How long would a holding test be for a 300 meter long train?

The duration of a holding test for a train typically calculates based on the length of the train and specified time benchmarks for track occupancy. In this case, for a 300-meter-long train, the correct duration of a holding test is determined by the standard protocols established in New South Wales Safeworking practices, which may prescribe a certain number of minutes per meter of train length.

Taking the 300 meters into account, if the recommended time per meter for the holding test is 0.063 minutes (which equals approximately 3.78 seconds per meter), multiplying this by the train's length results in 18.9 minutes. This rounds up to 19 minutes, aligning with safety and operational guidelines that ensure adequate holding time for equipment checks, safety inspections, and communication protocols before moving onto the next stage of operations.

This reasoning solidifies why the response points to 19 minutes, as it follows the calculations rooted in the guidelines and practices designed for safe train operation in New South Wales. Other time durations suggested in the choices would deviate from standard practices, thereby indicating their inaccuracy in this context.