Ely Subway

[1] The operators of the dock, the Taff Vale Railway Company, introduced a chain ferry across to the northern bank of the Ely as a shortcut for both their workers (many of whom lived in Grangetown) and members of the public.

Construction began in July 1897 on a subway designed by George Sibbering, the company's chief engineer, with works overseen by Thomas Taylor, a contractor from Pontypridd.

The ramped entrances at either end were dug by hand but the majority of the route—325 yards of the subway's total length of 400 yards—was tunneled with a Greathead shield, of the same design used for the Central London Railway.

The ground was largely a loose mixture of mud, gravel, and clay, and the cast-iron tunnel—only 11 feet below the river bed at its deepest point—was subjected to intense differentials in pressure between high and low tides in the bay above.

[8] The subway was officially decommissioned in 1936 as part of the wider closure of Penarth Dock, and the toll keepers were removed, but it nevertheless remained open to pedestrians.

It continued to be used as a conduit for power cables by the South Wales Electricity Board until 1976, when part of the Penarth entrance was demolished and some of the cast iron tunnel sections were removed.