UK EEZ Ships' Routeing Measures as approved by the International Maritime Organisation (IMO), and/or the Maritime and Coastguard Agency (MCA) (as National Competent Authority). A Traffic Separation Scheme (TSS) is an area in the sea where navigation of ships is highly regulated. It is meant to create lanes in the water where ships in a specific lane are all going in (roughly) the same direction. A TSS is created in locations with dense shipping where ships can go in different directions and where there is a high risk of collisions. Source: UKHO