Where are trains allowed to uncouple when they are coupled?

Trains are allowed to uncouple at a block or interlocking station because these locations are specifically designed to manage train movements and ensure safety. The infrastructure and operational protocols in place at these stations allow for controlled interactions between trains, including coupling and uncoupling processes.

In contrast, other scenarios—like uncoupling at any station regardless of conditions—could lead to unsafe situations if the necessary precautions and operational procedures are not followed. Uncoupling only on straight track, while it may seem sensible from a safety perspective, is not a universal rule within operating practices. Lastly, limiting uncoupling to designated sidings could unnecessarily restrict operational flexibility, as block or interlocking stations facilitate coordinated train operations while still adhering to safety standards. Thus, the answer focuses on where uncoupling can be safely and effectively performed.