Intrusive noise is normally dealt with under Envionmental Health legislation, monitored and enforced by the relevant Local Authority. There is no defined 'maximum volume', rather there is an expectation that industrial noise or any other nuisance noise does not exceed the 'background' noise level; this can also be determined by the Local Authority or by private acoustics surveyors and will vary over the course of a day/night. (There is also a EC recommendation based on a World Health Organisation report, that bedroom noise levels should not exceed a very low threshold but this has not been adopted by the UK.)
Most of the industrial uses, including railway noise, will be established uses and I've found that the legislation is more effective in controlling new developments and
ad hoc outbreaks of nuisance. Planning "use classes" make these allowances, although they don't interface well with EH legislation!
However, there will be allowances made for necessary and normal railway noise, but in my opinion, Public Address announcements may be considered as falling outside the neccessary and normal railway noise and your local authority might be willing to investigate your complaint and to enter into a constructive dialogue with the station operator, with the hint of legal action to support their investigation and recommendations (if any).
I think its worth having that discussion with your Envionmental Health Officers.
(PS Don't use the term 'tannoy' in this context as it is a brand name of the Tannoy Company who probably did not supply the offending equipment)
. . . is there no national guidance on automated platform announcements late at night or early morning?
There is a raft of guidance! Sadly I can't recall any referring specifically to automated platform announcements, but leave that to the EHOs. They have the training, qualification and experience in this field to select the most effective Standards to apply.
