This Port of Tacoma project raised Lincoln Avenue over key railroad tracks in the Port area, removing the at-grade conflict between rail activities and heavy vehicular traffic. The bridge design incorporated large earthen embankments founded on reclaimed lands composed of highly variable fill soils and landfill.
Malcolm Drilling installed approximately 120 dry, bottom-feed stone columns to a 55 foot depth at the planned locations of bridge abutments. The purpose of the stone column ground improvement was to reduce the liquefaction-induced settlements of bridge abutments and embankments during a seismic event. Malcolm utilized a B-27 Vibroflot featuring state-of-the-art technology to construct the stone columns on this project. Powered by a 180-hp electric motor, the B-27 Vibroflot generates more than 25-tons of eccentric force. The Vibroflot is suspended from a crawler crane and is modular in nature; enabling construction at depths from near-surface to greater than 100 feet and diameters ranging from 30 to 48 inches. A robust automatic data acquisition package is mated to the system to complement quality control measures. Offering an economical and convenient package to the general contractor, Malcolm also installed drilled shafts to support each bridge pier along the eight bents.