In the face of possible destruction by the state Department of Transportation, the Pierce County Council voted 6-0 June 18 to place the McMillin Bridge on the county’s Register of Historic Places.

The McMillin Bridge is a concrete truss spanning the Puyallup River near Orting; at the time of its completion in 1935, it was believed to be the longest bridge of its kind in the United States. The bridge was designed in the 1930s by Washington engineer Homer More Hadley, responsible for the proliferation of European concrete hollow-box constructed bridges in Washington state. His dream of a Lake Washington bridge floating on hollow concrete pontoons resulted in the construction of the Mercer Island Bridge, which opened in 1940; the Third Lake Washington Bridge was renamed the Homer M. Hadley Memorial Bridge in 1993.

The McMillin Bridge sits on the roadway of state Route 162; in recent years, WSDOT classified the bridge as “functionally obsolete” due to its narrowing of the highway to two opposing lanes. In 2011, the Department calculated average annual daily traffic for state Route 162 at 4,100 to 21,000 vehicles a day.

In 2010 and 2011, the Department worked on designs for a wider bridge adjacent to the existing bridge, and sought input on what to do with McMillin. One of the options discussed was a rerouting of the Foothills Trail onto the bridge, a plan the Department argued would require Pierce County to take ownership of the structure. They wrote a letter to the County offering to transfer ownership of the bridge as a Foothills trails route or lahar evacuation path, but County officials declined, noting that pedestrians were already served by a nearby footbridge.

Current plans call for wholesale replacement of McMillin with a modernized bridge, with construction scheduled for summer 2014.

The bridge was placed on the National Register of Historic Places in 1982. Councilman Stan Flemming, sponsor of the ordinance to put the bridge on the County’s register, said the vote was an additional step to encourage preservation of the bridge.

“It’s the only known bridge of its type in the world,” he said in a June 24 Pierce County press release.

WSDOT must await permit approval by the Army Corps of Engineers to move forward with bridge construction. Because the bridge is on the National Register of Historic Places, the Corps is bound to follow Section 106 procedures examining whether a project will adversely affect a historic property, and whether alternatives that minimize adverse effects can be reached. So far, the Corps has responded to all WSDOT Preservation Alternatives Analysis reports calling for the bridge’s demolition with further follow-up questions.

“The merit of being placed on the historic register may not ultimately save the bridge, but it is acknowledging that it’s worth the distinction,” Councilman Dan Roach said in the June 24 press release.