Doncaster PSB (Power Signal Box) is a signalling centre on the East Coast Main Line (ECML) railway in the United Kingdom, principally covering the line from London to Edinburgh but also encompassing other lines diverging and converging to the ECML. The signal box celebrated its 25th birthday in 2006.
The beginning of Doncaster PSB
On Sunday 8 July 1979, the first section of the control panel in the new signal box at Doncaster became operational, controlling the movement of all trains in the immediate area of Doncaster station. Not only was this a significant landmark in the progress of the whole resignalling and track rationalisation project, but it also represented a further major step forward in British Rail's drive towards the complete modernisation of the London – Edinburgh East Coast Main Line. The signal box was completed in 1981 and was officially opened on 8 December 1981.
East Coast Main Line upgrade
The Doncaster installation was the third major signal box to be commissioned on the East Coast Main Line, the previous two being King's Cross, completed in 1977 and Peterborough in 1973. Before the scheme's authorisation in 1974, train movement was controlled by a mixture of outdated semaphore and colour light signals operated from 52 signal boxes mainly containing mechanical lever frames, many dating from the 19th century.
Power signalling, however, was installed in two signal boxes, one at the north and the other at the south of Doncaster station. The work was planned and some equipment was on site before the Second World War but the installation was not commissioned until 1949. Searchlight colour light signals and electric point machines were controlled from switch panels. The interlocking equipment was unique being a sequence switch interlocking system manufactured by Standard Telephone Company using telephone switching techniques to the technical specification of the signal engineer of the then Southern Area of the London and North Eastern Railway. The sequence switches consisted of a rotary contact shaft which was rotated to a route position and proved a circuit through contact wipers. Each switch had a "home" position and eleven route positions. When a route was initiated, a clutch was engaged on the appropriate switch to rotate it into its correct position thus setting up the appropriate interlocking circuits through other switches and relays. The installations proved to be remarkably reliable, serving a very useful purpose but were eventually life expired.
In association with the resignalling scheme was a major programme of track improvements to enable trains to run at speeds of up to 125 mph. This was achieved by simplification and rationalisation of the track layout and realignment of curves at many places.
An early improvement was the adaptation of an existing railway bridge south of Doncaster to become a flyover enabling trains to and from the Lincoln Line to cross over the main line without conflicting with the mainline trains.
The largest alteration to the track layout was in the Doncaster area where the work was staged over an extensive period.
Marshgate Junction
Marshgate Junction to the north of Doncaster station forms the junction of the lines from the station to the double track to Leeds, York (ECML) and Thorne (thence Hull, Scunthorpe and Grimsby). The new layout entailed considerable changes from the then existing layout and it was estimated that the junction remodelling would take nine months of weekend work. A decision was made to carry this out during five weeks' continuous work in the spring of 1979 when the operation of trains through the area was drastically reduced and the Leeds Line was closed for a period of time. Although there were some inevitable diversions and retiming of trains, disruption of services was kept to a minimum and the project was completed on schedule.
The previous Marshgate Junction allowed for a maximum speed of 60 mph on the Doncaster – York main lines with diverging speeds of 25 mph on the main lines to and from Leeds and Thorne. Other speeds were 15 mph. The remodelling of the layout in association with other improvements in the Doncaster station area allowed speeds of 105 mph through the Doncaster section of the East Coast Main Line route. The divergence to and from the Leeds Line allowed a maximum speed of 70 mph. Other improvements on the Doncaster PSB area included raising the maximum permissible speed at Retford from 80 to 115 mph and at Newark from 80 to 100 mph.