Sellwood detour bridge may shave bucks off project
County considers a plan that could accelerate schedule
Multnomah County officials hope that by building a temporary bridge next to the crumbling Sellwood Bridge they can accelerate the bridge-replacement project and save possibly 'millions' in construction costs.
Mike Pullen, county public information officer, told county commissioners Tuesday morning that construction of a 'shoo-fly' temporary bridge might allow the contractor to begin work on the project this fall, instead of waiting until the summer of 2012.
Pullen said the commissioners would get 'hard numbers' in about a month on the amount of money they could save. But the sum could be substantial, he told commissioners during the briefing.
'We're talking about millions being saved,' Pullen said.
The idea of picking up and moving the main span of the existing Sellwood Bridge about 40 feet north surfaced this week. That bridge then would become a detour route during construction. The county's bridge construction team will meet with Portland planners in mid-April to talk about the project and work out permit agreements so the temporary bridge could be used, Pullen said.
By shaving time off the construction schedule, Pullen said the county would save money on the estimated $290 million work.
'We want to accelerate construction of this project, and we think we can get there,' Pullen told commissioners.
The proposal is a new idea suggested by Slayden Construction Co., the firm selected as the prime contractor for the project. Slayden did the same thing with the replacement Elkton Bridge project outside of Eugene, Pullen said.
The Sellwood detour span would be used for up to four years. Although moving the span would close the bridge for a week, it could shave a year or more off the construction schedule, saving more money than the move would require, Pullen said.
Before the span is moved, new temporary piers would be built north of the existing bridge in the Willamette River and on both the west and east banks. Temporary supports also would be built from the side of the existing bridge.
After the new bridge is completed, the old span and temporary supports would be removed. The process is called 'shoo-fly' in the construction industry.
But the commission and regulatory agencies would have to formally approve moving the deck later this year. Under the original construction schedule, work was not set to start until the summer of 2012. If the commission approves moving the deck, work could begin by November 2011, Pullen said.
Design changes have cut the cost of the project from $330 million to $290 million. Portland, Multnomah County and the state have all committed to helping fund the project.
Clackamas County's contribution, funded by a $5-per-year vehicle registration fee, goes to voters in mid-May. If approved, the entire project could still be about $20 million short. If voters reject the fee, the gap grows to about $40 million.
A new poll showed that a majority (55 percent) of 400 likely voters supported the fee.