"NEW mechanical damage associated with the responses"
("An assessment of the conservation risks and possible responses", author Fachtna McAvoy, English Heritage Research and Standards Dept. May 2005, finalised copy released 21 July 2005.)
Of course they are new tunnels, if the old infill material was all that was being removed they would remain the 1849 and Atkinson tunnels. This is a rebore that will take 10" off the walls. The walls will be of totally never before seen archaeology - it a new tunnel !