Martin C Knights, BSc, Mott, Hay and Anderson. This paper was first published in GE’s January 1975 edition.
A recent site investigation for the proposed Manchester Central Area Underground Railway (Knights, 1974) highlighted the varying behaviour of Bunter Sandstone in the presence of water. Therefore, it was important to identify this behaviour by a simple index test.
Existing surface railways north and south of the city centre of Manchester will be connected by twin tunnels 4500m long (Fig. 1). The section from Victoria Station to Piccadilly Station will be constructed in soft water-bearing Bunter Sandstone at an average depth of 20m below street level.