Portland engineers use dish soap to move century-old bridge


Engineers in Portland, Oregon, had to get creative when they needed to replace the Sellwood Bridge.

Cracks had begun to appear in the support beams of the 100-year-old bridge, and, as our sister site, Equipment World, reported, the structure’s unique design forced the engineers to move the bridge in one whole 1,100-foot piece.

The engineers built tracks, covered them with Teflon pads and poured liquid soap on them. Forty 150-ton hydraulic jacks lifted the 3,400-ton bridge and placed it on the soapy tracks to slide it into place.

Here’s a rundown of the process:

  • 3,400 tons: Weight of the entire bridge
  • 1,100 feet: Length of the entire bridge, including the overhang
  • 1,091 feet and 2-1/4 inches: Actual length on the continuous steel truss between end bearing points
  • Five: Number of concrete piers supporting the bridge (three in the river and one on each shoreline)
  • Two: Number of steel bearings supporting the truss at each of the five piers
  • Four: Number of spans between support piers
  • 245 feet, 300 feet, 300 feet and 246 feet: Lengths of each of the four spans
  • 10: Number of bearing points
  • 66 feet: Distance west end of the bridge was moved
  • 33 feet: Distance east end of the bridge was moved
  • 40: Number of hydraulic jacks used to lift the bridge
  • 19 hours: Amount of time it took to move the bridge
  • 1924: Year the individual parts of the steel truss were fabricated
  • 30,500: Number of vehicles that would have been rerouted miles away if the bridge was destroyed

Check out the video below to watch the 19-hour process take place in a 38-second time-lapse.

[vimeo 57807120 nolink]