What is the normal voltage of the third rail in the subway?

The normal voltage of the third rail in the subway system is 600 volts. This standard is utilized by many transit systems around the world due to its balance of safety, efficiency, and power delivery capabilities. A voltage of 600 volts is sufficient to power electric trains effectively without posing excessive risk to maintenance personnel or ground-level pedestrians, as it strikes a reasonable compromise between the power needs of trains and the safety measures in place.

Other voltages listed, such as 300 volts or 450 volts, are less commonly used in mass transit rail systems because they may not provide the necessary power for larger trains or longer distances. A voltage of 750 volts is often seen in other rail systems, but 600 volts remains the typical standard for subways, making it the correct answer.