Who is authorized to approve the substitution of DCS Rules for ABS Rules in case of a signal system failure?

The authorization to approve the substitution of Direct Control System (DCS) Rules for Automatic Block Signal (ABS) Rules during a signal system failure is granted to the Manager of Transportation Operations (MTO). This is because the MTO has the necessary authority and oversight on operations and safety matters that arise when there are failures in the signaling system. The substitution process must ensure that safety is prioritized while addressing operational efficiency, which falls within the remit of the MTO due to their expertise in managing transportation operations and regulatory compliance.

The other choices, such as the Senior Dispatcher, Operations Manager, or Head of Safety, might be involved in various capacities concerning daily operations, compliance, or safety oversight, but the final decision-making authority regarding the substitution of these specific rules rests with the MTO, ensuring that responses to signaling failures are coordinated and effective under the established protocols.