211
1 INTRODUCTION
Sincethe2000s,thesizeofcontainershipshasgrown
exponentially. The maximum transportcapacity was
8,000 TEU (twenty‐foot equivalent unit) in 2000 for
ships 300 metres long, compared with 24,000 TEU
today. The unit transport capacity has tripled very
quickly. As a strategic crossing point
between the
Atlantic and Pacific Oceans, the Panama Canalʹs
ʺPanamaxʺlockslimitedthegrowthincontainership
size. The economic and, above all, industrial
developmentofEastAsiaundertheimpulseofChina
has placed this area at the centre of world flows of
goods,particularlycontainerisedgoods.East
Asiahas
emerged as the new lung of international trade but
also as the heart of the global container system [1].
Themajorcontainershipowners have adaptedtheir
transportofferstorespondtothisevolutioninworld
trade.ThemainshippingroutesarenowlinkingEast
AsiatoEuropeand
NorthAmerica.Passagethrough
thePanamaCanalhasbeenfoundtobeunnecessary.
The increase in the size of container ships was
thereforenolongerconfrontedbytheincreaseinthe
sizeofthelocksinthiscanal.Fromthepointofview
of shipbuilding engineering, the limit of the
size of
containershipshasnotyetbeenreached,butitwillbe
limitedbythesizeoftheportinfrastructure(draught,
length of quays, capacity of gantries, etc.), which
cannot keep up with this development at the same
speed.Containerisedmaritimetransporthastherefore
developed very speedily and has undergone
major
upheavals in maritime organisations and operatorsʹ
strategiesinrecentyears.
Afterpresentingthe frameworkof ourstudyand
the evolution of the container ship fleets, we will
zoom in on the impacts on the maritime container
shipnetworkandonthecallstotheBalticSeaports.
Forthis
paperandanalysis,weusedatafromthe
IHSfairplaydatabasewhichprovidesusinformation
Modernisation of Container Ship Fleets: State of Play
and Consequences for the Baltic Sea
R.Kerbiriou
LeHavreNormandyUniversity,LeHavre,France
ABSTRACT:Inordertoadapttostructuralchangesinworldtrade,containershipownershavedevelopedtheir
transportservices.Thus,theunittransportcapacityofcontainershipshasbeenmultipliedby3inthespaceof
20years.Themaritimetransportofcontainershas
developedveryspeedilyandtherehavebeenchangesinthe
strategiesofshippingcompanies.
These giants of the seas, put into service on the maritime trades linking the worldʹs main production and
consumptionmarkets,haveledtotherepositioningofshipsonsecondarymaritimespaces.Thisisknownas
cascading.TheobjectiveofthispaperistostudytheimpactsontheportsandthemaritimenetworkoftheBaltic
Sea.Forthispurpose,wewillcarryoutananalysisoftheevolutionofcontainershipcallsfrom2012to2020
(number of calls, capacity offered in calls, ...) followed
by a graph analysis to study the evolution of the
maritimenetwork.
http://www.transnav.eu
the International Journal
on Marine Navigation
and Safety of Sea Transportation
Volume 18
Number 1
March 2024
DOI:10.12716/1001.18.01.22
212
onthetechnicalcharacteristicsoftheships(operators,
maximumtransportcapacity,draught,...)andonthe
movements(portofcalloftheshipanddateandtime
ofarrivalanddeparture).Thisdatabase is presented
inmoredetailinaseparatesection.
2 STUDYFRAMEWORK
Torespondtothe
developmentofinternationaltrade
and their growth needs, shipping companies have,
sincethe2000s,orderednewandlargerships(fig.1).
Currently, the largest container ships have a unit
transport capacity of 24 000 TEU, compared with 8
000 TEU in 2000. These very large ships allow
shippingcompaniestoachieve
economiesofscaleand
reduceconstructionandoperatingcostspercontainer
carried. New categories of container ships have
appearedandtheworldʹsmajorshipownershaveall
rapidlyequippedthemselveswiththesegiantsofthe
seas.Forthenew‐panamaxandabovecategories,for
example, wehave gone from 173
shipsin service in
2016to313in2020.
Figure1. Containerships categories. Production: Ronan
Kerbiriou,February2021.
These large ships are positioned on the main
global shipping trades linking East Asia to Europe
and NorthAmerica. This concentration andincrease
inshippingsupplyhasledtothedecommissioningof
smallervessels.Manyvesselsthatusedtooperateon
its major international trades and are now of
intermediate size,
have been repositioned on
secondaryshipping linesandother smaller shipping
areas. Larger container ships have replaced smaller
ones. This is known as cascading and has therefore
had an impact on the container traffic of Baltic Sea
ports. Thisis the subjectof this article, in which we
willlook
attheimpactoftheincreaseinthesizeofthe
container ship fleet on the Baltic Sea ports. To this
end, we willanalyse theevolution of container ship
callsfrom2012to2020in2‐yearsteps.Wewillstudy
theevolutionofthenumberofcallsperport,
butalso
the transport capacity offered at each call. We will
alsoexaminetheevolutionofthemaritimenetworkof
containershipsintheBalticSeain2012and2020.
We will base our analysis on themain Baltic Sea
portsaccordingtotheircontainertrafficin2020(Fig.
2).
Wehavethusretainedtheportsthathadatraffic
of more than 50 000 TEU in 2020, i.e. 23 ports. It
should be noted that, due to a problemof accessto
reliabledataoncallsintheportofAalborg,thelatter
couldnotbetakenintoaccountfor
thisstudy.
Figure2.ContainerstrafficinBalticSeaPortin2020.
Production:RonanKerbiriou,February2023.
3 DATAANDMETHOD
This work is based on the exploitation of maritime
data from IHS (https://maritime.ihs.com/). IHS
belongs to Lloydʹs, which insures more than 80% of
the worldʹs merchant ships. Through this platform
andviaasubscription,itispossibletoaccessdataon
ships with all their
identification information and
technical characteristics. We have built up our ship
databaseusinginformationfromIHS.
IHS also offers another module on ship
movementsbasedonAISsignals.Itisthuspossibleto
downloaddataonportcallsaccordingtoapredefined
listofships,duringagivenperiodand
byselectinga
particular country or port. AIS is an on‐board
positioning system used to provide information to
nearby vessels and to monitor the traffic situation.
This tool complements maritime radar as a collision
avoidance device, thus enhancing the safety and
security of maritime navigation. Regulated by the
IMO (International
Maritime Organization) SOLAS
Convention,theAISsystemismandatoryonallships
over 300 gross tons, which concerns almost all
commercial ships. The AIS can be diverted from its
originalpurposeandusedforotherresearchpurposes
and represents a source of new information for
scientificresearch[2].Indeed,AIS
messagescontaina
greatdealofinformationthatcanbeusedtoidentify
and locate the vessel. The analysis of the data
transmittedbytheAIS allowsthestudy ofmaritime
trafficandportpassage.Inthis paper,thesedataon
ships and their calls are the primary sources of
213
information that we will use to study the structural
changes of container ships and the impact on
containerisedmaritimetrafficintheBalticSea.
The data downloaded from IHS needs to be
preparedinordertobeusable.Todothis,weneedto
clean up the database to
remove duplicate calls,
harmonisethenamesoftheports(sometimesthecall
isindicatedinthenameoftheterminalforexample),
removeinformationwhentheshipisintheanchorage
area,etc.
4 RESULTS
Inthispartoftheresults,wewillcomparetheportsof
callinthedefined
ports(seepart2)byanalysingthe
years2012,2014,2016,2018and2020inordertohave
an evolutionary analysis over time. We will analyse
thedataingeneraltermsbeforeproposinganentryby
ports. To conclude this part on the results, we will
compare the evolution of
the maritime network
between2012and2020usinggraphanalysistools.
4.1 Overallapproach
Theanticipatedeffectofcascadinginamaritimearea
suchastheBalticSeaistoseeageneralincreaseinthe
average size of container ships calling. Indeed, as
previouslyspecified,operators,undertheeffectof
the
acquisitionofnewvesselswithincreasinglylargeunit
transportcapacities, have repositioned largervessels
onsecondarymaritimespaces.Wehavethereforefirst
observed the evolution of the average size of
container ships calling at the ports studied and the
number of calls (Fig. 2). A regular increase in the
averagesizeofcontainershipscanbeobserved.The
average size of container ships has increased from
1342TEUin2012to1903TEUin2020,i.e.anincrease
of42%.Atthesametime,thetotalnumberofcallshas
decreased from 9988 in 2012 to 8276 in 2020, i.e. a
decreaseof17%.
Figure2.Evolutionofthenumberofcallsandtheaverage
sizeofcontainershipscallingfrom2012to2020.Source:IHS
maritime.
Thefirstobservedimpactoftheconstructionand
commissioning of the giant ships is a significant
increaseinthesizeofcontainershipscallingatBaltic
Sea ports. On average, larger ships are calling, but
there are fewer of them. The trend is therefore
towards a contraction and concentration of the
transportofferonlargervessels.InFigure3below,it
can be seenthat the capacity offeredat ports of call
has also increased, driven by the increase in the
average size of container ships. There was a
significant jump between 2012 and 2014 before a
slightdeclineanda
furtherjumpin2020.Thecapacity
offered at port exceeded 15.5 million TEUs, an
increaseof17.5%comparedwith2012.
Figure 3. Evolution of the transport capacity offered by
container ships in port from 2012 to 2020. Source: IHS
maritime.
At the international level, the major shipping
companies,inordertorespondtotheincreaseintrade
inmanufacturedproducts, havehad to expandtheir
transport services. From the 1990s onwards, they
movedintonewmaritimeareas,competingwithlocal
operators.Smallercompanieswereabsorbedinorder
torecovertheirmarkets
[3].Fromthe2010sonwards,
mergers (the Chinese COSCO and China Shipping
merged in 2016 and the Japanese NYK, K‐Line and
MOLmergedin2017tobecomeONE)andlarge‐scale
acquisitions (CMA‐CGMʹs takeover of NOL in 2015,
Hapag‐Lloydʹstakeoverof CSAVin2014 and
NILE‐
DUTCH in 2021, etc.) have taken place [4]. The
number of shipping companies operating across the
variousseasoftheworldhasthuscontractedandthe
transportofferisconcentratedwithasmallernumber.
FortheBalticSeaarea(Fig.4),itcanbeseenthatthe
numberofshipping
operatorshasalsocontractedasa
result of various mergers and acquisitions. The
numberofcontainershipoperatorshasfallenfrom94
in2012to69in2020,withalowpointof57in2018.
Figure4. Evolution of the number of shipping companies
operating in the BalticSea from 2012 to 2020. Source: IHS
maritime.
On the other hand, the composition of the top
three shipping companies in terms of unit transport
capacityofferedatportsofcallhasnotchanged.The
samethreeoperatorscanbeidentifiedinthedifferent
214
yearsstudied:Maersk,UnifeederandMSCandtheir
relative weight remains similar. In 2012, they
accounted for 47% of the capacity transported,
compared with 50% in 2020. It is essentially small
operators, which offered a small number of calls,
whichhavedisappeared(mainlylessthan20callsin
2012).
The reasons for the disappearance of certain
operators are either economic bankruptcy and the
closureofthecompany,orabsorptionormergerwith
another company and therefore the company no
longer exists under the same name, or because the
companyhasstoppedservingthemaritimearea.
The regulardecrease inthe
number ofcalls since
2012 in Baltic Sea ports is thus explained by the
disappearance of small operators that offered
shippingserviceswithgenerallylow‐capacityvessels.
The main shipping lines serving the Baltic Sea have
maintained the number of calls during the period
under review, but they have mainly
increased the
averagesizeofcontainershipscalling.Theeffectsof
cascadinginrecentyearsarethereforeevidentforthe
portsand maritime spaceofthe Baltic Sea.We have
been able to observe changes in the structure of
containershipscallinginthismaritimearea.Afterthis
globalapproach,we
willcontinuetheanalysiswithan
approach at port level. Have all ports been equally
affected by the effects of cascading? Are there
winning and losing ports? In the next part of our
analysisoftheresults,wewillthereforecomparethe
capacitiesofferedin calls andthenumberof
calls in
thedifferentportsstudiedandtheevolutionoverthe
samestudyperiod.
4.2 Analysisofportpassage
Generally, comparisons between ports are based on
traffic statistics published mainly by the port
authorities.Theuseofdataonmaritimecallslinkedto
adatabase onshipsmakesit possibleto
extractnew
indicatorsthatenableportstobeputintoperspective
with each other. In order to study the effects of
cascading on the various Baltic Sea ports, we will
thereforestudy the evolutionofthe numberof calls,
the capacity offered in calls and the average size of
container
shipsbetween2012and2020.
Inthefirstpartoftheanalysisoftheresults,itwas
observed that the average size of container ships
callingincreasedoverall,butthatthenumberofcalls
decreased. At port level, the average size has
increased in all the ports studied (+60% in Gdansk,
+47%inGoteborg,+32% inAarhus,+82% inRauma,
etc.). However, there are disparities between the
different ports (Fig. 5). For example, in 2020, in
Gdansk, container ships calling had an average unit
transportcapacityof4846TEU,faraheadoftheport
of Goteborg (3090 TEU) or Saint Petersburg
(1860
TEU). The average size of container ships calling is
highestintheportsofGdansk,GoteborgandAarhus
andthefurthereastonegoesthesmallertheaverage
size becomes (less than 2000 TEU in Riga, Tallinn,
Klaipeda,St.Petersburg,etc.).Itcanbeobservedthat
in the three identified
ports, vessels with a unit
transportcapacity of more than 20000 TEU reached
the port in 2020. In the other ports, the largest
container ships calling are smaller than 10 000 TEU
(8241TEUinGdynia,5711TEUinKlaipeda,...).The
giants of the seas are therefore coming
to Baltic Sea
ports, thus interconnecting this area with the main
worldmaritimetrades.Theseportsthereforeseemto
bepart ofthesemaritimeservices,makingtheBaltic
Seaanimportantmaritimeareaandnotonlyaffected
bytranshipment.TheportsofGdansk,Goteborgand
Aarhuscanthusthemselvesbetranshipment
portsfor
otherBalticSeaports.
Figure5. Average unit transport capacity in 2020. Source:
IHSmaritime.
Between 2012 and 2020, the number of calls
decreased in all ports except for the Polish ports of
Gdansk and Gdynia and the Swedish port of
Helsingborg (Fig.6). The following graph shows the
evolutionoftherankingofthetop10BalticSeaports
accordingtothe number ofcontainer ship
calls. The
portofSt.Petersburgistheonewiththemostcallsin
alltheyearsstudied.TheportofGdansk,until2016,
was10thintermsofnumberofcalls,andfrom2018
onwardsitisranked5thin2020.
Figure6. Top 10 Baltic Sea ports by number of calls from
2012to2020.Source:IHSmaritime.
If the same analysis is carried out using the unit
transport capacity offered in calls, the majority of
portshave experienced a positiveevolution between
2012 and 2020 (Fig. 7). In the graph below, we can
observe the evolution in the ranking of the port of
Gdansk,whichhasbeenranked
number1since2018,
when its number of calls also increased. On the
contrary,theportsofSt.PetersburgandGothenburg,
whicharetwoportswithsignificantcontainertraffic,
have seena decreasein the numberof calls andthe
capacity offeredin calls(‐27% for Gothenburg and‐
5%
forSt.Petersburg).ThetwoPolishportsinthistop
10arethosewhichhaveseenthestrongestgrowthin
the capacity offered in calls (+123% for Gdansk and
215
+63% for Gdynia). As a reminder, the increase in
capacityforalltheportsstudiedwas+17%.
Figure7.Top10BalticSeaportsbyunittransportcapacity
from2012to2020.Source:IHSmaritime.
Theweightofthetop3orthetop5changesvery
littleovertheperiod.Thetop3overthevariousyears
accountforaround40%ofcapacityandthetop5for
around57%.Between2012and2020,therehasbeena
rebalancingofthedistributionofcapacitiesoffered
at
portsofcall(Fig.8).TheportofGdanskaccountedfor
10%ofcapacityin2012and18%in2020.Incontrast,
the ports of Goteborg (15% in2012 and 9%in 2020)
and St Petersburg (15% in 2012 and 12% in 2020)
concentrateasmallershareofcapacity.
Figure8. Relative weight in offeredcapacityofthe4main
ports.Source:IHSmaritime.
These analyses make it possible to highlight the
growing importance of the Polish ports, and more
particularly Gdansk, in the containerised maritime
networks. The latter has seen a significant
developmentof itstransport offerinrecentyears,to
the detriment of the ports of Goteborg and St
Petersburg. The port of
Gdansk seems to be
establishing itself as the strongest port in the Baltic
Seaandasaregionalhub.Itshouldalsobenotedthat
the smaller ports have also seen an increase in the
capacityofferedincalls.Between2012 and 2020,the
situation seems to change from three
main ports
(Goteborg, St. Petersburg and Gdansk) to one main
port(Gdansk),twoportsthatbecomemoresecondary
(GoteborgandSt.Petersburg)withsmallerports.To
confirm this assumption, we will analyse the
containerised maritime networks in 2012 and 2020
between the Baltic Sea ports and directly
interconnected with theexternal
ports. Thisnetwork
analysisusingtools from graphtheory willallowto
assess the evolution of the strategic positions of the
studiedports.
4.3 Evolutionofthemaritimecontainernetworkfrom
2012to2020
Based on data from container ship port calls, it is
possible to reconstruct inter‐port connections
and
consequently maritime networks. In order to study
the maritime networks of container ships
interconnected with the Baltic Sea, we will rely on
representations derived from graph theory.ʺGraph
theory constitutes a mathematical framework that
makes it possible to tackle problems in a very vast
field. In the domains of geography,
urban
development and spatial planning, graph theory is
used to tackle questions arising in the field of
networksʺ [5]. In our case, graph theory is used to
study the maritime networks of container ships and
thushighlightthenetworkstructurewithintheBaltic
Sea. Several methods exist to simplify a
graph with
the objectiveof removingcertain vertices orlinks in
ordertomakeitreadable.Thedifferentmet hodshave
been summarised and described in French by César
Ducruet [6]. We have chosen the dominant flow
method,whichisrelatedtothenodalregionmethod
[7].Thismethodhastheadvantage
ofbeingsimpleto
useandeasytounderstandforanuninformedreader.
Theprincipleofthismethodistodefineathreshold
and to keep only the relationships above it. The
graphsthusrepresentonlypartialinformationofthe
overallmaritimenetworkbutallowthedeepstructure
of the
network studied to be brought out. The R
softwareandtheʺigraphʺpackage,whicharefreely
available, were used to produce the graphs
constructed from the incidence matrices at the
vertices.
Thesetrafficflowswereselectedbyretainingonly
directinter‐portlinks,i.e.non‐stoplinks,whosetotal
capacity
carriedbetweentwo callsby allships,once
aggregated,remainedabovethethresholdof150000
TEU carried. We have selected direct connections
between theports in our study andalso with extra‐
balticports.Wewillcomparethemaritimecontainer
ship networks for the years 2012 and 2020 with
the
aim of analysing its evolution and deducing the
impact of the structural evolution of container ships
andcascading.
The Baltic Sea container ship network has
expanded between 2012 and 2020 with the
developmentofconnectionstoexternalports.In2012,
inter‐port connections were concentrated around
three external ports (Bremerhaven,
Rotterdam, and
Hamburg)comparedtosevenin2020.Newimportant
maritime connections are emerging, particularly
towardstheportofWilhelmshavenorfromtheport
ofZeebrugge.Ontheotherhand,betweentheBaltic
Sea ports, the unit transport capacities offered are
relatively low. The maritime connections with
external ports are
made with large capacity ships,
whileinternal connectionsare not. Thus,the port of
Gdansk is emerging as the main regional hub that
interconnects with external ports (Bremerhaven,
Zeebrugge,FelixstoweandWilhelmshaven).In2012,
theportofGothenburgwasthemainportattheheart
of the Baltic Sea maritime network.
Its position,
although still important, has been overtaken by the
port of Gdansk. The port of St. Petersburg has also
experienced a decline in importance. In 2020, the
capacities exchanged with external ports are less
216
importantthanin2012forthelatter.Theserelations
withtheportofRotterdamarestillhighin2020,but
those with the ports of Hamburg and Bremerhaven
havedecreasedsignificantly.However,asaresultof
the economic sanctions imposed on the Russian
FederationbytheEuropeanUnion,among
others,asa
response to the war in Ukraine, container traffic for
theportofSt.Petersburghasbeenstronglyimpacted
[8]. The aim of the economic sanctions is to isolate
Russia economically from international trade, which
in turn affects the countryʹs container traffic. The
Baltic Sea is Russiaʹs
only western maritime access,
whichmakesitamajoraccessforitsforeigntrade[9].
The port of St. Petersburg is therefore likely to
disappear completely from the maritime network as
longaseconomicsanctionsremaininplace.
Itisalsoimportanttonotethepositionoftheport
of
Hamburginthe2012and2020graphs.Itsposition
as a regional hub has been marginalised with
relatively low transport capacities exchanged to the
benefit of the neighbouring port of Bremerhaven in
particular.
Figure9. Sagittal representations of the graphs associated
with containerized maritime traffic in 2012 and 2020.
Source:IHSmaritime.
Intermsofunittransportcapacitiesexchanged,the
maritimenetworkofcontainershipswithintheBaltic
Seaandconnectedtotheoutsidehasevolvedbetween
2012 and 2020. The port of Gdansk has established
itselfasthemajorregionalhubintheBalticSea,with
connectionstotheportofBremerhaven
inparticular.
Theunittransportcapacitybetweenthetwoportsis
over 1.1 million TEU in 2020 in each direction. This
linkisstructuredbytheoperatorsofthe2Malliance,
primarily Maersk and MSC. With the recent joint
announcement by the two operators of the end of
theirmaritime
allianceby2024,itwillbeinteresting,
as a follow‐up to this paper, to study the possible
impactonthisinter‐portrelationship.
5 CONCLUSION
The economicand especiallyindustrialdevelopment
of East Asia, driven by China, has placed this
geographical area at the centre of world trade in
goods,
particularlyforcontainerisedflows,forcingthe
major shipping lines to adapt their offers. This
reorganisation has offered new development
prospects for containerised maritime transport with
theconstructionofnewcontainershipswhichcanbe
describedasgiantsoftheseasandwhich havebeen
putintoservicemainlyonthe
Asia‐Europetradeand
alsobetweenAsiaandNorthAmerica.Thisstructural
development has led to cascading and has had an
effectonthewholeoftheworldʹsmaritimeareasand
inparticularontheBalticSeaanditscontainerports.
Theobjectiveofthispaperhasthereforebeento
assess
theimpactovertimeoftheeffectsofcascadingonthe
Baltic Sea ports and maritime network. The main
conclusions that can be drawn from our analysis of
thestructuralevolutionofcontainershipsandthusof
cascadingare
Theaveragesizeofshipscallinghasincreasedand
atthesametimethenumberofcallshasdecreased,
concentrating and contracting the transport offer
onlargerships;
Manysmallshippingcompanieshavedisappeared
from the Baltic Sea port landscape, concentrating
the transport offer around a smaller number of
operators(27%decrease);
Emergenceofthe portofGdansk
(increasein the
number of calls, average size of container ships,
etc.)asanewregionalhub;
Development of the maritime network and
interportrelationswithexternalportsandwiththe
portofGdanskasarelay;
ThestrategicpositionoftheportsofGoteborgand
St. Petersburg
is declining and becoming more
secondary;
TheportofBremerhavenispositioningitselfasthe
mainporthubbetweenthemainworldtradesand
the Baltic Sea ports and at the same time the
position of the port of Hamburg has been
marginalised.
The developmentof container shipfleetsand
the
resulting cascading has had a significant impact on
maritime traffic and port passage in the Baltic Sea.
The maritime networks have been restructured
around a strong link between Bremerhaven and
Gdansk under the main impetus of the operators of
217
the 2M alliance (Maersk and MSC). This work
deserves to be continued over time to confirm the
previousconclusionsbutalsotoassesstheimpactof
theendofthe2Mallianceby2024.Continuedanalysis
willalso makeit possibleto studythe impactofthe
war in
Ukraine and the economic sanctions against
the Russian Federation on its maritime traffic in the
region and on the general structure of the maritime
networkofcontainershipsintheBalticSea.
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