Okay, so what is this type of bridge called?

[DKS]

I don't have a proto pic, because I've not had any luck finding one, but I know they exist, as I've seen them in person. I've also driven over the roadway equivalent.
I'm modeling one, at the top left corner of this diorama:



Basically it's a long concrete box, and its squared ends give it a distinctive appearance. I've occasionally seen it referred to as a "flying junction," but that's usually if it's associated with an actual railroad junction. I've even picked through Bridgehunter, with no luck. So, I figured someone here at the Wire should know. Let the discussion--and the drift--begin.

[Spades]

The boxy structure.  A caisson? Definition: a watertight chamber used in construction work under water or as a foundation

[thomasjmdavis]

I had better luck searching for "tunnel under highway" than "bridge" or "concrete bridge".

Here is a time lapse from the Netherlands, In this case, they are installing one to allow one highway to pass under another.  They do it just like model railroaders do- they build the tunnel, then cut the upper road and dig it out, and slide the tunnel into place.  Apparently, over one weekend.
https://wonderfulengineering.com/dutch-just-constructed-a-tunnel-under-a-highway-in-just-one-weekend-this-is-how-they-did-it/

Then tried "railroad tunnel under highway".

Here is something similar for a mass transit system- https://www.masstransitmag.com/rail/infrastructure/press-release/21213476/brightline-brightline-to-construct-rail-underpass-under-highway-system-using-innovative-boxjacking-method

[DKS]

Thank you, Tom, for trying. As it happens, I tried them too. Closest I came so far for an image was this, from a sim workshop:



Found a few examples from Europe, all brand new. But these things have been around since dirt. Saw an old abandoned one in North Jersey, would have photographed it but it was scary as f.

[wm3798]

Virginia Avenue tunnel in Washington looks a bit like this.
I'm not sure exactly where it is, but there was a big reconstruction project over the last few years to open up clearances for double stacks.  I've seen lots of pictures... Happy hunting!
Lee

[C855B]

Box flyover.

[Chris333]

Yeah I think the PRR called them a flyover.

https://www.google.com/maps/@41.1442417,-80.7045134,221a,35y,39.37t/data=!3m1!1e3
https://www.google.com/maps/@41.1280442,-80.6885303,220a,35y,39.37t/data=!3m1!1e3

[Chris333]

Well it looks like Google is calling any bridge over another track a flyover.

[thomasjmdavis]

Thank you, Tom, for trying. As it happens, I tried them too. Closest I came so far for an image was this, from a sim workshop:



Found a few examples from Europe, all brand new. But these things have been around since dirt. Saw an old abandoned one in North Jersey, would have photographed it but it was scary as f.

I think I've found it.  John Armstrong, Track Planning for Realistic Operation (mine is 5th printing, 1988- cover shows small layout on the nose of Conrail 3373). In my copy, it is part of Figure 3-15, "Flying Junction", p.33. In a corner of the graphic, he shows a track crossing over 4 tracks with the following caption:

For the shallow angle crossing of several tracks, the distinctive "RETAINING WALL" bridge is efficient and often used in congested locations. If a branch route were to go below two or more other tracks instead of above, you would have a "burrowing junction."

So, I am going with "retaining wall bridge."

[GimpLizard]

They built on of those a number of years ago over the CN tracks in Burlington WI.

https://www.google.com/maps/@42.673923,-88.2698194,317m/data=!3m1!1e3

[C855B]

That's fine, but bear in mind I worked for DOTs. We called them "box flyovers", because the construction technique was one of pushing a precast concrete box or boxes into place. Retaining wall construction is something different, usually with a block-built wall and a beam bridge, and not the squared-off tunnel as in David's example.

[thomasjmdavis]

That's fine, but bear in mind I worked for DOTs. We called them "box flyovers", because the construction technique was one of pushing a precast concrete box or boxes into place. Retaining wall construction is something different, usually with a block-built wall and a beam bridge, and not the squared-off tunnel as in David's example.

Sorry, I didn't mean to argue with you.  One of the links I posted earlier showed the technique you are referring to (I think). The book I referenced is over 50 years old in its first edition.  Have pre-cast boxes of that size been in common use for a long time, or is it a relatively new type of construction?

[DKS]

Well it looks like Google is calling any bridge over another track a flyover.

Although there have been some helpful suggestions here, so far any combination of the terms doesn't appear to net any good results from Google image search. I suspect the algorithms are trying too hard to translate my search terms into what it thinks I "really meant." Not surprisingly.

[C855B]

Sorry, I didn't mean to argue with you.  One of the links I posted earlier showed the technique you are referring to (I think). The book I referenced is over 50 years old in its first edition.  Have pre-cast boxes of that size been in common use for a long time, or is it a relatively new type of construction?

Relatively new. I'd say past 40 years or so, about the time tilt-up concrete methods came into vogue. It took combined advances in concrete chemistry and handling equipment to make it happen. That Dutch example you linked is amazing, frankly.

[Chris333]

Yeah they call this a flyover:
http://bridgehunter.com/pa/chester/whitford-rail