The probabilistic ships domain study and incidents model on the route between Swinoujscie and Ystad for Ro-Pax ferries.

Transcription

1 The probabilistic ships domain study and incidents model on the route between Swinoujscie and Ystad for Ro-Pax ferries. MSc Krzysztof Marcjan (I) Professor Lucjan Gucma (II) (I)(II)Maritime University of Szczecin, Wały Chrobrego 1-2, Szczecin, Poland (I) Abstract Swinoujscie Ferry Terminal is the largest and most modern of the four Polish ferry terminals and is also one of the most modern ferry terminal on the Baltic Sea. In recent years, the largest number of ferries that departured from Swinoujscie proceeded in the direction of the Swedish port of Ystad. There are three routes intersections with heavy ships traffic crossing the examined route between Swinoujscie and Ystad of ships proceeding from the direction of Arkona in the direction of Gdansk, with direction Arkona -the North of Bornholm and from the Danish Straits towards the North of Bornholm. The density of vessel traffic in areas of route intersections may be associated with the decrease in the distance between passing vessels which is particularly important because of the large number of ferries departing from Swinoujscie to Ystad. This paper aims to analyze the route from Swinoujscie to Ystad in terms of the passing distances between passenger vessels and other ships. The analysis is based on a probabilistic ships domain designated on the route and the amount of incidents which are understood as an close encounter between two vessels, during which the designated ships probabilistic domain is exceeded. Keywords: navigational safety, ship domain, incident analysis, navigational risk management. INTRODUCTION The Baltic Sea is closed water area in which an accident may have serious environmental and financial consequences. Due to the large number of narrow straits and shallow waters the Baltic Sea has always been a difficult area for ships to navigate. It is an area of heavy maritime traffic which has grown remarkably during recent decades increasing risk of vessel accidents [5]. Despite of huge investments in the protection in form of improved technical equipment and the training of navigators, on the Baltic Sea the lack of downward trend in the number of navigation accidents is observed which is quite alarming. Ship collisions are now about 40% of all accidents at sea. Their number is closely correlated with the limitations due to the available maneuvering area, vessel traffic density, the number of ships routes intersection and navigational conditions. Most vessels accidents in the Baltic Sea occur along the coasts of Sweden and Denmark, the Gulf of Finland and in particular in the Danish straits. This paper attempts to assess the safety of navigation on the basis of the analysis of navigational incidents (close encounters) on the route between Swinoujscie and Ystad. Due to the fact that on the route movement of passenger vessels is mainly observed, an analysis of ship passing distances during an encounter with a passenger vessel was

2 additionally carried out. For the purposes of this work, each encounter during which ship probabilistic domain in a given sector is exceeded, is called a navigational incident. Based on the AIS monitoring data within the period of one month (July 2011) two probabilistic domains were designated, one for all vessels in the study area, second domain designated for passenger ships. The location of the largest number of navigational incidents is called potentially dangerous for navigation. The intended result of the study is to increase the awareness of the navigators of the potentially dangerous places for navigation which shall result in keeping a sharp lookout in those places which finally will result in the reduction in the number of accidents on each route analyzed in such a manner. 1. THE STUDY AREA The study area is covering the route between the Port of Świnoujście and the Port of Ystad (Figure 1) starting from latitude 55 19,24 N longitude ,43 E and ends at latitude 54 08,79 N, longitude ,63 E. Vessels proceeding on the chosen route are mainly ferries which belong to one of these operators Unity Line or Polferries. The main objective of the work is to analyze the safety of ships in an open sea area, the study did not include approaches to the ports. Figure 1 The route between The Port of Ystad and The Port of Swinoujscie, ship traffic intersections. Ystad The study area is shown in Figure 1 by red line, along the route between Ystad and Swinoujscie. There are three main intersections numbered in the figure, with heavy vessel traffic crossing the examined route from the direction of Arkona in the direction of Gdansk, with direction Arkona the North of Bornholm and from the Danish Straits towards the North of Bornholm. It is assumed that the density of vessel traffic in areas

3 of route intersections is associated with the decrease in the distance between passing vessels. It is particularly important because of the large number of ferries proceeding between Swinoujscie and Ystad FERRY TRANSPORTATION IN THE BALTIC SEA In the years from 2000 up to the recession in 2009 Baltic maritime transport was growing very strongly. Container shipping had the highest growth rates of 14 percent, followed by ro/ro goods and liquid cargoes with growth rates of 7 percent. Cargo handling of ports from 2000 to 2007 showed an overall annual growth rate of 4,7 percent. Baltic ferry transportation in 2011, was still under the influence of unfavorable market environment. It is true that there has been the improvement in the economic situation of the Baltic states, which was reflected in the trade and thus in a trade flows, but sill most of the services did not reach pre-crisis levels. Also, passenger traffic has not increased in comparison with the previous year. Table 1. Ferry transportation statistics for two Polish operators (Polferries and Unity Line). Operator Year Passengers Passenger vehicles Trucks General In Poland Świnoujście Ystad Polferries Świnoujście Ystad Unity Line Świnoujście Trelleborg Unity Line RO-PAX FERRIES ON THE ROUTE BETWEEN SWINOUJSCIE AND YSTAD Ystad is a city located in the South of Sweden and also is one of the ports located on the coast of the Baltic Sea. The city was more strongly associated with Poland since 1990, when it became the city partner with Swinouscie. The port of Ystad (55 26'N, 13 50'E) with ferry terminal from which ferries to Ronne and to Swinoujscie leave. It is therefore an essential part of the transport infrastructure in Sweden, because along with functioning there sea crossing creates a very important central European transport system. Is connecting through the marine and terrestrial connections through Scandinavia with Central Europe and Southern Europe, and the Baltic States with Western Europe. Worth of mentioning is that the ferry connection Swinoujscie-Ystad has existed since It has since been rapidly developed, and the owners of the Polish introduced newer ferries on the line. The port of Swinoujscie (53 55 N, E) is a Polish seaport at the Baltic Sea located at the Swina strait, on two islands Wolin and Usedom. The port has passenger terminal, it is the youngest and dynamically developing Polish port at the estuary of Swina river to the Baltic Sea. The Port of Swinoujscie and the Port of Szczecin are managed by one authority and they are one of the largest port complexes at the Baltic Sea. Both ports are located in the top twenty among ro-ro/ferry ports in the Baltic Sea because of the number of transported freight units[1]. There are two ferry operators between the port of Swinoujscie and the port of Ystad. One of them is Unity Line and the other Polferries. Unity Line is a Polish company that operates RoRo and

4 train ferry services between Swinoujscie and the Swedish ports of Ystad and Trelleborg. Unity Line operates a fleet of seven ferries: between Swinoujscie and Ystad - MF Skania, MF Polonia, MF Jan Śniadecki, MF Kopernik. Between Świnoujście and Trelleborg- MF Galileusz, MF Gryf and MF Wolin Both these routes overlap in a small part. For the purpose of this work, the first four will be presented closer: MF Skania (LOA = 173,5m / Breadth = 24m / Passenger No. 1400) MF Polonia (LOA = 169,9m / Breadth = 28m / Passenger No. 1000) MF Jan Śnidecki (LOA = 155,1m / Breadth = 21,58m / Passenger No. 67) MF Kopernik (LOA = 125,61m / Breadth = 17,02m / Passenger No. 360) Under the operating name Polferries, the company runs ferry routes across the Baltic Sea between Poland and Scandinavia. Two of them operates between Swinoujscie and Ystad: MF Wawel (LOA = 163,96m / Breadth = 27,63m / Passenger No. = 1000) MF Baltivia (LOA = 147m / Breadth = 24m / Passenger No. = 250) 1.3. ACCIDENTS OF PASSENGER VESSELS ON THE BALTIC SEA. In the south western part of the Baltic Sea in years: there have been 23 cases of collisions between vessels, involving a passenger vessels [6]. Most of them occurred in the area of approaches to ports, where available maneuvering area is restricted (Figure 2). Figure 2. Passenger vessels collisions location between the year 2004 and own made based on the Helcom data.

5 In authors previous work [7] three of those accidents involving passenger ships were chosen, that took place between or close to the traffic separation schemes on heavy traffic routes: In position 54 24,0 N and 11 55,9 E, date in eastern entrance to the TSS South of Gedser. In position 54 30,0 N and 12 13,0 E, date in the TSS South of Gedser. In position 55 18,0 N and 12 40,0 E, date , in TSS in TSS off Falsterbo. Each of the locations were analyzed for incidents of navigation. The study used a factor of amount of incidents per 1 accident in order to assess the safety of navigation in TSS areas, where the accidents occurred. On the route Swinoujscie Ystad there were 4 minor collisions between ships involving passenger ships: On 27 th of March 2006 in position N E in the Swedish port of Ystad there was a harmless collision between the passenger vessel Villum Clausen" ferry and belonging to Polish operator Unity Line ferry Gryf. On 2 nd of August 2007 in position N E MF Galileusz had a minor collision with a tanker Bukowiec. 26 th of October in position N E MF Galileusz had a minor collision with a passenger vessel Nils Dacke. On 17 th of Jun 2011 in position N E a Unity Line s MF Gryf an hour after departure from Swinoujscie had a minor collision with a container vessel proceeding from Gdansk to Szczecin. For the purposes of this study it should be noted that in the past 10 Years on the waters of the south western Baltic Sea collision accidents involving passenger vessels occurred and despite the fact that these incidents took place in restricted areas or adjacent to their borders, there is a real risk of accidents on the open waters, particularly where intersect shipping lanes marked on Figure RESEARCH DESCRIPTION The first stage covers a wide range of activities, primarily selection and compilation of the relevant datasets. To perform substantive analysis large amounts of diverse riskrelated datasets are required, but the most important data are marine incidents. Similar studies are also carried out in other branches of transport [8]. The approach presented in this work of risk analysis in coastal areas consist of several steps such as: 1. Selecting waters with similar navigational characteristics and high-density traffic. 2. Hazard identification and Navigational incidents analysis in selected areas. 3. Construction of probabilistic domain for the three types of encounter situations between vessels subsequently analysis of their shape and size. 4. Risk analysis mostly on the basis of the incident statistics, comparison of a domain designated for all vessels with a domain designated on the basis of the encounter situations in which passenger vessels participated.

6 5. Designation of the areas with the highest number of navigational incidents on the route Swinoujscie Ystad, which hereinafter will be called potentially dangerous places. The reason for using incidents data for risk assessment is relatively small number of navigational accidents in such areas (few per year). This makes impossible to assess the risk by analyzing accidents only due to low statistical significance. The risk can be assessed on the basis of incidents to accident ratio which is established with use of presented incident model and historical data of accidents in the given areas. The concept of the ship domain for the first time was proposed by Japanese scientists [3]. A ship domain shall be understand as a certain area around the vessel which the navigator likes to keep clear of other fixed and movable objects. In order to construct the statistical domain around the ship, assumptions are used as described [4]. These involve searching for a range constituting a maximum distance over which most of the navigators passes other vessels while encounter on a defined relative bearing. As a navigational incident ("statistical incident") has been defined a meeting of two vessels with the distance less than average statistical ship domain border corresponding to a given encounter situation that occurred. Such concept is often defined by other researchers as close encounter. Navigational situation can be considered safe as long as any other vessel or navigational obstacle does not exceed the domains area. To determine ships domain shape, area around the vessel has been divided into 8 sectors (every 45 degrees starting from 0 degrees) due to relative bearing at the approaching vessel (Figure 3). Figure 3. The concept of ship s probabilistic domain [4]. The border a probabilistic domain is assessed by the distribution of vessels passing distance. It was assumed that the distribution of passing distances achieve a maximum around the point which is the distance over which most navigators will proceed clear of other vessels.

7 2.1. NAVIGATIONAL INCIDENTS ANALYSIS Figure 4. Probabilistic domain for all ships. Overtaking 0.55 Crossing Head-on N0 DATA N0 DATA Table 1. The statistics of probabilistic domain for all vessels. Encounter Number of Total length of Number of encounters domains boundaries incidents Crossing NM 59 Overtaking NM 55 Head-on NM (5 sectors) 33 In Figure 4 and Table 2 the numerical information about the vessel encounters in the study area are presented. On the basis of the shapes of vessels domains are determined and the amount of incidents of navigation, i.e. meetings between the vessels for which the limit was exceeded domain, are calculated. The shape of the domain for crossing situations is the closest to circles, due to the fact that the length of the boundaries are comparable to each other. This shows that either vessels while crossing ahead of the other ship (generally action by stand-on vessel), but also while crossing astern (generally action by give way vessel) kept the same passing distance. Most of the crossing encounters took place in sector VII ( ) with a total number of 270 encounters and 20 navigational incidents. Most of the overtaking encounters (78%) took place in sectors forward of the beam I, II and VII, VIII ( ) with a number of 40 navigational incidents. The shape of the domain for overtaking situation is narrowed on the beams because that is where the CPA are the smallest. For vessel on opposite directions the majority of CPA s occurred abeam, from which over 80 percent on the port side. Astounding is the number of 48 CPA s on the starboard side, in particular because COLLREGS Rule 14 about Head-on situation indicates that: (a). When two power-driven vessels are meeting on reciprocal or nearly reciprocal courses so as to involve risk of collision each shall alter her course to starboard so that each shall pass on the port side of the other.

8 Figure 5. Probabilistic domain for passenger vessels. Overtaking Crossing Head-on N0 DATA N0 DATA Table 3. The statistics of probabilistic domain for passenger vessels. Encounter Number of Total length of No of encounters domains boundaries incidents Crossing NM 48 Overtaking NM 25 Head-on NM (5 sectors) 27 The number of encounters, where passenger vessels were taking part in is about 60 percent of all encounters in the study area. Probabilistic Domains designated for passenger ships are larger than those designated for all vessels. It means that the distance at which passenger ships passes each vessel are larger than those on which other vessels pass each other. The largest difference occurs for overtaking where the total length of the domain boundaries differs by 1.5 NM, it may be associated with a high-speed of passenger ships which generally are the overtaking vessels. Domains associated with crossing encounters differ slightly because of the 1 percent.

9 Figure 6. Navigational incidents in the study area, the location of navigational incidents for three encounter situations. Figure 6. indicates the locations where the incidents occurred, additionally they are divided by colors due to the type of encounter. Head-on incidents occurred at the beginning and end of the route, near the ports, where vessels traffic flow is narrowed, and therefore the passing distances for vessels proceeding in opposite direction are reduced. Navigational incidents while crossing situation occurred primarily at the intersections of routes, especially where there is heavy traffic (1,2,3). The incidents during overtaking occurred mainly at the intersection of routes and at the approaches to ports N N and E E N N and E E N N and E E These coordinates define the places of the concentrated number of incidents that are identified as potentially dangerous for navigation.

10 3. CONCLUSIONS The article presents the results of the analysis of navigational incidents on the route between the Polish port of Swinoujscie and the Swedish port of Ystad, research period Incidents of navigation determined on the basis of the probabilistic domain around the ship, where by navigational incident each exceeding of domain boundaries was understood. In addition, due to heavy traffic of passenger ships on the route a probabilistic domain was designated also for ferries. An analysis of incidents, both in terms of their number and locations of occurrence was performed. For places potentially dangerous to navigate were considered those in the number of navigational incidents was one of the highest. For the examined route places with an increased risk of collision are route intersections. Based on vessel domains shapes it should be noted that the passenger ships CPA s are at greater distances than for the other vessels. In the examined area three locations with a high density of incidents were determined which are places potentially dangerous for navigation. The total length of the examined section of the route between the ports is 84 NM, in this section three locations considered as potentially dangerous to navigate were designated. This shows that the Baltic is a sea of high vessel traffic density both at the intersection of ships routes and the restricted water areas at ports approaches. Navigators approaching these locations should be taking into account the COLREGS regulations, especially speaking of the proper observation. Every vessel on the Baltic Sea shall at all times maintain a proper look-out by sight and hearing as well as by all available means appropriate in the prevailing circumstances and conditions so as to make a full appraisal of the situation and of the risk of collision. REFERENCES [1] "Baltic ro-ro/ferry yearbook 2012" edited by Baltic Transport Journal [2] COLREG (Convention on the Regulation for the Preventing Collisions at Sea), London, 20 October [3] Fujii Y. Tanaka K., Traffic Capacity. Journal of Navigation. 24 ( ). [4] Gucma L., Marcjan K., Probabilistic model of minimal passing distances of vessels navigating in Polish coastal waters. PSAM11&ESREL. [5] HELCOM (Helsinki Commission), Maritime Activities in the Baltic Sea An integrated thematic assessment on maritime activities and response to pollution at sea in the Baltic Sea Region. Balt. Sea Environ. Proc. No [6] HELCOM, Report on shipping accidents in the Baltic Sea area during. [7] Marcjan K. Gucma L., Gucma M., Different navigational areas for nautical incydent model development., Materiały konferencyjne IWNTM 2013 international workshop on Nautical Traffic Models 2013, Delft, Holand [8] Nazeri Z., Donohue G., Sherry L. Analyzing Relationships Between Aircraft Accidents and Incidents: A Data Mining Approach. Proceedings International Conference on Research in Air Transportation (ICRAT-2008), Fairfax, VA, 2008 Feb. [9] Praca zbiorowa, red. Ryszard Krystek Zintegrowany System Bezpieczeństwa Transportu. ZEUS, Politechnika Gdańska 2009 r.