What should an engineer do to report passed the last milepost when no other trains are in the area?

To accurately report having passed the last milepost, it's crucial for an engineer to ensure the precise location of the train. Measuring the length of the train plus an additional buffer of 500 feet ensures that the engineer has cleared the milepost safely and accounts for any train length discrepancies or necessary safety margins. This approach increases operational safety by ensuring that even the back end of the train is beyond the milepost before making any further communications or decisions.

Using any distance counter can be imprecise depending on various factors affecting its calibration or operation, which could lead to an inaccurate position. Signalling the dispatcher by radio is certainly an important communication step, but it should be done with clear and confirmed positional information. Waiting for the next signal to proceed is not applicable in this context since the focus is on confirming distance beyond the milepost rather than on awaiting clearance or instructions. Thus, measuring the train length plus an additional safety margin is the most logical and safe procedure in this scenario.