Castlefield, the site of Manchester’s first known settlement, the Roman Mamucium, is a cat’s cradle of canals and railways.

The Cheshire Lines Committee, a consortium of three separate railway companies, ran four tracks into the city centre, leading to its Manchester Central passenger station and the vast Great Northern Warehouse, both of which were reborn in recent times, respectively as a conference centre and a leisure complex.

The southern CLC viaduct was adapted to carry Metrolink trams in 1992, but the parallel viaduct has had no practical transport function since the track was lifted in the early 1970s. 

In 2021 the National Trust announced a scheme to use the viaduct to create a sky park – an elevated green space in an urban environment ~ by making use of the abandoned transport infrastructure.

The original linear sky park was the Coulée verte [green belt] René-Dumont (alternatively called the Promenade plantée [planted walkway] René-Dumont) in Paris, opened in 1993.  René Dumont (1904-2001) was a professor of agricultural sciences who began his career advocating the use of chemical fertilizers and eventually became an ecologist and an inspiration to the French Green Party.

The most famous sky park is the New York City High Line, a stretch of the New York Central Railroad’s abandoned West Side Line that was rescued from demolition and redevelopment by the Friends of the High Line.  It was opened in sections between 2009 and 2014.

These and other examples have demonstrated that it’s often cheaper and more profitable to make redundant rail infrastructure an amenity than to scrap it.  It’s well known that developers and property owners are attracted to inland waterways for sound commercial reasons, and it’s apparent that the effort to rejuvenate rail structures can similarly invigorate the surrounding area.

The Castlefield Viaduct is very much a temporary pilot project which is well worth visiting, a thousand-foot stretch accessible from the Deansgate/Castlefield tram stop:  A fly-though of Castlefield Viaduct – YouTube.  Funding for future development seems uncertain at present, and it would be a pity if the project had to be abandoned:  Castlefield Viaduct | Manchester | National Trust.

Other British cities have derelict railway structures that could be potential sky parks. 

Leeds has two such projects, the Monk Bridge Viaduct, built in 1846, closed in 1967 and now adapted as an urban garden, and the 1½-mile Holbeck Viaduct, built in 1882 and abandoned since 1987, for which ambitious plans exist.

Birmingham has the Duddeston Viaduct which, because of a disagreement between competing railway companies, was built and left incomplete in the late 1840s and has never carried a train.  

It would be satisfying to see it eventually find a useful purpose.