Basis for Recommendation
The investigation identified that the interpretation of SGI was identified as a factor in the incident. These are being interpreted as allowing signal protection to be granted with a train within the signal section, provided it has passed the location where the access to the line is required. Where track section indications do not or cannot provide a clear indication of the location of trains within a signal section safe implementation of signal protection is reliant on safety critical communications, increasing the risk of error.