Worlds first: light rail over a floating bridge

real_aurgathor

Sound Transit light rails are now doing test runs over Lake Washington over a floating bridge, which, apparently, is a world first, and probably not only for light rail, but regular rail as well.

For the first time, light rail trains will soon operate under their own power across Lake Washington — a milestone Sound Transit says marks a major step toward connecting Seattle with the Eastside by early 2026.

The agency announced this week that live wire testing will begin in July on the floating span of Interstate 90 that stretches Lake Washington, the world’s first light rail segment to cross a floating bridge. The test will involve running trains on electricity provided by overhead wires, simulating real-world operations along the seven miles of track dubbed the “crosslake connection.”

https://www.king5.com/article/news/local/light-rail-powered-tests-i-90-lake-washington/281-447c1a72-5f38-4c08-857f-ae295c20ec39

broknsymetry

Hmm, isn’t that the same stretch that sank in 1990?

MacLeech

real_aurgathor …is a world first, and probably not only for light rail, but regular rail as well.

Definitely not for regular rail…
https://en.wikipedia.org/wiki/Pile%E2%80%93Pontoon_Railroad_Bridge

In the late 1860s, the Milwaukee Road’s agent John Lawler conceived a ferry crossing, using barges with rail tracks on their decks. Because there are two channels separated by an island, each channel required a barge which was pulled across by cables, and a small rail yard crossing the island connecting the two ferries. This allowed transshipment of railroad cars without unloading, but was still less than efficient.

A better solution was found by Michael Spettel and Lawler, who patented a permanent pontoon bridge system to span the river in 1874.[1] This comprised piled trestles built out into the river, and two pontoons: A 210-foot (64 m) unit on the east channel, and a 227-foot (69 m) unit on the west. Each pontoon was hinged at one end to allow it to float open, and was pulled closed by a steam-powered cable. As well as allowing for river traffic, this allowed end-of-winter ice floes to pass down the river without risk of damaging the structure.

The pontoons were built with a timber-framed deck which could be raised or lowered by as much as 18 feet (5.5 m) to allow for changes in the river level

I don’t even think that was the first floating rail bridge by 1874 either, but maybe it was…
https://www.thegazette.com/history/time-machine-a-pontoon-rail-bridge/

Somewhat-Reticent

May eventually edge Galloping Gertie out for top local engineering fiasco.

vaxvms

Somewhat-Reticent The Homer M. Hadley Memorial Bridge opened in June 1989, 37 years ago and is still in operation. I can’t imagine the addition for LRV rails would compromise the structure. We shall see
https://en.wikipedia.org/wiki/Homer_M._Hadley_Memorial_Bridge.

real_aurgathor

Somewhat-Reticent May eventually edge Galloping Gertie out for top local engineering fiasco.

Highly unlikely.

real_aurgathor

broknsymetry Hmm, isn’t that the same stretch that sank in 1990?

Same area, but different bridge.

Not sure about the eventual outcome of the lawsuits that followed, but WSDOT insistence to store water used for pressure washing inside the pontoons was a significant contributor.