AIS-analysis

AIS-data (Automatic Identification System) contain ship and voyage information VHF-broadcasted by the vessel by means of standardized binary message structures. The AIS-data broadcasted on the Western Scheldt and the North Sea are received by more than 10 base stations and logged in a central server operated by the Scheldt Radar Chain (SRC). The AIS-log files stored by SRC hold ca. 0.5 gigabyte a day.

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AIS-data are an interesting dataset to analyse operational shipping trafic or manoeuvres but the voluminous datafiles are a real challenge. In 2013 to 2014 Flanders Hydraulics Research (FHR) developped a tool to analyse AIS information in a flexible and effective way. Voyage AIS_2.jpginformation was structured based on the passing times of predefined entrylines so that the AIS-data could be filtered on different parameters such as: ship characteristics (dimensions, type) or voyage characteristics (destination, in- or outbound sailing, draft, time). For visualisation purposes the AIS-analyzing tool supports export to kml-files which can be opened with Google EarthTM or other GIS-viewers.

On behalf of the Common Nautical Authority (CNA), FHR and Ghent University (UGent) studied the operationally applied ship speeds for different ship types and destinations on the Western Scheldt. The analysis was based on a combination of the IPS-database (Information Processing System) of CNA containing accurate vessel information (ship dimensions, draft and ship type), and AIS-data holding accurate voyage information. Two years (2012 and 2013) of AIS-data, supplied by SRC, corresponding to 382 GB binary data were processed. In order to reduce the dataset the study was limited to vessels longer than 200 m and wider than 30 m.

The study revealed for inbound and outbound manoeuvres to Flushing-Sloehaven and AIS_3.jpgAntwerp the influence on ship speed of ship type, draft, tidal conditions and operational boundary conditions.

Also for several other projects the AIS-analyzing tool was applied in 2014 and 2015. One example is the analysis of shipping traffic (passing distances and ship speeds) close to a wave gauge on the Western Scheldt in order to rely water level changes to ship waves. Another example is a replay function of ship trajectories between two entry lines in the port of Zeebrugge in order to evaluate realistic manoeuvring speeds and rate of turn for a selection of vessels.