Why do trains need to run on rails?

Question

could they not run on concrete paths with grooves in for the wheels? it would be easier to construct, and cheaper, than all that rail, ballast and sleeper stuff wouldn't it?

Answer 1

No. A train is very heavy with all its carriages attached, and if

run on a concrete path with grooves cut in it for the wheels to

follow it would wear out in a few minutes due to the immense

weight.

Answer 2

No because there'd be too much friction from concrete.. it's not smooth enough.

And also, they wouldn't be trains if they didn't run on rails! That's the point of a train!

It wouldn't be easier to construct - they'd have to make sure they were 100% aligned etc to make sure the train didn't de-rail, and therefore just as complex as normal rails!

Answer 3

take a look at the oldham and saddleworth web  and the whit walk

Answer 4

Apart from the structural issues, the system you propose would require a completely new signalling system. Railway signals mostly rely upon an electrical current sent along the tracks. If there is no train in the section then the current makes it all the way to the end, and allows the signal controlling entry to that section to show a green aspect. If a train is occupying the section then its wheels and axles short-circuit the current, making the signal show red.

Answer 5

try over takeing that on a moped

Answer 6

They don't there are camel trains waggon trains etc

If they ran in grooves they would be called trams and I doubt a tramway is cheaper to build than a ralway

Answer 7

Rails are necessary. Keep in mind that rails will flex too. I'm thinking about this time of year when the ground is soft, and we're doing switching (shunting) on industry tracks, at walking speeds. The track actually dips down under the wheels in the soft earth. Rails also expand and contract with temperature changes.

The most important value of the steel rail is that steel wheels on them present extremely low friction. And a 120 ton locomotive can pull 50 cars each weighing 130 tons without much trouble.

Concrete is strong, but it is also very brittle. I imagine it would begin to crumble since the contact area of a steel wheel is only the size of a coin. That's a lot of weight concentrated down to a very small contact point. A car or truck tire has a contact area about the size of your hand.

Good Question.

Answer 8

no.  Concrete isn't strong enough to handle the weight or force of a train.  It would take way longer and a lot more money to construct a raised concrete surface with grooves in it.  The metal holds up better than the grooves, and it's more durable than that the concrete and it's easier to replace.

Keep in mind that these freight trains use solid steel wheels and the locomotives alone weigh b/w 350 and 400 tons.  The roads have trouble handing 2 ton cars on rubber tires.

Answer 9

It's possible to run a train on steel bar that is sitting on concrete.

Concrete simply is not strong enough to handle the contact pressure of a steel wheel. Rail can handle approaching 100 KSI or 100,000 PSI. Concrete is strained to get 10 KSI.

The reason rails have such a low rolling resistance is that it has very high contact pressure over a small area. Many wheels compress to give a large area but low contact pressure. The result with this is high rolling resistance. Tires for example have very high rolling resistance.

Answer 10

They're heavy.  Concrete's wear resistance would be grossly inadequate.

Answer 11

No. because a train is heavy and also on rails it can travel faster as well

Answer 12

what about when it snowed,and froze over into blocks of ice,how would it get traction!

Answer 13

As others point out, concrete simply can't bear the WEIGHT of freight cars and locomotives.  At an airport, they have to pour 6 FEET of concrete (heavily reinforced) to take the "mere" 485 tons of a loaded 747.  I wish I had more figures...

BUT, Concrete isn't that easy to pour... you'd have to prepare the SAME bed as you'd need for rails... THEN you'd have to build forms to pour the concrete into, with precision grooves for the trucks.

Just NOT a viable option.

Answer 14

Because a train needs the rails to run straight. Look at it as a chain, and each link is a train car. if you pulled it along,and tried to turn it, None of the links, would follow the first link.

Answer 15

Rolling resistance would make it impossible to make the train move.Like Derail told you the contact patch of a train wheel is dime sized. As soon as a train moved on concrete it would destroy it.By the time a whole train passed over it you wouldn't have much left. A lot of people don't realise the sheer weight of a train. Each locomotive weighs 400,000 pounds give or take a bit.That's 200 tons for each one.We run 18,000 ton coal trains on my line.That's 36 million pounds! We move that 36 million pounds with 16,000 horsepower.The only way that is possible is because of the low amount of rolling resistance