Hi Folks,
I am going to build a curved trestle kit. I am looking for info about:
1. Trestle will be about 16" long, 4" high.
2. I need recommendations on kits that the curve radius is flexible to my needs.
3. Are there deck plates or stringers capable of supporting the trestle for several inches without the use of trestle bents underneath? I have curved double tracks underneath the trestle that somewhat parallels the trestle and the use of trestle bents are limited for 6 to 10 inches.
4. Could I jury-rig a viaduct footing(s) in lieu of some of the trestle bents for support? (footings found on page 379 of Walthers 2008 HO Reference Book)
5. How is track layed on the trestle?
Yours In Model Railroading,
John
Littleton, CO
1. You are modeling a short, relatively low trestle.
2. What is the radius? Wooden trestles can accommodate all radii, steel trestles a bit less so.
3. Yes, but the sharper the radius, the shorter the deck/stringers. 40 and 50-foot girders are common, as offered by Micro-Engineering. (Your tracks are underneath "parallel"? Don't you mean "crossing under" the bridge? How wide of a gap between vertical supports do you need?)
4. Yes, but it wouldn't be common for timber trestles and for steel viaducts of this small size.
5. The ties are laid (1) directly on the stringers or (2) on ballast, supported by a horizontal deck atop the stringers..
Mark
markpierce wrote: 1. You are modeling a short, relatively low trestle.2. What is the radius? Wooden trestles can accommodate all radii, steel trestles a bit less so.3. Yes, but the sharper the radius, the shorter the deck/stringers. 40 and 50-foot girders are common, as offered by Micro-Engineering. (Your tracks are underneath "parallel"? Don't you mean "crossing under" the bridge? How wide of a gap between vertical supports do you need?)4. Yes, but it wouldn't be common for timber trestles and for steel viaducts of this small size.5. The ties are laid (1) directly on the stringers or (2) on ballast, supported by a horizontal deck atop the stringers..Mark
On second thought, I don't have enough info to answer question 4 properly.
Hi Mark,
1.The radius is 18".
2. When I typed "parallel", I knew I should have found a better word! The double track crossing under the trestle creates a problem to have vertical supports. The gap between vertical supports is 9".
- John
1. Assuming you are modeling in HO scale, a steel viaduct made up of 30'-long plate-girder bridges may work. There should be enough vertical clearance between tracks (make sure you have tell-tails to warn crew if you model in an era where there is a chance railroaders will be on top of the cars.)
2. If you have to cross a 9" distance without the opportunity for vertical support for the bridge you're probably out of luck. What radii do the underlying tracks have, if any. At what angle will they cross under the bridge? What is the possible range of the distance of the two underlying tracks for allowing a bridge support between them?
http://www.blackbearcc.com/index.htm
You might find some info and ideas here. I've seen some curved trestle that were a series of straight trestles joined together on angles to form a curve.
Modeling B&O- Chessie Bob K. www.ssmrc.org
Mark,
The radii of the underlying tracks is also 18". They cross under the bridge at less than a 10 degree angle. the distance between the two underlying track beds are 1.25 inches, 2.75 inches on center.
Loathar, I saw your 2004 posting about this website when I did a forum search. Thanks for the reply and the email.
Bob, I figured that I would have to kit bash something to make this work. Glad you reinforced my thoughts.
Maybe the easiest solution is to put the lower tracks in a tunnel....but perhaps there is an answer using a steel viaduct.
If a bent can be fitted parallel, but in between, the lower tracks while providing enough clearance.....skew two 30-foot (or if that doesn't work, similarly skew two 50-foot) deck spans so that the ends match the angles of the middle bent and similarly-angled bents on the outside of the tracks. The two deck spans on either side would be modified so that the decks span are longer on one side side to match the skewed bents. The other deck spans, if any, to complete the bridge would have a normal rectangular shape. Something like this but on a curve:
[ ][ / / / ][ ]
I'm unsure how many spans in total will be needed, you may need to cut down the length of one or both end deck spans to fit your particular configuration. Perhaps only the four spans in the middle will be needed. Cut out some paper patterns and see if it could work.
Rather than lay the ties directly on the span, I'd put down a ballasted deck. This will help hide the distances between the curved track over the straight deck spans. Railroads wanted the track centers to be close to the middle of the spans for even weight distribution..
Good luck.
ME has come out with a new girder to compliment the 30' and 50' sections. I am not sure if it is a 70 or 80' girder. If you can clear the towers with that 70' the steel viaduct may be the best option. Generally 50-60' is about max span using 18" radius due to track overhangs on the straight beam, but if templated just right it shouldn't look that bad. The ME towers use the 30' small girder. Another consideration is the track separation (railhead to railhead). You will still need to maintain 3" clearance under the girder.
So your total span may need: from one abutment, a 30', 30' over a tower, 70' (the 50' would be best if works), 30' over tower, and the remaining 30' to the other abutment. The instructions for the ME viaduct are quite good and show how to template and "miter" the beams to fit the radius.
I didnt have to finagle the miters on a curved one I did, due to a straight easing into a 52" superelevated turn. A little sanding to fit the template. Tighter radius make the fitting more difficult.
The center span is a 50'
I cut the bottom section off the towers, you may need to modify them even more due to your elevation.
If you want to contact ME directly PM or email me for the info. No wesite that I know of yet.
Another option that hasn't been mentioned is the possibility of a stone arched viaduct. Built from foam, foam and laminated 1/4" or plaster castings. May work, and it would look quite nice. of coarse the center large arch wouldn't be that prototypical but don't know if that would bother you.
Mark and Bob,
Thanks for the info. I have thought about converting this whole thing to a tunnel but a trestle would look cool at this spot. And, I have other tunnels planned.
I scratch built this from plans in Kalmback's bridge and trestle book. Was easier than a kit. There are more pics in my sig. I would be glad to talk further if you private message me.