Two-track effort will address short and long-term needs of bridge

The Sellwood Bridge is the busiest two-lane bridge in Oregon. One reason the bridge is so popular is that it provides the only crossing for a 12-mile stretch of the Willamette River, between Portland and Oregon City. Many bridge users live or work outside Multnomah County.

Yet the bridge also has serious problems. The 79-year-old structure was not designed to support the weight of modern trucks and buses. In 2004 weight limits on the bridge were reduced from 32 tons to 10 tons, after cracks were discovered in concrete girders on the approach spans.

Prior to the reduction of weight limits, the bridge was an important secondary freight route, especially for local deliveries. Weight limits prevent many companies from using the bridge, forcing out-of-direction travel that adds to congestion on other routes and increases costs to businesses and consumers.

Other bridge deficiencies include:

  • Western approach is settling and sliding, leaving structure vulnerable to earthquakes.
  • Cracking in bridge deck, columns and beams. Large cracks discovered in concrete approach spans in 2003 were reinforced with steel plates. A 2004 inspection discovered additional cracks at east end of bridge.
  • Narrow traffic lanes with no center median or shoulders.
  • Tight ramps at west end cannot accommodate large vehicles.
  • Only one narrow sidewalk.
  • Traffic is at capacity during peak hours.
  • Structural sufficiency rating is 2 out of a possible score of 100. Bridges rated below 50are generally recommended for replacement.

Multnomah County’s Response

Reduced weight limits on the Sellwood Bridge are causing more than 1,000 trucks and buses to use a different river crossing each day. While this helps extend the life of the bridge, it adds to congestion on other routes and increases transportation costs. Multnomah County is addressing the Sellwood Bridge problem with two strategies: one short-term, one long-term.

Short-Term Strategy: Keep Bridge In Service

The short-term strategy is to keep the bridge in service for the 30,000 vehicles that use it each day, until a long-term solution can be achieved. The short-term strategy includes:

  • Quarterly bridge inspections: Federal law requires bridges to be inspected every two years. Because of the Sellwood’s many problems, the County is inspecting the bridge every three months. This increased schedule will help bridge engineers monitor the structure’s condition and ensure it remains safe to use.
  • Strengthening study: A consultant is being hired to conduct an intensive bridge inspection and propose retrofits to preserve and possibly strengthen the bridge. The study will help determine how the bridge can be kept in service for another decade. It will identify costs to strengthen the bridge so that it can support larger vehicles such as TriMet buses. The consultant’s report will be completed by the end of the first quarter of 2005.

Long-Term Strategy: Bridge Replacement or Rehabilitation?

In the long term the Sellwood Bridge needs to either be replaced or undergo a major rehabilitation to serve the needs of the region for this and future generations. A long-term solution will eliminate barriers to the movement of freight and improve safety and traffic flow for all bridge users. Multnomah County is aggressively seeking $4 million to begin design work on this long-term solution. If funds can be secured, design work will begin in 2005. The design phase will include extensive public involvement.

Issues to be considered in a long-term solution include:

  • Bridge replacement or rehabilitation? Multnomah County’s Capital Improvement Plan calls for replacement of the Sellwood Bridge. A 1999 study by Metro, the regional government, came to the same conclusion. But due to the high cost of a new bridge, the County will also explore the possibility of rehabilitating the existing bridge.
  • Two lanes, four lanes, or some combination
  • Upgrade bicycle and pedestrian facilities to current standards
  • Coordination with SE Tacoma Street plan
  • Alignment of new bridge: north, south or same location
  • Intersection or interchange at Highway 43
  • Right of way impacts
  • How to fund
  • Bridge type and cost
  • Construction closure: short, long or none

The preliminary estimate for a replacement bridge is $90 million. Cost factors include the length and height required for a span at this site. Because of the high cost, rehabilitation of the existing bridge will also be considered. The County will work cooperatively with local cities and counties, and with the state and federal governments to complete this important regional transportation project.