When must a train not clear or enter the main track at a switch?

A train must not clear or enter the main track at a switch without Form L authority because Form L provides specific instructions and limits regarding train operations in the vicinity of a switch. This authority ensures that train movements are coordinated and that safety protocols are being followed. The absence of this authority could lead to unsafe conditions, such as conflicting movements or derailments.

Ultimately, Form L authority is critical for maintaining the integrity of train operations, indicating that the switch is properly aligned and that other necessary safety measures are in place. Liquidating this requirement could jeopardize not only the safety of the train in question but also the safety of other trains using the track.

In contrast, while reaching a set speed, receiving instructions from the conductor, or the switch being locked are all relevant to safe train operations, they do not specifically govern the conditions under which a train can clear or enter the main track at a switch. Hence, without the essential Form L authority, the operation of a train at this point could be considered unsafe and inappropriate.