What is the purpose of all that gravel used on train tracks?

[ism]

I would just like someone or as many as feel the impetus to explain to me the purpose of all that gravel that is always strewn over and around the sleepers of train tracks.

Does anybody know?

[Chrome_Toaster]

Sleepers! I learn something new every day. I have always just called them railroad ties. So, are you British? (OK, can you tell I just looked it up?)

Anyway, I do believe it’s to keep the weed population near the tracks to a minimum. Otherwise weeds begin to grow in the spring and by Mid-July time they’re dry enough to easily catch fire with the help of a spark from a passing train.

At least that’s why they do it in the wide open spaces. I don’t know why they do it in the city setting. Perhaps to make it hard to walk or run right next to the trains so as to discourage trespassers/trainhoppers,etc.(?)

I will opine that railroad rocks are identical in every city, town, and wide spot in the railroad tracks in America. They are one of the only constants in the life of the weary traveler.

[GuanoLad]

I asked this here once before, and the answer I got that made the most sense was it keeps animals from walking along the tracks - because it’d be so uncomfortable for them.

[SPOOFE]

I always thought it was a ploy to lure kids near the tracks (kids just LOVE looking for nifty stuff in the gravel). Population control, you see.

“Ooh, gravel… SPLAT!”

[Xerxes]

Well, “http://www.trainstrainstrains.com/railfangloss.html” has definitions for:

Ballast. Selected material placed on the roadbed to support it and to hold track in line and surface. Ballast preferably consists of sized hard particles easily handled in tamping, which distribute the load, drain well and resist plant growth.

Subgrade. Gravel, crushed rock or the like, usually inferior to the ballast used in the track, spread on the surface of the cut or fill prior to distributing ties and ballast. That portion of ballast over 18" inches below bottom of ties is usually classified as subballast, commonly known as subgrade material.

Subballast. Any material of superior character, which can be spread on the finished subgrade of the roadbed, to provide better drainage, prevent upheaval by frost and better distribute the load over the roadbed.

So, some combination of load-distribution, frost-resistance, drainage and (as pointed out by Chrome Toaster) weed-control.