When cracks began to form in the Sellwood Bridge’s supports, engineers in Portland, Oregon were faced with an extreme challenge when it came to replacing the nearly century-old bridge: they had to move the whole thing at once.
According to Popular Mechanics, the engineers wanted to slide the existing bridge over a bit to create a detour around construction of the new bridge. However, the existing 3,400-ton bridge had a unique one-piece, 1,100-foot design that wouldn’t allow the team to move it in pieces. So, the engineers built tracks and covered them with Teflon pads and poured liquid soap on them to allow the bridge to slip along.
Forty 150-ton hydraulic jacks then lifted up the bridge and placed it on those tracks and the bridge was moved into position. The whole process took 19 hours, but you can watch it all in the 38-second time-lapse video below.