# viaduct v. flyover (AmE: overpass)



## natkretep

I'm just puzzling over the terminology for road structures here. We've had some discussion about flyovers (AmE: overpasses) and underpasses. We have road structures labelled as _viaducts _and _elevated roads_ here too. The labels _elevated road_, _flyover _and _underpass _are uncontroversial. As far as I can see, viaducts are more extensive flyovers that extend over longer stretches, with no necessity of them being over valleys or depressed structures.

My question is whether this use of viaduct is normal elsewhere, and whether this distinction between _viaduct _and _flyover/overpass _is also made.


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## Cagey

Are you talking about AE as well? 

I would use _viaduct_ only if I were talking about something that carries water.


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## natkretep

Thanks, Cagey. I was thinking of all English varieties - I wanted to know if the usage in Singapore was consonant with usage elsewhere.


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## GreenWhiteBlue

Cagey said:


> Are you talking about AE as well?
> 
> I would use _viaduct_ only if I were talking about something that carries water.


 
I would never use _viaduct_ to talk about something that carries water.  A structure that carries water is an _*aqueduct*_ (from the Latin _aqua_, meaning water, and _ducere_, to lead.)  A _viaduct_ (as the word itself shows; _via_ in Latin means "a road") is a structure that carries a *road* of some kind. One should note, though, that  viaducts do not only carry roads for motor vehicles; one may also have _viaducts_ for pedestrian paths, and for railroads.


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## cuchuflete

I am in general agreement with GWB, with a small addition.  I have seen viaducts for both railroad cars and for motor vehicles  that also had water mains in the structures.
They were not primarily aqueducts; rather, they served multiple purposes.


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## Cagey

Yup.  I got my roads crossed.


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## GreenWhiteBlue

Cagey said:


> Yup. I got my roads crossed.


 
Cagey, you  need to get your ducts in a row...


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## cuchuflete

GreenWhiteBlue said:


> Cagey, you  need to get your ducts in a row...


Given the elevated tone of this conversation, may I suggest that we go with the flow, 
and fly over to the thread topic?


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## sdgraham

When I was a child in northern Illinois, "viaducts" were always something that went _*under*_ railroad tracks or other roads. A "duct," after all, is a "tube or passage" and "via duct" would not equate to a bridge.

It had not previously occurred to me that there might be a big difference between "viaduct" and "via duct."


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## an0405

Hi, 
I am looking for a correct word in English for a 'viaduct' that goes over a highway (or big road in a district of a big city) for people to be able to walk through. There is a tram on the highway which goes in the middle and you need to get on the 'bridge' (just for pedestrians to go through the highway) 
How would you call it?  a bridge, flyover (carries a road or rail), a viaduct (a big flyover)? 

Thank you.


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## Loob

Response to post 10

Hi an0405

You're thinking of something like this - am I right? 

I'd call it a _footbridge_; I think I've also come across the more technical term 'pedestrian overpass'.


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## an0405

great pic! something like this just with trams going in the middle;-) 
thank you!


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## ewie

_Combined overhead tramway and footbridge_ ... ?

I know, it's not exactly very catchy, is it?  I can't think of any shorter way of conveying all that information, Ano405

(In reply to the original post: for me a _viaduct_ carries specifically *trains*; a _flyover_ *cars*.)


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## an0405

thank you. It will probably use a 'pedestrian overpass'.


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## Loob

ewie said:


> (In reply to the original post: for me a _viaduct_ carries specifically *trains*; a _flyover_ *cars*.)


That's how I'd usually differentiate them, too....  

There's also the fact that (the way I picture them, anyway) a viaduct can cross pretty much anything, including rivers and moorland; a flyover, though, definitely crosses a road.

Here's a viaduct; here's a flyover.


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## JamesM

Isn't there a fairly long flyover in London?  Doesn't it cross more than one road?


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## Loob

JamesM said:


> Isn't there a fairly long flyover in London? Doesn't it cross more than one road?



I should have said "a flyover crosses a road or roads".


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## JamesM

The reason I asked is that an overpass (in the U.S.) crosses over one road and is not usually very long. I was wondering if overpass and flyover are really synonymous. I'm not sure they are.

I guess my question is: what makes Hammersmith Flyover a flyover and not a viaduct?


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## Andygc

I think the significant difference between flyover and viaduct (in BE at least) is:

A flyover starts and finishes at approximately the same level as the road or roads over which it flies. Its purpose is to allow streams of traffic to cross without obstructing each other.

A viaduct provides a solution to taking a roadway over a valley - which is why most viaducts in Britain carry railways rather than roads - at the time the railways were being built nobody saw any good reason why horses and people should not carry on walking up and down hills. Trains, on the other hand, could not cope with steep hills, so a level path was provided by cuttings, embankments, tunnels and viaducts depending on the hilliness of the terrain.

PS. I think that answers the Hammersmith Flyover question - it goes up and over and then back down again.


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## JamesM

Thanks, Andygc. That makes a lot of sense. 

We have a few viaducts in Los Angeles, such as the 6th Street Viaduct. It starts at one level on the top of a hill and slowly slopes down to street level a few miles later. Although both sides are at street level, they are at entirely different elevations. 

Disneyland constructed a flyover over Ball Road to route traffic over this busy intersection and send it directly into their huge parking structure.

I really like your definition of a flyover. I think these are a rarity in Los Angeles. It also makes me think that an overpass and a flyover are not the same, or at least not _necessarily_ the same.


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## Loob

Andygc said:


> I think the significant difference between flyover and viaduct (in BE at least) is:
> 
> A flyover starts and finishes at approximately the same level as the road or roads over which it flies. Its purpose is to allow streams of traffic to cross without obstructing each other.
> 
> A viaduct provides a solution to taking a roadway over a valley - which is why most viaducts in Britain carry railways rather than roads - at the time the railways were being built nobody saw any good reason why horses and people should not carry on walking up and down hills. Trains, on the other hand, could not cope with steep hills, so a level path was provided by cuttings, embankments, tunnels and viaducts depending on the hilliness of the terrain.
> 
> PS. I think that answers the Hammersmith Flyover question - it goes up and over and then back down again.


Excellent and illuminating answer, Andygc!

(And James, I'm sorry I thought you were getting at me...)


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## JamesM

Just out of curiosity, what would the things we call "overpasses" in this picture be called in British English?

http://cache1.asset-cache.net/xc/84...5138A1ADE2ACF4B801C429B9A98E376711F73866912B6


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## Packard

When I lived on Long Island we had the "Roslyn Viaduct", which was a bridge that allowed Route 25 to overpass Old Route 25 (I think I got that right).  I always thought it was called a "viaduct" because when driving over it, you did not get the impression it was a bridge.  There was no structure above the roadway, as all the structure was below.  

I did a Google search and our not-too-beloved Roslyn Viaduct is about to be replaced:

http://query.nytimes.com/gst/fullpa...F930A25752C1A9639C8B63&partner=rssnyt&emc=rss

Although there was some water nearby, this viaduct had nothing at all to do with the flow of water anywhere.


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## Loob

JamesM said:


> Just out of curiosity, what would the things we call "overpasses" in this picture be called in British English?
> 
> http://cache1.asset-cache.net/xc/84...5138A1ADE2ACF4B801C429B9A98E376711F73866912B6


I'm sorry, James, your link doesn't work for me

What would this be in AmE? Click.


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## Rover_KE

Loob said:


> I'm sorry, James, your link doesn't work for me


 
Nor for me.



> What would this be in AmE? Click.


 
Is that S_paghetti Junction, _Loob?

Rover


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## panjandrum

JamesM's link (I can see it yah boo) shows a series of traffic-carrying things that cross left-to-right over a lower level traffic-carrying thing.
I wouldn't call those fly-overs.
I don't have an alternative term for them, other than bridge, because I have never seen the like!


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## Loob

Oooh, I can see James' link now!

I'd call the multiple bridges "flyovers"....


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## JamesM

Here's the alternate link I gave to Loob:

*http://tinyurl.com/29jylhn*

I hope that works for others.


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## JamesM

Loob said:


> I'm sorry, James, your link doesn't work for me
> 
> What would this be in AmE? Click.


 
That would be called an interchange. Depending on the design it might also be called a cloverleaf.

Here's a picture of a cloverleaf:

http://humanflowerproject.com/images/uploads/main-cloverleaf.jpg


Some of the components of either design could be called overpasses individually, but the collection is called an interchange.


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## ewie

JamesM said:


> http://humanflowerproject.com/images/uploads/main-cloverleaf.jpg


Now _that_ link doesn't work for me, Mr.M  I know exactly the thing you mean, though ... because it looks like a cloverleaf

The other one did, though.  Like Panjo I'd just (probably) call those bridges over an underpass


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## JamesM

Well, at that point the freeway drops down below normal street level for a few miles. I wouldn't call it an underpass. It's a lower-than-ground-level roadway (as if it were in a v-e-r-y l-a-r-g-e trench, I suppose).


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## Packard

The Roslyn Viaduct referenced above in post #23 was called the "village overpass" or "Old Northern Boulevard overpass" when you were afoot or driving in the village instead of driving over it on the Viaduct.


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## ewie

JamesM said:


> Well, at that point the freeway drops down below normal street level for a few miles. I wouldn't call it an underpass. It's a lower-than-ground-level roadway (as if it were in a v-e-r-y l-a-r-g-e trench, I suppose).


No, I wouldn't really call it an _underpass_ either (hence my ).  I used occasionally to drive along an identical roadway _[subterranean roadway???]_ in France and always wondered what it might be called in English ... I wonder what those bits of the London Underground which are sunk _below_ street level but actually open to the sky are called ...


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## JamesM

To confuse things a bit more, here is a picture of what we call a "flyover" in American English:

http://newsimg.bbc.co.uk/media/images/41871000/jpg/_41871672_ap300flyover.jpg


I notice this is from the BBC, so perhaps you use "flyover" for this as well in British English?


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## Packard

JamesM said:


> To confuse things a bit more, here is a picture of what we call a "flyover" in American English:
> 
> http://newsimg.bbc.co.uk/media/images/41871000/jpg/_41871672_ap300flyover.jpg
> 
> 
> I notice this is from the BBC, so perhaps you use "flyover" for this as well in British English?


 
Yes, that is how I would understand "flyover".  Moreover, I would often hear it as, "We did a flyover to assure ourselves of the enemy's strength."


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## Andygc

JamesM said:


> Just out of curiosity, what would the things we call "overpasses" in this picture be called in British English?


I would call those bridges, and I would, for lack of any other BE term, call the sunken roadway an underpass. We do have one or two of those around the UK, but not on the same scale.

When talking of viaducts earlier, I completely forgot the ones that _were_ built for horses. The best known is probably Holborn Viaduct in London (1863-9). Another fine example is in Exeter, but for some reason is called The Iron Bridge (1834-6) - of course, a viaduct is a type of bridge ...

PS, nice to see long-standing contributors (including a mod?) drifting off topic - but that aviation image to me is a flypast, not a flyover.


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## ribran

Loob said:


> What would this be in AmE? Click.



For me, that is an interchange (or, more precisely, a stack interchange), and the individual ramps are *flyovers*. 

This photograph shows an overpass.


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## wolfbm1

What do you call a bridge that carries a railroad and crosses a city road where cars and buses travel? I would call it a viaduct. Could it be a railroad bridge?
http://jezdzepopoznaniu.blox.pl/resource/27_11_przepadek.JPG


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## ribran

Hi Wolf,

It's definitely not a viaduct (a long bridge-like structure, typically a series of arches, carrying a road or railway across a valley or other low ground)*. I'd call it a railroad overpass.

*From our dictionary


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## JamesM

To me, a viaduct would be a extended portion of elevated track like this:

http://www.trainsarefun.com/lirrpho...or-Train-Montauk-Br-Viaduct-Hillside-6-66.jpg

I would call the structure in your image an overpass.  The cars travel though an underpass and the trains travel on the overpass.


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## wolfbm1

Thank you, ribran and JamesM. So a viaduct has to contain a series of arches or bridge spans. And the structure on my image is called a railroad overpass or just an overpass in American English.


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## JamesM

wolfbm1 said:


> Thank you, ribran and JamesM. So a viaduct has to contain a series of arches or bridge spans.



Well, it's not just that it has a series of arches or spans.  Bridges can have a series of arches or spans, like this one in Los Angeles:

http://farm4.staticflickr.com/3053/2827887377_5646d5bf84_m.jpg

A viaduct, as I understand it, is an extended elevated path for vehicles or trains that either spans uneven ground (such as a valley) or that places the traffic on a different level from surface traffic.  There is a long viaduct in Los Angeles near the airport that elevates the train traffic to eliminate railroad crossings on busy surface streets.

Some of the pictures I see of viaducts are structures I would call bridges, so I'm not sure where the line is drawn between the two.



> And the structure on my image is called a railroad overpass or just an overpass in American English.



Yes, that's correct.


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## wolfbm1

JamesM said:


> ... A viaduct, as I understand it, is an extended elevated path for vehicles or trains that either spans uneven ground (such as a valley) or that places the traffic on a different level from surface traffic. ...


I wonder if Gardiner Expressway in Toronto fits your definition. Here are the images: http://www.flickr.com/photos/ottawabusgallery/6733920259/in/photostream/  and  http://mw2.google.com/mw-panoramio/photos/medium/10552316.jpg


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## JamesM

In other words, what makes an expressway different from a viaduct?  Good question.  I don't have an answer.  :^)  Perhaps someone else does.

Ah, one thought comes to mind.  I would expect an expressway to have onramps and offramps, while a viaduct would carry traffic only from one end of it to the other (no onramps or offramps).  That may not be correct, :^) but that would be my assumption.


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## PaulQ

After reading the pages, my tuppence worth:

·         A viaduct is a term now all but solely associated with the railway – by virtue of their age and the then construction methods, most are made of bricks or stone and thus have arches.
·         A flyover is a road of recent (within the last 60 years) construction that passes over another road or roads (or rarely another type of obstruction); they are usually constructed of concrete and supported on concrete pillars.
·         A bridge is generic term for any road or pathway, which is used for the transport of persons, animals, vehicles, goods or materials above any obstacle by *passing over an obstacle from one side to the other*. Bridges may have, as their main construction materials, anything suitable from vines or rope to iron or concrete. Bridges need not be permanent nor a solid structure, see “transporter bridges” “drawbridges” etc. but must perform the bolded task.

All flyovers are bridges.
All viaducts are bridges.
Not all bridges are flyovers and/or viaducts.

An underpass is a short tunnel below the ground. It is longer than the widest bridge is wide. The point at which an underpass becomes a tunnel is either (i) subjective; a guide might be, “When you are halfway through it can you see the end?” If “Yes” then it is probably an underpass. (ii) as per the name given to it by the construction authority.

A road at below normal ground level from which a user may easily see the sky is a cutting, a term taken from the railways of the 19th century. Cuttings were originally to allow canals and other roads to pass overhead but are also used also to reduce inclines.

The expressway appears to be a flyover.


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## wolfbm1

Thank you, PaulQ. Would you call the structure in post #38 a railroad overpass? It can't be a viaduct because it doesn't have arches.


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## PaulQ

That is a railway bridge.  (Note *railroad *and *overpass *tend to be AE terms.)

This is a viaduct: http://www.flickr.com/photos/crayzy_ray/2763937264/ (The Ribblehead viaduct, Britain's most famous one.) Viaducts tend to be high, long and often pass over varied terrain/obstacles.

A rare exception to the "railway" "bricks and stone" and "arches" type of viaduct is the relatively modern Kingsmead Viaduct, which is on the A10, a little to the east of the English town of Ware* but this is also known as [the A10] *road bridge* and [the Ware] *elevated section. *It passes over a canal, a river a railway and some marshy land and is about 800m long.

Off-hand I can't think of another road classified or named as a viaduct.

* about 25 kilometres from where I live.


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## natkretep

Yes, I would say *railway bridge* or *rail bridge* too. I'm not sure why I don't say *rail(way) flyover *(because _flyover _is the BrE equivalent of _overpass_); I haven't encountered _flyover_ for rail bridges. That said, I found some instances of *rail(way) flyover* in google.

I've commented earlier on *viaduct*, which seems to be used strangely here: it seems to be used for complex or extended flyovers - but Ribran has given the standard definition.

*Expressway* is another term for *motorway* or *freeway - *as mentioned by James, and comes with _slip roads_​ (= on- and off-ramps, AmE) - and isn't used in relation to railways.


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## wolfbm1

Thank you, PaulQ and natkretep. I think I got it. So the structure in post #38 is a railroad overpass or just overpass in American English and a railway bridge in British English. It definitely isn't a viaduct. I think I have learnt a lot in this thread.


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