In 1948 the company was nationalised and became a part of British Waterways. By the 1960s traffic was dwindling and the official head of the main line of the navigation became the new steelworks at Aldwarke, below Rotherham. Repeated proposals were made in the 1960s and 1970s to upgrade the system to allow larger vessels as far as Rotherham. Go-ahead was finally given in the early 1980s: the channel was deepened to 8 feet and the locks were rebuilt to take 700-ton vessels. A new wharf and freight terminal were built in Rotherham utilising the disused riverside bus depot as warehousing; various other facilities on the navigation below Rotherham were upgraded. The improvements were opened in 1983. Although these have received traffic sporadically since (and are still used in a limited fashion today), the upgrade was not the success that was hoped.