When must crew members refrain from going between uncoupled locomotives or cars?

Crew members must refrain from going between uncoupled locomotives or cars when the clearance is less than 50 feet because this distance poses a significant risk of being caught between the equipment. Clearances of less than 50 feet can indicate that the likelihood of movement from another train or an issue with the air brake system could occur without warning, which could lead to serious injuries or fatalities. By adhering to this safety standard, crew members help ensure a safer work environment.

Other situations that could be unsafe, such as unclear conditions at night or personal judgment about safety, do not provide the same level of concrete safety guidance as the defined distance of clearance. Safe practices rely on established rules, like the specified clearance measurement, that mitigate risks associated with working around railroad equipment.