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the rail engineer • May 2014
Signalling Previously, Ipswich station area was provided with four-aspect signalling, with three-aspect signalling on the approaches to East Suffolk Junction from both the Norwich and Lowestoft lines. To allow for adequate junction signalling onto the new chord from both Norwich and Lowestoft lines, four-aspect junction signals have been provided for both new junctions with the provision of flashing aspects on the approach to the junction signal at each divergence. Signals on the curve are three-aspect. Visible on the chord are the new lightweight LED signals, clamp lock points, and apparatus or ‘location’ cases. However, out of the pubic gaze, in relay rooms and the signal box, the project has required significant and complex signal engineering works. Ipswich is on panel 5 at Colchester Signal Box. It is a combined near vertical control and indication NX Type and was manufactured by Henry Williams Ltd and commissioned in 1983. The panel consists of small individual battleshipgrey ‘Domino’ type tiles which slot into a metal lattice in the rear of the panel. The company has returned 30 years later to incorporate the curve into the track layout diagram. The section of the panel that the new chord line affects is at the bottom right hand side. It is already quite congested as the lines towards Norwich and Lowestoft are skewed to allow alignment with Panel 6. As the new layout incorporates new signal sections on both Up Main and Up Lowestoft lines as well as the Chord lines, there are new Train Describer (TD) windows, track occupied/route indications and buttons to be provided.
The main commissioning was in March 2014 but enabling works took place late last year during which the existing panel tiles were relocated to free up sufficient space for the Ipswich Chord lines. Henry Williams Ltd also provided signalling Class I power supply location cases.
Signal interlockings The Ipswich interlocking is situated in a room on the station. Unfortunately, the distance to the new junctions is just outside the maximum 1.25 miles distance for lineside multicore 50V DC signalling safety circuits. Beyond this distance, repeater relays would be required to ensure that induced currents from the 25KV OLE do not create a potentially dangerous false feed. There was insufficient space to locate the interlocking at Ipswich station for the new junctions, and this would anyway require long runs of multicore cables. The novel solution adopted has been to build a new relay interlocking in a relocatable building near Hadleigh Road bridge. Incidentally, for a small scheme such as this, a new relay interlocking is a more cost effective solution than a computer based version. This interlocking is linked by a new Time Division Multiplex (TDM) data transmission system to Ipswich relay room. The controls and indications data is then transferred via the existing TDM connecting the existing Ipswich relay room with Colchester. GE Transportation Systems (GETS) was the contractor for the TDM and TD systems. The existing interlocking at Ipswich is a GEC geographical relay system. Some minor modifications have been necessary for the chord, but this interlocking will be extended during this summer in conjunction with the East Suffolk Junction remodelling, of which more anon. Amaro Signalling Ltd was responsible for lineside signalling equipment, new interlocking and alterations to existing interlocking.
Ipswich Yard and East Suffolk Junction remodelling This project, also funded under CP4 and part of the Spencer Rail portfolio of works, will create a new longer reception siding. Currently the yard cannot take 775 metre long trains. When resignalled in 1984, the layout of East Suffolk was rationalised from a double junction to a single lead. This prevented a freight train arriving in the yard from the docks simultaneously with a passenger train heading for Lowestoft or Felixstowe. A new line will be installed using a disused arch of the Hadleigh Road bridge, thereby restoring the facility of parallel moves at the junction. This work is due for completion in August this year.
CP5 and beyond Further improvements on the F-N route are funded under the CP5 package including Haughley Junction doubling from single lead, Ely to Soham doubling and provision of Ely Dock Junction long freight loops. As well as increasing capacity for freight trains, Greater Anglia has aspirations to increase the current two-hourly Ipswich to Peterborough passenger service to hourly. As described above, the all important Felixstowe branch suffers from the severe capacity constraint of the single line. At GRIP Stage 2, options currently under consideration include a new dynamic loop, passing loops and the relocation of Westerfield station. Complete redoubling is unlikely, not least due to the Spring Road viaduct which would be very costly to replace. The Network Rail project team is hopeful of match funding from the Port of Felixstowe and that capacity improvements should be completed by 2030. Investment in this route is critical to improve the distribution of goods from Britain’s largest container port with the potential to take up to 750,000 lorries a year off the roads by 2030.