In ABS, when meeting an opposing train on the main track, do not line the switch until what occurs?

• A. The opposing train has entered the block in advance
• B. The opposing train has entered the block in advance and left the block
• C. The dispatcher issues a direct order
• D. The signal indicates proceed.

Answer: (A)

In ABS, you don’t line the switch toward the opposing route until the opposing train has entered the block in advance. This ensures there is positive protection from the block ahead before you move the switch, so you aren’t arranging the turnout to a path that the approaching train might still be occupying or entering. Waiting for the opposing train to enter the block ahead confirms that the space in front of you is secured before changing the switch, reducing the risk of a collision. Once the opposing train has entered the block in advance, the switch can be lined safely for a proper route.