That as maybe but Jerk was commenting on the photo in the Ipswich Star link of a Tunnel at Ipswich which does have overhead lines.
In the past I have seen photos of such wagons for use where they can be used but cannot remember any UK example, in places where the problem is frequent like some of the higher North American routes routes they had them.
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One of the UK canals had something similar for a canal tunnel but its main use was for removing soot deposited by steam powered craft.
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G.Harman