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Originally Posted by Ruffhauser

From todays DJC.

https://www.djc.com/news/co/12123789.html

July 24, 2019

Crews lay down track atop I-90 floating bridge

By BENJAMIN MINNICK
Journal Construction Editor

Crews have installed one of the eight specialized track sections that will allow light rail trains to cross the Interstate 90 floating bridge.

The 43-foot-long sections — called track bridges — will carry rail from the fixed ends of the Homer M. Hadley bridge to its floating part. They were designed to move with the bridge, which can flex in six different directions.

“This has not been done anywhere else in the world,” said John Sleavin, deputy project director in charge of final design at Sound Transit, during a Tuesday media tour of the bridge.

Laying track on a floating bridge has additional challenges other than the transitions, such as movement of the rail on the floating section, the weight of the system and isolating electrical current that runs in the rails.

Special isolators are used on the track bridges to keep electrical current from reaching the main bridge.






Nearly 9,000 light-weight concrete blocks support the track across the main bridge.