Amoskeag Northern - Simonds Industrial Branch

[Ian MacMillan]

As a geologist, I can confirm that having one big rock sticking out of the middle of a river has been observed in the prototype.

No he is referring to the color. The rock is more of a tanish color. Hey its what came out of the bottom of the Saco river!

It looks great Ian but one thing did just jump out at me. Are the signals on the wrong side of the bridge? Wouldn't it be safter to have them on the opposite side so viewing isn't blocked by the truss? This may need to be a girder so the FRA doesn't start writing violations,

Phil

Phil it maybe the angle of the photo. I made sure to check the line of sight for the signals and you can clearly see both targets on both signals if you were "standing" under the highway bridge or in the cab so that it will give the engineer plenty of time and distance to stop upon observing the signal.  Placement was also OK'd by an actual signal maintainer as well. I had thought about placing them on the other side of the bridge but it places it farther from the interlocking, almost too far, and the highway bridge would obstruct the view of the signal. Its not an ideal placing but its the best of the two options. I am still open to a through girder though and I may bash a cheapo to see how it looks.

There is (or were, I dunno if they changed em in the last few years) a similar set of "obstructed" signals in Ayer, MA...that I believe someone on this board has violated...

http://photos.nerail.org/s/?p=34965


And of course the example that I am using, the signals at CP-99 at the bridge in Springfield, MA are in their old locations on Bing Birds eye

[central.vermont]

Phil it maybe the angle of the photo. I made sure to check the line of sight for the signals and you can clearly see both targets on both signals if you were "standing" under the highway bridge or in the cab so that it will give the engineer plenty of time and distance to stop upon observing the signal.  Placement was also OK'd by an actual signal maintainer as well.

I think we need to confirm this by running a camera car on this. 

Jon

[Ian MacMillan]

Bring over John's!

The bridge side trusses are also much thinner on the CV kit so I think it will give a slightly better view. Here are some track level shots. Plenty of sight distance.





I could possibly move the signals back a tad, to the the right end of the X58


And here is a very quick mock up of a through girder at that location.

[DKS]

And here is a very quick mock up of a through girder at that location.

Hmmm... much as I like the truss, this too has merit...

[MichaelWinicki]

Both look good.

I like the through-girder a little more because it doesn't dominate the scene.

There's so much going on that scene to begin with, the truss bridge just adds to it and takes away from the other interesting details found in that part of the layout.

[Ian MacMillan]

I like the girders as well. The span is 130'...I'm not an engineer...would I need a center span? Lee? Skibbe?

[Dave V]

What you have looks good...  Two spans on a center pier.  I think 80' girders were common so two 65' spans are quite believable.

[Ian MacMillan]

Wish we hashed this out before I poured EnviroTex   

[Bsklarski]

I would stick with the original idea. The second idea was not always the prototypical case in the NE. Maybe a deck girder bridge instead?

[Dave Schneider]

There is a relationship between span length, vertical girder thickness, and capacity.  I think that this was published in Model Railroader in the 1980s. I will take a look for it tonight.

Best wishes, Dave

Edit: I was looking around a bit and came across this cool site of historical bridges. A search for railroad yields 700 results.
http://www.historicbridges.org/index.htm

[peteski]

Judging by photos alone (it might look a bit different viewed in-person), I prefer the original single-span truss bridge (as long as it isn't painted a bright rust color).    The 2-span girder bridge doesn't do it for me (and single span is also out of a question for me).

[wazzou]

For E72 Loading, 110' is the Max. single span.  Two 70' spans would need 8' deep girders and panels spaced @6'-6".
On E50 Spans, the girder depth is 7'-3-1/2", with the same panel spacing.
I'm sure you could make subtle adjustments for 65' spans.

[packers#1]

I much prefer the truss; without it you loose the balance it adds to the scene with the buildings to the right (artist hat).
As for modeler's hat, I don't dig through girders; they block most of the paint schemes etc. For a show layout, I want the locomotives as visible as possible

[Scottl]

+1 I like the truss too.  The river is perfect- I can't see a mid-pier in a situation like that where the current and depth would be highest.  They would use two piers near the shore and a three span bridge if they had too, but I think the truss would be fine too.

[DKS]

I can't see a mid-pier in a situation like that where the current and depth would be highest.

A center pier would be perfectly fine in a river like that, which would be at most only several feet deep.

It's a wash for me as to which bridge works best. I think they both have pros and cons.