HEALTH AND SAFETY BULLETIN Cwmbach Overlay Miniature Stop Light Level Crossing

    HEALTH AND SAFETY BULLETIN Cwmbach Overlay Miniature Stop Light Level Crossing


    Cwmbach OMSL – ELR VON

    An EBIGATE 200 OMSL was installed as part of the TAM A commissioning to notify pedestrians of approaching trains on the footpath at Cwmbach sidings.

    This consists of a red and green light and audible warning positioned on both sides of the crossing. With an OMSL, no indication is provided to the signaller at CVLICC. The crossing operates independently.

    The quiescent state of the crossing is to display a green light when no trains are approaching. This provides an indication to the user/pedestrian that it is safe to cross the line.

    The crossing is activated by approaching trains on the UP Aberdare, ELR VON between approx. 21m 12ch and 21m 52ch and the DN Aberdare, ELR VON between approx. 21m 25ch and 21m 65ch by way of axle counters. There are 3 axle counters on each line associated with the crossing (6 in total). When a train strikes in, the crossing will display a red light and sound an audible alarm. Bi-directional controls are also provided for wrong direction moves.

    If the crossing detects an issue or anomaly, it will go into a failed state referred to as ‘Dark Mode’. This will result in the red and green indications on both sides of the crossing being extinguished resulting in no indications to the user/pedestrian.

    Dark mode is activated by several issues as listed below –

  • First Axle counter operated but the Axle counter at the level crossing fails to operate and clear within 5 minutes.
  • Axle counters operated out of sequence.
  • Partial traverse on any Axle counter potentially caused by metallic objects within 300mm of axle counter head, or stationary vehicle/trolley stationary directly on top of axle counter head.
  • Hardware failure.
  • There have been several instances since TAM A commissioning where the railway has been handed back after possession and the crossing left in ‘Dark Mode’. Analysis has shown this is a result of possession activity and no consideration afforded to the crossing during the planning stage.


    At the planning stage, any works due to be carried out between 21m 12ch and 21m 65ch on the VON should consider the effect it will have on the crossing.

    The responsible manager for the works should plan to have competent SMTH staff available to restore the crossing to normal working in the event of the crossing going into Dark Mode; noting that these staff will not normally be available from the AIW Infrastructure Manager where applicable to Transformation led work. In the event of works being undertaken in the mileages above, the responsible manager should make necessary arrangements for the safety of the crossing during the works.

    Any works affecting the level crossing should be published in the WON.


    To be briefed to all transformation parties and IM. If you have any questions, please speak to your Line Manager or a member of the HSEQ Team



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