The operation (within defined limits) of trains in both directions on a single track on the mainline.

• A. Single Track Operation
• B. Reverse Traffic
• C. Automatic Block Signal
• D. Strobe

Answer: (A)

Handling trains in both directions on a single mainline track within defined limits is called Single Track Operation. This term precisely describes the situation where one track carries traffic in both directions, so movements must be sequenced and use passing places or sidings to avoid conflicts. Safe operation relies on careful scheduling, clear train orders or timing, and appropriate signaling to ensure trains meet and pass only at designated points. The other terms don’t capture the overall operating arrangement: Reverse Traffic isn’t a standard designation for this mode; Automatic Block Signals describe a signaling method rather than the basic track arrangement; Strobe is unrelated to mainline track operation.