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Safety Briefing No.73

    1. Capacitor failure at Waverley signalling centre (19/08/21)

    Edinburgh Waverley Signalling Centre suffered an incident where a capacitor in an Uninterruptible Power Supply (UPS) failed. The capacitor emitted smoke into the plant room, which spread to the Operations floor. The fire alarm was activated. The incident led to the building being evacuated, with attendance by the fire brigade. There was severe disruption on the network, resulting in significant train delays. Investigation has identified this UPS unit had been mistakenly removed from the annual maintenance inspection by the manufacturer (Vertiv) in 2017 and was not in Ellipse (it had previously been recorded in Ellipse). The capacitor had not been renewed since it was installed around 2001. The unit was a Vertiv Chloride EDP90, 80KVA unit.

    Things to consider:

    • Resilience of the network if a catastrophic failure occurs with critical equipment UPS equipment.

    • Are adequate maintenance arrangements in place for critical assets?

    • What age should capacitors be renewed? How do we inspect and maintain capacitors?

    • Should electrical equipment be located away from operational buildings or are fire separation measures within the building adequate?

    • Should fire suppression systems be installed within electrical equipment rooms?

    2. Unauthorised Open Line Working (07/07/21)

    On 21st June two track workers were patrolling and checking rail temperatures. They were walking in the 4-foot on a curved section of track without adequate sighting when a train approached. They reached a position of safety just three seconds before the train passed them. The work was planned in a line blockage with additional protection. But the protection had been refused by the green zone access controller (GZAC). The planner didn't know the team's normal arrangements for escalating refused line blockages; the Safe Work Pack (SWP) was not amended before being authorised by the Responsible Manager and issued to the Person In Charge (PIC). The location was known to have poor mobile phone reception so the PIC should have used a landline or satellite phone to call the signaller. But those phones had been in use the night before and were on charge in a welfare van, not accessible to the team. Despite being unable to contact the signaller to arrange protection through a lineside request the two track workers continued with the task without a safe system of work or suitable SWP. Unassisted lookout working is being phased out across Network Rail in 2021.

    3. Angle grinder chainsaw discs (15/07/21)

    It has come to the attention of the Plant Team via the Office of Product Safety and Standards (OPSS) that chainsaw disc attachments have been incorrectly sold for use with Angle Grinders. Due to "kick back" during operation these discs/blades cannot be used safely and can result in serious injury or fatality. This type of disc/blade grips the cutting surface and forces the angle grinder to sharply turn or jump out of the operator's hand. These products do not comply with the Supply of Machinery (Safety) Regulations 2008 and must not be used. It is thus mandated forthwith that if any chainsaw discs/blade similar to those in the images above are identified then they must be removed and not used on Network Rail managed infrastructure..

    4. Kings Cross remodelling runaway MEWP (17/06/21)

    On 16th May 2021 at around 03:30am Pod-Trak were on-tracking their Mobile Elevating Work Platforms (MEWPs) for OLE works. While ontracking the third MEWP, it ran away approximately 600m into Canal Tunnel. The MEWP ran through the worksite marker but remained within the possession limits. The team working with the MEWP were unharmed. RAIB inspected the MEWP to establish if there was a mechanical failure. The initial findings were that there appeared to be insufficient brake force to hold the MEWP on the Road Rail Access Point which had a 1.55 gradient. Later, under test conditions, the MEWP started to move at a gradient of 1.50. A further test was conducted with the hydraulic brake bypass valve closed during the test. When retested, the MEWP braking system worked correctly. The cause of the runaway appears to be that the override valve for the rail wheel parking brake system had been left in bypass during maintenance sometime before the shift. A second Safety Bulletin will be issued if any further learning is identified.