AIS-Data For Increased Insight Into Navigational Impacts Post Installation of Man-made Structures at Sea

The objective of this study is, through analysis of AIS-data, to investigate the navigational effects post installation of man-made structures at sea, in an attempt to provide increased insight into the resulting effects. The motivation behind the study is the current and expected development in ship traffic and marine activities in Norwegian waters. There is, according to literature, little understanding as to whether the modelling performed in navigational risk assessments prior to the development of for example wind farms accurately reflects the effects post construction. In addition are many of the risk calculation methods used sensitive to traffic changes. Small changes in the traffic post installation can, therefore, result in large variations between the modelled and actual traffic risk.
A case study of several locations along the coast of Norway is conducted. Information from AIS-data has been extracted and analysed through codes/programs developed for visualisation and statistical analyses. The data is used to visualise and present statistics for the traffic density, the longitudinal and latitudinal traffic distribution, vessel speed and type, as well as the distance and angle between vessels and the investigated objects, for both pre- and post installation scenarios.
Due to the unfortunate reason that only a limited AIS-database was available for this study, the objects investigated are oceanographic buoys. The size and location of these objects create challenges with respect to how the results should be interpreted, and the applicability of these, with respect to other larger structures, such as wind turbines and aquaculture facilities.
Although the results from the case study are a bit ambiguous, they do indicate some repeating trends in vessel behaviour when new obstacles are introduced. It seems like a reasonable distance to the new objects is kept, also for small objects such as met-ocean buoys, even if the mean distance of the traffic decreases. The results also show examples where the traffic is "compressed" due to circumnavigation or alterations in course by the vessels closest to the object. This may lead to a growth in vessel density, which again can result in increased ship-ship collision risk. Additionally, for some of the cases, increased activity near the object is detected. This introduces new situations that can be interesting to investigate in further studies. Also, for further studies, investigation of the correlation between size and degree of traffic is interesting.