Cartoon by John Sadler www.johnsadlerillustration.com

• THANK you for your article on rail noise affecting Underground passengers, (Strike threat as tube drivers are exposed to track screech, June 20). This problem has been evident for two or three years.

Your report is correct in noting noise north of Euston on the Northern line, Charing Cross branch, and on the Central line between Liverpool Street and Bethnal Green. The Jubilee line has significant problems too.

Pandrol are an international company who will be making a great deal of money from their product which, like many innovations, is heavily protected by patents.

Online literature produced by Pandrol suggests it is aimed at modern rail systems and ones which are mostly above ground so that sound can be dispersed.

Much of the London Underground is a Victorian-Edwardian railway built in restricted metal tubes below ground.

This means the sound, which is really only diverted away from the outside of the tunnel, has nowhere to go except into the ears of train operators and passengers.

London Underground report that they tested the Pandrol Vanguard system below residential streets in Southwark, early in the morning.

This means the trains would not be so busy (fewer passengers complaining) and the reduced disturbance to residents above ground could be assessed.

Effectively London mayor Sadiq Khan, Transport for London, and London Underground’s track engineers are reducing the effect of train noise on council tax revenues and property developments.

What the mayor apparently does not realise is that the residents who keep him in office are also tube passengers and tube workers being slowly deafened.

If there remains any doubt, commuters make their journeys frequently. Regular exposure to high levels of noise causes tinnitus and hearing loss.

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