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September 27, 2019

Infrastructure (non-transportation)

Photo provided by WACA
Amtrak's 380-by-80-foot pre-engineered metal service facility houses a 55-ton overhead bridge crane and a 125-ton drop table.

Amtrak railroad maintenance facility

Location: Seattle

Owner/developer: National Railroad Passenger Corp./Amtrak

Team: PCL Construction, general and concrete contractor; TKDA, architect; Hanson Professional Services, structural engineer; Cadman, ready-mix supplier

Demolition of an existing 35,000-square-foot, asbestos-contaminated warehouse was needed in Amtrak's King Street Coach Yard in Seattle to make room for the new 31,000-square-foot locomotive service facility.

This new maintenance shop sits atop 178 steel-driven pipe piles, each with a diameter of 24 inches. These piles were driven to a depth averaging 180 feet below grade. A heavily reinforced structural system of concrete-grade beams is used to tie the pile foundations together to support this new pre-engineered metal building.

The 380-by-80-foot pre-engineered metal building houses a 55-ton overhead bridge crane and a 125-ton drop table that is used to switch out traction motors and locomotive axles (trucks) for Amtrak's maintenance needs.

This drop table is located in a 25-foot-deep concrete pit in the center of the locomotive shop, as the trucks need to be removed from the underside of the locomotives. This complex structural system of building components and equipment is amplified as the poor soil conditions, high water table, high seismic hazard zone and dynamic loading from locomotives are all considered.

Other infrastructure upgrades in Amtrak's yard included an underground stormwater detention system, 12,000 lineal feet of yard track demo, realignment and new yard track installation. An underground force main for industrial waste was added and routed over 1,000 feet from the new locomotive shop to Amtrak's existing industrial waste treatment facility on site.

This line paralleled a new sanitary sewer force main that combined two existing buildings on the Amtrak site with the new locomotive shop’s needs. Together, four underground lift stations with depths up to 15 feet deep were needed to route over 2,500 lineal feet of industrial waste and sanitary lines through a variety of underground unforeseen rail yard debris and obstacles.

More than 7,200 cubic yards of concrete were placed into steel piles, grade beams, deep pit walls, and slab on grade to form the foundation for the new locomotive facility. The first concrete placements started with filling the 178 steel pipe piles. Concrete activities continued for seven months to complete the foundation that spanned approximately 31,000 square feet. Structural requirements for locations of construction joints meant that over 50 individual concrete placements had to take place, adding complexity to this robust structural system.

In addition to the heavily reinforced concrete grade beams and the more than 1,300 anchor rods that were cast, a challenging portion of this project was the construction of the 25-foot-deep drop pit, which measures 30 by 60 feet. Internally braced temporary sheet piling was installed to allow construction of the 24-inch-thick concrete walls and slabs. This pit concrete has an integral crystalline waterproofing admixture that keeps this critical work space dry as the ground water table sits 19 feet above the pit slab.

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