45 degree skewed bridge?

[Allegheny]

Has anyone on the kitbashed a skewed bridge that has ends at a 45 degree angle? Was thinking of using a couple of Kato n-scale double track bridges and modifying them to cover a 15" angled gap.
 

[tehachapifan]

I know you saw my reply on the "other" board but, for the sake of relatedness, I've included it here too.

Quite some time ago, I kitbashed this skewed N scale bridge from the Walthers double-track truss kit. I don't think it's exactly 45 degrees, but it fit where I installed it perfectly. I still have not completely finished this area or installed bridge track....

[Allegheny]

Tehachapifan
And in keeping with you lead on keeping both forum in the know I've copied my other forum questions.

Nice looking skewed bridge and is just the example I need. A few questions.
1. Are there stringers under the track and will you be using ME bridge track to finish the bridge.
2. Do you think I should kitbash Kato bridges or use a couple of Walther's kits?
3. Advantages/disadvantages to either?

Allegheny

[tehachapifan]

There are indeed stringers under the track and they were included in the Walthers kit (they are in little individual pieces that run from cross-brace to cross-brace).

I have not really evaluated the Kato bridge for tackling a project like this but, since the Walthers bridge was already in kit form and in pieces, it seemed the best choice at the time rather than taking apart the already-built Kato bridge (unless they also have it in kit form). The trusses in the Walthers kit are about 11" long and the Kato trusses are about 10" (at least on the Kato bridge I have).

 Yes, I believe it is ME bridge track that I purchased to eventually run across this bridge. It's been sitting in a box in the corner for years now.

[tehachapifan]

....regarding covering a span of 15" which neither the Walthers or the Kato bridge I have do, can you possibly have a pier at one end that supports the truss bridge on one side and maybe a short girder bridge on the other? The reason is, trying to lengthen a truss span could be challenging and could also cut down on the actual strength of the bridge with potentially weak joint(s).

[nkalanaga]

Sure, mixed truss and girder bridges are very common.  Depending on the situation, you might not have to skew the truss. if the pier(s) don't have to be parallel to the sides of the gap.  Build the truss as normal, then skew the abutment ends of the girder bridges.

[tehachapifan]

My question was directed at the OP to see if his arrangement would allow for a pier and a short girder section to attain the 15" span needed.

[eric220]

@TrainCat2 is still on hiatus, so these aren't available for purchase, but the pictures give some insight on how a skewed bridge is engineered.

http://www.traincat2.com/d_plategirder2.htm

[Allegheny]

Gentlemen
Thanks for the discussion. 

Tehachapifan & Nkalana - I'm crossing four tracks.  No place to put a regular pier between them.  So a plate girder bridge extension is out unless I can use a skinny steel pier between track 2 and 3.
Eric220 - TrainCat2's bridges angles are exactly what I want to do.  I just need a longer bridge.

I did some calculations today; good news/bad news.  I shifted the location of the bridge and depending on how close the piers can be to the outside of the tracks below, a slightly extended kitbashed bridge may work (11"-12").  The bad news is I have to cross over four tracks.  I'm wondering if there is a way to use tubing or a rod in the underside structure to strengthen the bridge and lengthening it at the same time.  
Thoughts?

[tehachapifan]

Are the tracks below straight or curved? If straight, the abutments can probably get pretty darn close versus curved track. Not sure how close the prototypes get but it's probably similar to, say, the distance to the side of a tunnel portal.

[nkalanaga]

You could put them that close, but most prototype bridges would likely have more than the minimum clearance.  The problem is that, if you hit a tunnel portal, you'll probably not bring the mountain down, but hitting a bridge abutment could collapse the bridge.  On the other hand, we modelers do things that the prototype wouldn't on a regular basis...

The NMRA clearance gauge is 16 ft wide, or 8 feet from the track centerline.  I'd go with that as the absolute minimum, then see if it couldn't be stretched a little. 

[Allegheny]

Tehachapifan - I did shift the bridge location from a curved location to a straight and gained some room.
Nkalagara - Looks like I'll have an inch+ clearance for the abutment. (16' = 1.2")
Thanks guys.  Back to the drawing board.

[nkalanaga]

An inch of clearance, from the centerline, will be plenty.  That would even allow a minimal maintenance access road squeezed in.

[Allegheny]

Nkalanaga
While reviewing my track plan, I saw an where rerouting a branch line reduced the tracks to bridge over from four to three.  Plenty of room now.  I'll still do the 45 degree skewed design as there is no room to do a straight 90 degree approach and exit.
Thanks.

[Mark5]

Quite some time ago, I kitbashed this skewed N scale bridge from the Walthers double-track truss kit. I don't think it's exactly 45 degrees, but it fit where I installed it perfectly.

Awesome.