Welche Bedeutung steckt hinter der hier vorgestellten Vokabel aus dem Bereich In the news?

The entire underground transport system ground to a halt today when a businessman jumped onto the track to pick up the briefcase he had accidentally dropped. No one was hurt, but for safety reasons all trains were prevented from moving for 30 minutes.

to grind to a halt

Do you know what it means?

• to be unable to move further
• to create powder
• to function smoothly