Loudness of PA announcements
Request ID: FOI-0331-1920
Date published: 03 May 2019
You asked
I am writing to you on the subject of station and in-train PA announcements which I tend to find excessively loud except for a very small percentage of cases. I travel mostly on the Tube, but sometimes also on overground rail.
When you say "they are always reported back to be within a comfortable level for passengers", I have to ask: who makes the report? Is it TFL staff and, if so, which staff members: drivers and/or guards and/or engineers? Is such a report made on every journey or only if there are special circumstances and, if so, what are these special circumstances?
When you say "they are always reported back to be within a comfortable level for passengers", what are the criteria? How do the compilers of these reports assess whether PA announcements are "within a comfortable level for passengers"? Is someone there with a sound meter determining whether or not the PA announcements are above a certain decibel level? The way you state it, the implication is that all that really matters is this report you talk about, which I assume is drawn up by TFL staff and not what customers such as myself experience. So much for "Mayor of London - Every Journey Matters", which appears as a footer in your reply email ..."
In Alex Constantine's reply email of 3 April to my email (Ref: 13210725), I received no answer to these questions. Can you answer my questions? If so, I would appreciate a response from you to these questions and the following questions:
What does the expression used here - "comfortable level" - and the expression Alex Constantine used in an email of 20 November 2018 (Ref: 12662279) "standard volume level" mean in terms of decibels both at stations and in trains?
Presumably, London Transport has determined a decibel level above which it would regard a PA announcement as loud and possibly injurious to people's hearing? What is that decibel level and what techniques would TFL service engineers use to measure decibel/volume levels?
Do train drivers have a discretion as to the PA volume levels and the ability to alter them?
Could you recommend a device which I could use to monitor the loudness of PA announcements?
We answered
TfL Ref: 0331-1920
Thank you for your email received by us on 18 April 2019 asking for information about the loudness of PA announcements.
Your request has been considered in accordance with the requirements of the Environmental Information Regulations and our information access policy. I can confirm that we hold the information you require.
I can advise that London Underground PA systems are normally commissioned to broadcast live and pre-recorded announcements at 10dB(A) above the ambient noise in the area. Many stations have devices called “ambient noise sensors” which lower or raise the broadcast volume in relation to microphone measured ambient (background) noise (broadcast higher when more ambient noise and vice versa). For all noise sensitive station PA systems new or upgraded the project manager / engineer should produce a “Noise Study” report. Additionally, upon being informed of a PA noise complaint for a given station or train they can conduct a survey to check/test the following:
a) the system is configured to the as-built system commissioning specification and this is compliant with current LU standards
b) the system has not developed any fault that is causing the noise problem
c) the user controlled settings and how many PA messages made per hour and if this conforms locally set schedule / local agreements as applicable
d) site and PA system information including measured noise emissions should be captured consistently in a survey form
Where the station relies upon the PA system for emergency evacuation, these will be broadcast at a pre-determined level of between 85 and 90dB(A) in accordance with British Standards and to maximise message intelligibility. There is no ambient noise sensor control when emergency messages are broadcast.
Turning to London Overground PAs, this system was designed to meet a Network Rail Standard (NR L2 TEL 30134), which sets out the ‘Design and Installation Requirements for Public Announcement, Voice Alarm and Long Line Public Announcement Systems’ at http://standards.globalspec.com/std/1457714/nr-l2-tel-30134-issue-2. The Network Rail Standard includes information on maximum and minimum levels of announcements and use of ambient noise sensors. Section 8.1 also states that “when designing the acoustic coverage due consideration shall be given to environmental requirements and regulations for noise pollution’.
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
Jasmine Howard
FOI Case Officer
Information Governance
Transport For London
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