Conversation so far:
where is the bridge that turns into a tunnel
The Chesapeake Bay Bridge–Tunnel is a bridge–tunnel crossing at the mouth of the Chesapeake Bay, the Hampton Roads harbor, and nearby mouths of the James and Elizabeth Rivers.
what state is the chesapeake bay bridge-tunnel in
The Chesapeake Bay Bridge–Tunnel is in the U.S. state of Virginia.

Question: how long is the bridge-tunnel
Self-contained rewrite: how long is the chesapeake bay bridge-tunnel