Track ballast
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Track ballast forms the trackbed upon which railroad ties (sleepers) are laid. It is packed between, below, and around the ties. It is used to bear the load from the railroad ties, to facilitate drainage of water, and also to keep down vegetation that might interfere with the track structure. Ballast also holds the track in place as the trains roll over it. A variety of materials have been used as track ballast, including crushed stone, washed gravel, bank run (unwashed) gravel, torpedo gravel (a mixture of coarse sand and small gravel), slag, chats, coal cinders, sand, and burnt clay. The term "" comes from a nautical term for the stones used to stabilize a ship.</onlyinclude> 
Q220229
railroad tie
Concept
Q7481320
drainage
Concept
Q187997
vegetation
Concept
Q1262699
crushed stone
Concept
Q133833
gravel
Concept
Q271768
slag
Concept
Q5087467
chats
UNK
Q177257
coal cinders
Concept
Q34679
sand
Concept
Q42302
clay
Concept
Q599697
Track ballast
Concept
made from material
made from material
made from material