The EL Starrucca Viaduct in Lanesboro PA is refered to as a “Viaduct” while the Detroit–Superior Bridge bridge in Cleveland which has a lower deck for a subway is refered to as a “bridge”. Is Viaduct just a fancy term for a bridge?
Erie Laccawanna Bridge- https://en.wikipedia.org/wiki/Starrucca_Viaduct
Detroit–Superior Bridge-https://en.wikipedia.org/wiki/Detroit–Superior_Bridge
I’ll bite- a quick Google search yields this explanation:
A viaduct usually refers to long bridges or series of bridges connected to one another by arch bridge structures that carries a road or a railway across a valley or a gorge. Viaducts mainly connect two points of the terrain which are similar in height in order to carry mostly rail and road traffic.
From the following website:
Why a duck? Why a no chicken?
Detroit Superior Bridge - the 12 concrete arch approach structures could be considered viaducts, but the steel part in the middle is a bridge. Typically in Engineering terminology, that makes the whole thing a bridge.
Here is the oldest and most famous railroad Viaducts, still in use:
https://en.wikipedia.org/wiki/Thomas_Viaduct
A Viaduct is a type of Bridge.
Sheldon
a bridge is supported on either end. One type of design of a bridge has an upper horizontal structure in compression and a lower horizontal structure in tension that minimizes bending. this same concept is used in I-beams as well as aircrafter wing spars.
Of course there are suspension bridges where the surface is supported from above
the surface of a viaduct is supported from the ground. The Romans invented the arch to minimize the material used to support the surface.
All viaducts are bridges but not each bridge is a viaduct.
A succession a number of bridges with short spans in relation to the total length the structure is called a trestle. If the spans are long, around 150 - 200+ ft, we have a viaduct.
The approaches of the Detroit Superior Bridge fit the viaduct definition, but as each approach span is an open-spandrel arch bridge, I would tend to arch bridge.
But that is disputable.
Regards, Volker
This structure has almost always been known (and continues to be known) as “the viaduct” in Milford, MI:
Former Pere Marquette, C&O, now CSX.
I guess Viaducts are based on roman aqauducts
I grew up in the New York area, and viaducts were always massive multi-arch affairs. I moved to northern Michigan, and in Manistee County there is a road called Viaduct Rd. I drove parts of the road a number of times looking for the massive works, but eventually realized that the single span girder bridge carrying the Ann Arbor RR over the road was the “viaduct”. The road narrows under this low clearance bridge. It was the least spectacular viaduct I had ever seen. Apparently in local parlance, a viaduct is any RR bridge that crosses over a road.
Adding to Mike’s response, I think terminology varies by region. I have never heard the name “viaduct” used around here, but then I don’t know of any massive stone bridges here in our flat land where no stones exist.
And I remember reading the term “flyover” years ago, and I was mystified. I finally figured out they meant “overpass.” Of course, we don’t have any spot that I know of where one RR track crosses over another, but in the last couple of years I noticed that on some of the TV traffic reports they have been using the term “flyover” where ramps cross over on highway interchanges. Must be furriners.
In my city, when people talk about the viaduct, they are talking about the main east-west street that goes over the top of a cluster of downtown railroad tracks. 100+ years ago, the city built the viaduct over the tracks because all the railroads came together in one spot and cut the town in half. The street now is actually two 3-lane streets that cross the river and then run 2-3 blocks over the top of the railroad property on concrete piers- no stone arches for us!
I think you will find that the difference between “viaduct” and “bridge” is that “viaduct” has 7 letters, whereas “bridge” has only 6.
I looked the two words up in my dictionary and find too much to copy here. The definition of a Bridge does not mention Viaduct, but Viaduct says it is a bridge that is characterized by being short spans supported on tall/high structures (either of stone/concrete or steel).
I think that us “humans” often blur the definitions of words out of ignorance of their true meanings and thus some “Bridges” are called “Viaducts” by mistake (or snootyness, but when that happens they are often pronounced as ‘Vee-a-ducts’ instead of ‘Vi-a-ducts’).
The first viaducts were built by the Romans to carry water across wide valleys to supply Rome. Since there were no efficient means to lift water uphill, the viaducts maintained the elevation of the hills with a slight grade for gravity-feed purposes.
I believe ‘flyover’ was a PRR term. Flyovers were built to eliminate crossovers and were especially useful at junctions. ZOO interlocking on Amtrak in Philly still has flyovers for trains heading NYC to Pittsburgh. N. Phila would be the only stop in Philadelphia, bypassing the reverse move at Broad Street Station. Trains to Broad street went underneath the Pittsburgh leg of the wye.
There’s another ex-PRR flyover on Amtrak between Claymont & Wilmington, DE, to allow SB freights to access the ex-DuPont Facility on the east side of the tracks without fouling the NB passenger main.
Because-a the water rolls off a duck’s back and a-chicken justa gets all wet.
Breaking the word “viaduct” into it’s two roots, “via” means “by way of”, while a duct is a way of getting something from here to there.
Technically, a duct is an enclosed space (by the definitions I saw), but in general what I just wrote kinda fits the bill.
And I agree - a viaduct is a bridge, while a bridge may not necessarily be a viaduct.
In the end, it’s whatever people have been calling it for years…
Yes, it is something like the difference between a spanner and a wrench. Or, the difference between a DS and an RTC.
Your inner Marx Brother is coming out…
As far as terminology goes, in a railroad sense (especially engineering and maintenance) bridges on railroads includes culverts and pipes carrying natural drainage under (and sometimes over) the railroad along with grade separations.
Just to make matters worse, I used to live in a town that had done a significant grade seperation project, like 80 years prior.
The RR mainlines through town were raised up on continuous earthen fill, raising the rails approx. 12 feet above their previous “at grade” elevation. Most city streets were bisected by this work.
Some of the major arteries through town were actually excavated down and under the rails, placing the height of the pavement roughly 4 feet lower than it’s previous at-grade elevation.
At the point where the rails on the raised fill crossed over these lowered streets, concrete bridges were built just sufficiently long for the railroad trackes to span over the roadways, giving like a 14 foot vertical clearance, with a span length of perhaps 50-60 feet.
The locals referred to these portals where roadways passed through the otherwise continuous raised earthen fill as “viaducts” .
Perhaps because they were “the way through” the track elevation that otherwise divided the city? (matter of perspective)
The word is aqueduct.
Via translates into road or way. The “duct” part comes from aqueduct, which means leading water, which applies to canals and pipes in addition to bridges carrying water. The association with aqueduct and bridges came from the Romans not having any means of piping water under significant pressure, so they put up a bridge to keep the aqueduct near level. Being the most visible part of an aqueduct, the word came to be associated with the bridges as opposed to canals or tunnels.