Western Railroad Discussion > What Is Ballast Made Of

Is ballast a mined rock or is it a mixture of several different minerals. And why is it dumped to the side of the rails instaed of
the inside too. I have noticed that on ballast dumping trains.

just plain ole' rock. Specially shaped to hinder walking when trying to repair a defect in route.

I would say 3/4 inch granit rock. I know I dumped enough of it, smaller in other areas 1/2 inch. Hope that helps some.

It's made of a little of this, a little of that, and a touch of the other stuff that was not mentioned before.

It can be dumped inside and outside of the rail. I've done it both ways.
YM

The source can vary. It is commonly quarried rock of a hard consistency for durability. It is crushed to approximately 3/4 inch although I never heard its size referred to in my M of Way experience. Crushed rock is used as opposed to stream run which is smoothly curved and more suitable for filler for both asphalt and concrete cement. The crushing process leaves roughly rectangular pieces which "key" together for a useful rigid mass when tamped under the rail. It can be dumped outside the rail for a skin or light raise during surfacing operations or dumped on the outside of only the high rail when elevation is going to be restored or increased. For any major sufacing operations that are going the raise the track "out of face", the track would have to be both center and side dumped to have enough to tamp firmly under an area extending about a foot on either side of the rail. Note that the center of the tie is not tamped. This is because the ballast is a load spreader from each rail to the subgrade. If ballast with age or because of soft subgrade settles so that there is pressure under the center of the tie, this is called "center=bound" track. Very undesirable because the track is not properly supported for passage of traffic and additionally could result in broken ties. Western railroads that have on line long standing smelter operations for precious metals or non ferous metals contract for the residual slag to be broken up by dozers with toothed blades. The resulting "slag" then makes excellent ballast. It is very sharp, and if you work much around the track it cuts shoe soles up very efficiently.

Joe S.

the new state of the art ballast operation is the computerized herzog train. the track supervisor will ride the track and record the locations where ballast is needed on the roadbed. this is then recorded and logged based on g.p.s. location. when the ballast train runs, it will start dumping based on this g.p.s. info. the train can dump at 15mph, move on at 45mph to the next location and dump again.
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very clean, very fast and very efficient. dumpiing is usually done at night when m.o.w. work is not in conflict.

Being a "tourist railroad" very close to sources of limestone, we use #1-#2(3"to6") for a base to fill washouts capped with #3-#4(1"to3") for the final ballasting. The original RR was grouted ( a layer of sorta-concrete ) with cinder ballast. The cinders have turned to dust and are prone to washing and no longer hold the track in horizontal alignment ( heat kinks ) . Outside ballasting with #3-#4 will help hold the track in place during temperature changes.

gel hints at an important point about ballast. You can tell by how much ballast lies outside the end of the ties just how much horizontal stability the track is designed for. Thus you can tell something about the speed limit by checking the ballast "shoulders".

You will also see extra ballast outside the ends of the ties on curves and turnouts since they have extra side forces with the passage of trains.

When you can see the ends of the ties sticking out, this is hopefully straight track and likely not very high speed.

Ballast has two main purposes--provide drainage to keep the ties dry and spread the train load evenly into the subgrade. Smooth or round stones cannot do this--they just "squirt around and out" when loaded. Crushed stone interlocks together and takes a hard set.

Much of the ballast used on UP is granite from a quarry on Sherman Hill at Granite, WY just up the road from Cheyenne

CPB284 wrote:
>
> Much of the ballast used on UP is granite from a quarry on
> Sherman Hill at Granite, WY just up the road from Cheyenne



UP uses several sources accounting to geography. There is an Arkansas quarry that supplies areas roughly south of KC, and for areas north of there, ballast is loaded at Rock Springs, WI, on the former CNW. This rock is a nice pink/red colour, and has been used on the CNW for quite a while. UP used the Dresser, WI trap rock (dark gray) on certain projects where the train could be turned every other day. In Missouri Valley, near Omaha, several sources were used to restore the second main line of the former CNW. Keeping equipment moving during the busy work season is key.

RRKen
Mason City, IA

Interesting that other commentators have mentioned the shape of ballast. Even before welded rail well kept mainline track had ballast level with the tops of the ties and nicely sloped shoulders outside the tie ends that correspond with the natural angle of repose of the material. The space between ties is called the "crib" and mainline standards always called for full cribs and good shoulders. This is even more critical in the days of welded rail to keep the track in alignment under compressive stress on hot days. Incidentally, The nice shape of the ballast in the machine age is provided by the "ballast equilizer" which has plows and baskets to shape and transfer ballast as required. The last finishing is to broom the residual ballast off the tops of the tides for which the ballast equilizer is equiped. With wooden ties, the abrasive fines of ballast left on top of the ties can work its way along the spikes and reduce their hold on the tie. If this condition is severe, the condition is called "spike killed" ties.

Joe S.