Why are trains better at transporting large amounts of cargo than the trucks?
In: 0
I think it comes down to a single train being a single engine pulling multiple cars, whereas to take the same amount of good with trucks would require multiple engines.
They can be significantly longer, don’t have to deal with road traffic, and have a significantly more direct route from point A to point B. Trucks need to route over roads that may not be direct, and have other cars constantly driving around them that they have to be mindful of…and have a limited size they can be (excluding specialized trucks to transport really big items).
The amount of rolling resistance from rolling depends on how hard the wells are. Trucks use pneumatic tires but rain uses steel wheels on steel tracks. We talk about less then a tenth of rolling resistance.
Steel wheels do not provide any suspension and you need a hard surface that can keep sustaining the high pressure from the small contact area. So you can use a steel wheel on a regular road because the wheel will shake itself apart at speed.
You also have resistance from drag when you move. A significant part of that is from the front and rear of the vehicles. Adding an extra wagon does not increase that a lot. It should be said that the same effect in play for trucks where the tuck and the trailer or a box truck and a trailer are close together. Large trucks are more efficient in transporting stuff the small they are just practical imitations on a road.
Air resistance depends on speed too, it is not uncommon for large cargo trains to move are relatively low speeds, and the tend to be slower than trucks on the road.
So lots of wagons connected one after another and lower rolling resistance on steel wheels is the main advantage
In short: The rolling resistance of a train is much lower than that of a truck. Therefore the amount of energy needed is much lower and it becomes cheaper.
Inland shipping is even more cheap.
They don’t have to stop/start very often. This has 2 effects: Kinetic energy isn’t wasted by braking, and the locomotive can have a very low amount of horsepower per weight of cargo (because it can afford to take a long time to build up to speed).
Also the friction between a steel wheel and steel rail is very low. They don’t need the traction that a rubber pneumatic tire provides since they turn by contacting the rail, and again, don’t need a lot of traction for accelerating/braking.
These all contribute to the very poor ability of trains to climb a hill. Cargo trains don’t have enough horsepower and passenger trains don’t have enough traction. James May has a very informative video on YouTube explaining all of this!
Also just had a thought, the fact that each car follows so close behind the cars in front of them means that the train can be quite aerodynamic for what it is. This is kinda like how geese fly in formation.
Latest Answers