A federal district court judge in Washington state has approved a $1.8-million settlement between contractor Flatiron West and its subcontractor, PTS Surveying Inc., for survey errors that caused a misalignment on a bridge that was part of a completed $206-million segment of the state's $4.51-billion State Route 520 Bridge Replacement and HOV program

The program, intended to link the road to Interstate 5, features a full replacement of the world’s longest floating bridge across Lake Washington in Seattle.

Flatiron West was general contractor for the West Approach Bridge North project, a 6,000-ft elevated roadway connecting the floating portion of SR 520 with the surface road in a Seattle suburb. The West Approach Bridge was a precast girder bridge founded on large-diameter cast-in-drilled-hole piles, primarily over water, that was designed to bring westbound vehicles from the new floating bridge to Montlake Avenue near the University of Washington.  

The project started in July 2014 and completed in January 2017. The new floating bridge opened in April 2016. Hillsboro, Ore.-based PTS was the project survey subcontractor under a $1.08-million contract.

The structure is built on 41 drilled shaft piers. PTS had the job to verify the primary horizontal and vertical control points furnished by the Washington State Dept. of Transportation and expand them by adding stakes and hubs and additional survey control needed for the project. “This entailed establishing the location and elevation of critical components of the project substructures, including the foundation shafts and columns,” Flatiron said in its suit filed in February 2019.

After construction began in 2014, state DOT surveyors noted an apparent 3-in. discrepancy between the actual and intended location of the drilled shaft centerline for one pier.

Two additional survey contractors hired by Flatiron reviewed the secondary control points and found a gradually worsening north-south misalignment of the substructure from piers 18 to 42, resulting in a 5-in. discrepancy where it met the floating bridge.

A significant portion of the substructure from piers 18 to 42 had been built and many of the foundations and columns already installed when the errors were discovered. WSDOT and Flatiron determined that the least costly fix was to redesign the superstructure to accommodate the substructure horizontal misalignment, the complaint said. Flatiron calculated the damages to be no less than $1.8 million.  

PTS denied the errors but agreed to settle the complaint after learning that its professional liability insurance policy excludes bridge work, according to the April 28 settlement order.

The firm said continued litigation would present significant financial hardship and it could not afford to defend itself. “Given these circumstances, it was reasonable for the parties to seek settlement by covenant judgment,” Judge Marsha Pechman said in her order.

With work on the original SR 520 Bridge Replacement and HOV Program complete, WSDOT still manages what it calls the Rest of the West, continuing to tie the SR 520 corridor to Interstate 5, an ongoing $1.64-billion project.