This information relates to the new Sauvie Island Bridge that opened in 2008.
With less than a year to go before it opens, the new Sauvie Island Bridge is taking shape. Support columns have been poured and deck sections now span every set of columns except for two in the Multnomah Channel. This October, that final section will be filled when a barge floats the main arch span into place. Here is an update on construction of the new bridge.
The Main Arch
The main arch that will span Multnomah Channel is 365 feet long and 82 feet tall at its highest point. It is made of weathering steel that was fabricated in Tigard by Fought and Company. The arch is made up of hundreds of steel components connected by tens of thousands of bolts. To ensure that it all fit together, Fought assembled every steel section at its Tigard plant. Then the arch was disassembled and trucked in pieces to the Port of Portland’s Terminal 2 on the Willamette River north of the Fremont Bridge. There it was reassembled by Schneider Up ironworkers and prepared for final installation.
In a feat of good old American know-how that surprised even the project team, not a single bolt hole needed to be reamed (or enlarged) when the pieces were reassembled. Every bolt hole lined up perfectly. Fought used a computer program to mark each hole in a precise spot before it was drilled.
In October, sub-contractor DIX/NORSAR will move the arch onto a barge, using a system of rolling skids not too different than what the ancient Egyptians might have used to build the pyramids. Moving the arch onto the barge will take about 18 hours. Once on the barge, the arch will be jacked up about 70 feet above the water (depending on the water level at the time of installation), to the height it needs to be when it is placed on the columns at Sauvie Island. The float downriver will only take a few hours, and may take place at night.
At Sauvie Island, it will take several days to set the arch on the bridge columns. A number of factors, including weather and a dock strike in California, could affect the schedule for placing the arch. Multnomah County staff are working to make sure the public and the news media will have a chance to watch this historic event.
Meanwhile, back at the island
While ironworkers assembled the arch in Portland, employees of prime contractor Max J Kuney have been busy making sure the new bridge is ready to support the arch when it arrives. Key work items this summer include:
- Pouring the concrete upper deck and sidewalks on the island side
- Threading post-tension cables through the new deck on the island side and then tensioning them to give the bridge its strength
- Working on the mainland to tie all bridge components together to maintain structural stability during installation
After the main arch is installed, key tasks will include:
- Pouring the concrete deck and sidewalks and installing the railing on the main arch span
- Preparing the island approach ramp by removing the top of the embankment, laying rock base and asphalt, installing manholes and catch basins, and laying drain pipe
- Removing much of the construction material under the bridge, including concrete forms, bracing, scaffolding and piling
- On the mainland, the focus will be to complete the deck and install post-tension cables, an impact panel at the abutment at Highway 30, storm water collection and treatment facilities, and a new traffic signal
If the current schedule is maintained, the new bridge will open to traffic sometime next summer. Then it will be time to remove the old bridge, reshape the island approach to the bridge, and build a new parking lot on the island with a bus stop and storm water swale.
After the old bridge is removed, its fans may not have to travel far to see it. The City of Portland is working on a plan to re-use the main span of the old bridge as a new bridge for bicyclists and pedestrians across Interstate 405 on NW Flanders.