Linslade Tunnel

A total of three bores have been constructed to date, the first of these being the central bore. This is the tallest of the three, and the only one that carries twin tracks. It was also the first tunnel on the site to be constructed, an individual contract for its construction on behalf of the London and Birmingham Railway being issued around 1834, shortly after the purchasing of land along the route was authorised by an Act of Parliament in 1833.[1][2] The engineering work was performed by the pioneering railway builder George Stephenson.[3] The local geology largely consisted of clay and iron sand.[4] Possessing a length of 280 yards (260 m) and a depth of roughly 55 yards (50 m), its excavation involved the removal of 20,433 cubic yards of spoil.[5] Atypically, the bore has a slight curvature or bend along its length.[4] This first bore was completed during 1837, and services commenced running through it thereafter.[6] Contemporary accounts around the time of its opening described the original Linslade Tunnel as being relatively spacious.[5]

During 1859, the eastern bore became the second to open, carrying a single track to serve a branch line from Leighton Buzzard to Dunstable, which has since been permanently closed.[7] In 1876, the single track western bore was the third to open, it is the narrowest tunnel of the three. The northern portals were finished with a brick castellated retaining wall that incorporated all three of the horseshoe-shaped arches.[2] On 1 May 1975, the northern portals were recognised as a grade II listed building, the listing text observing that it is "an interesting example of early railway architecture".[8] The southern entrance has also been listed despite being noticeably less ornamental than its northern counterpart.[9]

A steam-hauled express emerging from Linslade Tunnel's southern portal, October 1948

During the 1960s, Linslade Tunnel, along with the majority of the West Coast Main Line, had overhead electrification apparatus installed, which facilitated the line's transition to using electric traction.[2]

On 9 December 1982, during the British Rail era, a fatal incident occurred at Linslade Tunnel, an inadequately secured load that had fallen from one train was struck by the next train passing through the tunnel, causing its derailment and the death of its driver.[10][11]

During the late 2010s, deteriorated parts of the brickwork within Linslade Tunnel were repaired.[12] In early 2020, the tunnel was again subject to engineering works, largely focused upon a comprehensive track renewal, to improve service reliability.[13]

The eastern bore and the eastern side of the central bore are used by goods traffic and West Midlands Trains services to and from London Euston respectively to mainly local stations including traffic using the Northampton Loop Line connecting to and from Birmingham, Rugby, as well as several stations further to the north. The current maximum speed on these lines between Euston and Northampton for passenger traffic is 110 mph (180 km/h). The western side of the central bore and the western single bore are used mainly by Avanti West Coast services to and from London Euston respectively services, at up to 125 mph (201 km/h).