Seattle rail crossing is world first

Sound Transit is set to begin work next month on a US$3.7 billion project in Seattle, to connect light rail services to the city’s Eastside suburbs over the I-90 bridge on Lake Washington.

The project is part of the East Link rail service that will create a 22 km cross-river connection, including the first ever construction of a railway structure on a floating bridge.

To overcome the obvious challenges, Sound Transit engineers designed a ‘track bridge’, with rails that rest on a series of bearings and plates, allowing them to move with changing water levels and bridge movements.

Two full-scale prototypes were initially built by Sound Transit, in partnership with Parsons Brinckerhoff and Jesse Engineering of Tacoma.

During testing – which was undertaken at a the Transportation Technology Center in Pueblo, Colorado – two Link rail vehicles were passed over the prototype bridges at speeds in excess of 80 km/h.

Having passed all critical testing, the East Link is now set to enter service in 2023.