Wednesday, April 24, 2013

TriMet begins light-rail bridge deck concrete pour

Crew members installed form travelers (the yellow-object on the left) at each end of the West Tower pier table. Crew members installed form travelers (the yellow-object on the left) at each end of the West Tower pier table. TriMet

TriMet hit a major milestone on April 24, as the first bridge segment was poured for the Portland-Milwaukie Light Rail Transit Bridge over the Willamette River.

Kiewit Infrastructure West, the bridge contractor, cast the first of 78 concrete segments for the bridge deck. Two concrete form travelers have been erected at each end of the west bridge tower. Each form traveler will support 200 tons of concrete to be cast into a 16-foot long by 75-foot long segment that will make up the future roadway.

After the first segment is poured on the west side of the tower, the east side of the tower deck pour will occur on April 30. The concrete will have anchors cast into the concrete that will secure the cable stays once installed.

Once the concrete achieves a specified strength, post-tensioning tendons (treated-steel cables) are pulled tight by a jack before the form traveler is moved. Then, the permanent cable stays are pulled from the west side of the bridge deck through the bridge tower and reconnected on the east side of the deck.

The bridge deck segments constructed from each tower are expected to join together in spring 2014 at the bridge center point over the Willamette.

The light-rail bridge is the first bridge built across the Willamette River in Portland, Ore., in more than 40 years and will be the first cable-stayed bridge for the region, extending 1,720 feet over the Willamette River. It is the first of its kind, carrying light rail, buses, bikes, pedestrians and a future Portland Streetcar extension, but no private vehicles.

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