Monday, 18 March 2019

Mega Tunnels 5 - Dudley

Mega Tunnels 5. Dudley Tunnel
March 2019

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.

Saturday, 16 March 2019

Mega canal tunnels 4 - Lapal

4. Lapal (or Lappal) Tunnel
The 3,795 yard Lapal Tunnel was built as part of Dudley No2 Canal in 1798, connecting the industrial area around Dudley with the Worcester Birmingham Canal without crossing the waters of the neighbouring Birmingham Canal Navigations.
Western Portal - now buried
This tunnel was built to minimalist proportions offering a very tight seven feet nine inches at the waterline and six feet of headroom. This confined channel resulted in slow passages and transit by legging or poling took up to three hours.
California Portal
During its construction its brick lining was supplied by the ill-fated Lapal Brick Tunnel Company of California, near the southern portal and owned by one John Garlick.  He installed various brick making machines, but none would work satisfactorily. Being a very impulsive and quick tempered man he became enraged at the constant failure to get good results and one Sunday morning he was found attacking a recently installed machine with a sledge hammer, breaking it to pieces. Shades of Basil Fawlty come to mind and unsurprisingly his limited company failed within a year and Garlick was declared bankrupt.

In an attempt to address the slow speed of passage caused by the narrow dimensions an innovative steam engine and scoop wheel was introduced in 1841 at the Halesowen end along with stop gates. This allowed the owners to alter water levels at either end and help flush boats through.
 Exploring the Lapal collapse

Following extensive mining subsidence a number of collapses occurred and the tunnel was finally closed in 1917. Whilst the Lapal is lost, its dimensions are mirrored in the much shorter 563 yard Gosty Hill Tunnel, also on the Dudley No2 Canal. Progress through its restricted channel is nothing short of glacial, especially when towing, and provides an interesting insight into the frustrations of passing the much longer Lapal Tunnel a few miles to the south.
Today the Lapal tunnel remains collapsed in several locations, its portals covered over and is bisected by an M5 cutting, with no prospect of reopening.  However, restoration plans are in hand for the Dudley No2, but this time using a flight of locks supported by back pumps.
All photos are sourced from the internet

Thursday, 14 March 2019

Mega Tunnels 3 - Sapperton

3. Sapperton Tunnel

The third place is occupied by another abandoned tunnel, this time located on the summit pound of the Thames and Severn Canal.

This 3,817yard tunnel was built 15 feet wide and 15 feet high to accommodate the Severn Trows, which were the target market for this connection between the rivers Severn and Thames.

It was completed in 1789 after five years of construction and was one year over schedule, not a bad result by tunnel building standards of the day. As so often happened, the original contractor only managed to complete one third before he hit financial problems and the remaining work passed to others. In the end the tunnel Included 25 intermediate shafts the deepest of which was 244 ft.

The Sapperton Tunnel held the record as the longest from 1789 till 1811, when it was eclipsed by the completion of the Standedge in the north.

With declining trade the tunnel was officially closed in 1910, but remained passable till 1966 when roof falls in areas passing through the unstable Fullers Earth blocked it as a through route.

Today occasional trips are made as far as the roof fall and plans are well advanced to reopen the tunnel as part of the ongoing Cotswold Canal restoration project.

All photos sourced from the internet - I am not brave enough to go inside!