Table of Contents
What is Transport Network?
Transport network or transportation network refers to an integrated pattern in which route of group of centres also known as nodes (place of offloading and offloading of goods) are linked by routes. Transport network is the overall system consisting of transport route and mode. Networks are connected through roads and streets, railways, pipes, aqueducts, and power lines.
Network density is the number of links per unit area or the total network length divided by the area it covers. In some instances, the beta index could also be used. Network by the number of links is made up of density of transportation network, it is easily measured mainly in terms of an index of density length (mainly measured in Km/s) of road, railway or the transport medium per 1000sqkm of network area.
Network density may indicate state of economic buoyancy (Prosperity). The greater the density and the better the index, the more advance a country is. There are variations in transportation networks, these is measured in terms of concentration, extent and efficiency due to physical, cultural, technological and economic factors. Network density is a transportation component that is always overlooked and simplified, but when it is utilized properly, network density can yield increase in efficiency and save cost. The network varies in terms of concentration, extent, and efficiency. In transportation, the ultimate good is to increase efficiencies within carrier networks so that savings can be achieved.
Density: When fright is located together geographically and moving at approximately the same time, carriers have more choices and opportunities, this is called density
Major types of transport Network
There are six (6) major types of transport network, these six types of transportation network was identified by Bunge (1966), he identified the six major types of transportation based on hypothetical assumptions of five modes indicated as follows:
- Paul Revere Network
- Travelling salesman network
- Centre-oriented network
- Circuit network
- Branching network
- Branching Circulatorynetwork
Paul Revere Network
Paul Revere Network is the simplest and it exists where a single route connects all modes, its main disadvantage lies in the fact that the return journey from E- A must pass through the intervening modes which can be slow and tedious. A solitary railway line linking a part with a mining settlement would be an example of this type of network.for example a line from Sept.less to Schedferville in Labrador and this type of network is also common in developing countries for example in Nigeria, Blanca and Zapala.
The travelling salesman network provides the shortest route around all the nodes but journeys between the nodes still involve movement throughout other nodes. In this case, travel from B-D would mean passing through C. Such a network may exist in less developed regions in areas of difficult terrain or islands. The main road around the isle of Arran (Scotland) is one example.
Centre Oriented Network
This network tends to result in congestion at certain points since cross-country movement is impossible. Example is the diagram below. In this case, all traffic must pass through D, which will thus be congested. Many countries towns are linked by road to surrounding villages in this way so that inter-village movement must involve these towns. For instance, both rail and road networks in South-East England centre on London, making that city the route focal point, while the railways of Prairies (Canada) centre on Edmonton.
This is a network where all nodes are connected to all the other nodes and movement between any two settlements. This is the most efficient network since connection is by the shortest route. This pattern offers the least cost to the user but has the disadvantage of being the most costly to the builder. Roads especially those in developed countries tends to have this type of network.
If circuit networks are more preferred by the customers, branching networks are most preferred by the builders. Such a pattern provides the shortest route connecting all the nodes, while at the same time allowing all journeys to by-pass intervening nodes. Thus travelling from B-D will not involve A, C and E. railway network tend to be of this type
Branching Circulatory Network
This network is a compromise between branching networks and circuit networks; it provided fairly efficient routes at less than maximum cost. The London underground railway system is an example of this type of network. Often areas contain not a single network but several in super imposed unto the other that is why we have trunks A, B and C. Similarly, railway networks can be subdivided into major routes and branch lines, air networks between international, national and local traffic.
Techniques of Transport Network Analysis
The degree of transport network efficiency can be measured by a number of indicators and techniques.
- The first indicator of efficiency is the degree of connectivity of the network- connectivity is the relationship between the number of nodes and the number of links or routes within a single network and it is measured by the Beta index () and the alpha index (). The Beta index is obtained by dividing the total no of links by the total number of nodes. Connectivity increases as the index increase for a given number of nodes the more routes that connects them, the greater the connectivity. The alpha index on the other hand compares the observed number of links with the maximum possible number of links for a given number of nodes.
- Another indicator of network efficiency is the degree of centrality of nodes. Centrality is measured by means of Konig index which is the maximum number of links from each nodes to the other nodes in the network, the lower the value, the greater the centrality.
- The third measure of transport network is density pattern. The density of a transport network is usually expressed as the number of links per unit area, i.e. the total network length divided by the area it covers. The density can also be measured by Eta index () which is obtained by dividing the total length of network by the number of links which makes up the network and the greater the density, the more efficient the network.
- The forth measure of network of efficiency is by extent which is the degree of a compactness or dispersal of transport network. This is usually measured by the diameter index, which is the number of links used in crossing the network from one side to another at its widest point and the lower the index, the more compact, and more efficient the network will be.
- The fifth measurement of network efficiency is the fineness of the network and it refers to the degree in which the network of individual link has effect upon the area through which it passes. Fineness usually depends on factors of various localities to each route as it passes through. Road networks usually have greater fineness than railway and the air networks. Other indicators of network efficiency include flexibility, rate of flow, technological characteristics. In most cases, road network has flexibility than other transport system.
Factors influencing transportation Development
Emergence of transport and communication system within any area of any region is usually influenced by a variety of factors. Ullman (1956) identified three basic factors influencing transportation development and these are:
- Regional complementarity
- Intervening opportunities
- Regional complementarity: regional complementarity is usually created by special differentiation in the availability of resources and goods. For two places to interact there must be a demand in one place and supply at the other place and demand and supply must be complementary. Regional complementarity is therefore an important condition for spatial interaction and transport development.
- Intervening opportunities: this refers to the occurrence of alternative supply or demand for goods and services between two regions which are involved in spatial interaction. Complementarity between places can generate spatial interaction and interchange only in the absence of intervening opportunities. Intervening opportunities may curtail or restrict the development of transportation.
- Transferability: transferability refers to the constraint imposed on movement of goods and people over certain distance and transferability is usually measured in time and cost. Where transport cost between two places is too high, spatial interaction and movement between such places may be limited. This can happen even in a situation where there is perfect complementarity and absence of intervening opportunities. Transferability conditions are usually not static. They change with time as a result of improvement in transportation with classes of movement and modes of transport.