Role and Types of Aids to Navigation

☆Vessel Traffic Service Station(Vessel Traffic Advisory Service Center) 
 The stations collect information on the movement of vessels within ports,particular channels and neighboring waters, and areas with heavy traffic,and inform the position of the vessel and the movement of other vessels by wireless telephones and electric flash boards. 
The Tokyo Wan Vessel Traffic Advisory Center at Kannonzaki on the Miura  peninsula at the mouth of Tokyo Bay is also a vessel traffic service station. 
 Here,information obtained from highly efficient radars installed at Kannonzaki, Honmoku pier and Urayasu are processed by computers,and stations provide the movement of other vessels,meteorological features and necessary information to support the safe navigation and control of vessels. 
  Vessel Traffic Advisory Service Centers are also established in the port of Nagoya, Akashi Straits,Bisan-Seto,Kurushima Straits and the Kanmon Straits with heavy vessel traffic. 
☆Tidal Stream Signal Station 
 Tidal Stream Signal Stations are facilities which in form vessels of the direction and speed of tidal streams in straits with strong tidal streams by means of light signal boards,particular features,lights and radio telephones. 
  In the Kanmon Straits and the Kurushima Straits in the Seto inland Sea,the navigating route is narrow and bending,and the maximum speed of the stream is 10 knots. 
  The streams greatly affect the maneuvering of vessels. 
  At times,vessels run aground on reefs,or collide with vessels coming from the opposite direction. 
  To prevent such disasters,the direction of the stream,the speed and the future speed are provided on light signal boards,display and radio telephones. 
 ※Examples displayed on the light signal board (letters, numbers, and arrows are lighted 2 seconds for each signal) 
 E:indicates that the stream is east flow(flowing toward the east direction). 
 6:indicates that the speed of the stream is 6 knots. 
 ↑:indicates that the speed of the stream will become faster.