"While conducting functional testing of the hydraulic systems we were able to identify this issue before it became an operational problem," said WSDOT region administrator Kevin Dayton.

Engineers are trying to determine why the rear hydraulic lifts of the three structures that make up the west-half draw span are operating more slowly than the front lifts. The systems are producing different pressures, which are causing the lift spans to operate at different speeds. Final testing work by contractor Kiewit-General had been scheduled for completion by the end of February.

The Hood Canal Bridge's west half was widened in 2006 with retrofit work on the lift systems taking place in 2009. The entire east half was replaced in 2009 and continues to operate and open for marine vessels while the west-half retrofit continues.