Under what circumstance can a train exceed the speed limit according to NORAC?

Under NORAC Operating Rules, a train can exceed the speed limit in an emergency situation, provided there is proper communication. This is crucial because emergencies may arise that require immediate action to prevent accidents or to address unexpected developments on the railway. The emphasis on "proper communication" ensures that the actions taken to exceed the speed limit are coordinated with other personnel and systems in place, allowing for a safer response to the emergency.

This answer highlights the importance of safety protocols, which are designed to protect not only the train crew and passengers but also the integrity of railway operations. It reflects an understanding of the need for swift action while adhering to operational guidelines that maintain overall safety and reporting procedures. Other situations such as having no traffic ahead, during maintenance work, or while passing a signal do not typically meet the criteria established by NORAC for safe speed exceeding, which underscores why those scenarios are not valid circumstances for breaching speed limits.