Portland construction crews began pouring the first concrete deck segment for America’s largest car-less commuting bridge Wednesday. This bridge crosses the Willamette River. This cable-stayed span will connect Portland’s South Waterfront to the east bank near the Oregon Museum of Science and Industry.
The Portland-Milwaukie light rail line is being built in 78 concrete segments. The crew must balance deck segments one at a time on each side of the west towers. TriMet spokeswoman Mary Fetsch called it a “dance,” according to The Oregonian.
The crew is using balance cantilever construction, which includes a beam anchored only at one end that carries the load to the support. This allows for overhanging structures without external bracing. The segment cast on the west side of the tower on Wednesday will require a week to cure before the crew can pour a second section on the east side.
TriMet also announced Wednesday how it will name the bridge. This is the first new bridge over the Willamette River in over 40 years. TriMet will name a “blue ribbon committee” to help it “in shepherding the bridge naming process through some kind of public process,” according to The Oregonian. TriMet’s Customer Information Services Department will also develop a public information and participation campaign for people to name the project. They plan to have the name selected by the end of 2014.
The bridge will be 1,720 feet, and it will carry MAX trains, streetcars, TriMet buses, and bikes. It is the main part of the $1.5 billion Portland-to-Milwaukie MAX Light Rail line, which will be the Orange Line. The Orange Line is scheduled to open in September 2015.
The bridge will cost $134 million, and the segments will extend over the water until they eventually meet in the middle. Two concrete form travelers have been erected at each end of the west bridge tower, and the concrete will have anchors in the concrete to secure the cable stays.
Wednesday, about 200 tons of concrete were poured, making the 16-foot long by 75’ wide section of the deck. When the concrete achieves the necessary strength, a jack will pull treated-steel cables tight before the form traveler is moved. The construction crew will then pull the permanent cable stays from the west side of the bridge deck through the bridge tower and reconnect them to the east side of the deck. The process will be repeated weekly. This will be a long and arduous process, but in the end, the Portland-Milwaukie light rail line will create easier transportation for all.