Communication based train control is like playing a game with trains, but there are special rules and helpers to make sure the trains don't crash into each other.
Every train has a special computer in it that talks to other computers, like friends on the phone. These computers tell the train where to go, how fast to go, and when to stop.
But that's not all! The computer can also see what other trains are doing, and will change the plan if it sees a train coming in the opposite direction or if there's an obstacle in the way.
It's like having a game manager who tells each player what to do, and makes sure everyone is safe while playing. That way, all the trains can get where they need to go without bumping into each other.