Mega Tunnels 5. Dudley Tunnel
Staying with the Birmingham Canal Navigations we come to number five in the shape of the 3,172 yard Dudley Tunnel. This comprises three sections: Main tunnel (2,942 yards), Lord Wards (196 yards) and Castle Mill Basin (34 yards).
By 1778 the first section from Lord Wards Canal at the Tipton end had reached the thin bed limestone which was being loaded directly into boats at what is now Shirt Mills Basin. This was later extended to the thick bed limestone at Castle Mill Basin. The Tipton portal was rebuilt in the 1840’s but part of the original sandstone structure can still be seen to the left.
With the completion of the Dudley Canal to the west it was soon apparent that there would be great benefit in linking this to the Birmingham Canal and construction progressed in fits and starts for a period of seven years from 1786, its owners working through a succession of engineers and contractors.
The Birmingham Canal, was always paranoid about potential loss of its water, insisted on a stop lock in the tunnel at Castle Mill. The Dudley Canal was therefore held at a slightly higher level than the Wolverhampton Level till the canal companies were merged in 1846, after which the stop lock was removed. For the intervening years the Dudley Canal had to identify a water source to feed the tunnel pound. A reservoir was built about a mile away at Gadds Green, just above today’s Netherton Tunnel entrance, and the water fed in through the Grazebrook Arm.
In addition to the main tunnel a further 1,227 yard branch tunnel was dug to connect Castle Mill Basin to two further underground basins for limestone extraction.
The southern end of the tunnel has always suffered from subsidence, largely attributable to coal mining beneath its bed. Issues were reported in 1798 and this eventually resulted in a section being rebuilt in 1884.
Like the Lapal to the south, the narrow Dudley Tunnel became increasingly popular and resulted in severe congestion. By 1836 plans were being made to build an additional tunnel at Netherton.
The Dudley Tunnel closed in 1962 but was restored and reopened in 1973 following extensive work by the Dudley Canal Trust and Dudley Council. Two new tunnels were built in 1989 to offer a unique visitor attraction taking passengers on a circular trip back to the Jurassic period when the Oolitic limestone beds were laid down.
A through passage is still technically possible for craft with very low air draft, but with very poor ventilation no diesel engines are allowed. Effectively this involves a tow by an electric tug or a long spell of legging. Today most visits to the tunnel are on the Dudley Canal Trust’s electrically powered trip boats.