Tacoma bridges: functionally obsolete vs. structurally deficient

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As work continues on street repairs funded by two voter-approved measures two years ago, Tacoma has a number of bridges in need of improvement. The city’s Public Works Department is responsible for maintaining 43 bridge segments across 37 bridges. The federal government requires all bridges more than 20 feet long to be inspected at least every other year. Nine of these are classified as “functionally obsolete” and seven as “structurally deficient.”

The first term is used to describe a bridge that no longer meets current design standards in terms of roadway width and vertical clearance. A bridge in this category is not necessarily unsafe. As federal design standards change, a bridge may be placed in this classification if it was built using older standards. This includes the Puyallup River Bridge (two segments), the I-705/Schuster Parkway ramps (four segments), the East 34th Street Bridge over State Route 7, the South 48th Street Bridge and the Murray Morgan Bridge.

The second term is used when the load carrying elements are in poor or worse condition. This does not necessarily mean a bridge is on the verge of collapse. This category includes the Puyallup River Bridge (four segments), East 11th Street Bridge (two segments) and the East 34th Street Bridge near Pacific Avenue.

Of these bridges, the Puyallup River Bridge is weight restricted and partially funded for replacement. A 2014 structural evaluation led to a reduction of the maximum vehicle weight to 10 tons, closing it to most truck traffic.

In 2014 the city did a structural evaluation of the East 11th Street Bridge. This resulted in the city closing it to all vehicles and pedestrians. Public Works Director Kurtis Kingsolver said it is uncommon to close a bridge to both. “We never like to see a bridge get to the point that it needs to be closed.”

The East 34th Street Bridge underwent a routine inspection in 2017. It is deemed structurally deficient due to some erosion on the west side, but is open to all traffic.

The Puyallup River Bridge was closed on May 21, a closure expected to last nine months. The first phase of this project began in March with a pole line near the bridge being undergrounded. The second phase includes demolition and replacement of three spans west of the Puyallup River to Portland Avenue.

Funding comes primarily from two federal grants. The Bridge Replacement Advisory Committee provided $15.6 million and the Surface Transportation Program provided $12.2 million. This will replace two segments and partially replace a third. Two state grants were used. The Department of Commerce provided $6.9 million and the Freight Mobility Strategic Investment Board provided $5 million.

This leaves four segments in need of work. “Right now, I cannot see that being funded in the foreseeable future,” Kingsolver remarked.

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