Volume Ten - Pre-Victorian to the Present Day - Even more aspects - Investigation into the Condition of the Ely River Subway 1991 . . .

Construction of the Subway commenced on the north bank of the river in April 1897, the initial length of the cast iron lining being constructed in open cut. Once the tunnelling shield had been delivered to site, in July 1897, the construction of the Subway continued in tunnel.  The tunnelling shield comprised a Steel cylinder, approximately 100mm larger in diameter than the outside diameter of the cast iron rings.

The shield had a cutting edge around its front rim and was pushed forward into the virgin ground using hydraulic rams reacting against the last ring placed.  Once the shield had been jacked forward sufficiently the rams were retracted and the resulting excavated material removed from the tunnel, a further lining ring was then constructed within the rear of the shield, thus allowing the process to continue.

• 23rd August 1897 - Open end of Subway on the north bank + 1st July 1897 - View of tunnelling shield.

Compressed air was used to dewater the excavated face of the tunnel and this was piped into the tunnel from steam powered compressors on the surface.  A pair of lock doors built into the tunnel lining provided the necessary access in and out of the tunnel for men and materials.

• April 1898 - Tunnelling shield and excavation of face in heading + Hauling segments along the tunnel.