Background

The original Sauvie Island Bridge was built in 1950. It was replaced with a new bridge that opened in 2008. The old bridge connected State Highway 30 with Sauvie Island approximately eight miles north of downtown Portland, Oregon, and outside the urban growth boundary. Sauvie Island, a rural community within Multnomah County encompassing approximately 15,400 acres of land, is important because it contains significant agricultural, industrial, and residential areas, as well as significant natural and recreational resources. The Sauvie Island Bridge is critical to the welfare of the island community because it provides the only vehicular access between the island and the mainland. It carries a mix of local residential, agricultural, logging, and recreational traffic. The 1999 average daily traffic (ADT) was 3,800. In 2000, the bridge was determined to be eligible for listing on the National Register of Historic Places.

The original structure consists of a 200-foot, main span, steel through truss with 200-foot, steel deck truss flanking spans and 588 feet of reinforced concrete deck girder (RCDG) approach spans. The total overall length of the structure is 1,178 feet, and the main span provides a vertical clearance of 80 feet above low water. The overall width is approximately 35 feet, which includes two 11-foot travel lanes, and 2-foot shoulders and 4-foot sidewalks on each side. The bridge approach from the island includes grades of up to 7 percent.

The bridge is classified as functionally obsolete and structurally deficient according to federal and state standards. Its current sufficiency rating is 8 out of a possible rating of 100. With the recent temporary repairs, the bridge currently can carry legal loads (40-ton capacity). However, the existing bridge, even with the temporary repairs, is not adequate to meet the current needs of the island’s farmers and industrial businesses, is substandard for bicyclists and pedestrians, and is at the end of its service life.

Purpose

The purpose of the project is to provide a new bridge to move people, goods, and service vehicles between Sauvie Island and the mainland. The new bridge would meet current federal, state, and local standards, and maintain existing navigation clearances.

Need

A new bridge is needed to provide a safe, efficient connection for automobiles, trucks, buses, bicyclists, and pedestrians between the mainland and the island; to meet current standards; and to provide adequate capacity for anticipated future traffic volumes. The new bridge would consist of two 12-foot travel lanes, with six-foot shoulders/bike lanes and six-foot sidewalks on both sides.

Objectives

The objectives of the project are to:

  • Maintain the rural character and agricultural viability of Sauvie Island
  • Comply with ODOT’s transportation system operation requirements for Highway 30
  • Minimize the distance between the new crossing and heavy truck trip origins on Sauvie Island
  • Explore options to keep the existing bridge in service as a second island connection
  • Support efficient transportation system operations with existing island infrastructure
  • Meet 100-year flood elevation standards for the new bridge approach on the island
  • Comply with applicable federal, state, and local laws and regulations
  • Recognize the needs of Willamette River and Multnomah Channel users
  • Recognize the needs of all bridge users and involve the public in the project development process
  • Recognize the island’s role as an outdoor recreation area for the region
  • Satisfy Multnomah County land use planning values