Safety Bulletin NRB22-12 Multiple trains in a signal section

Safety Bulletin - A Serious incident has taken place - Multiple trains in a signal section

Scope: All Network Rail line managers, safety professionals and accredited contractors
Ref: NRB22-12
Date: 17/11/2022
Location: Wingfield, Alfreton, Derbyshire
Contact: Adrian Moss, Principal Engineer (Signalling)



On 26th October 2022, two following trains entered
the same signal section due to an incorrect aspect
sequence being displayed to the drivers of both
trains. The irregularity resulted from a failure to
carry out signal maintenance testing (SMTH).
Ballast cleaning works undertaken in the area
required disconnection at DY586 signal and
associated equipment. When the signalling system
was reinstated following completion of the track
works, the yellow and red aspects on DY586 signal
were transposed.

The incorrect aspect sequence resulted in the first
train passing the signal at red when it should have
been yellow, and a yellow aspect shown to the
following train when there was a train in the
forward section.
Testing to reinstate the signal after the works, was
not carried out in accordance with the Signal
Maintenance Testing Handbook (SMTH). Testing
steps in the SMTH would have identified the
transposition of the aspects had they been
followed. The error was not self-revealing.



B229 NRB22-12

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