Request ID: FOI-0128-2324 Date published: 04 May 2023
You asked
This is in relation to computerised clocks located on station entrance and upon the platform 'Amber' Dot matrix screens, within a 'Tube' Station and the Oyster/Barrier charging system
1. Is the station clock a separate computer system to the barrier charging system?
2. Is the station clock sync'ed to the barrier charging system?, or vice versa.
3. Are the station clocks calibrated? if so, What is the maintenance schedule?
4. Are the barrier clocks calibrated? if so, What is the maintenance schdule?
5. Where do both clocks (Station and Barrier, if separated) gain/source the GMT time information from?
6. Are all 272 stations and barrier systems clocks (if not separated) sync'ed together via one central computer?
We answered
Our ref: FOI-0128-2324 Thank you for your request received by Transport for London (TfL) on 11 April 2023 asking for information about TFL Station Clocks / Computerised System Sync.
Your request has been considered in accordance with the requirements of the Freedom of Information Act and our information access policy. I can confirm that we hold the information you require. Your questions and our replies are as follows:
This is in relation to computerised clocks located on station entrance and upon the platform 'Amber' Dot matrix screens, within a 'Tube' Station and the Oyster/Barrier charging system.
Is the station clock a separate computer system to the barrier charging system? Yes.
Is the station clock sync'ed to the barrier charging system?, or vice versa. No.
Are the station clocks calibrated? if so, what is the maintenance schedule? Digital clocks are synchronized to multiple Network Time Protocol (NTP) master clocks; NTP is used to synchronise time for networked assets. These are monitored on a network management tool and are constantly monitored.
Are the barrier clocks calibrated? if so, What is the maintenance schedule? NTP does this automatically.
Where do both clocks (Station and Barrier, if separated) gain/source the GMT time information from? Station clocks are synchronized to multiple NTP clocks, one on the station and 2/3 others on the London Underground network.
Are all 272 stations and barrier systems clocks (if not separated) sync'ed together via one central computer? No.
If this is not the information you are looking for, or if you are unable to access it for any reason, please do not hesitate to contact me.
Please see the attached information sheet for details of your right to appeal as well as information on copyright and what to do if you would like to re-use any of the information we have disclosed.
Yours sincerely
Sara Thomas FOI Case Management Team General Counsel Transport for London
