Bridge, Viaduct - same thing or different?

[Anonymous]

Well out here in Oregon we dont have viaducts that I have heard of!! On the "hill" here we have bridges of all kinds and one trestle that is curved over Oregon Hwy 58 ( the hwy I live on) and Salt Creek to take the tracks back westward and up the hill again. It is something to be driving uphill on 58 and see the UP going over your head on what seems to be a spider web!!! And if you are ever out this way to see the bridge at MP 545 os so that seems to be hanging on the side of the cliff by bolts??? Wow!!!

[ironhorseman]

QUOTE: Originally posted by BR60103

QUOTE: Originally posted by PBenham

"I'm gonna ask you only once more! Why a duck?" [:o)][:p]

Why-a no-a chicken?

I've always vvundered the same thing

[markpierce]

In common (dictionary) useage, a viaduct is a series of spans or arches, carrying trains, vehicles, water, etc. It can be built with stone, concrete, steel, or whatever. Nevertheless, it is interesting to notice that in Clement C. Williams's Design of Railway Location (copyrighted 1917 and 1924, and used as a college railroad engineering textbook), makes no mention of viaducts; bridges and trestles, yes, but not viaducts. This suggests that perhaps it may be best to avoid using "viaduct" in a railroad context.

[daveklepper]

Tell that to the New York City Transit Authority!

[PBenham]

"What does a chicken have to do with this?" "Well, boss, I ain't had a meal inna four days, a chicken would do reeel nice righta now!"[:o)][;)]

[rrandb]

Using 2500 year old technoligy the romans built a system of canals and viaducts that dropped only 56 feet in 30 miles and yet delivered over a million gallons of water a day. Not bad for no lasers or motor power. A bridge can be as simple as a plank across a stream and on up from there but a viaduct requires at least one arch to support it. [2c] As always ENJOY

[dragonsparrowblue77]

QUOTE: Originally posted by vsmith

Bridge is a general term

Viaduct is a specific type of bridge (usually with stone or concrete arch spans), just like trestle, plate girder, suspension or truss, are all bridge, but a Viaduct is not a trestle is not a plate girder bridge is not a suspension bridge is not a truss bridge.

Here in Seattle we have the Alaskan Way Viaduct, which they are now trying to figure out how to fix or replace, due to earthquake damge, and wear-and-tear. Smart, huh!!

It is a double-decker elevated highway, that is a series of short spans of concrete reinforced bridging. The double-deck, not so great for earthquakes, but it is basically just a series of bridges, or one long one, with many spans.

[coldguy]

I've always thought that the differrence was whether it spans water or land. A bridge spans a river or lake, a viaduct spans a valley or depression. In Milwaukee, we have many viaducts that cross over the Menomonee valley. But in doing so, they also cross the Menomonee River. They are viaducts then because the majority of their span is over land? Then there is the HighRise bridge(I94/I43 over the same valley) and the Hoan Bridge(I794, also over the same Menomonee Valley) but they are called bridges.

The aqueducts carried water over land, so that would seem to reinforce my thinking. As long as we are studying etymology, there are bridges in lots of other terms. I use bridge clips to connect binding posts together. Some digital cameras use a 'PictBridge' to connect to a computer. The term 'bridge' seems to be generic for 'connecting'. I would submit that a bridge connects things, binding posts, peripherals, sides of a river or other 'gap' in level terrain, or sections of a roadway or railway, while a viaduct is the path, the thing itself, rather than a connector of two things.

I have a feeling that these structures are called what people prefer to call them. Most of the bridges and viaducts are named. Those names were chosen by politicians. Since when do they know what they are talking about?!!!

[dragonsparrowblue77]

QUOTE: Originally posted by coldguy

I've always thought that the differrence was whether it spans water or land. A bridge spans a river or lake, a viaduct spans a valley or depression. In Milwaukee, we have many viaducts that cross over the Menomonee valley. But in doing so, they also cross the Menomonee River. They are viaducts then because the majority of their span is over land? Then there is the HighRise bridge(I94/I43 over the same valley) and the Hoan Bridge(I794, also over the same Menomonee Valley) but they are called bridges.

The aqueducts carried water over land, so that would seem to reinforce my thinking. As long as we are studying etymology, there are bridges in lots of other terms. I use bridge clips to connect binding posts together. Some digital cameras use a 'PictBridge' to connect to a computer. The term 'bridge' seems to be generic for 'connecting'. I would submit that a bridge connects things, binding posts, peripherals, sides of a river or other 'gap' in level terrain, or sections of a roadway or railway, while a viaduct is the path, the thing itself, rather than a connector of two things.

I have a feeling that these structures are called what people prefer to call them. Most of the bridges and viaducts are named. Those names were chosen by politicians. Since when do they know what they are talking about?!!!

I would agree.

[Anonymous]

Based on the definitions I've heard, Chicagoans almost always use some terms wrong. A "viaduct" here is what's called any old plate-steel bridge (sans trestle) that carries RR ROW over a vehicular street.

[Anonymous]

QUOTE: Originally posted by smalling_60626

Based on the definitions I've heard, Chicagoans almost always use some terms wrong. A "viaduct" here is what's called any old plate-steel bridge (sans trestle) that carries RR ROW over a vehicular street.

Common use of the term viaduct around Chicago, usually in reference to a flooded underpass, is part of what prompted my question. I'm begining to think the entire elevated ROW, mandated by law in Chicago, is the actual viaduct and people began refering to any part of it using that name. This would be consistent with the elevated heavy rail ROW's mentioned in in New York and some other cities. Unlike the L, these structures are a combination of concrete retained fills, plate girder bridges, and some other types of bridges.

A show on the Discovery Channel about building a very long, very high Autobahn crossing of a very large valley used both terms in reference to the same structure. A series of bridges wouldn't seem to qualify as then the entire Bay Bridge complex in Frisco would be a viaduct, but I've never heard it called that.

[Dayliner]

QUOTE: So is an SD45 locomotive both an engine and a motor?

In a word, yes. That would be an engine under the hood, and motors on them axle-thingies. Or you could just call the whole set-up "the power" and save a lot of confustication.

[Eric Stuart]

In England, we generally consider a bridge to be a bridge if it has no more than two or three spans. Beyond that, it would be a viaduct.
A structure carrying water is an aquaduct, irrespective of number of spans.
The material of which the structure is made should make no difference to whether its a bridge or viaduct.
Hope that helps!!!!
Eric Stuart