The activity level of the ports is closely related to the dynamics of the hinterland, subject to continuous changes in terms of accessibility and logistics. The competitiveness of a port depends on several factors as the network transport supply to move freight towards the inland final destination [1]. According to some researchers, hinterland connectivity is the second most important factor driving the port competitiveness, after costs to cross the port [2, 3]. The ability to penetrate the hinterland is realized through efficient inland logistics and connections able to guarantee the speed of goods flows. Ports have to be configured as an efficient and logistically effective interface between oceanic maritime trade and inland trade which have different characteristics, dimensions and rhythms.

Some analyses emerging from the COREALIS research project [4] show the impact that a mega container ship (14,000 TEUs) can give on a port hinterland (Fig. 1). Assuming 8,000 TEUs are unloaded in port, of these 4,000 TEUs are destined to the hinterland (10% by rail and 90% by road), 11 trains and about 2,500 trucks would be needed, with a great impact on hinterland in terms of traffic and freight flows.

The concept of port hinterland has been treated within the European ISTEN project (Interreg Programme VB) by the authors and a specific bibliographic analysis proposed [5].

There are many definitions of ports hinterland. The first definition of the port hinterland was provided in 1938 by Sargent as “the area served by a port” [6]. According to some other authors, the hinterland is a land space on which a port sells its services and interacts with its customers or a market area; other researchers define the hinterland as the area in which a port has a monopolistic position, i.e. the inner region provided by a port [7-9].

The port hinterland is made up of two parts (Fig. 2): the main hinterland and the competitive margin hinterland [10]. The main hinterland is the market area surrounding the port; it is a terrestrial space on which a port sells its services and interacts with its users. It represents the regional market share that the terminal owns, compared to other terminals that serve the same region. It brings together all the customers directly connected to the terminal and the land areas from which it draws and to which it distributes traffic. The competitive hinterland is the market area in which the port must compete more closely with the others for the companies.

Fig. (1). Impact on hinterland generated by a mega containership port call [4].

Fig. (2). Port hinterland types [10].

The main hinterland of a port is generally continuous. The density of hinterland origins or destination of a port decreases with distance. Hinterland “islands” can exist far from the port through the use of intermodal connections that allow the port to reach a competitive advantage in terms of costs and services compared to rival ports.

The hinterland can be further classified in relation to the kind of managed freights; in fact, each type of freight originates from a particular supply chain with specific spatial relationships.

A hinterland can have three basic sub-components: macro-economic, physical and logistical. The macro-economic hinterland tries to identify which factors are shaping transport demand, particularly in a global setting. The physical hinterland considers the nature and extension of the transport supply, both from a modal and intermodal perspective. Finally, the logistical hinterland is related to the organization of the flows [11].

Table 1 summarizes the main characteristics of the hinterland sub-components with particular reference to the transport supply sub-component. Transportation costs have been added as attributes time and cost reduction has been considered as a challenge.

The characteristics and dimensions of the port hinterland depend on many factors as:

• The type of moved freight, for example, for perishable goods, the time has great importance and the port hinterland is made up of the areas that can be reached in a time window compatible with their conservation [12];
• The degree of land connectivity, linked to intermodal transport services capable to guarantee the goods distribution in an efficient, reliable, rapid and economical way;
• The maritime connectivity which affects transport costs on the foreland side and consequently on the hinterland size; in fact, if the cost to reach a port is low, the number of shipping companies increases and the extension of the port hinterland increases too;
• The institutional and bureaucratic aspects as well as the presence of Special Economic Zones.

Many of these factors are not stable over time but may undergo intra-periodic (within the same period) and inter-periodic (among different periods) variations caused by changing local and global commercial, economic and geopolitical conditions.

It is important to study and analyse the port hinterland relationship in order to improve market access through the development of trade corridors, the fluidity of trade and integration into a wider logistics network.

One aspect of the analysis concerns the identification of the port's hinterlands and the definition of their dimensions; it is a theoretically complex issue due to factors such as:

• The hinterland can only be evaluated in relation to other ports as it is made up of all the areas where a port has generalized transport costs that are competitive with respect to other ports;
• The hinterland differs by type of cargo, type of stakeholder and destination abroad;
• The hinterland is not stable over time.

The paper is divided into three parts beyond the introduction and conclusions. In the first one, a state of the art model useful for the identification of the port hinterland is presented; in the second part, the proposed approach of the research and the methodology are described; the attention is focused on the cost functions useful for determining the generalized transport costs. Finally, an analytical application is proposed in order to identify and compare the potential hinterlands of two Italian container ports, Gioia Tauro and Genoa.

The proposed methodology has been applied to the two biggest Italian ports in container traffic, Gioia Tauro and Genoa, in order to identify their potential hinterland and to compare them. These two ports have different characteristics; in particular, whereas transshipment in the port of Genoa represents around 12% of total activities, the port of Gioia Tauro is dedicated exclusively to transshipment operations.

The Genoa port is one of the main ports in the Mediterranean basin and a fundamental element for the industrial activities in Northern Italy. It is configured as a multi-function port, with many terminals equipped to accommodate all types of traffic: containers, general cargo, perishable products, metals, forestry, solid and liquid bulk, petroleum products, and passengers. A part of the port offers highly specialized complementary services as shipbuilding and repairs, technology and information technology.

Gioia Tauro port is an Italian transshipment hub, it has a central location in the trades among Asia, the Mediterranean Sea and the East Coast of the United States. For this reason, the port has a relevant role in intercontinental maritime traffic. Its location represents a meeting point between the East-West Sea lines and Europe. In relation to international trade fostering the route of the Suez Canal, the port has potential in relation to large communication plans and business development. The traffic affecting the port of Gioia Tauro mainly concerns the transshipment of containers and vehicles. A railway gateway has recently been built near the port; it is today operational and regular connections are guaranteed through the Thyrrenian railway to different Italian regions.

In order to carry out the analyses, foreland has been divided into 8 large zones (Middle East; India, South East Asia; China and Japan; Southern Africa; South America and West Africa; USA/Canada and Central America; Oceania) represented through a representative container port in a barycentric position. Italy has been considered a potential hinterland and it has been divided into 18 zones corresponding to the Italian regions (excluding the islands), represented through sites corresponding to regional railway freight stations.

The evaluations have been made taking into consideration a 20’ container loaded with non-perishable goods worth € 2,000, for a total mass of 25 tons.

Table 9 shows the distances by sea between the foreland areas and the ports of Gioia Tauro and Genoa; Table 10 shows the distances by rail between the ports of Gioia Tauro and Genoa and the hinterland zones. table 11-16 show the matrixes of times, monetary costs and generalized transport costs for F-H pairs through the Gioia Tauro and Genoa container ports.

Not having indications about the availability to pay by the field operators for reaching the final destination, the hinterland dimension has been defined considering an upper bound in relation to the average generalized transport cost from each foreland to each destination port. Comparing the values obtained for Gioia Tauro and Genoa ports, the upper bound has been assumed as the higher average value (Table 17); the potential hinterland is defined as the set of the region for which the generalized transport cost does not exceed this threshold.

An analysis of the results (Fig. 5) shows that the hinterland for the Gioia Tauro port is represented by the whole Italian Country for goods from the Middle East; whereas some regions of Northern Italy are excluded if the forelands are India (Piedmont, Val d’Aosta), China, Japan and Oceania (Piedmont, Val d’Aosta, Friuli Venezia Giulia), South East Asia (Piedmont, Val d’Aosta, Liguria, Lombardy, Trentino Alto Adige).

Fig. (5). Potential Hinterland for Gioia Tauro and Genoa ports with reference generalized cost.

The freight coming from South Africa, USA/Canada and Central America, South America and West Africa, landed in Gioia Tauro, will have Central and Southern Italy as a potential hinterland.

Concerning the hinterland of Genoa port, it consists of all the Italian regions if the goods come from South Africa, USA/Canada, Central America, South America and West Africa.

The forelands Oceania and China and Japan have a Genoa hinterland represented by Central-Northern Italy. The same situation occurs in the Middle East, India and South East Asia with the exception of the Italian region of Friuli Venezia Giulia.

Comparative analyzes are not easy in relation to the heterogeneity of sources and the variability over time of the transport supply, particularly in shipping.

From the analytical results obtained, it emerges that the hinterland dimension of each port is also linked to the accesses of ships to the Mediterranean basin, Suez (East), or Gibraltar (West).

In fact, it emerges that for goods crossing the Strait of Gibraltar (South Africa, USA/Canada and Central America, South America and West Africa) the port of Genoa is more attractive.

For the goods crossing the Suez Canal to reach their destination (from Middle East, India South East Asia, China and Japan, and Oceania), the Gioia Tauro port is more convenient, in fact, its hinterland is more extensive.

Gioia Tauro records a growing trend of transshipment traffic (since 2,4 million TEUs, in 2017, to about 3,1 million in 2021 and a forecast of 3,5 TEUs at the ned of 2022) and in the last years, a part of the traffic has been shifting to continental rail transport (2,5% expected for 2022). This trend could be greatly strengthened following the ongoing upgrading of the Adriatic-Ionian railway corridor, as highlighted in the ISTEN research, as the transit time towards Central Europe could become competitive with respect to that relating to maritime transport from Suez which today reaches ports of the European Northern range through the Strait of Gibraltar, the Atlantic Ocean and the English Channel.

Gioia Tauro and Genoa ports are configured as direct competitors; really Genoa port is currently more attractive as the Gioia Tauro port is affected by the bottlenecks related to railway intermodality and the Ionian-Adriatic railway corridor.

Further analysis has been made to evaluate the extension of the hinterland of the Rotterdam port. The hinterland of Rotterdam reaches Northern Italy in relation to the road and railway transport costs (time, cost or generalized cost), thanks to the high performance of the port (on average, the goods stop for 1 day at the port before being loaded on the wagons). The improvement in the performance of the Gioia Tauro port and the enhancement of the Adriatic-Ionian railway in progress would push probably its hinterland up to Central Europe.

The paper has proposed a methodology for identifying the hinterland of a port based on considerations relating to transport costs and times. The methodology has involved a careful analysis of port-hinterland connectivity. The port-hinterland corridors can develop differently depending on the regional economic conditions and their intensity on the territory, on the importance of ports at the regional level and the characteristics of the freight transport corridors on a local, regional, or national/transnational scale. The paper has proposed furthermore an application for the identification of the Gioia Tauro port hinterland in relation to the Genoa port.

The port of Gioia Tauro could be configured as a direct competitor of the Genoa port when its inland connections will be fully operational in the next future.

The results of the proposed analyses have shown that the geographical distribution of the port hinterlands changes significantly in relation to the values of the generalized transport cost which integrates into a single indicator the travel time and information relating to the monetary cost.

A proposed methodology is an original approach that allows overcoming the limits of the geographical approach that focuses attention only on market aspects and leaves aside the transport component. The methodology is transferable to other contexts and other types of freight interchange sites by adapting the cost functions appropriately.

The research is part of the activities carried out in the ISTEN project (Integrated and Sustainable Transport in the Efficient Network), financed by the ADRION Community Program, in the context of the Interreg EU Program, aiming to improve the intermodal connections among the maritime ports of the Adriatic-Ionian area and among the ports and their hinterlands. In evaluating the potential hinterland for the Gioia Tauro port, the use of railway Ionian-Adriatic corridor could have a positive impact and could increase its international role.

In recent years, there is a strong growth of the Gioia Tauro port in terms of rail connections with Central and Northern Italy. Also, in relation to the constant growth of containerized flows (since 2,4 million TEUs, in 2017, to about 3,1 million TEUs in 2021) and furthermore, to the continuous strengthening of transport infrastructures, in particular along the ADRION corridor (Adriatic-Ionian), growth is expected in the role of the Calabrian port in relations with Central Europe. This could lead to a greater competitiveness of this port and therefore to a greater extension of its hinterland on the European continent.