93
1 INTRODUCTION
Theincreasingtrafficintensityalongwithvesselsizes
and higher speeds continue to draw researchers
interestandefforttotheproblemsofmarineshipping
safety andeffectiveness.Thisrefers,inparticular,to
areaswherevesseltrafficisdense.Oneofthewaysto
reducethenumberofaccidentsintheseareas is the
i
ntroduction of additional principles of traffic
management. An example of these are traffic
separation schemes (TSSs), regulating vessel traffic.
TSSsarecomposedoftrafficlanes,eachindicatingthe
directionsoftrafficflowswithintheTSS‐coveredarea.
The increased, organized vessel traffic makes it
difficulttoa
pplytheclosestpointofapproach(CPA),
one of the fundamental criteriaof navigational
safety. The shipʹs domain may be an alternative for
theCPAcriterion.Theshipdomainisdefined asan
areathatthenavigatorshouldmaintainfreeofother
vessels (Fuji & Tanaka 1971). The most frequent
ly
reporteddomainsaretwo‐dimensionaldomainswith
defined shape and size. It is possible to include the
third dimension‐domain depth. Its introduction
permits to take account of safe distances to
underwater dangers. A number of factors affecting
thesizeandshapeofthedomaincausesdifficultiesin
itsdetermination.Thesefact
orscomprisethetypeof
area (open, restricted), types and sizes of vessels,
hydro‐meteorological conditions. The human factor
should also be taken into account. The relevant
research found in the literature deals with both
restrictedandopenareas.TSSsarespecificareasdue
to intensive vessel traffic. For thi
s reason they are
classified as restricted areas, even if they often lack
physicalboundariesofthemanoeuvringarea relating
todepth,lengthorwidth.Ananalysisofthecriteria
for assessing navigational situations in these areas
seemstobe essentialdue tothat specificity.Forthis
reasonTSSsmayrequirecrit
eriasomewhat different
from those used in both open and restricted areas
wherenavigation is restricted by physically
available manoeuvring area. This concerns traffic
lanesaswellasprecautionaryareasinTSS.
Ship Domain as a Safety Criterion in a Precautionary
Area of Traffic Separation Scheme
Z.Pietrzykowski&J.Magaj
M
aritimeUniversityofSzczecin,Szczecin,Poland
ABSTRACT: The ship domain is one of the criteria for navigational safety assessment. It is particularly
importantinrestrictedareaswithhighintensitytraffic,wherethecriteriaofclosestpointofapproach(CPA)
andtimetoCPAaredifficulttoapply.ThisresearchcontinuestoexamineshipdomainsinTrafficSeparation
Schemes (TSS). We have analyzed p
recautionary areas established within TSSs in connection with changed
arrangementsofvesseltraffic.Besides,wehavedefinedshipdomainsinaprecautionaryareaofa specificTSS,
andcomparedthemtodomainsofvesselsproceedingalongtrafficlanes.
http://www.transnav.eu
the International Journal
on Marine Navigation
and Safety of Sea Transportation
Volume 11
Number 1
March 2017
DOI:10.12716/1001.11.01.10
94
2 TRAFFICSEPARATIONSCHEMES
2.1 TSScharacteristics
Trafficseparationschemesareestablishedtoenhance
the safety of navigation by introducing specific
principles of vessel traffic organization in order to
keepitundercontrol.InaccordancewiththeSOLAS
Convention SOLAS (SOLAS 1974),, the IMO is the
only international institution that
issues guidelines
andrulesforTSSsystemsattheinternationallevel.
Principles for the establishment and organisation
of TSS have been laid down in the IMO Resolution
ʺGeneral provisions on ships routingʹ(IMO 1985)..
These systems, by separating the flows of vessel
traffic,vitallyincreasethelevelofsafetyof
lifeatsea,
navigational safety and effectiveness, and
environment protection. The designated traffic lanes
encompassone‐wayvesseltrafficwithinthescheme.
TSSareasaregovernedbyIMOregulations.Rule10
of the International Regulations for Preventing
Collisions at Sea (COLREGs 1972) defines the
behavior of ships navigating in these
systems. This,
however,doesnotrelieveshipsfromcomplyingwith
the other rules of the Collision Regulations. An
example of a traffic separation scheme is shown in
Figure 1a. Traffic lanes are often defined by
conventionalboundaries.Thismeansthatabreachof
the lane boundary does not lead to a
direct risk of
grounding or collision with a shore structure. In
accordancewith the definition, the traffic laneisʹan
areawithindefinedlimitsinwhichone‐waytrafficis
established(IMO1985).
a)
b)
Figure1.Trafficseparation Scheme: a)separationoftraffic
at a crossing; b) precautionary area at a junction, with
recommendeddirectionsoftrafficflow(IMO1985)
Some TSS areas comprise precautionary areas
(Figure1b).Precautionaryareaisdefinedasʹarouting
measure comprising an area within defined limits
where ships must navigate with particular caution
andwithinwhichthedirectionoftrafficflowmaybe
recommendedʹ(IMO1985).
Precautionaryareasmayalsobeintroducedforthe
termination
ofanysingleroute.
Traffic separation schemes are established
throughouttheworld.OntheBalticSeatheseinclude
TSSAdlergrund,TSSInBornholmsgate,TSSNorthof
Rügen, TSS Słupska Bank, TSS Gdansk Bay
(Pietrzykowskietal.2015).
2.2 TSSBornholmsgat
TSS Bornholmsgat is one of the traffic separation
schemes
ontheBalticSea(IMO2005).Densetrafficof
different vessel types and sizes is observed, moving
from the Danish Straits and the Kiel Canal to the
eastern Baltic Sea and in opposite directions (Figure
2a).Withinthatareatherearesixtrafficlanesandone
precautionaryarea.
The number of
vessels that transited the area in
2011 was over 64000(HELCOM 2011). Figure 2b
illustrates trails of vessels registered in the AIS sys‐
temduringfourdaysofJune2011.
a)
b)
Figure2. TSS Bornholmgate: a) traffic lanes and
precautionary area; b) vessel tracks recorded in the AIS
systemwithinfourdaysofJune2011