How long is a track warrant in effect?

A track warrant is a form of authority issued by a dispatcher that allows a train to occupy a particular section of track. It is considered effective until it is either cleared by a crew member or voided by the dispatcher. Clearing the track warrant typically involves the crew acknowledging that they have completed their work within the specified limits, ensuring that the section of track is again available for other trains. Voiding it refers to the dispatcher canceling the warrant, which can happen if operational circumstances change. This mechanism ensures safe train operations and clear communication about track occupancy. Other options, while they might imply different durations or conditions, do not accurately represent the specific process and requirements governing the validity of a track warrant.