Another ballast question

[Blind Bruce]

When I lay track down on my 36" long girder bridge, do I ballast it? If I don't, what is supposed to hold the ties in place? (protopype Imean).

BB

[jimrice4449]

It depends. There, doesn't that help? If you're modeling the Milwaukee Road ballast the deck I don't know of any other RRs that preferred ballasted decks but I'm sure there are some as, most likely, there are those that ballasted some and used open decks on others. From a MRR point of view the ballasted would be simpler since you could use a solid pice to bind the tracks to the trestle structure.

[jimrice4449]

It depends. There, doesn't that help? If you're modeling the Milwaukee Road ballast the deck I don't know of any other RRs that preferred ballasted decks but I'm sure there are some as, most likely, there are those that ballasted some and used open decks on others. From a MRR point of view the ballasted would be simpler since you could use a solid pice to bind the tracks to the trestle structure.

[stokesda]

In prototype non-ballasted decks (open decks), the ties were attached directly to the bridge structure, usually girders running the length of the bridge, right underneath the rails.

The open decks definitely look cooler, but if you don't have all that detail on the bottom of your model bridge (girders, x-braces, etc.), then ballasting is OK. I read somewhere that in "real life," railroads would generally use open deck bridges, but if it was going over another track or a road or something, they would use a solid deck (to keep stuff from falling down onto things under the bridge). I guess the solid deck may or may not have ballast, but all the ones I've seen pictures of had ballast.

[selector]

I'm going to stick my neck out for the big chop and say that you most probably should not ballast a bridge deck. Ties held the rails just fine, and they were usually much closer together, just like on a trestle, so there were many more of them along the length of the deck. The ties were spiked using 20" spikes that went down into the long stringers placed under the ties and directly below the rails.

Don't forget the guard rails. The prototypes used them universally.

[bogp40]

If you chose to run an open deck, check out the Micro Engineering bridge flex track. This comes as a 36" section of code 83 w/ bridge ties, code 70 gaurd rails, sections of gaurd timber and fire barrels/ platforms. Just finished a kitbashed curved ME tall viaduct. To curve the flex w/o any kinks, I made an offset pattern from the curved template out of 1/4 ply and bent the track to it. Excellent kit and directions. One tip for securing the track- use Pliobond, is very flexable and will tend to cushion the loads of heavy equipment.
Note: If using this bridge track, the bridge girders/ abutments and shoes need to be set lower than your roadbed due to the added thickness of the ties for railhead alignment.
Very happy with the outcome of this project, but still have not run trains over it. After intallation it was removed for scenery below and behind.
Bob K.

[Anonymous]

BB

You may want to read threw this thread on the trains forum.

http://www.trains.com/community/forum/topic.asp?TOPIC_ID=43305

A lot of good information about ballasted vs open deck bridges. Also if you decide to go open deck, and don't want to buy ME flex, which is good stuff, I did this to my flex track on an open deck bridge, I cut the plastic between each tie and pushed them together. This gave me the proto look of how ties are spaced on a bridge. There was an article in MR about this also, but I did it first [;)] kidding, but is is very simple.

You can sort of see the tie spacing in this picture on my N scale layout.

[orsonroy]

QUOTE: Originally posted by selector
[Don't forget the guard rails. The prototypes used them universally.

Actually, they didn't! I found that little factoid out when I started researching my prototype, the NKP between Peoria and Bloomington, IL. When I quadded the ROW two years ago, I was horrified to see that NONE of the NKP's bridges on that line have guard rails! Even the one "big" bridge across the Mackinaw River (190 feet long, 80 feet in the air) has never had guard rails.

The Mackinaw River bridge is odd too, in that it's got three different styles of spans. The western aproach is a standard through girder bridge (no ballast) about 50 feet long. The middle span (across the river itself) is a through truss type 100 feet long. Finally, the eastern span is a ballasted deck girger bridge 40 feet long. I always wondered why that span was a ballasted deck type, until Stokesda mentioned the obvious - falling objects onto the river road below!

I've noticed that MOST small bridges (under 100 feet long) in Illinois don't have guardrails. Virtually none of the small runoff creek trestles have them, and even most of the more substantial road overpass-types don't have guardrails. At least, not on the NKP, P&E, IC, TP&W or CB&Q, which is what I chase.

[selector]

Well, I guess I stand corrected, Ray.

Every bridge I have seen in Canada has guard rails, even 50 footers. They also have a pair of 6X6" or 8X8" wooden guards running outboard of the ties along the length of the bridge. This is true on abandoned/dormant lines, and on the mains across Canada for both the CPR and the CNR.

However, you are correct to check for the protoytpe, clearly, as not all of them do/did that.

Thanks for pointing that out.

[jrbernier]

Many older bridges are 'open', and have larger 'bridge' ties spaced closer together. The current 'tend' is to build 'ballasted' deck bridges if possible. These have 2 advantages:

o - No side girders/members to get struck by a 'shifted' load.

o - They can 'ballast' the deck and it gives a smoother 'ride' accross the bridge.
MOW equipment can continue working down the line without changing 'gears'.

Jim

[loathar]

I always thought railroads didn't ballast bridges for fear of gravel falling from the bridge and causing injury or damage to people and object below.(just a thought) MR had an article a few issues back about cutting the web on flex track to pu***he ties closer together for a more prototypical look.

[Anonymous]

You guys should really study that link to the train forums, there was so much of what is being asked that will really open up the theory behind it. I have the MR Bridges and Trestle book, but they really didn't do a pro/con on bridge types. I am looking for some shots of the pedistals that the bridge rests on to the concrete, still in need of those on mine...

[Anonymous]

Don't know what happens in US in detail but track on bridges here doesn't have to have ties... track can be laid direct on way beams... gauge maintained by tie rods... when not ballasted track will normally be on waybeams NOT direct to structure... spreads load and damps vibrations.

[robert sylvester]

[:D]I have several types of bridges on the WTRR. Some of the spans have solid floors or solid decking and each of these are ballasted. I just lay the track over the bridge then ballast the track and spray with alcohol and disluted white glue and let it dry, and this fixes the track to the foundation. To support the bridge I use painted foam to look like concrete pillars, Atlas supports, wood blocks cut to look like concrete supports, Woodland Scenics pillars.
If the track is on an open grid truss bridge or similar open span bridge, after adjusting the ties, I glue the flex track ties directly to the bridge with CA glue. I make sure the abutments at either end of the bridge support the bridge. Walthers has a double track span bridge with the track with guard rails, and the bridge is designed to accept the track, I just glued the track with CA right to the girded spans of the bridge floor, leveled it on either side of my river, with the correct abutments to provide support.[8D]
Robert
WTRR
Hub City Division