Chart No. 1 · M 10–13
Traffic separation scheme (TSS)
Areas & limits
Magenta lane arrows and a separation zone organize shipping — small craft cross at right angles.
What it means
Broad magenta outline arrows show the established direction of traffic in each lane (M 10); a magenta band or line between them is the separation zone or line (M 12–13) that traffic must keep out of.
Why it matters
COLREGs Rule 10 applies: join and leave at lane ends or shallow angles, cross on a heading at right angles to the flow, and do not impede through traffic. Vessels under 20 m and sailing vessels must not impede power-driven vessels using the lane.