The bridge finally began to move just after 8 p.m., inching forward until the first set of wheels reached the top of the ramp. After that, it was a series of starts and stops as the crews slowly guided the first pair of trailers down to the barge, pausing frequently to take measurements and make sure everything remained properly lined up.
The process took hours — at 10 p.m., the bridge was still only about halfway onto the barge. It was fully transferred by Tuesday morning, but BNSF spokesperson Courtney Wallace said the barge will remain in Vancouver until Thursday while crews perform more tests and wait for the arrival of a tugboat.
Once it departs, the bridge will take about 24 hours to travel upriver and reach Drano Lake, Wallace said, passing through the Bonneville Lock about halfway through the trip. Once it arrives, it will be moved to a set of temporary foundations in the river about 100 feet south of the existing bridge. Crews will then reposition the barge perpendicular to the bridge and lift it back up to await installation.
BNSF has replaced several outdated bridges along its Columbia River Gorge main line in recent years, but the $15 million Drano Lake project stands out because it’s relatively rare for new bridges to be built remotely and floated into place, retired BNSF spokesman Gus Melonas told the Columbian in April.
The rail line and the adjacent state Highway 14 run across an artificial causeway that separates Drano Lake from the Columbia River. A channel connects the two bodies at the western end of the causeway, and the rail bridge carries the line over the gap — but that means there’s no adjacent land on which to build a replacement bridge.
Instead, BNSF opted to have the bridge assembled in Vancouver while crews worked at the Drano Lake site to prepare new permanent foundations for it. The new bridge truss is longer than the old one, which means its foundations are wider-spaced and could be built while the old bridge and foundations were still in place.
The actual swapping of the bridges will take place in mid-September, Wallace said, and it will be done as quickly as possible in order to minimize the disruption to the rail line. The BNSF line carries an average of 40 trains per day through the Columbia River Gorge, according to Melonas, including Amtrak’s Empire Builder line. BNSF is aiming for the line to be out of service for no more than 36 hours.
When the rail shutdown begins, crews will use cranes to lift out the steel approach spans at either end of the existing bridge and use “removal barges” to lift up the central truss from underneath and float it out of the channel. It will later be broken down and scrapped for the steel, Wallace said.
The installation barge will then move into the channel and lower the new bridge onto its permanent foundations, Wallace said. Crews will install two prefabricated 40-foot approach spans — one on each side — and finish by rebuilding the railroad track across the new structure.