why do train tracks have rocks around them?

Answer 1

For drainage of water!

Answer 2

I'm a railroad construction engineer. Here is the info...

Large rocks and boulders are piled along the route (or "road" as we call it) on the ground, then the "berm" is built higher with ballast (in other words, railroad gravel). Then, wooden crossties are spaced out along the route with a 1-foot gap between each tie. Steel rails are then laid on the ties, secured to the crossties with spikes and "tie plates". Afterwards, more ballast is spread to fill the gaps between the ties.

Most of these answerers were right about drainage and stability... without these features the track would shift and immediately become unstable under the enormous weight of trains. A typical train engine weighs 398 thousand pounds and there are usually six of those pulling every freight train. A loaded train car is often around 150 thousand pounds. Imagine trying to lay the tracks on dirt... the tracks would sink, shift and fall apart, especially once the dirt became wet from rain. Even with ballast, the rugged rails bounce up and down like flimsy ribbons of steel under the weight of a moving train.

Everyone who mentioned the environment was clever, but wrong. We've been using ballast since the 1860s in the Civil War era... nobody cared about pollution back then, and ballast has no "kitty litter" properties (although that was a very clever guess). In fact spilling chemicals, grease, fuel and all manner of "acceptable contaminates" spill along the tracks and wash down through the ballast.

As you probably have imagined, new ballast must be spread on the tracks periodically as the berm (false hill the track is built on) slowly shifts and spreads to each side under the vibration of trains.

Most railroads own rock quarries to create their own ballast. Also, crossties are soaked in creosote, like telephone poles, to prevent rotting, but eventually must be replaced.

These built-up routes, which are berms, are called "fills". Places where the route must dig through the land like a trench are called "cuts". The removed dirt and rock from cuts are used to help build the base of the fills further down the line. You'll notice if you look closesly at a railroad that even in "cuts" the cut is made deeply enough to contain a small berm (mound of ballast along the route); this allows drainage, even though the railroad is recessed below normal ground level (it still has to have at least a mini-ditch down in there on each side of the tracks).

I hope this answers your question.

Answer 3

FIRST, the rocks (called BALLAST) serve to provide a strong and stable base for the ties and track... They also provide DRAINAGE: so that rainwater doesn't collect and turn the area under the tracks into mud ! Remember that a train is a HUGE amount of weight, and could SINK the rails into mud, sand, or dirt.

Ballast also has the added benefit of keeping weeds to a minimum and providing a LESS flammable base for the ties. MANY new track installations use concrete-ties by CSX.

Answer 4

Gravel is cheap and it weighs the cross
struts down so the track can't move.

It is very very bad if the track moves while
the train is running on it!

It also prevents grass, etc. from growing up in
the tracks and eventually becoming an
obstacle to the train.

Answer 5

As others have said it's called ballast. It would be impossible to lay the tracks directly on to the ground surface. This would not be level. You would find, if you were able to take a cross section of a road, that this is made in the same way. The surface you drive or walk on is laid on top of a road bed made of gravel.

Answer 6

It is called ballast, it is use to surface the track (make each rail level to each other), to raise one rail higher on a curve.
Drainage ( mud will cause the rail to sink), hold the tie in place( the compacted edge of the rock dig into the tie).

Answer 7

so when the train is on the tracks the tracks dont move around and cause problems for the train PEACE

Answer 8

That holds the railroad ties in place (rocks are packed tight around ties). In addition the rocks will not catch fire if there are sparks from the train.

Answer 9

Best answer I could think up for that one is this. It's possible that the rocks serve as some kind of solid foundation for contracting the rail over. Another possibility maybe that it's laid down for environmental reasons? Perhaps to capture hydraulic fluids, gas, oil, or grease from trains? Like some kind of kitty litter. Well, that's my best guess.

Answer 10

It allows them to drain correctly, and provides a solid (not moving) surface for the rails. Dirt or clay would tend to flex with moisture and can wash away in places. Also, gravel tends to absorb the vibration better than something more solid (like concrete).

Answer 11

Ballast , as it is called is used to support the ties and rails
and since there rocks they never get soggy, only wet,so they drain the water away.