Buzzer codes

A (one day) comprehensive listing

Last update 8 February 2024

Additional information is always gratefully received, whether entirely new records (particularly historical records) or information to fill in gaps or correct errors, via the contact link under the Miscellaneous entry in the navigation bar above. Thank you.

Please select a feature list from the links below:

Historically, there was limited communication between drivers and guards. To provide concise communication, a series of codes tapped out on a buzzer was developed. Although nowadays it is more than likely that drivers and guards can talk directly through a telephone system, the codes are retained because each message has a very specific meaning. In a safety-critical environment, their use prevents misunderstanding. When used, the buzzer message must be repeated back to the sender by the recipient to signify full understanding of the message. The most common code likely to be heard by the passenger will be the guard sending '2' (ready to start) to the driver, who then repeats back '2' to the guard and starts the train.

Code number of buzzes or groups separated by pauses Meaning
1 Stop
1-2 Close doors
2 Ready to start
2-2 Do not open doors
3 Set back
3-1 Lock central door locking
3-2-1 Testing doors
3-3 Driver/guard required to attend telephone (or Loudaphone, etc.)
3-3-1 Release central door locking
4 Slow down
5 Driver/guard leaving the train
6 Draw forward
7 Correct vacuum indicated in rear guards van during test
9 Police assistance required