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Rail Engineer • March 2016
SIGNALLING AND TELECOMS
(Left) LiDAR. (Right) Radar detectors.
commissioning went smoothly and the line was handed back to traffic on the Monday morning as planned. A number of modifications/ improvements have been made to the SSL modular signalling system resulting from lessons learned on Ely - Norwich. These include facilitating easier fault finding and maintenance, equipment room reliability and overall system safety.
Level crossings
Aslockton station.
The Grantham line has a number of level crossings. Existing Automatic Half Barriers at Scarrington Lane and Normanton are largely unchanged (Normanton had a new signal within its strike-in point and thus needed adjustment to the control circuitry) but with their alarms and status indications now shown on the Netherfield workstation at Derby ROC. At Bingham and Orston Lane, the manually controlled full barriers have been converted to Obstacle Detection semi-automatic operation (MCBOD), whilst at Aslockton station, the previous AHB has been converted to an MCB-OD crossing. These use detection equipment to prove that nothing is trapped between the barriers, whence a sequence is initiated to lower them automatically and clear the protecting signals. The detection process uses a combination of RADAR and LiDAR, the former mounted up to 915mm above rail level to scan the crossing as a general area, the latter (light detection) being two units, one at chest height, the other at near-ground level, to scan the roadway for any object that the RADAR might miss. SSL was asked by Network Rail to manage the pilot introduction of OD technology on the Ely - Norwich project, but a key challenge was encountered with the low level LiDAR lens becoming obscured by dirt thrown up by trains and road traffic. As a result, all crossings using OD technology are
risk assessed to establish if the lowest level detector is actually needed. Some light traffic crossings may be judged not to require it. Both LiDAR units are now equipped with a motorised shutter which automatically opens when the scanning process is taking place. This has solved the problem of dirt accumulation. At Bingham, an additional safety feature has been introduced, namely Barrier Protection Management (BPM). This comprises an inductive loop mounted in the roadway to detect if a vehicle is stopped where the barriers would come down. If activated, it stops the lowering sequence. The road here is much busier than the others and it is possible for traffic to queue across the railway. It is the first application of this feature by SSL but will be used elsewhere in similar circumstances. Should any of the detection equipment pick up a problem, then the initiation sequence is stopped and the signaller investigates the situation, taking whatever action is needed.
Onwards to the Lincoln line The Lincoln line will follow a similar pattern this coming autumn but with some added complications. Signalboxes at Lowdham, Fiskerton Junction, Staythorpe crossing, and Newark Castle, together with Gate Boxes at Fiskerton station and Rolleston, will be closed. The level crossings at these locations will be converted to MCB-OD operation except at Newark Castle. The barriers here are currently locally controlled from the
adjacent signalbox and will be converted to remote CCTV monitoring under the control of Derby ROC. AHBs at Gonalston and Thurgarton will stay the same but with alarms and indications sent to Derby. The AHB at Bleasby will be converted to MCB-OD operation. With all these crossings to be altered and tested, it has been decided to commission the line in three stages, planned for September, October and November 2016, rather than having a changeover in a single weekend. However, this does necessitate establishing temporary fringe boxes at Fiskerton Junction and Staythorpe for a short duration. The Newark flat crossing with the ECML will need an interface with Doncaster Power Box to be developed.
Lessons learned Modular signalling can offer a much cheaper solution for secondary lines when compared to conventional signal technology. By using a state-ofthe-art computer-based interlocking (CBI) like Smartlock, the system will be future proofed to accommodate ETCS. Cable lengths from the TFMs are calculated to be within limits to ensure effective immunisation for any future electrification. This scheme has been the second modular signalling project for SSL and has enabled the company to consolidate the experience gained from the Ely to Norwich project. SSL believes it places the company in a strong position to deliver further modular-based schemes, realising resignalling on secondary lines at a much lower cost than traditionally designed schemes. Thanks to Andy Cokayne (project director) and James Suter (project engineer) for explaining the scheme in detail, and to Judy Viitanen for arranging the visit.