What metro is made of
An urban railway separated from the streets; the first was in London.
- Turnstile — has part. Turnstiles.
- Electric locomotive — uses. The first lines were steam-operated; electric trains since 1890.
- Railway track — uses. It runs on rails.
- Tunnelling shield — uses. Metro tunnels were built with shields.
- Tunnel — uses. Tunnels.
- Brick — is made of. The vaults of the first tunnels are brick.