Washington State Department of Transportation is building the new crossing over Lake Washington in the north-west of the USA to replace the existing floating bridge, which is showing its age after half a century of use.
The eight being floated this week are the last of 44 pontoons to be built for the project at the Tacoma yard, where casting began in January 2012. Their completion means that 74 of the new bridge’s 77 pontoons are now constructed. Just three remain to be built; these will be completed next spring at the project’s other casting site, in Aberdeen.
The eight that have just been completed are ‘supplemental stability pontoons’, which will flank both sides of the bridge to give it added stability and flotation.
The first of the eight pontoons – each 30m long by 18m wide - was towed out of the casting basin by tugboats yesterday. All eight will be floated out within the next few days and taken to the bridge site at Lake Washington.
The 33 built in Aberdeen include 21 of the massive longitudinal main pontoons, each 110m long and weighing 9,980 metric tonnes.
