Which Bridge?

[Pitchwife]

When you are crossing anything from a gully to a river, except for the length of the span, is there any rhyme or reason to determine which type of bridge to use as opposed to another? I know that there are a bunch of different types and figured there must be a reason to use one over another but so far I haven't figured out what they are. Ideas??

Clark

 

[Clerk]

Hi Clark. I don't know what the system is for what type bridge, but for gullys and rivers I prefer trestles. Others will come on and give their views for different types of bridges and for what purpose.

 

[Lighthorseman]

Choosing Bridge Types...

Unless you're a prototype modeller who has to model specific bridges in specific locations, here is the way to choose.


"Hmmmm....Hey, that's a cool bridge. I'll put it, ummmmm, here."

That's what I do.

 

[N Gauger]

Hi, Clark,

You've hit upon the very basis for platform construction. You buy or build something, you look around to see where it will be most pleasing to the eye. Then place it there & build around it.

Good Luck!!

 

[rockislandmike]

I have a book about building bridges for model railroads at *home*; I believe there is a rationale, but I'll have to gander at it again before I pass on any info. I will do so tonight if I get a chance.

 

[Ravensfan]

Originally posted by N Gauger

... You buy or build something, you look around to see where it will be most pleasing to the eye. Then place it there & build around it.

Or, imagine your layout, in your mind or on paper, and go from there. In fact, that's what I'm doing right now. Imagination is a great tool.

 

[RailRon]

Hi Clark,
if you really want to be prototypic, try to get Paul Mallery's "Bridge & Trestle Handbook" (Carstens Publications, $22.95 - but you might be lucky by finding a copy in a public library!). There you find about everything about every bridge type to every sort of landscape...
If you're freelancing, follow N Gauger's advice: Put the bridge you like most to where it shows to its best advantage

Happy bridging troubled waters!
Ron

 

[N Gauger]

Originally posted by RailRon
Hi Clark,
if you really want to be prototypic, try to get Paul Mallery's "Bridge & Trestle Handbook" (Carstens Publications, $22.95 - but you might be lucky by finding a copy in a public library!). There you find about everything about every bridge type to every sort of landscape...
If you're freelancing, follow N Gauger's advice: Put the bridge you like most to where it shows to its best advantage

Happy bridging troubled waters!
Ron

Here's a link to Amazon.com

Bridge and Trestle Book

 

[Pitchwife]

Thanks for all of the advice. I'm not prototyping anything in particular, I just didn't want to have someone come up and tell me that no railroad designer in his right mind would put that type of bridge there. Still, there must be a reason for all the different types. Maybe something like load bearing or material cost. Otherwise a lot of engeneers would be out of business.

 

[Paul Davis]

there are a couple of things. Generally the more complex bridges like canteliver,arches, suspension will be used for long spans while plate girder etc will be used for shorter spans. Also generally through bridges are only used when clearance is a problem under the bridge.

Just use common sence. After all a 3ft long girder bridge (without any piers) would look flimsy and stupid but on the smae note a 6" suspension bridge would look out of place too.

 

[chapmon]

Bridge type

One of the things described in Mallery's Book, is an engineering principle called "Cooper Loading".

IN essence, the length, weight of average tonnage using the bridge, and the availability of material can dictate these design principles. It also might be determined by what it is you are spanning, i.e., roadway, creek, river, etc. A railroad also might determine that for a slow flowing creek, a culvert might do, in that when original surveys were done, the railroad always built with an eye towards cost. If a fancy bridge wasn't necessary, it didn't get built, and something cheaper may do until that design failed (flooding or other disaster).

The books go into that in detail.

There is also a book available on American Railway Bridges (I don't remember the publisher).

chapmon

 

[billk]

IN essence, the length, weight of average tonnage using the bridge.......

But in most cases, this would limit us, in our layouts, to not much more than a simple culvert!