Station Refurbishment
Cool it! A
nyone who’s ever been on the Tube on a hot sticky summer day understands the need to find a way of cooling London
Underground. The Cooling the Tube Programme was to do just this. Each line and station has a unique environment, so the LU’s Cooling the Tube team has undertaken extensive research into the exact conditions of each station to develop possible solutions to combat rising temperatures.
One such solution is drilling boreholes into London’s chalk aquifer to draw water that is then circulated through parts of the network by air-handling units. For those stations where it is not possible to use borehole technology, preconditioned water via a chiller in the heat exchanger coil of the air-handling units was to
Engineers have been working out how to reduce temperatures on the London Underground system. Robert Hadfield explains
be used. Extensive research and the use of prototypes to prove that concepts meet the demands of the varying environments are key to the programme’s success. LU commissioned TÜV SÜD Product Service to support it through the development programme of a Platform Air Handling Unit (PAHU).
The first stage was to ensure that the air-handling units were safe and compliant with health and safety requirements for LU. A series of factory acceptance tests and systems integration trials also made sure that the air- handling units would deliver against the requirements set. This included assessing if the tunnel structure would support the weight of the units and that all train and passenger clearance requirements would be met.
As each unit weighs three tonnes and is the equivalent length of half the length of a London double-decker bus, lifting the whole unit into position and then ensuring it remains securely fastened to the tunnel ceiling represented a significant challenge. TÜV SÜD was, therefore, asked to design the structural support system.
As part of the rigorous assurance process, extensive systems integration trials were undertaken. This included the construction of a test rig at its laboratory, which replicated the dimensions of the tunnel ceiling where the air-handling units would be installed. The trials helped to prove that six key requirements could be met:
• The structural support system had to fit multiple tunnel ring configurations
SEPTEMBER 2012 Page 27
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