Several configurations for the replacement of the aging Interstate 5 bridge over the Columbia River were unveiled late last month.
During a May 25 meeting of the Interstate Bridge Replacement Program (IBRP) Executive Steering Group, program administration showed examples of the bridge that included single and double-level configurations, as well as a moveable span similar to the current bridge’s operation.
The visualizations are not examples of what will be the final design of the replacement, IBRP Administrator Greg Johnson said.
“What we’re trying to show is some of the potential, to get folks to think about what they want this bridge to look like in context,” Johnson said.
The images shown at the meeting showed four vantage points from both the Washington and Oregon sides. Johnson said more vantage points will be added as the program continues.
The visualizations did not include where the bridges touched down into Washington and Oregon due to those design elements not being ready, Johnson said.
Although many details were left out, having something for people to see is important to the IBRP as it makes its way through the multi-year process prior to breaking ground on the replacement.
“We know folks are chomping at the bit to see what the potential bridge types and configurations could be,” Johnson said.
Six configurations were shown at the meeting. Those included bridges with extradosed and finback constructions, which had pillars extending above the level of traffic.
Other visualizations included a concrete design similar to the Interstate 205 bridge to the east and one using steel girders. Compared to concrete, steel construction requires maintenance like painting, which leads to cost savings up front but a need to maintain it in the long run, Johnson said.
Only one of the bridges had a double-level configuration similar to what was seen with the Columbia River Crossing project.
The last visualization included a moveable span, something the IBRP began studying more recently, following a requirement from federal regulators to include it in the process.
The U.S. Coast Guard identified users that would be impacted by a clearance of 116 feet, IBRP assistant administrator Ray Mabey said. That height was permitted by the Coast Guard during the Columbia River Crossing. Now, they have identified current users of water traffic that would be impacted by that low clearance.
Mabey wasn’t able to talk much about the discussions with those users on solutions, but said there’s been “healthy exchange” between the program and those who would potentially be impacted.
The moveable span would raise the platform vertically, which is similar to how the existing bridge operates. Johnson said a drawbridge was considered, but the span lengths proved infeasible.
All of the designs included fewer pillars in the water than the existing bridge. They all keep the pier areas the same to keep in line with previous environmental agreements, Johnson said. The designs also shift the highest clearance for water traffic closer to the center of the river.
The general configurations of single and double-level bridges, alongside the moveable span, will be included as the program continues through its environmental review process, IBRP assistant administrator Frank Green said.
The IBRP Executive Steering Group is composed of a number of representatives of local governments, transportation departments and stakeholder agencies with interests in the program. That includes Southwest Washington Regional Transportation Council Director Matt Ransom, who was excited to see the visualizations, particularly because the most popular questions he hears are from those who are curious about his work with the executive steering group.
“The first thing my neighbors ask (is) what’s it going to look like,” Ransom said.
He encouraged more public outreach on the design aspect as the project dives more into the details.
“Aside from the details that we’re worried about, people want to have a bridge that they’re proud of,” Ransom said.
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