At the edge of a big city, where the houses stop and the tracks begin, there is a place where trains go to get sorted. It's called a switchyard, or a train yard. And it is one of the busiest places you will ever see.
Tracks spread out there like the fingers on a hand, dozens and dozens of them side by side. Train cars of every shape and color sit on them: red boxcars, round black tank cars, open hopper cars full of coal and grain, long flatcars carrying pipes and logs.
And in the middle of it all works a small, hardworking engine named Pip.
Pip the switcher
Pip isn't a big, fast engine like the ones that pull long trains across the country. Pip is a switcher. Switchers are short and strong, and they're very good at one thing: moving train cars around the yard, a few at a time, back and forth, back and forth, until every car is in exactly the right place.
It's getting dark. The yard lights flicker on, tall and bright. And here comes a long train rolling in from far away. It has fifty cars, all mixed up.
"All right, Pip," says Rosa, Pip's engineer, climbing into the cab. "Big night tonight. Let's get these cars sorted."
The great mix-up
Here's the problem. Each car on the long train is going somewhere different.
The red boxcar full of toys is going to a store in the city. The tank car full of milk is going to a dairy. The hopper car full of corn is going to a farm in another state. The flatcar with the big pipes is going to a building site by the river.
They all came in on one train, all jumbled together. Pip's job is to take the train apart and build new trains, one for each place. All the cars going to the city on one track. All the cars going to the farm on another track. All the cars going to the river on another.
It's like sorting your toys at cleanup time: blocks in one bin, cars in another, stuffed animals on the shelf. Except each of these toys weighs as much as ten elephants, or even more!
Switches and tracks
How does Pip get a car onto the right track? With a switch.
A switch is a special part of the track where one track splits into two. It has two rails that can slide a little to one side or the other. Slide them one way, and the train goes straight. Slide them the other way, and the train turns onto a different track. It's like choosing which way to go at a fork in the path.
"Switch three, please!" Rosa calls on her radio. Click-clunk! A switch moves. Pip pushes a red boxcar slowly onto track three. Clank! The boxcar's coupler lets go, and it rolls into place with the other cars going to the city.
Coupling up
Train cars hold onto each other with couplers. A coupler is a big metal hand on each end of a car. When two cars bump together gently, the hands close around each other and lock tight. Clunk! Now they're coupled, and they'll stay together until someone pulls a handle to open them again.
All night long, Pip works. Forward and back. Couple and uncouple. Switch this way, switch that way. Clank, clunk, click. Pip has to be careful and gentle, because bumping into the cars too hard could damage them, or what's inside them.
"Slow and steady, Pip," says Rosa. "Slow and steady gets it right."
Over the hump
At the biggest train yards, there's an even cleverer trick. It's called a hump.
A hump is a little hill built right in the middle of the yard. A switcher pushes the train slowly up one side. At the very top, one car at a time gets uncoupled. Then, all by itself, the car rolls down the other side. Gravity pulls it down the hill, and switches send it onto the right track. Special brakes on the rails slow it down so it doesn't crash into the other cars.
Whoosh, click, roll! One car after another, down the hill and onto its track, like marbles rolling down a marble run into different cups.
Good morning, trains
By the time the sun comes up, the yard looks completely different. The long, mixed-up train is gone. In its place are neat new trains, each one with all its cars going to the same place.
Big road engines couple onto the new trains and pull them out of the yard, one after another, heading off to the city, the farm, the river and places far away. The toys will get to the store. The milk will get to the dairy. The corn will get to the farm.
And nobody will ever know that a little switcher named Pip worked all night long to put everything in its place.
Rosa pats Pip's side. "Good job, Pip," she says. "Rest up. Another train comes in tonight."
And Pip, warm and tired and proud, sits quietly in the morning sun, ready to do it all again.
The End