BCN Main Line - BCN New Main Line

BCN New Main Line

Over the next thirty years, as more canals and branches were built or connected it became necessary to review the long, winding, narrow Old Main Line. With a single towpath boats passing in opposite directions had to negotiate their horses and ropes. As traffic grew the locks at Smethwick Summit were still a constriction.

In 1824 Thomas Telford was commissioned to examine alternatives. He famously travelled the route of the Old Line and reported the existing canal as:

"… little more than a crooked ditch, with scarcely the appearance of a towing path, the horses frequently sliding and staggering in the water, the hauling lines sweeping the gravel into the canal, and the entanglement at the meeting of boats being incessant; whilst at the locks at each end of the short summit at Smethwick, crowds of boatmen were always quarrelling, or offering premiums for the preference of passage; the mine owners injured by the delay, were loud in their just complaints."

Telford proposed major changes to the section between Birmingham and Smethwick, widening and straightening the canal, providing towpaths on each side, and cutting through Smethwick Summit to bypass the locks, allowing lock-free passage from Birmingham to Tipton. Telford's proposals were swayed by the threat of a new Birmingham to Liverpool railway. His suggestions were accepted and he was appointed chief engineer on 28 June 1824.

By 1827 the New Main Line passed straight through, and linked to, the loops of the Old Main Line, creating Oozells Loop, Icknield Port Loop, Soho Loop, Cape Loop and Soho Foundry Loop, allowing continued access to the existing factories and wharves.

A year earlier he had built an improved Rotton Park Reservoir (Edgbaston Reservoir) on the site of an existing fish pool, bringing its capacity to 300 million imperial gallons (1,400,000 m3). A canal feeder took water to, and along, a raised embankment on the south side of the New Main Line to his new Engine Arm branch canal and across an elegant cast iron aqueduct to top up the higher Wolverhampton Level at Smethwick Summit. The reservoir also fed water to the Birmingham Level at the adjacent Icknield Port Loop.

The Smethwick Summit was bypassed by 71 ft cutting through Lunar Society member, Samuel Galton's land, creating the Galton Valley, 70 feet deep and 150 feet wide, running parallel to the Old Main Line. Telford's changes here were completed in 1829.

Telford designed a cast iron bridge, the Galton Bridge, to span his cutting. It was cast in the Horseley Iron Works, as was the Engine Arm Aqueduct and many of the wide roving bridges.

In 1837, after Telford's death, a new section of his planned canal was opened together with the 360 yard Coseley Tunnel, complete with double towpath, cutting out the long detour around Coseley and Wednesbury Oak, and therefore relegating it as the Wednesbury Oak Loop. As with many of the branch canals on the BCN, most of the Wednesbury Oak Loop became officially abandoned from 1954, but the northern stretch remains navigable to the British Waterways workshops at Bradley.

By 1838 the New Main Line was complete: 22⅝ miles of slow canal reduced to 15⅝; between Birmingham and Tipton, a lock-free dual carriageway. It was also called the Island Line as it was cut straight through the hill at Smethwick known as the Island.