483
1 INTRODUCTION
Constantly growing global seaborne containerised
trade leads to increasing flows of containers in
seaports.Increasingnumberofhandledcontainersis
visible at global, regional and national level.
Generally speaking, this increasing trend is
depended on the economic development, for which
themainindicatorisGrossDomesticProduct(GDP).
On 22 March2008(9:30 pm), a Ukrainian vessel
Neftegaz‐67 collided against a Chinese bulk carrier
Ya
o Hai in Hong Kong, and 18 seamen were lost.
Therewillbeaneedtoestablishanextgenerationof
vessel traffic service in an extreme busy port like
HongKong.In2013,HongKongportreceivedover
500arrivalsperday.
Marine t
raffic has its special features and is
fundamentally different from highway, air and
pedestriantraffic.Althoughtrafficsciencehasbeena
prolificfieldforhighway,airandpedestriantraffic,
the existing understanding on traffic is not very
helpful to marine t
raffic. The assumption of
homogeneity in many traffic models is significantly
violatedin marine traffic. The manoeuvrability of a
shipislargelyrelatedtoitslength.Theshiplengths
range from a few metres to over 300 metres, while
thehighwayvehicle lengths are limitedtoabout20
metres.Therefore,inma
rinetraffic,heterogeneityof
vessels clearly exists due to the varying ship
manoeuvrability.
Marine traffic management in congested
waterways may not be a new issue. The first radar
based VTC was introduced at the port of Douglas
and Liverpool in 1948. The first guideline of vessel
trafficservices(VTS)wasint
ernationallyadoptedin
1985.VTS areusedinports,harbours,coastalwaters,
and international straits (e.g. Dover Strait, and
Malacca Strait). The conflict among several ships
becomes clearly critical for either high density or
highlyheterogeneoustraffic.
We propose the concept of passage planning
system(PPS)foranextgenerationofVTS.Basedona
predeterminedset of crit
eria,thePPSwillacceptor
rejectthepassagerequestofvessels,beforeanumber
ofvesselsaregoingtocrossastrategiclocation,e.g.a
precautionary area. In this respect, the system
Pa
ssage Planning System in Ports: An Overview
T.L.Yip
TheHongKongPolytechnicUniversity,HongKong
ABSTRACT:Aconceptualmodelisproposedtomonitormarinetrafficthroughprecautionaryareas,whichcan
provideuswithasystematiccontrolofpassageplanninginports.Ononehand,vesseltrafficcontrolhasits
specialfeaturesandisfundamentallydifferentfromhighway,airandpedestriantrafficcontrol.Theexisting
trafficcontrol systems cannot be simply extended to vessel trafficcontrol without addressing marine traffic
features.Ontheotherhand,existingvessel trafficcontrolfocusesononeshiportwoshipsbutdoesnotaddress
theflowsofmarinetraffic.
http://www.transnav.eu
the International Journal
on Marine Navigation
and Safety of Sea Transportation
Volume 9
Number 4
December 2015
DOI:10.12716/1001.09.04.04
484
objectives mirror the human‐centred automation
models that are being developed by NASA for air
trafficcontrolapplications,so‐calledarrivalplanning
inairtrafficmanagement.ThePPSwillenhanceport
safety with the new navigation aids (e.g., ECDIS,
AIS).
In the pre‐implementation phase, a survey of
marinetraffic
instrategicareasshouldbeconducted
andthelocalfieldvalueofmarinetrafficproperties
should be determined. The PPS will be developed
basedonlocalunderstandingofmarinetrafficflow.
Moreover, the effectiveness of PPS as a proposed
elementofVTSwillbeassessed.
AnewconceptofPassage
PlanningSystem(PPS)
is proposed to enhance marine safety in strategic
areas.Whenashipmastermakesapassageplan,the
PPS of vessel traffic services (VTS) will advise the
ship master and pilots of potential vessel conflicts
and the PPS will approve or reject the proposed
passageplan.Inresponse
totherapidgrowthinport
traffic, efforts are being made to improve the
effectiveness and efficiency of VTS. Many countries
have invested heavily in VTS recently, since it has
been identified that ship accidents in ports have
become more serious. The financial, environmental
and social costs of incidents have
risen steeply in
recentyears.
Recently, a review of marine traffic risk in ports
concludedthat ship collision isthe major hazard in
port traffic. The existing traffic control concepts are
nothelpfultounderstandthemarinetraffic,whichis
different from highway, air and pedestrian traffic.
Existingvesseltrafficcontrol
focusesononeshipor
two ships but does not address the marine traffic
flowsincongestedports,providingourmotivationto
analyzetheregulationofmarinetrafficinbusyports.
Onereasonforthisisbecausemostmarineaccidents
involve one or two ships and the effect of
background
traffic level on marine accidents has
been ignored. Another reason is because ship
masters, rather than port authorities, are the ones
who are liable for any ship accidents and ship
handling appears to be the solution of collision‐
avoidance.
TheporttrafficinHongKongisthebusiestinthe
world.
ManyfairwaysinHongKonghavemorethan
2,000vesselmovementseveryday.Thesafetyandits
reliability are key issues of port developments. The
PPS is proposed to serve as a base for the next
generationofVTS.TheproposedPPSwillbeableto
enhanceportsafety.Many
ports,astheycontinueto
develop, will face similar traffic control issues
observedinHongKongporttodayinthenearfuture.
UnlikeexistingVTS,PPSisproactivewhichmay
cause significant change in port traffic risks. The
range of usage is highly innovative and complies
with all future international ship
safety and
environmentalrequirements.
2 LITERATUREREVIEW
Systematic studies of traffic flow have been
conducted for more than five decades. A basic
building block is the kinematic waves in traffic
(LighthillandWhitham1995;Richards1956),which
relatesthemacroscopictrafficflow,thetrafficspeed
and the traffic density. The
focus of the paper is
relatedtothemodelsofmarinetrafficflow(e.g.Yip,
2012).
Highway traffic has attracted considerable
attention for decades, for example, Gazis (2002).
Many highway traffic models assume the
homogenous vehicles are not applicable to marine
traffic. The heterogeneity is recently considered in
highway traffic research,
for example, Wong and
Wong (2002), Park et al. (2010). They however did
notconsiderasa wholewherethepassageplanning
canbeusedaspartofvesseltrafficcontrol.
In the air traffic control, Andersson et al. (2003)
proposed a novel optimization approach to analyse
collaborative airport arrival
planning. Ship
manoeuvring simulators are common in many
maritimecountriesandgenerallyoperateinthetime
domain. Their use ranges from the full mission
bridge simulator to PC‐based simulator. Existing
Traffic Alert and Collision Avoidance System
(knownasTACSII)isusedtodetectthealtitudesof
aircraft and then
resolve (altitude crossing)
encountersintheverticaldomain.Ifanencounteris
identified, TACS II will command one aircraft to
climbandtheothertodescend.However,shipscan
only manoeuvre horizontally and ships have
different manoeuvrability. Different from air traffic
control, VTS is only an advisory service for ships;
ship masters are responsible for a ship’s course,
speedandsafety.
Previous research may not be applicable to
marine traffic, as existing studies do not take into
consideration the differences between ships. Traffic
inpreviousmodelsisconsideredascontinuousflow
and not as single ships with their individual
characteristicsof
type,dimensionsandvelocity.Real
marinetrafficisnotconsistedofships of equal size
moving at equal velocity. The depth of water has
considerable influence on the rate of ship’s turn
which may be obtained at a given rudder angle. If
navigation in confined waters require large
alternationsof
course,theturningmanoeuvresmust
be commenced in due time with the knowledge of
how much room the ship needs to carry out the
alterationofcourse.Thiswill,especiallywithregard
tolargeships,necessitatepre‐conceivedplanning.
Ship‐ship collision models have been developed
on the basis of geometrical
distribution and/or
encounter‐to‐collision. Pedersen (2002; 2010),
Montewka et al. (2010), Debnath and Chin (2010),
TanandOtay(1999)developedgeometricalcollision
probability models that describe the geometrical
probability model of collision. Fowler and Sorgard
(2000)estimatedthecollisionbasedonencountersby
assumingthetrafficisindependent or
uncorrelated.
USCG (1999) found different types of encounters
have different relative significance, with crossings
morehazardousthanhead‐onencounters,whichare
in turn more risk prone than over‐takings. These
assumptions are applicable only when the traffic
densityislow.Inreality,shipsmaychangespeedor
directionsoas
toavoidpossiblecollisions(Merricket
al. 2002). The crossing traffic models cover only a
crossing situation of two vessels. In particular, in
485
heavily trafficked ports, like Hong Kong, three or
evenmore shipsmay approachanareaatthesame
time. In this kind of situation, a collision is more
difficult to avoid when the actions of several other
vesselsneedtobeobserved.
3 PASSAGEPLANNINGSYSTEM
A vessel traffic service (“VTS”) is a service
implementedbyacompetent aut
hority,designed to
improvesafetyandefficiencyofvesseltrafficandto
protecttheenvironment.Theserviceshouldhavethe
capability to interact with traffic and respond to
trafficsituationsdevelopingintheVTSarea.AVTS
should be in compliance with the requirements,
guidelines and recommendations promulga
ted by
the IMO and the IALA (IMO, 1985). A VTS
contributesto:
1 improvingthesafetyofVTSparticipatingvessels
with regard to incidents of collision and
grounding;
2 reducingtheriskofdamagetoVTSparticipating
vesselsandprinciplewaterways;
3 enhancingtheefficiencyoft
rafficmovementsfor
VTSparticipatingvessels;and
4 supportingportadministration.
AVTCservesthefollowingfunctions:
1 monitoring all vessels and their movements
withintheVTSwatersanditsapproachesusedby
vessels;
2 identifying all VTS participating vessels,
collecting and evaluating data on their
movements and interaction with other vessels,
andcoordinatingandregulatingtheirmovements
withinVTSwaters;
3 providingvesselt
rafficinformationandadviceto
VTSparticipatingvesselstoassisttheminmaking
navigationaldecisions;
4 maintaining and operating a database on the
particulars and movements of VTS participating
vessels;and
5 supporting allied activities, including
immigra
tion, customs and quarantine controls;
pilotage and tug services; entry and clearance
activities;portstatecontrol;collectionoffees;and
emergencyservices(e.g.pollutioncontrol,search
andrescue).
ThedevelopmentofPPScanbedividedintothree
phasesandninemajorsteps(Table1).
Table1.APassagePlanningSystem
_______________________________________________
Step ProcessActivities
_______________________________________________
Phase1–Pre‐ImplementationPhase
_______________________________________________
1 Operational Collectportuserrequirements;
requirements Seekregulatoryrequirements
2 Createteams Recruitteammembers
3 DefinePPS Agreescope,objectives,andtime
schedules
4 AnalyseConducttrafficsurvey
referencescenarios Assesswaterwaycapabilities
5 SafetyandConductriskassessment
performancecriteria
_______________________________________________
Phase2–ProcedureDevelopmentPhase
_______________________________________________
6 Developmentof Defineassumptions,constraints
hypotheticalmodels
7 ProcedureDesigninitialprocedure;
developments Designroutes;Designvolumes
_______________________________________________
Phase3–ProcedureValidationPhase
_______________________________________________
8 Trail LaunchPPS
9 Implementation OperatePPS;Validatethesystem
_______________________________________________
3.1 Phase1–Pre‐ImplementationPhase
Dependingonthelocalsituation,thedevelopmentof
PPSmaybe initiatedby different stakeholderssuch
as port authority, and port operators. The whole
team may be divided into the core team and the
extended team (Figure 1). The core team should be
theonewhowillconductpilotimplementationalong
thedevelopment.
Figure1.ImplementationTeamforPPSdevelopment
ExtendedTeam
CoreTeam
Shipmasters
Portauthority
Portengineers VTS Portusers
Safetyexperts
Data AISexperts
Thefirststepistoanalysethemarinetrafficdata.
Traditionally,radardataisused.Theradardatacan
becapturedatregulartimeintervals(e.g.,1minute).
Owingto the presence of radarblindsectors, ship’s
tacks have been broken. Inevitably the tracking has
significantmeasurementerrorsandthefrequencyof
occurrence of tra
cking errors is quite high. The
accuracyoftheshiptracksobtaineddependsmainly
ontheresolutionofradarandthesizeofradarblind
sectors.
The Automatic Identification System (AIS)
providesanewsourceofmarinetrafficdata.AISis
designed for ships and vessel traffic services to
elect
ronicallyexchangeinformationwitheachother.
AIS allows VTS to observe marine traffic and to
informvessels forexample about passage planning.
AIS operates primarily on two dedicated radio
channels but it is capable of being switched to
alternativechannels.AportableAISreceivercanbe
used to track ships, when and where each ship is
moving to. Ship tra
ck data with ship identification
486
numbers are very suitable to establish reliable ship
tracks.
Toinvestigatethemarinetraffic,twoorthreesites
willbeselectedfordatacollection.Thedataobtained
attheselectedsitesshouldbeadequateandreliable
for calculating the navigation speeds of ships, and
marine traffic flow rates. Non‐consecutive
days of
survey should be conducted to assess the marine
traffic activity. Traffic survey collecting data via
Automatic Identification System (AIS) can be
compared against data collected in the VTS, Pilot
BookingSchedule,operators’dataandotherrecords.
A database of traffic routes will be developed,
such routes having been
determined from a
comprehensive analysis of radar data or AIS data
over a period of time. A PPS should need the
followingdata:
1 Waterway data‐Data on the fairway situation,
electronicnauticalchart,etc.
2 Vessel data – Data on vessel type and length,
Estimated Time of Arrival (ETA) to
a particular
waypoint,vesselspeed,etc.
3 Trafficsituationdata–Dataonnumberofvessels,
intendedmovements with respect to maneuvers,
destinationandrouting,etc.
While most collision‐avoidance manoeuvres are
definedbytheSteering RulesfromtheInternational
Rules for the Prevention of Collisions at Sea
(Cockcroft
and Lameijer, 1996), these may be
superseded by local rules in congested waterways.
Suchconsiderations dependlargely on the size and
typeofeachship.Thetrafficdatashouldbeanalyzed
torevealcurrentandlocalpracticeinmaritimetraffic
and their contemporary operations. Marine traffic
activitiesonroutesfromAIS
datawillbefactoredfor
differentshiptypes(e.g.,ocean‐goingvessels,coastal
vessels, high speed craft, fishing ships, etc.). The
manoeuvrability of different vessel types and sizes
willbedetermined.
3.2 Phase2–ProcedureDevelopmentPhase
HypotheticalmodelswillbedevelopedinthisPhase.
Themodelswillbe
usedforstudyingtheprocedure
and behaviours of marine traffic. Through this
model, we are able to determine not only marine
traffic but also any possible traffic with
heterogeneous ability of passage. The hypothetical
models will be a core element of the passage
planningsystem.
In hypothetical models for vessel traffic
control
andpassageplanningsystem,weshouldincorporate
the heterogeneous manoeuvrability (of different
vesseltypesandsizes)andintroducetheconceptof
imperfect turning (sub‐optimal turning). For some
reasons,a ship does not turn as much as it should.
The amount of imperfect turning depends on
variablesofship
manoeuvringuponencounters.The
amountofimperfectturningalsodependsonawide
seriesofhumanfactorsassociatedwithperceptionof
theshipmasters,thedecisiontaken,bridgeteamco‐
ordination, and the interaction of both ships as a
collisionisavertedornot.
In the navigation literature, collision‐avoidance
turning
is triggered by the closet point of approach
(CPA) between adjacent vessels, if the CPA drops
below a prescribed minimum value, an avoiding
action is initiated. It should be noted that we will
determine “encounters”, which occur when ships
within the model activity take steps (change of
course and/or speed)
to avoid another ship. These
eventsarenotcollisioneventsinthemselvesbutthe
initiating events for a potential collision. The
likelihoodofanincidentthenoccurringembracesthe
degreeofimperfectturning.
Shipsteeringandturningcanbemodeledbythe
second‐order Nomoto model (1957), Norrbin model
(1963), and
Bech model (1968). Suppose that there
existsaminimalturningofcollision‐avoidance,and
the ship master intends to turn the ship a certain
degree.Imperfectturningdoesoccur.Iftheimperfect
turningislargerthantheminima lturning,acollision
willbeavoided;butotherwiseacollisionwillbe
the
result. The introduction of imperfect turning allows
us to investigate a wide range of factors of near
collisionevents.
3.3 Phase3–ProcedureValidationPhase
Aftergainingtheknowledgeofthemarinetrafficin
strategicareas,aPassagePlanningSystem(PPS)can
betestedinsimulatedenvironments.Theconcept
of
PPS is mainly concerned with vessel traffic to and
from a waterway junction, likely a precautionary
area.ThedevelopmentofPPSshouldtakeaccountof
thenatureofwaterwaysandthepropertiesofmarine
traffic.ThePPSshouldpredictwhichvesselswillbe
located in which strategic locations in
which
particular period of time, based on hypothetical
models. As the manoeuvrability of a ship is closely
related to its particulars (length, draft, ship type,
tonnage), hypothetical models are used to predict
shipmovementsafterthecomprehensiveanalysisof
marinetrafficversusanumberofparameters.
ThePPSwillbedeveloped
toreceiveandprocess
passage plans from a ship which will provide
informationonitsproposedarrival/departuretime,
destination within or exit from the port limits and
clearinformationontheproposedrouteandspeedof
navigation.
The PPS may be tested in the simulation for
maritime traffic
systems, with a focus on passage
planning at strategic locations in ports. A series of
experiments will be carried out in the simulated
environmenttoexplorePPSstrategiesofvesseltraffic
control. The track of manoeuvring can be recorded.
Manyrepeatedrunscanbecarriedoutandoverlaid
soas to
obtain the spread of multiple tracks of one
givenscenario.
VTS operators, harbour pilots and some other
stakeholders should be invited to comment on the
effectiveness of the PPS. The purpose of PPS is to
improve the safety and efficiency of navigation,
safetyoflifeatseaandtheprotection
ofthemarine
environment. Therefore, it is critical to review how
wellthePPSassiststhedecision‐makingoftheship
master concerning the actual navigation and
manoeuvringoftheship.
487
4 CONCLUSIONSANDDISCUSSION
Recent developments in ship simulation and real‐
time AIS data survey create the opportunities for
integratingelementsoftheproposedPPSwithinVTS
architecture.ThebenefitsofimplementingaPPSare
thatthePPSallowsidentificationandmonitoringof
vessels, strategic planning of vessel passage and
provisionofnavigationalinformationandassistance.
ThepotentialtoenhanceVTSsystemswithreal‐time
AIS data identifying the relative risks of different
passagepla nsallowstheportauthoritiestomoveto
thecontrolofmarinetrafficinthesafestmannerwith
thegreatestefficiency.
Inthispaper, theidea
ofPPS and proceduresin
principle are suggested. The technique of air traffic
control is proposed to be extended to vessel traffic
management in congested waters. Future work of
this research is to develop generic hypothetical
models.Thesemodelsshouldincludeallofthesafety
criteriasuchasminimumunderkeel
clearance,safe
speed,andshipmanoeuvrability.
ACKNOWLEDGEMNTS
Thisresearchwassupportedbyagrantfrombythe
General Research Funding sponsored by the
Research Grants Council (Reference No. PolyU
5300/12E).
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