My son asked, and I couldn’t tell him.
Drainage and stability of the track; otherwise it’d sink and kink
Interestingly, we don’t really need ballast in 3-rails but it actually works like the real thing in Garden layouts.
dav
Actually the track does sink or rather dishes. (no pun intended)
As the engine traverses the track it depresses it forming a dish -like shape that it pushes as it moves. The train is alway traversing inside a concave “dish”
The reason for the ballast is to force the deformation of the ties vertically so they don’t twist while pushing the dish. Concrete ties do not deform as much as wood ties so there are energy savings not having to pu***he dish as much.
Alan
So they knew where to put the track.[:D]
The ties hold the rails in gauge, the ballast holds the the ties in place and allows rainwater to drain away instantly.
Actually, we can use ballast to hold down even flexible track; many people screw the track down, apply ballast, fix it with water-and-glue and then remove the screws when the fixture sets up. The track won’t budge.
I ride the MARC commuter train between Baltimore and Washington, D.C. and they provide written updates on maintenance by their host railroads. I was interested to read that the individual rocks in the ballast have sharp edges so that they will interlock with each other and provide the necessary holding power for the ties. Over time the edges become more rounded and the ballast has to be replaced. I’m glad we don’t have to deal with that on our layouts - truly, such a layout would never be finished!
That’s right 4kitties, often the ballast just sort of moves away, and fresh is added, and the track re dressed.
“Naked” track looks kind of funny, ties totally exposed and resting directly on the dirt. The railroads use a lot of special equipment to keep the track in good shape. The Lionel ballast tamper is not very accurate. The railroads use a machine that actually lifts the track and then vibrates causing the ballast to get under the ties and knit together. Funky gizmo to say the least! [swg]
4kitties, when is a layout ever finished[swg], possibly when we start dismantaling them.
i thought the railroads did it to make it look like ours!?![:D][;)]
I always thought ballast was for stability (imperfections in the grade are smoothed by the ballast) and most importantly - drainage. The ties sit on the ballast and not wet dirt or puddles. Water drains through the ballast, although Woodsytc may be right, too.
Frank from Allied Hobbies