From
New Civil Engineer - a good summary:
Highways England’s rail responsibilities
The Historical Railway Estate includes legacy bridges, abutments, tunnels, cuttings, viaducts and similar properties associated with closed railway lines and was previously known as the Burdensome Estate – but how did it end up being the responsibility of Highways England?
The structures were not transferred to Railtrack, which became Network Rail in 2002, when British Rail was privatised in 1994 but stayed with the British Railways Board (BRB‡), which was part oft of the Strategic Rail Authority. Department for Transport took responsibility for the BRB estate when the Strategic Rail Authority was disbanded in 2005 and it was then passed to the Highways Agency in 2013 when the BRB was abolished.
and in the news as they're letting a new inspection contract:
Tender documents for a 10 year framework deal to undertake inspection work for Highway England’s Historical Railway Estate have been published, valuing the work at £30M.
According to the details published in the Official Journal of the European Union, the work will involve inspection and remedial design for disused rail bridges and tunnels across the UK▸ .
The work covering 3,800 assets, including 77 listed structures such as the Leadersfoot Viaduct in the Scottish Borders and the Castlefield Viaduct in Manchester, is the second contract term to be let following transfer of the structures to the Highways Agency [now Highways England] in 2013. The work was previously let in 2015 under four regional contracts with Carillion securing the North, East and West deals and Balfour Beatty winning the South contract. Balfour Beatty took over the contracts when Carillion went into liquidation in 2018.
Is there a list of these assets? By area??