Columbia River Crossing officials like to call it “substantial technical analysis,” but figuring out a new—and taller—vertical clearance height for the proposed $3.5 billion Interstate 5 bridge was really a necessity after getting laughed out of the room when initially announcing a 95-ft height early in 2012.
After the U.S. Coast Guard all but said any bridge application passing its desk with a 95-ft clearance wasn’t going to get approved, officials for one of the largest transportation projects in the Pacific Northwest and certainly the most important two-state project on the boards—the bridge spans the Columbia River and connects Portland to Vancouver, Wash.—had to reconfigure plans. Following months of new analysis, the CRC team now says that a “bridge with a 115-ft vertical clearance reduces the number of vessels potentially impacted while minimizing additional community, environmental, freight and cost impacts.”
Research was done on bridge heights between 100 and 125 ft, in five-ft increments.
“The selected bridge height must balance the interests of river users, freight mobility, needs for flight paths over the bridge to Portland International Airport and Pearson Airfield, connections to downtown Vancouver and cost and schedule of the project,” the CRC teams says in a press release.
Of the 2,600 commercial river users, up to 11 may be affected at 115 to 116 feet. Additional structure costs to get to the new height will likely increase about $30 million, a figure included in the current cost estimate.
CRC officials hope to submit a formal bridge permit application to the Coast Guard in January 2013, receive a permit in late 2013 and start construction in late 2014, assuming, of course, “funding is secured.”
Deh Cho Bridge
After a complete restart roughly three years ago on the largest public infrastructure project Canada’s Northwest Territories has ever contracted, the $202 million all-weather Deh Cho Bridge spanning the Mackenzie River—Canada’s widest river—is now open.
At nearly 3,500 ft in length, the bridge replaces an ice-crossing bridge and a ferry.
Work originally started on the bridge in 2008, but was halted after an independent design-review team found the superstructure didn’t meet standards. Canadian company Infinity Engineering stepped in fresh—the original engineers and contractors were removed from the job—and started to rework the design on an already started substructure.
The final result is a two-lane, nine-span composite steel truss bridge with a cable-assisted main span of 623 ft. Overall, Infinity reduced the amount of structural steel needed by 25 percent from the original design and realized a 30-percent reduction in the concrete needed for the deck, helping ease any potential strain on the structure.
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