Beitrag Müller

The Historical AIS Data Use for Navigational Aids

Prof. Dr.-Eng. Reinhard Mueller
Hochschule Wismar - University of Technology, Business and Design; Department of Maritime Studies
Dr.-Eng. Anke Zoelder, Dipl.-Eng. Frank Hartmann
Shipping Institute Warnemünde

A new technology has been introduced into commercial shipping, known as the Automatic Identification System (AIS). The AIS is a seaborne technology which transmits position and identification data as broadcast messages in short time cycles. In a typical range of FM transmitters the current ships data is continuously available in VTS centres or on the receivers of other ships. A replay of tracks from a ship is feasible after recording a representative data stream. Different filters can be used to focus on different types tracks of a ship in selected areas. Habits and typical tenors in the routeing of a ship can be shown. Shore based safety measures for the navigation of a ship can be enhanced by current, real-time AIS -based information about sailing locations and sailing streams.

Traffic information in shipping about lanes, routes or traffic density could be gathered by the monitoring of vessels leaving and approaching harbours. The Baltic Sea for instance, is basically an enclosed body of water bordered by a lot of ports. Intensive transit traffic and ferry traffic crossing the Baltic reflects a growing demand to better regulate vessel traffic. The source for statistical traffic calculation has been very basic - almost primitive - and often not very efficient in the past. Results about shipping traffic and routeing have often been very different. A great amount of information used in navigation has been based on assumptions about Baltic vessel streams and routes in earlier investigations. With earlier, more traditional navigational aid, there was no possibility to prove the availability of real sailing ways on the Baltic, to track a vessel trafficking the Baltic or to map an optimal route for a vessel which would take real-time weather and traffic situations into consideration. The introduction of shore-based radar has enhanced the sea traffic observation ranges. The harbour areas were completely covered by radar. Typical radar coverage ranges from twenty-four nautical miles out into the coastal waters. Harbour -leaving Ferries cross the radar observation sector and disappear into a "black hole". The expectation is that the vessel will reach its destination on time without any complications; this situation would not be allowed in air traffic. The risk factor would be too high and dangerous.
First investigations for introducing the AIS technology in shipping show new possibilities for monitoring and recording the tracks of ships.
AIS information includes the speed velocity of a ship. The short repeating rate of broadcasting the speed and position of a ship allows all tracks to be displayed and to be processed in conjunction with other traffic.

1 Problems and Aims

The following paper will describe and analyse the current traffic situation in the Baltic Sea and the possibilities for better and safer path guidance for vessel traffic.
In addition to the existing traffic safety systems and regulations additional solutions will be introduced in the paper. The proposals have been mapped out in close cooperation with the Federal Maritime and Hydrographic Agency of Germany, the Waterway and Shipping Directorate North, the Pilot Associations and the Baltic Ferry Companies TT-Lines and Scandlines. The very first investigation results was sponsored by the Federal Ministry of Transport, Building and Housing.
The main proposal resulting from the research is a software tool to evaluate path guidance of the navigational space encompassing several variations. The present paper may serve a basis for future vessel traffic regulations in the Baltic Sea or other waters for authorities and institutions.
The Baltic Sea is seen as one of the booming regions of Europe in respect to its great economical potential. Where does this optimism come from? And what are the effects of increasing trade and commerce? These questions have to be answered especially with focus on the existing and expected transport volume on the Baltic Sea, which is the connecting element between economical, logistical and political fields.
The development of sea traffic and of the regional harbours has a central effect in regards to the efficiency of the transport and reshipment of goods, which are the integral parts of international trade.
But in this sector the lack of enforced safety measures can quickly become a great danger for humans and for the environment. In order to minimize dangers in shipping the following investigations will analyse and describe the traffic situation of a current ship and its conclusions for navigational safety and efficiency. The risks for the environment can then be assessed, and possibilities for decreasing potential danger can be proposed.

1.1 Sea Trade in the Baltic Region

Trade between countries bordering on the Baltic Sea reaches hundreds of billions of US$ per year and world trade involving the Baltic region amounts to another 15 billion in US$ annually. Around 30% of European business power is concentrated in the Baltic Region. One third of European export is produced by these countries [// 1].
These intensive trade connections correspondingly impact Baltic Traffic heavily. In 1995 the volume of commercial goods reached over 460 million tons. With a predicted increase of 3% per year [// 2] and taking into consideration the conjunctional change and regional differences, transport volume could soar to over 700 million tons in 2010 (Table 1).
A difference in transported goods in the Baltic Region has become evident. The maritime shipment between traditional market-economical countries is mainly bilateral with finished and refined products. On the other side, goods, which are exchanged between western countries and Transformation Countries, go along one-way streams. Exported goods are mainly raw materials, imported goods are finished products.

In addition to the harbours on the North Polar Sea and some ports on the Black Sea the Baltic Sea is the only seaside access to the western and central areas of the Russian Federation. Because of the dominance of the Russian raw material export (1998: 41.4%),its sea traffic correspondingly is of great importance. The Baltic Countries play an important role due to their geographical and strategical position; the Baltic remains ice-free in the winter and it offers commonly-trafficked routes. The number of shipments show: 105million tons of transit goods were shipped through the ports of the Baltic Regions (SF,RUS, EST, LV, LT). Russia depends on its ice-free harbours. About 1/5th of Russian petrol is exported through the harbour of Latvia alone.

 Shipment in Baltic HarboursCargo daily through the Baltic SeaDaily shipped cargoDensity of cargo per year
1998500 Mill. T1.0 Mill. T1.3 Mill. T800 T/km²
2010 (Prognosis)700 Mill. T1.5 Mill. T2.0 Mill. T1000 T/km²

Table 1: Transport volume in the Baltic Sea Area [// 3]

Currently over 350 million tons of cargo per year are transported on the Baltic Sea; this is ca. 7% of the world sea traffic. The yearly average cargo density of the Baltic Sea (circa800 tons per km²) is more than 50 times bigger than the yearly average cargo density of all world seas (circa 15 tons per km²). Traffic - including the sum of all ships and ferries with transporting routes - across the Baltic Sea is one of the most concentrated world-wide.

Special vessels in inland and international traffic transport raw materials and products of petrol. Partly-finished and finished products and general cargo are generally transported by containers or trailers. Their transportation is almost always performed by ferries or Ro/Ro-vessels because of their high-loading efficiency.
Existing regular ferry and Ro/Ro routes between Germany, Poland and Scandinavia represent the world-wide highest concentration of their kind. The relatively young and currently still low level traffic routes from and to eastern Transformation Countries have the potential to greatly influence the volume of traffic on the Baltic and an increasing density of the passenger and trade traffic will further effect traffic density.

By 2010 seaside transport via the Baltic Sea is estimated to double. In this context the importance of the separation of the transported goods must be stressed. Trade flow between western industrial countries will represent the greatest effect on the volume of traffic in the future (// 4); the greatest impact on traffic will be made by countries in Eastern Europe. Container and trailer cargo will increase - especially in East European traffic.
Because of the growing cargo density and cost digressive effects, the average ship size in Baltic Sea Traffic will continue to grow, especially the size of container ships. The dimension of tankers is naturally limited by the water depth of the shipping routes. The increase of the speed of the liner ships (mainly container, Ro/Ro ships and ferries) will stay be minimal because the distances across the Baltic Sea are comparatively short (max.1000 nautical miles) - passenger traffic being excluded. Passenger traffic is performed by High Speed Crafts (HSC); higher reserves of speed are used to balance possible delays and to attain a higher reliability of service.

1.2 Traffic flow in the Baltic Sea - Transportation density and growing environmental pollution

In general transportation of goods over the seas is pictured as friendly. But nevertheless, ships may give rise to environmental pollution in a serious way. Spilled petrol is the most evident and most well-known danger. 11.3% of all petrol spilling into the seas is caused by tankers, 14.4% of petrol contaminating the seas is produced by other ship types which have crashed and lost petrol.
But there is another type of dangerous pollution, which is not immediately evident. The shipping industry is responsible for ca. 12% of environmental pollution of the seas by faulty substances like petrol products, chemical substances, containerised dangerous goods, faeces, waste, ballast water and so-called antifouling paint. Although chemical substances and dangerous container goods have great potential to create heavy damages, pollution instigated by crashes has been significant up to now. Pollution caused by faeces and waste has continued to increase - even with existing regulations being observed (MARPOL [// 5]).

The following are important criteria to regulate in order to protect the Baltic Sea:

  1. The sea traffic of dangerous cargo
  2. The ships number and size including technical equipment and crew qualification
  3. The natural conditions including water depths
  4. The situation inside harbours
  5. The traffic regulated measurements and vessel traffic services
  6. Telematic infrastructure for serving navigational aids.

In view of statistics the groundings and collisions represent the greatest risk of causing environmental pollution of the Baltic Sea. That is why ships with dangerous cargo like petrol, petrol products and chemical substances have to be monitored carefully, because their poisonous cargo can cause the most serious damages. In the past for statistical approaches to define the probability of groundings or collisions would be used material like the follows:

About 65,000 vessels shipping through Sund and Great Belt into the Baltic Sea every year; of the 65,000 vessels, 2,200 tankers and 2,520 bulkers with 50,000 tonnes and bigger are trafficking the Baltic.
Year by year over 150 million tons of petrol and petrol products are transported from and to ports of the Baltic Sea. Raw petrol represents 40-45 per cent of this. Ca. 70% of the volume is transported by smaller and medium-sized tankers and the other 30% by larger ships with a volume of 70,000 up to 150,000 tdw. Additionally ca. 4,000 journeys of various ship types cross the Baltic Sea with dangerous cargo in containers/trailers and circa 12loaded chemical tankers also use the Baltic to transport goods (Helsinki Commission2001, [// 6]).

30 million tons of oil from the Russian ports of Primorsk and Muja will be exported in the future. The main route for oil transportation is through the Cattegat and the Great Belt, via the Kadetrenden, the south-eastern part of the Baltic Sea and into the Gulf of Finland.
Petrol transports on chosen oil tanker traffic routes in the Baltic were observed in a other study from 1995 [// 2]. All the stored information has been analysed to determine and estimate transportation patterns, quantities of oils and oil products carried by tankers in the Baltic Sea Area as well as the number of ships and journeys for different ship type categories. The main transportation routes in the Baltic Sea Area are divided into a number of segments (Figure 1, Figure 2). But as there is no ship reporting system, a harbour reporting form was to be filled in with information about ship, cargo and route.
However, information about the used routes in/out of the Baltic Sea was missing in a number of cases; the route had to be assumed in order to carry out the analyses. In some cases when the reported data were incomplete the following assumptions were made:

  • In the cases when the route in/out of the Baltic Sea was not specified, the route was assumed to be the same route as during other similar journeys made by the vessel. If this information was not available, the route in/out of the Baltic Sea was assumed to be the most frequent route used by other ships trafficking from the same port of origin and heading to the same destination.
  • In the cases when different ship data (for instance ship type category or total cargo capacity) was reported for the same ship, the ship data most frequently specified was registered and used in the analysis (Figure 1Figure 2).

After the first AIS -based investigation had been carried out the important conclusion was that the main traffic stream does not pass south of the Island of Bornholm but to the north between Bornholm and the Swedish continent.
It appears clearly from the AIS analysed chart plots that the assumptions concerning the most frequented transport route were not conclusive. Earlier transport frequencies studies must be substitute by results of historical AIS records evaluation. With the introduction of a compulsory ship reporting system for deep draught and dangerous vessels (tankers, bulkers), more knowledge and transparency about dangerous goods from the loading harbour to the exit of the Baltic Sea Area could be gained. In the future, new AIS technology could facilitate this knowledge about goods transportation and traffic routes.

Figure 1 Traffic streams

Figure 2 Transport routes

1.3 Presentation of existing Vessel Traffic Service

The VTS-Centre Warnemünde is an example of a modern Vesssel Traffic Centre. Today the Centre is one of the most up-to-date VTS-Centres in Europe. Vessel traffic entering the port of Rostock - besides having modern visual shipping signs as navigational aids - is offered a powerful vessel traffic service made available by operation of this new centre. The main goals of the vessel traffic service are to give traffic information, define traffic regulations and offer navigational assistance.
The VTS-Centre Warnemünde consists of a high performance vessel traffic system which is equipped with efficient radars and ship data processing. There are two radar antenna stations, the first of them is installed directly at the antenna tower of the VTS-Centre (71 m), which has a monitoring area of 24 NM (Figure 3). A further 30 m high antenna station lies in Groß Klein. This station enables the VTS operators to monitor the sea canal and the port of Rostock.
Traffic situation displays are produced by processing radar information together with data from the automatic identification systems (AIS). The installation of ashore AIS - infrastructure creates the basis. By installing additional repeater stations at Darßer Ort, Bug and Stubbenkammer the range of AIS could be expanded to receive AIS information from vessels located in the Kadetrenden.

Figure 3 Shore based Radar Picture

1.4 Automatic Identification System (AIS)

AIS is an acronym signifying the Automatic Identification System for ships. A law will go into effect which will assert the AIS as mandatory for special vessel types according to the regulations of the IMO; vessels will have to be equipped by 21.12.2004.

Vessels equipped with AIS send their identification and position clearly to other ships, also course and speed information and further data is relayed. AIS serves as a collision avoidance tool at sea, organizing the automatic exchange of information between ships as well as between ships and ashore stations and VTS-Centres on the coast. AIS is an additional element in maritime safety aiming to increase the safety of life at sea, the efficiency and safety of navigation and ship transportation as well as promoting the protection of the maritime environment.

Along the German coast, an AIS-Infrastructure is being installed now and will be finished next year; this is a tremendous contribution to maritime safety.

AIS was developed to transport automatic and continuous information with high precision from ship to ship or ship to shore. It should be used in collision avoidance and as an information supply. The permanent information flow is guaranteed in contrast to radar dates, which can be impaired by natural obstacles like islands, sea clutter, rain. This is a fundamental advantage of AIS. Using AIS on a transit lane could contribute enormously to traffic safety. AIS allows for a clear identification of the traffic participants among themselves and at shore by sending the name of the ship, its type and cargo. Exact position and navigation dates are used for an enhanced traffic situation display. AIS is an aboard transponder system which works by means of the broadcast procedure. Elementary ship based information ([// 7]) is transported to the equipped VTS stations and to the participating ships inside the VHF range.

AIS benefits are [// 8, // 9]:

  • For the first time ships will be able to cooperate interdependently; this telematic interfacing is made possible by AIS equipment.
  • Ship to ship cooperation allows the automatic coordination of the traffic flow.
  • The coordination of vessel traffic generally includes an increase in efficiency and safety in comparison to the traditional way of shipping which has become more inaccurate in view of the expanding number of vessels.
  • AIS protocols include a large amount of essential information for the analysis of traffic flow.

2 Starting situation for the expanding of traffic safety regulations

Up to now many route counselling regulations exist for the Baltic Sea Traffic authorized by IMO. Between the singular traffic routes the ship masters themselves have the choice of the routes. A continuous route guidance for deep draught ships (tankers) through the whole Baltic Sea does not exist. But by this way ship safety and the reduction of environmental hazards can be increased enormously. For instance it would be possible to increase the safety of a deep draught tanker if the ship master would take a recommended route right from leaving a petrol harbour throughout the whole Baltic Sea. The observation and possible counselling for this process would also be easier. Facts for developing traffic safety measurement:
  1. Seagoing traffic is going to expand in the next couple years.
  2. The cross tonnage of Baltic passing Vessels has been increasing recently and will continue to grow.
  3. Baltic traffic is largely dominated by combined car ferries and deep draught tankers and bulkers.
  4. Traffic density has also steadily been increasing. Navigational space will be reduced by wind offshore parks in coming years.
  5. Traffic Separation Schemes and deep water ways have been partially installed.
  6. The entire Baltic Sea area is now covered by DGPS stations.
  7. AIS repeater stations are currently under construction.
  8. VTS stations are presently being placed in traffic bottlenecks.
  9. Traffic observation by radar is currently being completed as far as required.
  10. Special tug boats are going to be added to coastal equipment implemented in the case of a tanker catastrophe.

Assumptions for navigation safety enhancing effects due to further AIS based researches:

  1. Transit traffic should flow in traffic lanes which could be supported by navigational assistance.
  2. Transit traffic should be organized in such a manner that a potential collision risk between ferries and tankers is obsolete.
  3. Conflicts between users of transit routes and crossing traffic must be minimized.
  4. The users of traffic routes should receive support in grounding avoidance.
  5. Installation of traffic routes should be carried out effectively and in accordance with the latest technology.

2.1 Historical AIS Data

The determination of a traffic ways, sailing routes for merchant vessels across the Baltic Sea via AIS has been available in a more and representative value since August 2003. For statistical purposes a data collection over a long time period is necessary. First consistency checks of the raw AIS data material allows the data to be filtered in an algorithm.

AIS Data Gathering:

  • Data collection over a long period
  • Post-Processing of the historical AIS data
    • Plausibility check
    • Check of consistence (filtered out gaps, errors, time stamp inconsistencies)
  • Filtering of NMEA-Messages
    • Elimination of status and administration messages
    • Delete own ship data
    • Delete data without latitude, longitude, speed-over-ground (SOG) or course-over-ground (COG)
  • Processing of AIS data from other vessels only.

2.2 Post processing handlings

In post processing handlings the AIS data sets can filter out different data strings containing special criteria (Table 2). The following effects and representation can be achieved by selection of various parameters:

Filtering ParametersEffects and Results
Latitude, Longitude (Figure 4)AIS Traffic coverage
Latitude, Longitude, COG (Figure 5)Traffic directions, opposite traffic areas and crossing traffic areas
Latitude, Longitude, COG, Ship's typeMain traffic routes of different ship's types (Tanker Routes, Ferry Routes…)
Latitude, Longitude, COG, Navigational Status / Draught (Figure 6)Traffic routes of dedicated vessels, for example deep draught vessels /constrained by her draught
Latitude, Longitude, SOGHigh speed traffic areas

Table 2: Data processing handling after different filtering parameters

Figure 4: Results of AIS data processing handling with plotted out AIS positions

Figure 5: Results of AIS data processing handling concerning position and COG information:
Traffic density and traffic directions in the western Baltic

Figure 6: Results of AIS data processing handling to filtered out all vessels with dedicated
Navigational Status or Draught

2.2.1 Filtering Parameters: Latitude, Longitude and COG

A first AIS data selection in respect to course over ground (COG) was given by the separation of the west going (red lanes) and east going (green lanes) traffic (Figure 5). The true traffic zones were displayed in ECDIS-environment. The vessel routes cover an around 20NM wide lane. A right hand traffic was depicted also in open waters. The main traffic direction stream of shipping in the Baltic Sea direction and vice versa is detectable. In the predominantly plots a right hand orientated traffic flow exists. Areas with opposite traffic directions were detected (black lanes). The archived level of data analysis allows further ships routing measurements in conformity with habitualness of current ship's traffic.

2.2.2 Filtering Parameters: Latitude, Longitude, COG and Ship Type "Tanker"

The analysis gives an overview about deep draught vessel and tanker passages. No differences between tanker routes and other shipping routes were detectable. The cross distances between opposite tanker plots are available. The tankers navigate right hand orientated in the above mentioned area. Opposite direction tanker traffic take place leaving or reaching the Kadetrenden easterly.

2.2.3 Filtering Parameters: Latitude, Longitude, COG and a dedicated Navigational Status or dedicated Draught

Information in respect to regional separation of opposite traffic flow of tankers and deep draught vessels were depicted (Figure 6). A selection of ships constrained by her draught or tankers about a long distance in the Baltic Sea was possible to separate. Future tanker track recommendations can be given in harmony with the real traffic flow in the Baltic. A traffic concentration on a relatively small lane (5NM) was detected for tankers with a draught deeper 10 meters between the Kadetrenden and the Bornholms Gatt.

2.3 Traffic Profile on various Places

To generate a traffic profile on various places is an other approach for using historical AIS data. A fictive observation line orthogonal to the expected vessel traffic (gate) allows different kind of traffic account in an interested navigational space. In an example a gate was placed easterly of the Kadetrenden (Figure 7) with a length of thirteen point four Nautical Miles. The dimension of gates orientates on traffic stream. The gates were separated in ports defined breath (e.g. 0.5NM) to count ship's passages by crossing the gate line. As a raster placed number of gates allows a determination of frequencies and lateral profiles of real traffic. After definition of gates it is possible to process and to evaluate gate data in a defined time period concerning different AIS -parameters. The results are shown as follows:

Figure 7: Gate definition easterly of the Kadetrenden

The AIS data related to the gate was processed concerning COG for a defined time frame. The diagram Figure 8 shows the lateral distribution of the west-going and east-going traffic. Statements to the absolute number of ships in a certain port position and to the lateral separation of traffic are possible.

Figure 8: Lateral Traffic distribution concerning COG on the gate
(Time period 364 hours with 774 Passages)

The Figure 9 shows an other evaluation of the same gate. How much traffic activities in a short time period between 24 to one hour is very interesting to see at the gate. This example shows 54 ship passages in 24 hours that means approximately two ships pass the gate line in one hour. In data analysis of many hundred hours the hourly average traffic flow of two ships could be confirmed on this selected gate.

Figure 9: Lateral Traffic distribution concerning COG on the gate in a short time period of 24 hours (54 Passages)

A other approach is the use of AIS data as statistical background for modelling different traffic scenarios. At the Shipping Institute Warnemünde a software tool (Traffic Lane Evaluation Tool) was developed for investigating recorded historical AIS Data in more detail. Future intended traffic regulation measurement or the installation of new Traffic Separation Schemes (T.S.S.) could be checked in advance. Long term AIS records can be used for statistical issues in focused shipping areas. Proposed traffic lanes or crossing points (precautionary areas) will be used in simulation runs. The simulation scenarios contains the statistical traffic data exactly for routes or lanes which was proposed. The reachable effects by using the Traffic Lane Evaluation Tool are:

  • The current traffic situation and its changing due to the installation or modifying of proposed traffic regulation measurements are comparable.
  • The enhancement of navigational safety by new traffic regulations can be proofed in advance by simulation procedures.
  • Expected future development in ships traffic, passages or sailing directions can considered in planning new lanes, recommended tracks or T.S.S.

An example of the current situation in distribution of ships high density traffic areas is given in Figure 10. To specify this areas defining risk areas or high risk areas is reachable by historical A IS data analysis.

Figure 10: Current situation in distribution of ships high density areas

3 Conclusions and Outlook

Routes have been traditionally developed in the various traffic zones or are be given by the traffic safety systems. Satellite based orientation and navigation are be coming more and more essential key methods for a traffic safety infrastructure for many traffic zones of the shipping industry.
Many comprehensive possibilities for a modern traffic management system and for the coast safety result from knowing the exact position and using of an automatic communication.
The European Union decided to develop a European and civilly used satellite navigation system (GALILEO, [// 11]). Now a new generation of various services can be created.
The world-wide installation of AIS till 2004 is an essential aspect for enhancing navigational safety in world wide maritime shipping.

Practically procedures we have to consider parallel to developments in last technologies. In case of good visibility and open seas, the navigation is currently realized by one person alone. The navigational demands of the crew increase in case of a restricted water or bad visibility, so that 2 or 3 persons have to be on the ship's bridge. In case of approaching a port, narrow passages and unknown waters increase the navigational demands are even more. Then an experienced pilot, radar piloting or service personal of a shore based radar station support the crew during manoeuvres. So the number of the involved navigational staff is expanded to 4 or 5 persons.

What happens in vessel traffic stations (VTS)? How does it look like with ECDIS, overseas piloting, navigational space? Will it be much narrower? Will it get shore based support?

In front of this background the maritime shipping has come into a situation which is worldwidely characterized by traffic stations with working conditions according to maritime shipping standards of 10 years ago. By using automatic track systems in connection with ECDIS and high performance positioning systems, there is a contradiction between the support by traffic safety systems and the technical equipment standards of the user of these safety systems. This contradiction is intensifying by the installation of AIS, the development of three-dimensional ECDIS and the following installation of GALILEO aboard the ships.
On the other hand, some existing ships are equipped on a very low level. There is no updated sea chart or the radar system does not work or something else.
Today and in the future the aboard information of complicated regions and their current conditions is still essential for maritime shipping. The reception and realisation of this knowledge is currently executed by additional staff on various levels.
The ship safety is guaranteed by increasing the men power performance for traffic safety support, if the navigation gets more complicate.
This current kind of service has a critical factor of safety and a cost aspect. The restricted capacity of the channel for the information reception by the ship master is used by the aboard systems. Visual and numerical information are dominant. The information of the traffic safety system or of the shipside pilot will be transmitted in a verbalised form. An additional translation performance for getting a local and complete image of the ship state is required by the ship master.

It can be note, that there is no adequate level of shore based supporting compares to the ship side equipment currently. This is also a consequence of the fact, that the ship's identification is mainly achieved by radar dates in connection with vocal communication. There is not always a safe and clear identification of the traffic participants because of falsified radar information due to shadows, sea clutter or else. Only by using AIS technology the improvement of identification is possible.
But the equipment constraint does not exist for all ships participating in vessel traffic. That is why the generated traffic situation display can be different from the real traffic flow. On the other side, the existing traffic safety system is only able to monitor and observe the traffic flow and includes low level assistance functions.

The role of the cost-line is shown by the increase of cost pressure in maritime shipping. A reduced ship crew and the one-person-bridge have come to stay. The expansion of men power is realised solely by using external staff like pilots.
But these additional performances also produce costs. The density of traffic and the consumption of time and petrol increase very much during the boarding of the pilot (ship stopping, ship powering).
After that, the yearly transportation cost of the pilot for getting by a pilot boot or helicopter is increasing, because the operational cost of the vehicles and installations is expanding, too. The cost of the pilots themselves is the next cost factor, which every ship owner has to pay.
But in situations of fog, ice drifting and bad weather conditions the knowledge and experiences of the pilot are essential for navigation and the ship's safety. But even in bad weather conditions it can be very dangerous and time consuming to get the pilot. Maybe the pilot does not appear. Thus, the costs will be even more.

A shore based traffic support infrastructure exists for the navigational areas with a high traffic density. The staff and operating costs for using the installations make out the cost of this monitoring and identification service. Assistance functions for the maritime shipping exist on a low level. In view of a cost minimization taking into account the ongoing ship safety and coast protection, there an urgent need of investigation. The investigation results, based on a high level of traffic safety, could also be evaluated for national and international usage.

4 Literature

// 1Baltic Chambers of Commerce Association (2001):
// 2Transportation of oils in the Baltic Sea Area 1995: SSPA Maritime Consulting AB Report 7596-1
// 3Assmann, T. (2000): Das russische Hinterland als Schlüssel zur Entwicklung baltischer Transithäfen. In: Schiff & Hafen. Heft 7/2000. p. 11 - 12.
// 4Breitzmann, K.-H. (ed.) (1997): Wirtschaft und Verkehr im Ostseeraum.
// 5MARPOL - International Convention for the Prevention of Pollution from Ships, 1973,
// 6Declaration on the Safety of Navigation and Emergency Capacity in the Baltic Sea Area", HELCOM Copenhagen Declaration, 2001, Helsinki Commission 17
// 7Technical characteristics for a universal shipbore automatic identification system using time division multiple access in the VHF maritime mobile band: Recommendation ITU-R M.1371-1
// 8Müller, R.: The transponder are coming. HANSA Heft 9/1997 S.14-21 Hamburg
// 9Die Schiffahrt als kooperatives System: Müller, R., HANSA Heft 7/96
// 10Koordinierungen in der Schiffahrt in einem Transponder basierten kooperativen System; Müller, R. in DHZ: Deutsche Hydrographische Zeitschrift 48; 1997
// 11Galileo A new GNSS designed with and for the benefit of all kind of civil users, European Commission, DG Energy and Transport, ION September 2001