12-01-2018, 10:29 PM
There are no expansion joints - in fact, I can't think of a single expansion joint on the entire system anywhere, and I've essentially crawled over the entire system for the past 4 years! I specifically noticed the ones in Cincinnati, on some sections of their streetcar which was built over an existing parking structure/highway, because they looked so alien to me. If anyone can find one and take a photo of it, I'd love to see it!
The ballasted track was chosen to specifically avoid needing expansion joints, and because of mass (it's lighter than the embedded track slab that would have otherwise been required), which saved them rebuilding the bridge from scratch. The convex bow in the bridge profile, plus the somewhat flexible ballast, makes expansion joints unnecessary.
(Safety disclaimer - I took these photos early on a weekend morning, shortly after construction had wrapped up in the area - obviously don't head out there now!
Here you can see the interface between the ballasted and embedded track - it's welded.
The extra piece of rail is simply a restraining rail, for safety.
Conventional ballasted track over the top - you can see the convex bow in this shot very well. If the bridge were flat, this technique wouldn't have worked.
The ballasted track was chosen to specifically avoid needing expansion joints, and because of mass (it's lighter than the embedded track slab that would have otherwise been required), which saved them rebuilding the bridge from scratch. The convex bow in the bridge profile, plus the somewhat flexible ballast, makes expansion joints unnecessary.
(Safety disclaimer - I took these photos early on a weekend morning, shortly after construction had wrapped up in the area - obviously don't head out there now!
Here you can see the interface between the ballasted and embedded track - it's welded.
The extra piece of rail is simply a restraining rail, for safety.
Conventional ballasted track over the top - you can see the convex bow in this shot very well. If the bridge were flat, this technique wouldn't have worked.