Think about the engineering challenge faced by running miles of narrow ribbons of steel track on top of the ground: they are subject to heat expansion and contraction, ground movement and vibration, precipitation buildup from rough weather, and weed and plant growth from underneath. Now keep in mind that while 99 percent of the time they are just sitting there unburdened, the remaining one percent of the time they are subject to moving loads as heavy as one million pounds the weight of a Union Pacific Big Boy locomotive and its tender.
Put all this together, and you have yourself a really, really interesting problem that was first solved nearly years ago, and hasn't been significantly improved since. The answer is to start with the bare ground, and then build up a foundation to raise the track high enough so it won't get flooded.
On top of the foundation, you deposit a load of crushed stone the ballast. On top of the stone, you lay down perpendicular to the direction of the track a line of wooden beams on You then continue to dump crushed stone all around the beams. The sharp edges of the stone make it difficult for them to slide over each other in the way that smooth, round pebbles would , thus effectively locking them in place. The beams are made of hardwood usually oak or hickory , and impregnated with creosote for weather protection.
Why are there crushed stones alongside rail tracks? Answer by David S. Rose , entrepreneur, angel investor, author, on Quora :. The crushed stones around train tracks are what is known as ballast. Their purpose is to hold the wooden cross ties in place, which in turn hold the rails in place.
Think about the engineering challenge faced by running miles of narrow ribbons of steel track on top of the ground: they are subject to heat expansion and contraction, ground movement and vibration, precipitation buildup from rough weather, and weed and plant growth from underneath. Put all this together, and you have yourself a really, really interesting problem that was first solved nearly years ago, and hasn't been significantly improved since!
The answer is to start with the bare ground, and then build up a foundation to raise the track high enough so it won't get flooded. On top of the foundation, you deposit a load of crushed stone the ballast. On top of the stone, you lay down perpendicular to the direction of the track a line of wooden beams on You then continue to dump crushed stone all around the beams.
The sharp edges of the stone make it difficult for them to slide over each other in the way that smooth, round pebbles would , thus effectively locking them in place. The beams are made of hardwood usually oak or hickory , and impregnated with creosote for weather protection. Sidebar for the truly geeky, with fun facts about railroad ties: There are approximately ,, ties in the United States, supporting , miles of railroad track.
So, instead, the rails are attached to the sleepers by clips or anchors, which hold them down but allow them to move longitudinally as they expand or contract. So there you have it: a centuries-old process that is extremely effective at facilitating the movement of people and material over thousands of miles The ballast distributes the load of the ties which in turn bear the load of the train on the track, held by clips across the foundation, allows for ground movement, thermal expansion and weight variance, allows rain and snow to drain through the track, and inhibits the growth of weeds and vegetation that would quickly take over the track.
David S Rose , entrepreneur, investor, mentor. Why are there crushed stones alongside railway tracks? Ask a question, get a great answer. Learn from experts and get insider knowledge. Join thought-provoking conversations, follow other Independent readers and see their replies.
Want to bookmark your favourite articles and stories to read or reference later?
0コメント