The Canal Tunnels are a pair of single track railway tunnels in north London which connect the East Coast Main Line to St Pancras low level railway station. Their name comes from the Regent's Canal, which they pass closely beneath. Constructed as one element of the overarching Thameslink Programme, the Canal Tunnels enabled trains to travel directly from Peterborough and Cambridge to St Pancras, along with numerous other stations in London, Gatwick Airport and down to Brighton. They were constructed between 2004 and 2006, while fitting-out was performed between 2013 and 2014. The first services were run through the Canal Tunnels during February 2018, while its official opening occurred three months later. The Canal Tunnels run from Belle Island junction, north of King's Cross station, to Canal junction.
Construction
The Canal Tunnels were constructed as part of the wider Thameslink Programme; a £6 billion project to upgrade and expand the Thameslink rail service crossing the capital. These tunnels were the first major element of Thameslink's infrastructure to commence construction. One primary purpose of the tunnels was to facilitate the integration of services running on the East Coast Main Line into the Thameslink network; a junction connecting the tunnels to the ECML is positioned barely 100 meters from the northern portals. The tunnels were designed with safety and resilience in mind. While power is normally directed from infrastructure built for the nearby Midland Main Line, provisions to use the ECML's power supply have been made. For safety reason, emergency service radio systems has been installed along with a walkway and automated LED lighting at four meter intervals to provide an escape route in the event of an passenger evacuation within the tunnel. On account of the Regent Canel's close proximity, flood management measures were also built, including a drainage system with a sizable sump beneath the tunnel, which is pumped into the ECML's existing drainage network. The infrastructure has been designed to facilitate bi-directional working for greater operational flexibility. The construction process itself took roughly two years, commencing in 2004 and work being declared complete during 2006. The timing of the construction was intentionally planned to coincide with adjacent railway engineering works to redevelop St Pancras railway station and to connect it with High Speed 1. The tunnels themselves were driven using tunnel boring machines. Each bore is in diameter, the walls being covered with a pre-cast concrete lining. The northbound tunnel is in length, while the southbound tunnel is long; this length discrepancy is due to curvature. The tunnels feature relatively steep inclines, at some point as high as 1 in 34; the lowest point of these gradients was deliberately positioned in line with the incorporated flood control measures. Despite their problem-free completion, the Canal Tunnels remained unused for numerous years; this was largely due to the tunnels having been completed well in advance of numerous other Thameslink elements, such as the delivery of the new British Rail Class 700 multiple units ordered for the service and other infrastructure works. During this interval, the installation of track, power supply, and signalling systems were performed ahead of the commencement of passenger services. In August 2012, railway infrastructure owner Network Rail announced that the construction company Carillion had been appointed as the principal contractor for the fitting-out of the Canal Tunnels. The fitting-out process commenced during 2013 and was completed during the following year, despite this milestone occurring several years ahead of services running; this was reportedly to facilitate stock movements and to take advantage of available land to facilitate such work. The signalling systems installed were integrated with Thameslink’s High Capacity Infrastructure; in additional to conventional colour light signalling, two further signalling systems are present, the European Train Control System and Automatic Train Operation; Thameslink officials claimed that this arrangement was the world's first implementation of such technology on a mainline 'heavy' railway. Wherever possible, all wiring, mechanical, and electrical equipment was cleanly ran within a pair of troughs built into the tunnel. Amongst the last elements of the work was the connection of the new track to the existing lines via the insertion of several new junctions.
Services
On 26 February 2018, the first passenger service traversed the Canal Tunnels; numerous out-of-service trains traversed the section prior to this for testing purposes. The tunnels were officially opened to traffic during May 2018, forming a part of the Thameslink core route from that month onwards. Capacity was traditionally limited to 16 trains per hour from Bedford, Luton and St Albans southbound via the Midland Main Line; the presence of the Canal Tunnels has added another eight per hour from Cambridge and Peterborough, achieving the objective of 24 trains per hour peak service between St Pancras and Blackfriars. Much of these movements are automated, making use of the route's sophisticated digital signalling to do so.
