Infraco Sub-Surface Ltd.

November 2001 - Design and presentation of AFILS training seminars for InfracoSSL and LUL engineering staff, and LUL Chief Engineer’s Dept. and Transport for London (TfL) staff.

In November 2001, we designed and presented a training course for staff from Infraco Sub-Surface Ltd.'s Comms Delivery team. The training was designed to provide them with a level of expertise that would help them ensure the quality of Audio Frequency Induction Loop Systems (AFILS) installed under the forthcoming Public-Private Partnership (PPP) contract.

Those attending judged the training a great success, and they felt they had gained a better understanding of the effects of metalwork on the performance of the AFILS, the problems of magnetic noise for hearing-aid users, and the problems of interference and loss of privacy that can occur in neighbouring AFILS.

However, there was no data available on the effects of underground station buildings on the AFILS, or on the levels and types of magnetic noise to be found in this environment. So it was not possible to predict in advance the performance of an AFILS, or how suitable the magnetic environment would be.

D.G.Edworthy Associates were commissioned to perform a survey of seven representative stations to answer two questions; 1) How much magnetic noise is present, and is it at a level that would cause problems for hearing-aid users?, and 2) What effect does the building construction have on AFILS performance? (see ‘Induction Loops (AFILS)’).

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