Present Bridge Clearance message

Introduction/Additional information:

1.1.1              Introduction:

This message shall be sent from shore only, to inform about the about the minimum vertical clearance of a certain bridge opening. The information shall be displayed on an external display such as Inland ECDIS.

1.1.2              Additional Information:

  • This message should only been send by a competent/waterway authority from shore only.
  • The ISRS code indicates the position of the signal and shall allow the match with the IECDIS display. It consists of UN country code, Fairway section number, Object code and fairway hectometre as published in the ISRS code as part of the RIS Index published in the European Reference Data Management System (ERDMS).
  • The bridge clearance value is the actual measured distance from the water surface to the lowest part of the bridge opening according to the width of the fairway given in the IENC.
  • The time to the last measurement is the known time in minutes from the measurement to the transmission over AIS.
  • If an accuracy information is provided it has to be subtracted from the given actual bridge clearance in worst case. It must by no means seen as indication of additional actual bridge clearance.
Message number:
Number of slots (max):
Reporting Rate:
Send if necessary from shore
Technical point of contact:


Parameter Bit Description
Message ID 6 Identifier for Message 8; always 8
Repeat Indicator 2 Used by the repeater to indicate how many times a message has been repeated.
Default = 0; 3 = do not repeat any more
Source ID 30 MMSI number
Spare 2 not used, should be set to zero (reserved for future use)
Binary data Application Identifier 16 DAC = 200, FI = 25
Version indicator 3 The version number of the message default = 0, rest for future use
UN country code 12 2*6 Bit characters
Fairway section number 17 bit coded numerical value 1-99999, 0=unknown, rest not used
Object code 30 5*6 Bit characters
Fairway hectometre 17 bit coded numerical value 1-99999, 0=unknown, rest not used
Bridge Clearance 14 from water surface to lowest point of the bridge in the fairway [in cm]
bit coded numerical value 1-9999, 0=unknown, rest not used
Time to the last measurement [min] 10 age of bridge clearance value in minutes
bit coded numerical value 0-720, 721=older than 12 hours, 722=unknown, rest not used
Accuracy 5 bit coded numerical value indicating the accuracy of the bridge clearance 0=unknown, 1-30 = accuracy (+/-) in cm is better than the given value, 31=accuracy worse than +/- 30cm
Spare 4 not used. Should be set to zero
Total 168 occupies 1 slot