What supports and protects the 3rd rail in railway systems?

The correct answer highlights the use of insulating covers and supports, which are crucial for the function and safety of the 3rd rail in railway systems. The 3rd rail is electrified and provides power to trains, so it needs to be effectively insulated to prevent accidental contact and ensure safety for both workers and the general public. The insulating covers help to guard against electrical shocks while the supports keep the rail securely in place and maintain the necessary electrical connections.

In contrast, while concrete barriers and wooden planks may provide some level of physical protection, they do not serve the specific function of insulating or properly supporting the electrified rail. Safety nets do not apply to the 3rd rail itself and are more associated with falling hazards in different contexts, rather than support or protection of electrical components. Therefore, insulating covers and supports are essential to both the structural integrity and operational safety of the 3rd rail.