 However, there was a difference in the water levels and a lock was required to compensate for the 1 ft (0.3m) drop.At its southern end, to the south of Southall wharf, the canal split into two, with the main line continuing to Coalport via the two inclined planes, and the Horsehay branch running to Brierly Hill, terminating on the hill about above the Coalbrookdale works.A tramway from the works tunnelled into the hill, ending in a cavern below the terminus of the canal.