I wish to make a second FOI request: I understand that modifications have been made to rail mountings to reduce ground-transmitted vibration in response to complaints from residents who live above tube lines. Please provide the following information in relation to the Northern Line between Archway and Euston: The technical specifications of the modifications that have been made The precise locations of modified rail-mountings The effectiveness of these modifications in reducing ground-transmitted vibration The effect the modifications have had on noise levels measured inside the trains

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TfL Ref: EIR-0633-1920

Thank you for your email of 30^th May 2019 asking for information about noise on the Northen Line.

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.

Your questions are answered in turn below:

Please provide the following information in relation to the Northern Line between Archway and Euston:

The technical specifications of the modifications that have been made:

Answer: It is not entirely clear what you mean by the “technical specifications” of the modifications that have been made. The modifications involve the fitting of the ‘Pandrol Vanguard’ rail fastening system. This can be retrofitted in place of the existing rail fastening assembly used on sections of the London Underground, improving the attenuation of vibration transmitted into the tunnel track slab. More information can be found online here: https://www.pandrol.com/product/vanguard/

The precise locations of modified rail-mountings:

Answer: The locations are as follows:

Line	Station From	Station To	Direction	Start (m)	End (m)	Length (m)
Northern	Kentish Town	Tufnell Park	NB	270	390	120
Northern	Camden Town	Kentish Town	NB	320	780	460
Northern	Kentish Town	Camden Town	SB	290	740	450
Northern	Euston	Camden Town	NBFast	750	870	120
Northern	Euston	Camden Town	NBFast	960	1240	280
Northern	Camden Town	Euston	SBFast	470	640	170
Northern	Camden Town	Euston	SBFast	790	910	120

The effectiveness of these modifications in reducing ground-transmitted vibration:

Answer: Reduced noise levels by up to 16dB.

The effect the modifications have had on noise levels measured inside the trains:

Answer: We are aware that there has been some increase in noise levels inside trains, although we do not have before and after measurements to make a direct comparison. Although not ideal, this trade-off has significantly improved the noise levels in local homes - something residents were living with multiple times an hour.

If this is not the information you are looking for 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,

David Wells

FOI Case Officer

FOI Case Management Team

General Counsel

Transport for London

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