Prior Work
South Willamette River Crossing Study (1999)
In May 1999, Metro's Joint Policy Advisory Committee on Transportation made final recommendations for the South Willamette River Crossing Study (pdf, 8.7 mb) area, which included the Sellwood Bridge. The study identified needed improvements for cars, transit, bikes, and pedestrian traffic crossing the river.
The study examined several options for the Sellwood bridge, including:
- Keeping the Sellwood Bridge in its current configuration
- Upgrading it to meet current seismic, vehicular, bike, and pedestrian standards
- Closing the bridge to auto traffic, but leaving it open only for bikes and pedestrians
- Replacing the Bridge with a two- or four-lane facility
- Making modifications to the Ross Island Bridge in an effort to reduce bottlenecks at the west end of that bridge and to increase the Ross Island Bridge to three lanes each way
- A new crossing in Clackamas County
- Increasing transit services and other programs that would reduce travel demand on the Sellwood Bridge
The study recommended the following:
- Preserve existing Sellwood Bridge or replace it as a 2-lane bridge with better service for bike and pedestrian travel
- Consider improvements to the Ross Island and I-205 bridges in a different study
- Increase motor vehicle capacity on regional facilities, such as McLoughlin and Highway 224
- Mitigate traffic on Tacoma Street, Highway 99E in Milwaukie, and on A Avenue and Highway 43 in Lake Oswego
- Increase transit services and improve bicycle and pedestrian facilities in the corridor
- Bring more jobs to Clackamas County
Phase 1: Planning Under NEPA(2006-2010)
The Sellwood Bridge project began as a planning effort to develop a community-supported solution to address the long-term transportation deficiencies posed by the deterioration of the bridge. Because the study involves federal funds, Multnomah County and its local, state, and federal agency partners followed a National Environmental Policy Act (NEPA) planning process. NEPA is a 1969 federal law that ensures that governments give proper consideration to the environment (natural and human) before undertaking major projects that will require federal funds to build.
For the Sellwood Bridge project, Multnomah County prepared an environmental impact statement (EIS) to comply with NEPA. An EIS is a document that determines the significance of social, economic, or environmental impacts of a proposed project. The EIS summarizes the major environmental impacts, outlines issues, examines reasonable alternatives, and identifies a preferred alternative for the project. A Notice of Intent (pdf, 39 kb) to prepare the EIS was published on the Federal Register on November 9, 2006.
Project Organization and Decision Points
The project has been guided by a structured decision-making process with input from a Community Task Force (CTF), Project Management Team (PMT), and Policy Advisory Group (PAG). The decision process was organized into six major decision milestones as identified on this timeline graphic (click on the image below to enlarge it):
1. Establish Decision Process and Structure
This first decision point ensured understanding and agreement about how decisions were made – what process will be followed and the roles, responsibilities, and membership of the various groups.
This decision point was formally reached on June 7, 2006, by the Policy Advisory Group. The Decision-Making Structure and Process memo (pdf, 165 kb) has been finalized and will be used throughout the project.
2. Define Purpose and Need
This decision point defined the problem to be solved and established a factual, defensible basis for why the problem is authentic and important. It defined the specific transportation needs that provided the framework for future work.
The Purpose and Need Statement was recommended by the Community Task Force and adopted (pdf, 94 kb) by the Policy Advisory Group, then went to the agencies for concurrence.
A presentation (pdf 163 kb) regarding the Purpose and Need was given to the Community Task Force, along with the Structural Deficiencies (pdf, 784 kb) and Roadway Deficiencies (pdf, 829 kb) memos.
The bridge has numerous deficiencies, including:
- Poor structural condition, with a limited service life
- Weight restrictions, which have forced an average of 1,400 trucks and buses each day to find a different river crossing route
- Geologic instability on the west end that has resulted in land slides
- Narrow travel lanes with no shoulders or median
- Short stopping distances and lines of sight for motorists
- Traffic that is at capacity during rush hours
- One narrow sidewalk insufficient for bicyclists and pedestrians
- Poor connections to established trails at each end of the bridge
- Tight ramps at west end that cannot easily accommodate large vehicles
- High risk of structural failure in the event of an earthquake
- A National Bridge Inventory sufficiency rating of 2 out of a possible score of 100
3. Establish Evaluation Framework
This decision point created a “tool” to assist with assessing and comparing alternatives. The evaluation framework set criteria and quantitative performance measures for gauging the effectiveness and feasibility of alternatives — how well they solved the problems identified in the project purpose and need (pdf, 94 kb) and how well they performed against the broad range of stakeholder values.
The Evaluation Framework (pdf, 412 kb) was adopted by the Policy Advisory Group on January 29, 2007.
4. Develop Alternatives
The CTF reviewed concepts (pdf, 1.7 mb) that met the threshold criteria during spring 2007. Some of the concepts were viewed as clearly inferior to others, and the CTF recommended elimination of them. In June 2007 the Policy Advisory Group (PAG) considered CTF recommendations and adopted a Range of Alternatives (pdf, 1.7 mb) to be advanced for further analysis. The various combinations of alignment, cross-section, and interchange elements totaled 124 different alternatives. Concepts dropped from the range of alternatives were not considered further.
5. Screen Alternatives
This decision point evaluated the alternatives against the criteria developed by the Community Task Force (Evaluation Framework(pdf, 350kb) to see which ones performed better. The Alternative Evaluation Memo (pdf, 610kb) explains this process in more detail. As part of this step, a small group of selected alternatives was given a more detailed analysis in the environmental impact statement (EIS).
The Policy Advisory Group adopted, on October 19, five alternatives (pdf, 136 kb) to be considered in the Draft EIS.
6. Select Preferred Alternative
During the sixth decision point, detailed data developed for the Draft EIS was used to re-evaluate the remaining alternatives against the evaluation framework. The public was asked to participate in the selection of a preferred alternative.
In January and February 2009, the CTF and PAG recommended and selected a preferred alternative (originally called Alternative D):
- To be built in its current alignment and widened 15 feet to the south to allow for continuous traffic flow during construction
- A cross-section of 64 feet at its narrowest point: two 12-foot travel lanes, two 12-foot shared use sidewalks, and two 6.5-foot bike lanes/emergency shoulders
- A grade-separated and signalized interchange at the OR 43 (SW Macadam Avenue) intersection on the west end
- A pedestrian-activated signal at the intersection of SE Tacoma Street and SE 6th Avenue on the east end
- Consistent with the Tacoma Main Street Plan
- Restores buses and trucks; accommodates possible future streetcar
The preferred alternative recommendation was approved by the partner agencies (Multnomah County, City of Portland, Metro, ODOT and Clackamas County) in early 2009.
Over the summer of 2009, additional refinements were made to the Preferred Alternative based on agency and resident/business feedback. Design refinements included:
- Bridge cross-section was narrowed from five lanes to four lanes at the OR 43 interchange on the west end
- Bicycle/pedestrian facilities on the west end were improved. The spiral ramps were replaced by single, long switchback ramps on the north and south sides of the bridge
- Access refinements have occurred based on meetings/discussions with west side property owners
- Measures have been explored to mitigate impacts to parks and historic and natural resources
Extensive public outreach occurred prior to each of these decision points to ensure that the public was involved in the process in a meaningful way. The public had the opportunity to comment on issues before the various project groups made recommendations at each decision point. Your input helped shape the parameters of this project; thank you for your time and interest in the project.
Phase 2: Bridge Type Selection (2010)
The Community Advisory Committee (CAC) met in spring of 2010 to form a recommendation for the type of new replacement bridge to be built.
Eleven bridge types were originally considered for the replacement Sellwood Bridge. Any new bridge must meet the following criteria:
- Cross-section without a raised center median
- Cost of the bridge structure less than $170 million*
- No long term traffic closures
- Construction footprint must minimize impacts to adjacent businesses and residences
- Versatile cross-section to accommodate future streetcar
*Includes river span, east approach, temporary construction, demolition of existing bridge and buildings within the alignment, design and construction engineering, contingency and inflation to the year 2014. Full cost of the project is estimated at $330 million.
The renderings of the bridge types are for illustrative purposes only - they are not meant to depict the final designs and they do not include design details like color, texture, lighting, etc. Additionally, the interchange with Hwy. 43 will require that the bridge deck be wider on the west end of the bridge to give vehicles enough space to queue before turning. This additional deck width is not illustrated in the renderings. Renderings with additional bridge views will be available later this year.
Girder Bridges
Box and Plate Girder bridges are clean, modern, and cost-effective to construct and maintain. These bridges can be steel or concrete. Their straightforward, functional form allows a blank canvas for deck features. Their classical arch profile offers options for architectural detail in the shape of the girders and piers, slopes, shadows, and textures. These bridges’ moderate price and flexibility in accommodating varying deck widths make them a common bridge type throughout the world. The Glen Jackson Memorial Bridge (I-205) and the Bybee Boulevard Bridge are examples of concrete box girder bridges. The Abernethy Bridge (Oregon City I-205 Freeway Bridge), is an example of a steel plate girder bridge.
Delta Frame bridges, sometimes called Y-Leg, are in the girder family. These concrete structures are named for the unique look achieved by their Y-shaped piers. This bridge design offers a high level of architectural interest for a moderate price. This bridge would be a new bridge type in Portland (similar to the Alsea Bay Bridge in Waldport, Oregon).
Arch Bridges
Deck Arch bridges offer a classical architectural style. The arch form is a very popular style, especially in Oregon, which offers broad opportunity for deck features and architectural detail in color, texture, and shadow. Arch bridges limit navigational channel clearance more than other bridge types. Southwest Portland’s Vista Bridge is an example of a Deck Arch bridge.
Through Arch bridges offer a striking profile and create an iconic gateway presence. They are more expensive to build than other bridge types and the arches and hangers require more intensive maintenance. This type allows for a slender deck depth with cables providing support from above. This bridge type has limited construction staging options. The Fremont Bridge is an example of this bridge type.
Extradosed Bridges
Extradosed bridges are a cross between a box girder bridge and a cable-stayed bridge design. This light and elegant form can be constructed with either concrete or steel. Concrete and steel extradosed bridges are in the upper to moderate price range. The design creates architectural interest by stringing support cables from short pylons above the box girder deck. This bridge type has limited construction staging options and the layout is more challenging with the variable roadway width of the preferred alternative. This would be a new bridge type in Portland.
CAC Recommendation
On October 25, 2010, after 11 meetings and consideration of public feedback throughout 2010, the Community Advisory Committee (CAC) recommended a Steel Deck Arch bridge type to the Public Stakeholder Committee (PSC). The PSC will consider this input and forward a recommendation to the Multnomah Board of County Commissioners for a final decision in early 2011.
The CAC recommended the Steel Deck Arch bridge type for the following reasons:
- Reflects community values – arched form has neighborhood scale and fits the natural setting; use of steel echoes the existing bridge; arched bridge type was popular in the summer online survey
- Source of civic pride – adds to the city’s unique collection of bridges; has aesthetic appeal without adornment
- Within established budget – attractive at a reasonable cost (mid-range of the cost options)
- High technical performance – minimizes construction duration and traffic closures while maximizing construction waste recycling
- Enhances local jobs – provides more opportunities for local firms to produce materials, fabricate and construct the bridge than some of the other types
Phase 3: Final Design (2011-2013)
Guiding the design process was a consultant team led by T.Y. Lin International and CH2M HILL. David Evans & Associates were advisors to the county. JLA Public Involvement provided community engagement services and the bridge architect was Safdie Rabines Architects of San Diego, which has designed signature bridges throughout the United States. Slayden/Sundt, a joint venture of Slayden Construction Group and Sundt Construction, built the new Sellwood Bridge.