{"id":773,"date":"2021-03-21T17:39:57","date_gmt":"2021-03-21T17:39:57","guid":{"rendered":"https:\/\/localhost\/monitraffic\/?page_id=773"},"modified":"2023-11-10T11:38:19","modified_gmt":"2023-11-10T11:38:19","slug":"task-1","status":"publish","type":"page","link":"https:\/\/monitraffic.tecnico.ulisboa.pt\/?page_id=773","title":{"rendered":"Task 1"},"content":{"rendered":"\t\t
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Task 1<\/h1>\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t
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Design requirements of the integrated system \u201cMonitraffic\u201d<\/h2>\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t
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Task 1 assessed the current practice on traffic analysis and monitoring and identified the needs and requirements of the tools to be developed in the scope of the project. Different needs and options of a data-based maritime traffic analysis platform for ship trajectory data provided by the Automatic Identification System (AIS) have been discussed in an initial project workshop on \u201cMonitoring and Surveillance of Maritime Traffic off the continental coast of Portugal\u201d held on 25th November 2020 at IST.<\/p>

The workshop gathered several relevant stakeholders from the local maritime community, such as, representatives of the VTS control centre and EMSA, as well as ship operators and the research team. The needs in terms of tools and information to support their activities were identified. The benefits of the developed tools\u00a0 in the project were demonstrated.<\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t

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\n\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/i><\/span>\n\t\t\t\t\t\t\t\t<\/i><\/span>\n\t\t\t\t\t\t\t\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t\t\tAIS data<\/a>\n\t\t\t\t\t<\/div>\n\n\t\t\t\t\t

The introduction of the Automatic Identification System (AIS) by IMO in 2004 [1<\/span><\/span><\/a>] has provided an immense level of detail over maritime operations at sea. SOLAS regulation v\/19 establishes the requirement for deployment of AIS transponder on board ships.\u00a0<\/p>

Coastal stations, such as Vessel Traffic Service (VTS) centres or Rescue Coordination Centres (RCC), are among those who most benefit from AIS. This system expands VTS\u2019s control range and functions, enhancing identification, tracking and vessel monitoring capabilities [2<\/span><\/span><\/a>]. AIS data received from ship stations can be recorded and subsequently used to study maritime traffic, making it an exceptionally valuable tool. AIS is also used for Search and Rescue (SAR), namely by Rescue Coordination Centres (RCC), SAR vessels and aircrafts, or on AIS Search And Rescue Transponders (AIS-SART) and AIS Man Overboard (MOB) devices. Aids to Navigation (AtoN) can also be equipped with AIS, which improves and enhances services provided to mariners [3<\/span><\/span><\/a>].\u00a0<\/p>

Since AIS messages are transmitted over VHF, its range is limited in practice by the curvature of the earth and by the power of the transmitter. However, the \u201cline-of sight\u201d limitation for earth stations may be overcome by the use of Satellite based AIS (Sat-AIS) [4<\/span><\/span><\/a>]. In the case of Sat-AIS, the average interval between available reports is between 4 and 5 hours, much longer than Terrestrial based AIS (T-AIS).<\/p>

There have been some security concerns with AIS, as the system is vulnerable to security threats, such as spoofing, hijacking and availability disruption [5<\/span><\/span><\/a>]. Possible spoofing (faking the message source) attacks to AIS include ship spoofing, AtoN spoofing, SAR spoofing, CPA spoofing, distress beacon spoofing or faking weather forecasts. Hijacking attacks involve tampering with
information from existing AIS stations. Availability disruption attacks prevent normal communication between AIS stations and may include slot starvation, frequency hopping and timing attacks.<\/p>

AIS information is available on the internet in some popular websites like MarineTraffic.com, AIS Hub, Vessel Finder, and others. IMO\u2019s Maritime Safety Committee (MSC) considers the publication
of AIS data on the world-wide web or elsewhere detrimental to the safety and security of ships and port facilities, urging Member Governments to discourage those who make such data available for publication and condemning those who publish the data [6<\/span><\/span><\/a>].\u00a0<\/p>

While the public availability of AIS information has raised security concerns, researchers have been taking advantage of this source of data to study subjects as diverse as traffic, logistics and transport economy and efficiency, collisions, emissions, oil spills, noise, interaction with whales, fishing, ice and monitoring.\u00a0<\/p>

AIS messages are transmitted in an encoded format and must be decoded in order to be interpreted [7<\/span><\/span><\/a>]. The AIS data used in the scope of this work was recorded by Centro de Controlo de Tr\u00e1fego Mar\u00edtimo do Continente<\/em> (CCTMC), the Portuguese coastal VTS centre.\u00a0<\/p>

The integrity of all AIS messages can be verified using a checksum, which is found at the end of each message. However, it is possible to find messages with correct checksums, but wrong bit length for the specified message type [8<\/span><\/span><\/a>]. In addition, a number of other errors may be found in AIS data, resulting from poor human input, incorrect installation or faulty sensors.\u00a0<\/p>

Data inconsistencies (position inconsistencies in particular) are a major setback when using AIS, and they should be dealt with before the data can be used. Regarding the data used for this research work, the following problems were detected:<\/span><\/p>