I’m putting together a Micro Engineering girder bridge kit for my RR club. The piece of track included with the kit is an ~8" piece of ME track - with the ties bunched closely together. That got me to thinking. On the prototype, is the rail tie spacing over a bridge or viaduct identical to the tie spacing over the ballasted portions of track or are they different for some reason? Gut feeling says the same but figured I’d go ahead and ask anyhow. Thanks!
Tom
Depending on the type of bridge, the ties are spaced closer together. A ballasted deck bridge, for example, will have the ties closer to the spacing you see on the ground, but an open bridge (where you can look down between the ties and see what the bridge crosses) they will be spaced closer. It has to do with the fact that the only support under the tie is the bridge structure and the tie is only supported at these points.
I don’t know for certain but…
Edit, after re-reading your original post… What are you comparing the 8" length of track to? Is it other ME track or a different make? That might explain the difference.
I suspect that this may depend on era and company.
Ties do not normally sit direct on the bridge structure (except in so far as way beams may be considered part of the structure).
You could check out/get Micro Engineering’s Bridge Track… wonderful stuff. The more I see posts about bridges the more I wonder whether it’s for trestles and those bridges that are supporting under girders only though. (But, if so, why are the ties longer… they will only hang out into space???)
4.On deck bridges where the track is ballasted the ballast intervenes between the ties and the structure and spreads the load.
On open bridges there is usually a longitudinal timber under each rail which spreads the load. (I’m perfectly happy for someone to show me I’m wrong on this…)
US tie spacing is so close that I doubt that (a) it would be reduced or (b) the reduction would show on a model.
Micro Engineering are pretty good… I’d go with what they supply.
Whatever you do someone will come along later and declare that you did it wrong… loudly.
On an open deck bridge, the ties are both longer, and fatter. They are also spaced very close together, in some cases almost touching. In this case, the ties directly transfer then weight of the train to the bridge structure. And while not an encouraged practice, they provide a walking surface for trainman.
Nick
Thanks for the responses fellas. [:)] That really helps to clear up some things for me.
All three ME kits are deck girder bridge kits. The first one I completed (but didn’t add the track to yet) is a 50’ open deck girder bridge. And the short section of track supplied with that kit has the longer and closer ties spacing that Nick described. The other two kits are 85’ ballasted deck girder bridges that come with two (2) concrete decks each and you supply the track.
That leads me to another question. I know that the RRs often added bent lengths of guard or “guide” rails to the entrances of each end of certain bridges that were to help with eliminating derailments as the train traveled over those bridges. Why would a locomotive and train be more prone to derail there than over another section of track? Would that practice be true for both open and ballasted deck bridges? The shorter ME open deck girder bridge kit doesn’t come with a guide rail. However, the longer ballasted deck girder bridge kits - although neither has the rail nor track supplied with it - has the description for adding both included in with the instructions.
Anyway, many thanks again for your helpful input guys…[:)]
Tom
While not more derailment prone, bridges often include guard rails as added insurance. Because a derailment is bad, but a derailment on a bridge is much worse. What could the car fall on or into? How do get the rerailing equipement in? If the car falls off the bridge, how do you get it out again?
Ballasted deck bridges use conventional track.
Nick
The way I figure the US use of guard rails on bridges is as follows.
A car may derail any place. It is then possible for it to run quite some way held pretty much in line by the couplers/drawgear. This isn’t good for the track or the car. It gets a whole lot worse if the car meets the end of a bridge or gets part way through and then side swipes it.
I think that this is where the guard rails come in. There is a good chance that the guard rails will keep the flanges, therefore the wheels and therefore the whole car within limits so that they won’t actually hit the bridge… they’ll keep on messing up the track and the car but they won’t have the devastating efect hitting the bridge structure will have.
I’m interested in those different bridges… do they have Walthers numbers? Do you have any pics of them yet?
[:P]
I’ll work on that Dave and post 'em as soon as I can. I’ll also get the ME model # for you.
Tom
Okay, here’s the promised pics:
50’ deck girder bridge (Click pictures to enlarge)
85’ deck girder bridge
Guard rail picture in directions
I’m only about 1/2 way done with the 85’ bridge. (I still have to add the cross supports and glue it together.)
Dave, here’s the Walthers web site links to the bridges you wanted:
Micro Engineering 50’ deck girder bridge (ME #75-501)
Micro Engineering 85’ deck girder bridge (ME #75-505)
Tom
Great! Thanks! Do bridges like that get used in urban / semi urban-industrial areas?
I’m pretty clear that they get used for passenger service… what happens if the train breaks down and they have to detrain the passengers? (All our bridges are decked and/or have walk ways).
TIA some more [8D]
Dave,
Oh, yea. There are a number of them in downtown Cleveland.
These are probably used more in the freight department - at least around here. Amtrak only comes through here once a day - and usually only in the wee hours of the morning.
Tom
Dave,
I reckon the passengers would have to walk through the train until they came to a door that was not leading on to the bridge. We have progressed from the old compartment carriages that we called dogboxes at home.
A few pictures below that I took thinking I might be able to use one day. It is a different type of bridge, but for what it’s worth. It is on the main line between Sydney and Newcastle in NSW, heavily used by passenger and freight traffic. Well maybe not heavy traffic by US standards, but it is a main line.
See how the concrete sleepers (ties) stop before the bridge, and wooden sleepers are used on the bridge?
Sorry the quality is not too good, [:I] but hope it gives you some ideas.[:P]
If you would like to contact ME directly, (No website) they are
Micro Engineering, 1120 Eagle Rd, Fenton, MO 63026 Tel (636) 349-1112
I call in orders and have them usually within a week. Ask for a catalogue, they do offer many related kits, additions and extensions. Great people to work with.
Yes, passenger trains cross these types of bridges as well. Here’s a bridge over the CT river between Windsor Locks and Thompsonvile, CT that I’m modeling:
Right now I’m doing a pseudo-model using the ME 50’ open deck girder bridges and the Walther’s double track truss bridge. The bridge in '48 was double-tracked. I believe it’s ballasted as well, but this version won’t be. Once I have a larger basement I’m planning on doing the whole bridge properly. It has a second truss that is off this picture to the right (I didn’t take the picture), and the whole bridge will be about 17 1/2 feet long in HO scale.
Randy