has set aside space for spare parts, the storage of fuel and oils, and repairs.
Ma said the bypass project is valuable in terms of experience.
“We are learning a lot,” he said. “This is probably the most complicated bridge I've ever built in my lifetime and it's the same for a lot of the people involved. The concrete work is pretty complicated as the bridge is on a big curve with high radiuses and trying to accommodate that requires a lot of engineering and a lot of thinking outside the box to get it done.”