On double track, how must trains move unless otherwise instructed?

On double track, trains must keep right unless otherwise instructed. This is established to ensure that trains maintain a consistent and predictable flow of traffic, reducing the risk of collisions and ensuring safety on the tracks. By mandating that trains move to the right, the rules create a standard pathway for trains to follow, which helps both crew members and system operators anticipate train movements.

The concept of keeping right aligns with broader traffic conventions observed in many regions, further enhancing safety and clarity in train operations. This rule becomes especially important in scenarios where trains may be operating simultaneously on adjacent tracks, as it minimizes confusion regarding which direction a train is expected to move, streamlining operations and promoting efficient railway use.