Connectivity is the extent to which passengers or freight flows from a node can reach other nodes directly (direct connection) or indirectly through another node or a series of nodes. It draws from conventional graph theory, which investigates the arrangement of nodes and links in networks. Therefore, connectivity is a relative concept since a node has a level of connectivity in relation to other nodes. While a node can represent many functional entities such as a corporation, a city, or a region, transportation and trade connectivity usually focus on terminals such as ports and airports that are fundamental nodes and the carrier services between them. There are three main types of connectivity effects:
- Economic. Concerns interactions that connectivity makes possible between actors such as producers, retailers, or wholesalers. Thus, an increase in connectivity enables less costly commercial interactions, which results in more opportunities to trade. The outcomes of connectivity are often difficult to predict since commercial decisions about importing and exporting are made by numerous entities that make their own assessments and independently act upon them.
- Network. Concerns the configuration of the transport services and the physical infrastructure between nodes with attributes such as capacity, reliability, and even resilience. Connectivity remains strongly dependent on transportation networks that provide the physical capability to reach places which can be done through a single or a series of modes. The main actors are terminals that provide the intermodal handling of flows, the carriers that handle the movements between nodes, the shippers that organize the distribution of cargoes, and infrastructure managers (e.g. port authorities, transport ministries) that maintain and expand nodes and modal links.
- Spatial. Connectivity is impacted by and impacts the spatial structure and is subject to policy interventions. Nodes are servicing spatial entities such as metropolitan areas or regions that act as their hinterland, making connectivity a factor of spatial competitiveness. The outcome of differences in connectivity is usually the clustering of activities around the most connected nodes, which is associated with inequalities in development opportunities. Therefore, governments and civil society have an interest in maintaining and improving connectivity since it has direct welfare outcomes over their territories.