Volume Ten - Pre-Victorian to the Present Day - Even more aspects - The Ely River Subway 1900 - 1963 . . .

A plan and cross-sectional view of the Ely River Subway from the article.

This section curved southwards through an angle of about 75 degrees, so that the final length was almost parallel to the river bank on the Penarth side. The curve was some 267 feet long on an arc radius 205 feet, the final length was 166 feet making a total of 1250 feet.

The subway was of tubular design and lined with cylindrical cast iron sections 10 feet in external diameter and 18 inches wide. The date of manufacture is cast in each section. As they were extremely heavy, possibly weighing 6000 lbs. each, the sections were cast in 6 parts, which were bolted together as they were installed by the miners. The internal diameter of the Subway was 8 feet 10 inches, and a concrete walkway 6 feet wide gave a headroom of 7 feet 6 inches.

Work commenced in April 1897 at the Ferry Road end, and by July 1st a trench had been completed to take the first sections of lining, which were installed by means of a steam crane. The final sections at the Penarth end were also laid in a trench. All these sections were covered and protected by brickwork which, at the Ferry Road end still exists.(at least it did back it 1963!)

The two trenches were connected by means of tunnelling through the river banks and below the river bed, the lowest section being 11 feet below the river.

The geology of the estuary would have been well known as a result of the excavations needed for the Dock and Harbour, and Mr Sibbering had undertaken borings, but the tunnel was excavated through a great deal of made ground, and through the loose River and Glacial Gravel which underlies the alluvial mud. The deepest part of it rested about 15 or 16 inches into the Keuper Marl below the Gravel. These circumstances made the use of compressed air and an airlock essential.