Planning and Simulation of Intermodal Freight Transport on International Networks

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Article Planning and Simulation of Intermodal Freight Transport on International Networks. Hub and Spoke System in Euro-Mediterranean Area

Domenico Gattuso, Margherita Malara and Gian Carla Cassone *

DIIES Department, PAU Department, Mediterranea University of Reggio Calabria, 89100 Reggio Calabria, Italy; [email protected] (D.G.); [email protected] (M.M.) * Correspondence: [email protected]; Tel.: +39-0965-1693294

Received: 18 October 2019; Accepted: 20 January 2020; Published: 21 January 2020

Abstract: The remarkable demographic growth and economic development of the Southern and Eastern Mediterranean regions stimulate an ever increasing need for trade between the shores, especially from regions of North Africa and the Middle East towards Western European countries. Today, these exchanges take place mainly by sea and by roll on-roll oﬀ (Ro-Ro) ships; but the connections by container ships and by road transport are important too. Ro-Ro services are particularly crammed in some North-South directions, with relationships among few ports and with rather limited frequencies. Road transport, especially between the Middle East and Europe, has diﬀerent limits in terms of cost, safety, and reliability. The paper proposes a hypothesis of a logistic organization on a Euro-Mediterranean scale, through the transition from a network of direct links to a hub and spoke (H&S) network, according to the scheme envisaged for air transport. The research aims to explore, within a framework of the socio-economic system and the mobility demand system, the feasibility of a H&S network for Ro-Ro freight in the Mediterranean basin, based on a hub with high logistical performances, limiting the planning to supply and process consequent impact assessments.

Keywords: short sea shipping; planning and simulation; hub and spoke system

1. Introduction The analysis of the freight transport is a topic characterized by numerous aspects. This complexity is determined, unlike what happens in the transport of people, by the variety of transported freights and by the fact that there are real constraints due to the location of production activities. Furthermore, it must be considered that the structure of the decision-making processes, which generate the movement of freights, is very complex due to the large number of relationships between the interested stakeholders and the high degree of organization that must be guaranteed. The right operation of the freight transport sector is fundamental to guarantee the economic development of a region and, because it is a constantly evolving sector, the phenomena concerning freight transport are very important in all fields of study that deal with territorial structures and their transformations. The research proposes a reorganization of the roll on-roll off (Ro-Ro) transport network of the Mediterranean, currently based on point to point connections (P2P); specifically, the structuring of a hub and spoke (H&S) network is presented, with a hub located in Calabria and spoke, maritime and/or rail links, to reach the final destinations. After an analysis of the limits and the potentialities of short sea shipping in the Mediterranean basin, as well as the economies of scale and scope derived from the use of a H&S network structure, the methodological approach adopted to analyses is illustrated and an application to a test network is proposed. The research proposes an analysis with explicit reference to the transport supply and to the possible configurations of the network that could determine

Sustainability 2020, 12, 776; doi:10.3390/su12030776 www.mdpi.com/journal/sustainability Sustainability 2020, 12, 776 2 of 14 economic advantages in the perspective of a Ro-Ro shipping operator. Further developments include surveys for the detection of traﬃc and the deﬁnition of a simulation model that takes into account the demand-supply interaction. In this phase of the research, the analysis was carried out taking the perspective of a Ro-Ro shipping operator as a reference, considering just maritime spoke links.

2. Short Sea Shipping in the Mediterranean Sea. Potentialities and limits The concept of short sea shipping (SSS) is specified in the communication n. 317 of 1999, in which the European Commission defines SSS as “the movement of goods and passengers by sea between ports located in geographical Europe or between these ports and ports located in countries outside Europe with a sea coast closed to the borders Europe”. The motorways of the sea represent a specific type of SSS. They are freight transport services by sea, scheduled, high frequency, reliable, integrated in door to door logistic chain through intermodal transports. These services are realized using Ro-Ro ships, that are loaded and unloaded with horizontal operations and haul specific load unit: trailers (for unaccompanied transport) and trucks (for accompanied transport). The motorways of the sea could be focused on specific relationships, since a Ro-Ro line requires large volumes of traffic. It is necessary to use fast, high-speed ships capable of guaranteeing high frequencies in order to make Ro-Ro services competitive (in terms of costs and delivery times) with road and rail transport. All this would lead to a concentrated development on some routes and few ports. The importance of the SSS, and in particular of Ro-Ro transport services, in the development of efficient and sustainable transport networks, is evident from the attention given to this sector both by the European Community [1,2] and by academic researchers. In the sector literature, several studies have been carried out in order to analyze the potential of maritime transport with reference to the efficiency of the Ro-Ro terminals [3–5] but also to the environmental sustainability of this kind of transport [6,7]. The Mediterranean ports equipped for Ro-Ro services number around 56, and a dense network of routes (88 lines), which are being integrated with the territory, spreads throughout the basin. Currently, the services of SSS in the Western Mediterranean are all attested on pairs of ports, and mostly on direct connections, without intermediate stopovers (Figure1). On the eastern side, the Ro-Ro maritime transport network is less dense, developed mainly within the Adriatic Sea with connections between the Balkan area and the Italian peninsula; however, there are also connections between Turkey, and Eastern Europe, and Italy. The absence of some maritime relationships (for example between the states of the northern shores of the Mediterranean and Arab countries such as Egypt, Israel, and Syria) is partly explained by the poor coherence of transport demand, in part by the lower competitiveness of direct maritime relations of Ro-Ro with regard to maritime container transport and road transport. However, the high transit times that characterize container transport and the high cost of road transport do not facilitate the growth of trade and therefore of the respective markets. If the exchanges between the Italian and Arab countries are taken as an example, it is possible to observe that the full container maritime services offer boarding from the Adriatic and Tyrrhenian ports on a weekly and/or fortnightly basis, but due to the intermediate stops port to port, travel times vary from 7 to 13 days. Meanwhile, truck services have a much higher cost than maritime services and are therefore hardly sustainable for the transport of consumer goods. Sustainability 2020, 12, 776 3 of 14 Sustainability 2020, 12, 776 3 of 13

Sustainability 2020, 12, 776 France 3 of 13 Croatia

France Croatia Albania Turkey

Spain AlbaniaGreece Turkey

Spain Greece

Morocco Tunisia Morocco Tunisia Routes to Morocco Routes to Corsica Routes to Croazia Routes to Tunisia Routes to Malta Routes to Morocco Routes to Corsica Routes to Croazia Routes toRoutes Greece to Tunisia RoutesRoutes to Turkey to Malta Routes toRoutes Spain to Greece RoutesRoutes to Albania to Turkey Routes to Spain Routes to Albania

FigureFigure 1.1. Roll on-roll ooffﬀ (Ro-Ro)(Ro-Ro) InternationalInternational routesroutes inin thethe MediterraneanMediterranean SeaSea [[8].8]. Figure 1. Roll on-roll off (Ro-Ro) International routes in the Mediterranean Sea [8]. In this regard, a study [9] relating to the competitiveness of short sea shipping (SSS) corridors and In thisIn regard,this regard, a study a study [9] [9] relating relating to to the the competitiveness competitiveness of of short short sea sea shipping shipping (SSS) (SSS) corridors corridors road transport, by comparing the costs of moving food products (olive oil) from Spain to several Italian and roadand roadtransport, transport, by comparingby comparing the the costs costs of of moving moving foodfood products products (olive (olive oil) oil) from from Spain Spain to several to several ports, shows that the transportation cost for the road alternative is about 35% higher than the SSS. ItalianItalian ports, ports, shows shows that that the the transportation transportation cost cost foforr the roadroad alternative alternative is isabout about 35% 35% higher higher than than the the SSS. ItSSS. should also be noted that most of the Mediterranean Ro-Ro and Ro-Pax (freight and passengers) routesIt (bothshouldIt should on thealso westernalso be benoted andnoted that eastern that most most sides) ofof climbthethe MediterraneanMediterranean Italy, consolidating Ro-Ro Ro-Ro theand and gaps Ro-Pax Ro-Pax in the (freight TEN-T(freight and (Trans and Europeanpassengers)passengers) Transport routes routes (both Network) (both on onthe the corridors western western and (Figure and eastern eastern2); this sides) applies climb climb toItaly, Italy, the consolidating west-east consolidating corridor, the thegaps gaps alongin the in the the bridge-BalkansTEN-TTEN-T (Trans (Trans Barcelona–Italy;European European Transport Transport to the doubleNetwork) Network) Adriatic corridcorrid corridorors (Figure(Figure that 2); connects2); this this applies Italyapplies withto theto Greece thewest-east west-east (Trieste, corridor, along the bridge-Balkans Barcelona–Italy; to the double Adriatic corridor that connects Venice,corridor, Ancona, along Bari,the bridge-Balkans and Brindisi all Barcelona–Italy; have a historical to link the with double Igoumenitsa–Patras) Adriatic corridor and that Turkey connects and Italy with Greece (Trieste, Venice, Ancona, Bari, and Brindisi all have a historical link with fallItaly within with theGreece countries (Trieste, of the Venice, Middle Ancona, East; to Bari, the Tyrrhenian and Brindisi connections all have witha historical the North link African with countries;Igoumenitsa–Patras) and to the connections and Turkey between and fall Italy,within Malta, the countries Corsica, of andthe Middle Albania East; (the to Bari-Durresthe Tyrrhenian line is Igoumenitsa–Patras)connections with andthe North Turkey African and countries;fall within and the to countries the connections of the betweenMiddle Italy,East; Malta,to the Corsica, Tyrrhenian historical). connectionsand Albania with (the the Bari-Durre North Africans line iscountries; historical). and to the connections between Italy, Malta, Corsica, and Albania (the Bari-Durres line is historical).

Mediterranean Corridor Adriatic Baltic Corridor Rhine Alps Corridor Orient East Med Corridor Scandinavian Mediterranean Corridor Mediterranean Corridor Adriatic Baltic Corridor Figure 2. FigureRhineIntegration 2. Alps Integration Corridor among among Ro-Ro Ro-Ro lineslines and and TEN-TOrient TEN-T EastCorridors. Corridors. Med Corridor Scandinavian Mediterranean Corridor

Figure 2. Integration among Ro-Ro lines and TEN-T Corridors. Sustainability 2020, 12, 776 4 of 14

Table1 shows some features of the main currently operating Ro-Ro lines that allow the connection between the southern and northern shores of the Mediterranean. In the last 20 years, the traffic of Ro-Ro ships in the Mediterranean has exceeded 4 million units, with a growth of 255%, which has led to freight transported by ferry reaching the same level as freight moved with containers. In 2017, 70,000 Ro-Ro vessel positions in the Mediterranean were detected, with an increase of 7.4% compared to 2012 [10]. According to some recent studies in the Euro-Med area, Ro-Ro traffic moves over 84 million tons of goods, of which around 30 million is SSS. In 2015, approximately 14.9 million tons of goods were exchanged between Italian ports in the Adriatic and ports in the Balkans and the eastern Mediterranean using Ro-Ro maritime transport, and about 15 million tons of goods were exchanged between the Tyrrhenian Italian ports and Maghreb and Western Mediterranean ports [8]. At the geo-economic level, the Mediterranean interfaces the Atlantic and North European markets on the one hand and the Asian and African markets on the other. For this reason, the centrality of the basin in an international context is a strong factor of attractiveness for public and private investments in the transport and logistics fields, which continue to grow despite some critical social and political situations. The Mediterranean is a privileged transit route for containerized traffic, but it is also a very significant area for short-distance Ro-Ro traffic, particularly in the North-South direction. This situation determines new market needs that require, not only transport services, but also integrated logistics services that presuppose the existence and functionality of an intermodal network system capable of projecting the Mediterranean basin regions at the center of Europe. In particular, the market requires integrated services that also include processes of freight handling and transformation, to generate added value and minimizing monetary costs and logistic times. Hence the hypothesis of a hub and spoke network structure to realize an integration between the TEN-T networks and the Ro-Ro sea routes coming from the southern and eastern shores of the Mediterranean in order to produce significant economies both for transport operators and users.

Table 1. Some Ro-Ro lines in the Mediterranean.

Distance Declared Origin Destination Operator Number of Travel/Week (Miles) Travel Time (h) Tunis Genoa GNV 462 22 3 Tunis Marseilles Corsica Linea 467 21 3 Tunis Civitavecchia GNV 318 25 1 Tunis Salerno Grimaldi Lines 300 24 2 Tangeri Med Genoa GNV 871 52 3 Tangeri Med Savona Grimaldi Lines 853 60 1 Tangeri Med Sete GNV 681 40 2 Nador Sete GNV 595 34 1 Skikda Genoa Algerie Ferries 460 19 1 Algeri Marseilles Corsica Line 410 23 3 Annaba Marseilles Algerie Ferries 410 19 1 Bejaia Marseilles Corsica Line 396 22 1 Oran Marseilles Algerie Ferries 534 25 1 Skikda Marseilles Algerie Ferries 396 20 1 Instanbul Salerno Grimaldi 1029 96 1 Instanbul Trieste Un Ro-Ro 1152 66 1 Instanbul Leghorn Grimaldi 1212 120 1 Mersin Trieste Un Ro-Ro 1320 102 1

3. A Hub and Spoke Network to Produce Economies The spatial efficiency of a transport network, deriving from its configuration and structure, involves the consideration of economies of scale, economies of density, and economies of purpose [11]. Economies of scale derive from the expansion of traffic and the size of the network (reduction of average costs due to the increase in traffic volumes and network size); density economies derive from the expansion of traffic with a constant network size (greater exploitation of existing capacity); finally, Sustainability 2020, 12, 776 5 of 14

economiesSustainability of scope 2020, 12 (better, 776 fleet rotation and/or greater average load factor) refer to the impact5 of 13 on average costs by the addition of new services within a single dimension of network space [12]. The structureimpact of on a transport average costs network, by the therefore,addition of representsnew services an within important a single endogenous dimension of variablenetwork space of spatial [12]. The structure of a transport network, therefore, represents an important endogenous variable of efficiency that determines the process of minimizing costs together with the structure and sequence of spatial efficiency that determines the process of minimizing costs together with the structure and connections, the capacity offered, the type of logistic and intermodal services, and the possibility of sequence of connections, the capacity offered, the type of logistic and intermodal services, and the integrationpossibility and cooperationof integration between and cooperation the stakeholders between inthe the stakeholders supply chain in forthe door-to-door supply chain services. for Thedoor-to-door hub and services. spoke (H&S) model allows a reduction of the average cost due to the economies of densityThe on hub the and single spoke links. (H&S) The model presence allows of a reduction these economies of the average and thecost possibilitydue to the economies of adding of new connectionsdensity toon thethe networksingle links. structure, The presence achieving of th economiesese economies of scope, and the makes possibility it convenient of adding to new adopt a H&S structureconnections [13 to] the as hasnetwork been structure, demonstrated achieving in air econ transport.omies of scope, makes it convenient to adopt a TheH&S term structure H&S [13] means as has a been network demonstrated scheme in in air which transport. there is a central node (hub) where most of the displacementsThe term H&S are means concentrated, a network connectedscheme in which to a set there of peripheralis a central node nodes (hub) through where amost set ofof rays the displacements are concentrated, connected to a set of peripheral nodes through a set of rays (spokes). This model has considerable advantages over a solution with point to point (P2P) connections (spokes). This model has considerable advantages over a solution with point to point (P2P) between all the nodes of the network. For example, if it is necessary to connect six different nodes, the connections between all the nodes of the network. For example, if it is necessary to connect six total numberdifferent ofnodes, P2P the connections total number would of P2P be connections equal to 42 would (Figure be 3equala); with to 42 an (Figure H&S 3a); approach, with an inH&S which an intermediateapproach, in hubwhich node an intermediate is appropriately hub node inserted, is appropriately the number inserted, of connections the number wouldof connections drop to six (Figurewould3b). Indrop general, to six (FigureN is the 3b). number In general, of theN is connectedthe number nodesof the connected and the number nodes and of the links number is N ( ofN -1)/2 · for a P2Plinks network, is N·(N-1)/2 but for only a P2P (N network,-1) for a but H&S only network. (N-1) for a H&S network.

(a) (b)

Figure 3. Network schemes: (a ) Point to Point (P2P) Network; (b) Hub and Spoke (H&S) Network.

Figure 3. Network schemes: (a) Point to Point (P2P) Network; (b) Hub and Spoke (H&S) Network. It follows that, with the same flow and if the traffic between two nodes is conveyed through a hub, a greaterIt follows saturation that, with of the the intermediate same flow and sections if the traffic is possible. between Therefore, two nodes if is it conveyed were not through economically a convenienthub, a (duegreater to thesaturation reduced of flows) the intermediate to connect twosections nodes is (Apossible. and B) Therefore, of the network if it were directly, not the transiteconomically from a hub convenient could make (due it to possible the reduced to realize flows) a to connection connect two (even nodes if (A indirect) and B) of by the exploiting network the greaterdirectly, flows the to/from transit the from hub a itself.hub could Moreover, make it ifpossi a supportble to realize hub is a used,connection the greater (even if saturation indirect) by of the sectionsexploiting to/from the the greater central flows node to/from allows, the in thehub unititself of. Moreover, time, a greater if a support frequency hub is of used, connections the greater to/from the hubsaturation itself and of the therefore sections also to/from between the central two “peripheral” node allows, nodes.in the unit Compared of time, a to greater a direct frequency (feasible) of trip, connections to/from the hub itself and therefore also between two “peripheral” nodes. Compared to the main disadvantage is the longer travel time caused by the greater distance traveled between node a direct (feasible) trip, the main disadvantage is the longer travel time caused by the greater distance A to node B, passing thought the hub (AH + HB > AB). traveled between node A to node B, passing thought the hub (AH + HB > AB). The H&SThe H&S system system offers offers the the opportunity opportunity to to exploit exploit the economies induced induced by bythe the concentration concentration of flowsof flows at a transshipmentat a transshipment point, point, but but it it naturally naturally requiresrequires an an efficient efficient orga organizationnization of degroupage, of degroupage, storage,storage, and groupageand groupage services, services, so so as as to to facilitate facilitate the the operationsoperations of of sorting sorting and and distribution. distribution. The choiceThe choice of hub of hub nodes nodes must must be be made made according according to the the economic economic and and temporal temporal profile profile of the of the territoriesterritories that that can can be servedbe served using using land land and and sea sea feederfeeder links. The The presence presence of a of hub a hub in a inspecific a specific geographicalgeographical area hasarea ahas synergistic a synergistic and non-competitiveand non-competitive function function with with the the other other regional regional freight freight nodes. The requirementsnodes. The requirements that a hub that node a hub should node have should are: have are: • Strategic position; Strategic• position; • Rapid handling times of goods (turn-around); Rapid handling times of goods (turn-around); • Sustainability 2020, 12, 776 6 of 14

Sustainability 2020, 12, 776 6 of 13 High level of service characterized by efficiency, productivity, and competitive costs; • HighFrequent, level fast, of service and effi characterizedcient land (road by and efficiency, rail) and productivity, maritime connections and competitive that allow costs; the expansion • Frequent,of the area fast, of influence and efficient of the node;land (road and rail) and maritime connections that allow the expansion of the area of influence of the node; Added value of logistics activities; • Added value of logistics activities; Use of advanced technologies for the management of information and physical flows. • Use of advanced technologies for the management of information and physical flows. Given its peculiarities and its strengths, the H&S model is proposed, with appropriate specifications, Given its peculiarities and its strengths, the H&S model is proposed, with appropriate for the modeling of Euro-Mediterranean freight transport networks where an equipped logistics system specifications, for the modeling of Euro-Mediterranean freight transport networks where an equippedin a central logistics region ofsystem the Mediterranean in a central region is assumed of the as Mediterranean the hub. The proposed is assumed model as the is oriented hub. The to proposedobtain economies model relatedis oriented to the to configuration obtain economies of an intermodal related to sea-rail the configuration network with of a huban intermodal in Calabria sea-railon which network the connections, with a hub coming in Calabria from on the which southern the connections, shore of theMediterranean coming from the and southern/or from shore Eastern of theEurope, Mediterranean stand and spokesand/or services from Eastern (rail or Europe, sea) allow stand the connectionand spokes with services Central (rail and or Western sea) allow Europe the connection(Figure4). The with figure Central shows, and through Western chromatism, Europe (Figur thee decomposition4). The figure shows, and re-composition through chromatism, of the goods the decompositionloads by destination. and re-composition of the goods loads by destination. Calabria, in in the the heart heart of of the the Mediterranean Mediterranean basin, basin, is a is region a region equipped equipped with with ports ports of great of great and mediumand medium capacity capacity (Gioia (Gioia Tauro, Tauro, Vibo Vibo Valentia, Valentia, Crotone, Crotone, Corigliano) Corigliano) that that are are able able to to assume assume the connotations of an integrated European logistics platform projected on both the Adriatic–Ionian corridor and the Tyrrhenian corridor.corridor. The The ongoing ongoing upgrade upgrade of of the Italian rail transport network along the Ionian-Adriatic route, with the Southern te terminalrminal in the port port of of Gioia Gioia Tauro Tauro (railway C line with transit capacity for 750 m trains), with servic serviceses structured structured to to link link in in sequence sequence the the four four ports, ports, prefiguresprefigures a reliable, eefficient,fficient, and eeffectiveffective option of spokes towards Central Europe that could be very advantageous compared to direct transport byby seasea inin termsterms ofof costscosts andand traveltravel times.times.

Figure 4. H&SH&S system system for for Mediterranean area.

4. Impact Impact Analysis Analysis for for a a H&S H&S Network. Methodological Methodological Approach Approach The methodological approachapproach forfor thethe evaluation evaluation of of the the impacts impacts deriving deriving from from a reorganizationa reorganization of ofmaritime maritime services services from from a P2Pa P2P conﬁguration configuration to anto an H&S H&S structure structure is ais simulative a simulative approach approach (What (What if); if);however, however, some some analyzes analyzes are are also also underway underway through through the the optimization optimization approach approach (What (What to). to). A macroscopicmacroscopic and and stochastic stochastic simulation simulation model wasmodel used. was Figure used.5 schematizes Figure 5 the schematizes methodological the methodologicalapproach followed approach in the research.followed in the research. Sustainability 2020, 12, 776 7 of 14

Sustainability 2020, 12, 776 7 of 13

Network Graph Cost Functions

Time Monetary Cost

Network Model

Set of Paths Evaluations

Results and Comparisons

FigureFigure 5. 5.Methodological Methodological approach. approach.

It providesIt provides for for the the schematization schematization of maritime maritime connections connections by means by means of a graph. of a graph.The graph The G = graph G = (N(N,L,L)) isis defineddefined by identifying identifying the the set set of of nodes, nodes, N,N and, and the the set setof links, of links, L (consistingL (consisting of nodes of nodes pairs pairs belongingbelonging to N ).to The N). nodes The representnodes represent the maritime the portsmaritime where ports Ro-Ro where lines Ro-Ro have anlines origin have/destination. an origin/destination. The nodes are characterized by times and costs related to freight handling and to The nodes are characterized by times and costs related to freight handling and to the stop in port. The the stop in port. The links, instead, represent a phase of connection that is the distance covered on links, instead, represent a phase of connection that is the distance covered on maritime routes and/or maritime routes and/or activities related to the displacement; in any case, the crossing of the link is activitiescharacterized related toby thetravel displacement; times and costs. in anyThe case,network the model crossing is obtained of the link through is characterized the association by of travel timesspecific and costs. cost functions The network to nodes model and islinks. obtained through the association of specific cost functions to nodes andThe links. assessment of path costs can be realized in terms of generalized transport cost or by Theconsidering assessment the separately of path costs non-homo can begeneous realized cost in terms components of generalized (time and transport monetary cost cost). or In by the considering first the separatelycase, it is possible non-homogeneous to have a summary cost componentsindicator, which (time is very and useful monetary in the cost).comparison In the of first different case, it is possiblealternatives. to have aIn summary the second indicator, case, instead, which the is very interpretation useful in theof comparisonphenomena by of distakeholdersfferent alternatives. are In thesimplified; second case, in fact, instead, they consider the interpretation time or monetary of phenomena cost in relation by stakeholders to the delivery are and simplified; the freight in fact, type. The paths are generated with reference of graph and the related evaluation are realized in they consider time or monetary cost in relation to the delivery and the freight type. The paths are terms of: generated with reference of graph and the related evaluation are realized in terms of: • Network length or distance (L) traveled; Network• length or distance (L) traveled; • Service frequency (q); Service• Number frequency of ships (q );necessary to guarantee services (nS); • • w NumberMiles of traveled ships necessaryin a week ( toM guarantee); services (nS); • • Capacity offered by services, given the network configuration (NC); Miles traveled in a week (Mw); • • Monetary cost for a Ro-Ro shipping operator (CSO). Capacity offered by services, given the network configuration (NC); • The frequency of the service (q) on the single connection can be evaluated in relation to the time Monetary cost for a Ro-Ro shipping operator (CSO). • taken to complete a trip (tv): The frequency of the service (q) on the single connection can be evaluated in relation to the time tv = ts + t(p_O) + t(p_D) + tr, (1) taken to complete a trip (tv): where tS is the travel time by sea, tp_O and tp_D are, respectively, the time spent at the port of origin tv = ts + t(p_O) + t(p_D) + tr, (1) and the port of destination for the exit/entry from/to the port of the ship and for loading/unloading whereoperations,tS is the traveland tr is time the time by sea, for thetp_O shipand re-equipmenttp_D are, respectively, for a new journey the time and spentthe re-alignment at the port of of the origin and thedeparture port of times. destination Starting for from the the exit time/entry required from/to to thecomplete port of a thejourney ship andexpressed for loading in days,/unloading it is operations,possible and to evaluatetr is the the time number for the of shiptrips re-equipmentthat can be made for in a a new week: journey and the re-alignment of the departure times. Starting from the time requiredq to= 7/(2· complete tv). a journey expressed in days, it is possible (2) to evaluate the number of trips that can be made in a week: The miles traveled on the network in a week (Mw) to carry out the services are evaluated as:

i Mwq == ∑7i /M(2w =t v∑).i qi · Li, (3) (2) ·

The miles traveled on the network in a week (Mw) to carry out the services are evaluated as: X X i Mw = Mw = q L , (3) i i i · i Sustainability 2020, 12, 776 8 of 14

i where Mw are the miles traveled in a week along the link, i, qi is the frequency of the service related to the link, i, and Li is the maritime distance between the ports connected by the link, i. The line capacity oﬀered by the network is given by: X X N = N = q S . (4) C i Ci i i · Ci where NCi is the line capacity oﬀered on link i; qi is the frequency of the service related to the link, i, and SCi is the capacity of the ship used on link i. The evaluation of the monetary cost (CSO) incurred by the Ro-Ro shipping operator is carried out with an aggregate model: C = cu L, (5) SO · where L (sea miles) is the distance by sea and cu (€/mile) is the unitary cost that can be evaluated as the ratio between the annual cost (Cyear) of the service on the route and the miles annually traveled on the same route (Lyear): cu = Cyear/Lyear. (6)

In particular, Lyear is evaluated by using the following formula:

Lyear = nw n Lp, (7) · f · with nw being the number of weeks of annual navigation, nf being the number of trips per week, and Lp being the port-to-port distance expressed in nautical miles. The Cyear cost is expressed according to the meters-miles (MM) produced by the ship in a year as:

Cyear = cyear MM, (8) · where: MM = Lyear T l , (9) · · T where T is the average number of transported trailers on a trip and lT is the average length of the trailer. The annual unit cost (cyear) is a function of numerous factors such as the ship’s amortization and interest (cd), insurance costs (cin), fuel and lubricant consumption (cf-l), ordinary and extraordinary maintenance (cm), crew costs (cc), and fees related to the port such as pilotage, mooring, ground staﬀ, loading/unloading charge, and agency general costs (cp):

cyear = cd + cin + cf-l + cm + cc + cp. (10)

Table2 shows the formulas for the evaluation of each cost components. The need to report annual costs to the MM arises from the heterogeneity of the parameters that come into play in determining the annual cost for the shipping operator. For the determination of the unit transport cost, in the perspective of a Ro-Ro shipping operator, the following assumptions were made:

Characteristics of the ships shown in Table3 (two di ﬀerent kind of ship); • Loading of the ship equal to 60% of the capacity; • Average journey distance of 800 nautical miles; • Service frequency equal to three routes per week; • Operational transport service for 48 weeks/year; • Unit costs incurred at the ports of origin and destination (pilotage, mooring, loading/unloading, • agency fees), according to Table4. Sustainability 2020, 12, 776 9 of 14

Table 2. Operating costs composing the annual unitary cost, cyear.

Formula Variables V–ship cost (€) cd cd = (V/VU + I)/(MM) VU–ship life (years) I–interests (€/year) c c = (O 12)/(MM) O–monthly insurance charges (€/month) in in · D–annual travel days CDF–daily fuel consumption (tons/day) c c = [(D C c ) + (D C c )]/(MM) c –fuel unitary cost (€/tons) f-l f-l · DF· f · DL· l f CDL–daily lubricants consumption (tons/day) cl–lubricants unitary cost (€/t)

CO–annual ordinary maintenance cost (€/year) cm cm = (CO + CE)/(MM) CE–extr. maintenance annual cost (€/year)

Nc–crew number cc cc = (Nc sc m)/(MM) sc–average monthly salary for crew (€/month) · · m–months of work in a year

ca–shipping agency cost (€/docking) cp-m–piloting and mooring cost (€/docking) nw–weeks of navigation in a year nf–travels per week CAd–monthly administrative cost (€/month) m–months of activity cp = [(ca + cp-m) Nw nf + CAd m+2 Np sp m + cp · · · · · · Np–staﬀ in port (cbl-O T NW nf) + (cbl-D T NW nf)]/(MM) · · · · · · sp–av. monthly salary for staﬀ port (€/month) cbl-O–handling cost to origin port (€/m) cbl-D–handling cost to destination port (€/m) T–average number of transported trailer nf–travel number Nw – number of week

Table 3. Ships characteristics.

Measure Unit 18 Knots 25 Knots m 2500 3500 Cars 5.0 m long 65 400 Ship capacity Truck 16.5 m long 12 80 Trailer 12.0 m long 260 20 Ship cost € 25,000,000 45,000,000 Ship life years 15 15 N◦ main engines unit 4 4 Main engine unit consumption tons/h 2 5 Main engine operating hours h/day 21 21 IFO180 main engines consumption ton/day 160 300 N◦ generators unit 2 2 Secondary engine unit consumption ton/day 2 2 IFO180 secondary motor consumption ton/day 4 4 Monthly lubricant consumption ton/month 0.4 0.4 Crew unit 30 45

Table 4. Unitary costs at ports.

Cost Measure Unit Value Maritime agency €/docking 1000 Pilot and moor €/docking 2000 Port oﬃce €/month 1500 Handling €/m 6 General fees €/month 15,000 Staﬀ in port unit 4 Sustainability 2020, 12, 776 10 of 14

5. Application to Test Network and Results Discussion An application is proposed on a simpliﬁed test network (Figure6), in order to highlight the Sustainability 2020, 12, 776 10 of 13 potential advantages of a structural change in the network with the transition from a diﬀuse P2P networkSustainabilityD to 2020 a H&S, 12, 776 network. EFD EF10 of 13

D EFD EF

A BCA BC

(a) (b) A BCA BC

(a) (b) Figure 6. Test network: (a) P2P Configuration; (b) H&S Configuration. Figure 6. Test network: (a) P2P Configuration; (b) H&S Configuration. It is assumed Figurethat ports 6. Test A, network:B, and C ( aare) P2P located Configuration; on the southern (b) H&S Configuration.shore of the Mediterranean Sea It is assumed that ports A, B, and C are located on the southern shore of the Mediterranean Sea (Algeria, Tunisia, and Egypt), while ports D, E, and F are on the northern shore (France, Italy, and (Algeria, Tunisia, and Egypt), while ports D, E, and F are on the northern shore (France, Italy, and Greece).It is Inassumed the H&S that network ports A, configuration, B, and C are located the hu bon (H) the was southern considered shore ofin thea barycentric Mediterranean position Sea Greece). In the H&S network configuration, the hub (H) was considered in a barycentric position (Calabria(Algeria, Tunisia,region). andIn the Egypt), first case,while the ports network D, E, ancodnsists F are of on six the nodes northern and shorenine links,(France, while Italy, in andthe (Calabria region). In the first case, the network consists of six nodes and nine links, while in the second secondGreece). case In thethe H&Snumber network of nodes configuration, is equal to se theven hu andb (H) the wasnumber considered of links isin reduceda barycentric to six. position case the number of nodes is equal to seven and the number of links is reduced to six. (CalabriaDistance region). matrices, In the assumed first case, in the the network analysis co fornsists both of networksix nodes configurations, and nine links, are while shown in the in Distance matrices, assumed in the analysis for both network configurations, are shown in Figure7. Figuresecond 7.case the number of nodes is equal to seven and the number of links is reduced to six. Distance matrices, assumed in the analysis for both network configurations, are shown in Figure 7. D E F Tot D E F Tot H A 410 1,240 1,281 2,931 584 620 691 1,895 D E F Tot A 447 B 467 916 934 2,317 D E F Tot B H 296 A 410 1,240 1,281 2,931 584 620 691 1,895 C 1,405 1,191 673 3,269 CA 821447 B 467 916 934 2,317 Tot 1,564 Tot 2,282 3,347 2,888 8,517 B 296 C 1,405 1,191 673 3,269 C 821 Tot 1,564 (b) Tot 2,282 3,347(a ) 2,888 8,517

(b ) Figure 7. Distances(a) matrices (miles): (a) P2P configuration; (b) H&B configuration. Figure 7. Distances matrices (miles): (a) P2P configuration; (b) H&B configuration. The adoption of an H&S configuration allows a considerable reduction ( 146%) of the distances − to beThe covered adoptionFigure for connections of 7. anDistances H&S configuration betweenmatrices (miles): the considered allows (a) P2P a considerableconfiguration; ports: 8517 reduction( milesb) H&B in configuration. the (−146%) P2P case: of the 3459 distances in the H&Sto be case.covered for connections between the considered ports: 8517 miles in the P2P case: 3459 in the H&STable Thecase. adoption5 shows of the an frequencies H&S configuration obtained allows for carrying a considerable out transport reduction services (−146%) in the of case the distances of a P2P networkto beTable covered configuration. 5 shows for connections the frequencies To guarantee between obtained these the frequencies,considered for carrying ports: nine out ships 8517transport aremiles necessary services in the P2P (1in per thecase: link).case 3459 of ina P2P the networkH&S case. configuration. To guarantee these frequencies, nine ships are necessary (1 per link). TheTable frequencies 5 showsTable 5.the recordedMatrix frequencies of in service the obtained case frequency of a forH&S (trips carrying configuration/week) out in P2P transport networkare shown services configuration. in Table in the 6. Tocase guarantee of a P2P network configuration. To guarantee these frequencies, nine ships are necessary (1 per link). the service, six ships are required. D E F Tot The frequencies recorded in the case of a H&S configuration are shown in Table 6. To guarantee the service, six ships are required. A 3 1 1 5 Table 5. Matrix of serviceB frequency 2 (trips/week) 1 1 in P2P5 network configuration. C 1 D 1E F Tot 2 4 Table 5. Matrix of service frequency (trips/week) in P2P network configuration. Tot 6A 3 41 1 5 4 14 B D2 E1 1F Tot5 CA 13 1 21 45 The frequencies recorded in the case ofTotB a H&S62 41 configuration41 145 are shown in Table6. To guarantee the service, six ships are required. C 1 1 2 4 Table 6. Service frequency (Trips/week)Tot 6 4 4 in14 H&S network configuration.

Origin Destination Trips/Week Table 6. Service frequency (Trips/week) in H&S network configuration. A H 2 OriginB DestinationH Trips/Week 3 CA H 2 HB DH 23 HC HE 2 H DF 2 H Tot E 13 2 H F 2 Tot 13 Sustainability 2020, 12, 776 11 of 14

Table 6. Service frequency (Trips/week) in H&S network conﬁguration.

Origin Destination Trips/Week A H 2 B H 3 C H 2 H D 2 H E 2 H F 2 Tot 13

Given these frequencies, it is observed that in the case of a P2P network, about 22,655 miles are traveled in a week compared to the 13,736 traveled in the case of an H&S configuration, with a reduction of 65%. The capacity of the system in terms of transported trailers per week is almost unchanged between the two network configurations. The costs incurred by the shipping operator are instead reduced by 65% when moving from the P2P network to the H&S network. The fleet has reduced by a third (six ships instead of nine ships). Table7 shows a summary that allows comparison between the two examined network configurations.

Table 7. Summary framework for network comparison.

H&S Parameters P2P Origin-Hub Hub-Destination Total Distance (miles) 8517 1564 1895 3459 Frequency (trips/week) 14 7 6 13 Ship number 9 3 3 6 Network length (miles/week) 22,655 6591 7145 13,736 Capacity (trailers/week) 8068 4255 3368 7624 Cost for shipping operator (€/week) 2,686,309 781,481 847,266 1,628,746

To make the service more attractive in the case of a H&S network conﬁguration from the perspective of a multimodal transport operator (MTO), it is possible to use a number of ships equal to those used in the case of a P2P network (i.e., nine ships), thus ensuring a greater frequency of service on some links (in this case, the longer ones). Even in this case, good results can be obtained in terms of miles/week traveled and costs for the shipping operator (Table8) obtaining advantages also for an MTO or services with higher frequency and an increase in transport capacity.

Table 8. P2P and H&S comparison.

H&S Parameters P2P ∆ Origin-Hub Hub-Destination Total Distance (miles) 8517 1564 1895 3459 146% − Frequency (trips/week) 14 9 6 15 +8% Ship number 9 5 3 8 13% − Network length (miles/week) 22,655 9384 7580 16,964 34% − Capacity (trailers/week) 8068 5340 3560 8900 +9% Cost for shipping operator 2,686,309 1,112,724 898,812 2,011,536 34% (€/week) −

The results obtained on the test network show an effective convenience in the adoption of a H&S network configuration. However, it is of benefit to observe that a real change implies a specific agreement among the existing shipping operators or the monopoly of the maritime services. The Sustainability 2020, 12, 776 12 of 14 reduction in traveled distance can give significant energy and pollution savings, as well as increasing general safety. A further analysis was carried out with reference to the current status considering some of the maritime connections operating between the southern and northern shores of the Mediterranean

(FigureSustainability8), assuming 2020, 12, 776 an H&S network as the scenario conﬁguration. 12 of 13

Trieste

Genova Marsiglia

Civitavecchia

Salerno

Mersin Skikda Tunisi

(a)

Trieste

Genova Marsiglia

Civitavecchia Salerno

Calabria Hub Mersin Skikda Tunisi

(b)

Figure 8.8. Ro-RoRo-Ro network:network: (a) CurrentCurrent configuration;configuration; CurrentCurrent Status—P2PStatus—P2P connections;connections; ((b)) ScenarioScenario Configuration;Configuration; Scenario—H&SScenario—H&S Configuration.Configuration.

Table9 9 summarizes summarizes the the obtained obtained results. results. TheThe transitiontransition toto aa H&S H&S network network configuration configuration leadsleads toto aa 0.75%0.75% increaseincrease inin thethe distancesdistances toto traveltravel andand 10%10% inin thethe milesmiles travelledtravelled inin aa week.week. TheThe H&SH&S configurationconfiguration alsoalso allowsallows anan increaseincrease inin frequencyfrequency ((+28%)+28%) andand transporttransport capacitycapacity ((++28%)28%) againstagainst the use of eighteight shipsships againstagainst the fivefive currentlycurrently inin useuse onon thethe currentcurrent status.status. There is also an increase in costs ((++1010%)%) for Ro Ro-Ro-Ro shipping operators.

Table 9.9. Comparison between P2P network (Current Status)Status) andand H&SH&S (Scenario).(Scenario).

H&SH&S ParametersParameters P2P P2P Δ (%) ∆ (%) Origin-HubOrigin-Hub Hub Hub-Destination-Destination Total Total Distance (miles)Distance (miles) 38153815 16641664 21802180 3844 3844 0.75 0.75 Frequency (tripsFrequency/week) (trips/week) 1313 66 1212 18 1827.78 27.78 Ship numberShip number 77 33 55 8 812.50 12.50 Network lengthNetwork (miles length/week) (miles/week) 6386 6386 27132713 44054405 7118 7118 10.28 10.28 Capacity (trailersCapacity/week) (trailers/week) 23212321 10711071 21432143 3214 3214 27.78 27.78 Cost for shippingCost for operator shipping (€ /operatorweek) (€/week) 220,700 220,700 93,76193,761 152,237152,237 245,998 245,998 10.28 10.28

ItIt shouldshould be be noted noted that that the the transition transition to the to scenario the scenario conﬁguration configuration allows a allows considerable a considerable increase inincrease frequencies, in frequencies, guaranteeing guaranteeing a rapid service a rapid and service the strengthening and the strengthening of the transport of the transpor supply. t supply.

6. Conclusions The configuration of the H&S network improves the cost/service ratio and allows the reduction of efficiency losses related to P2P transport due to poor reliability, high costs and times, low frequency, restricted space penetration, unbalanced traffic by direction, and low utilization of the maritime Ro-Ro lines. A system with hub nodes (logistic/intermodal terminals) and feeder connections (by road, by rail, and by sea) offered in terms of unique contractual/transport tariffs can determine a higher average utilization coefficient of the network, a higher frequency of services, a Sustainability 2020, 12, 776 13 of 14

6. Conclusions The configuration of the H&S network improves the cost/service ratio and allows the reduction of efficiency losses related to P2P transport due to poor reliability, high costs and times, low frequency, restricted space penetration, unbalanced traffic by direction, and low utilization of the maritime Ro-Ro lines. A system with hub nodes (logistic/intermodal terminals) and feeder connections (by road, by rail, and by sea) offered in terms of unique contractual/transport tariffs can determine a higher average utilization coefficient of the network, a higher frequency of services, a greater spatial extension through the increase in the number of achievable destinations, and a more efficient use of transport units and loading units. The paper proposes the results of the first phase of research, in which the point of view of the Ro-Ro shipping operator has been examined and only maritime-type spoke connections have been considered. The research foresees different future developments:

Extension on a large real context; • Analysis of MTO and community point of view; • Consideration of rail spoke connections to promote intermodality; • Analysis of H&S systems in term of transport demand impacts; • Evaluation of eﬃciency and eﬀectiveness of the hub node (groupage/degroupage operations). •

Author Contributions: Short Sea Shipping in the Mediterranean. Potentialities and limits, D.G. and G.C.C.; Hub and Spoke network to produce economies, G.C.C.; Impact analysis for a H&S network. Methodological approach, D.G., G.C.C., and M.M.; Application to test network and results discussion, D.G., G.C.C., and M.M. All authors have read and agreed to the published version of the manuscript. Funding: This research received no external funding. Conﬂicts of Interest: The authors declare no conﬂict of interest.

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