Traffic separation scheme

A traffic separation scheme or TSS is a maritime traffic-management route-system ruled by the International Maritime Organization or IMO. It consists of two (outer) lines, two lanes, and a separation zone. The traffic-lanes (or clearways) indicate the general direction of the ships in that lane; ships navigating within a lane all sail in the same direction or they cross the lane in an angle as close to 90 degrees as possible.

Source: Wikipedia — Traffic separation scheme (CC BY-SA 4.0)