The only way the Washington State Dept. of Transportation can describe building a highway off-ramp in the wrong location: “Unfortunate and embarrassing.”

Construction reached 90% completion on the eastbound ramp to Sprague Avenue as part of the $119.9-million Nalley Valley interchange that addresses traffic snarl where Interstate 5 meets State Route 16 in South Tacoma before the problem surfaced. Tearing out a portion of the ramp and changing the profile for 700 ft begins to right the wrong.

Kevin Dayton, WSDOT regional administrator, says this mistake got past several checks in the system. “The ramp should have been flat, it wasn’t,” he says. “It caused (crews) to scratch their heads. The ramp was originally designed for an off connection for a two-lane freeway. In the design process, a third lane had been added.”

The wider freeway meant the off-ramp would connect to an overpass at the wrong spot and needs lowering. “The bridge over State Route 16 is at the right point,” Dayton says. “The ramp either needed to move outward laterally or have its profile changed.”

The problem stems from three projects meshing together and too much disruption in the process, says DOT spokesperson Lisa Copeland. The interchange had three funding sources for the westbound, eastbound and HOV connector sections. Several engineers worked for multiple years to design the westbound project.

“This phasing clearly required a great deal of coordination between the design teams to ensure the designs meshed together,” Dayton says. “The addition of a third lane to the eastbound project was not communicated or coordinated with the current westbound project.”

A change order for nearly $900,000 — out of the project’s contingency fund at the cost of WSDOT— was worked out with project contractor Guy F. Atkinson Construction of Renton, Wash., and has already started. Removal of panels of the retaining wall lowers the grade change to a maximum of 12 ft. The work should take 12 weeks and not delay the project.

A spokesperson for Atkinson was unavailable for comment, but in unfortunate foreshadowing, Kathleen Wilcox, Atkinson’s project manager told ENR in April: “The most difficult thing about the project is the size of everything. Everything is so high and so big it takes a lot of preplanning and scheduling.”

Copeland says that WSDOT, as a direct result of this situation, plans to incorporate more checks and reviews during all points of design and construction.

“Mistakes get made, checked and corrected and sometimes they don’t get caught till the last minute,” Dayton says. “Never have I been personally involved in a job like this where it was corrected after constructed.”