Similar to land, there are different "roads" designated at sea for the use of vessels. We call these "roads" as "Principal Fairways" and "Traffic Separation Schemes".

There are currently 13 Principal Fairways and 2 IMO adopted Traffic Separation Schemes in the waters of Hong Kong. These "roads" are provided to improve the safety of navigation in the areas where marine traffic density is high or traffic movement is restricted.

Although we can't see these "roads" with our naked eyes, the nautical charts show the positions of these Principal Fairways and Traffic Separation Schemes clearly.

The idea of traffic lights does not only exist on roads, but also can be adopted at sea. Among the 13 Principal Fairways in Hong Kong, the Ma Wan Fairway utilizes a Marine Traffic Control System similar to the traffic lights on roads.

The Ma Wan Marine Traffic Control System divides marine traffic into two main directions, West/North Bound and East Bound. When three occulting red lights are emitted from specific Signal Mast, vessels from respective direction shall wait at designated areas.