What is an underground train?

An underground train (sometimes called a subway or metro) is a long, fast train that runs under the ground in tunnels. It carries lots of people from one part of the city to another.

How does it travel in tunnels? (Step by step)

1. Tracks keep it straight: The train rides on two metal rails. These rails guide the train so it goes straight through the tunnel.
2. Electric power makes it move: Most underground trains use electric power from overhead wires or a rail next to the tracks. Electricity makes the train's engines turn and the wheels roll.
3. Controlled speed: Train drivers and computers control how fast the train goes. The tunnels are made so trains can go quickly and safely.
4. Signals and stations: Signals (like traffic lights for trains) tell the driver when to stop or go. Stations are places where the train stops to let people on and off.

Why is it often the fastest way in the city?

• No road traffic: The train is under the ground, so it doesn’t get stuck in car traffic or red lights.
• Direct routes: Tunnels can go straight from one place to another, so trains don’t have to take long winding roads.
• Stops are quick: Trains stop only at stations, not at every corner, so trips can be fast.
• Strong motors: Electric engines pull trains quickly and smoothly.

Safety and riding tips for a 7‑year‑old

• Always hold an adult's hand when going into the station.
• Wait behind the yellow line on the platform until the train stops.
• Let people get off before you try to get on.
• Hold the handrail when the train starts or stops so you don’t fall.

Fun facts

• Underground trains can carry hundreds of people at once.
• Because they are electric, they don’t make big smells like cars do.
• Some cities built their first underground trains over 100 years ago!

Short summary: An underground train runs on tracks inside tunnels, uses electricity to move, and is often one of the fastest ways to travel in a busy city because it avoids street traffic and goes straight between places. Always follow safety rules when riding.