TRANSPORT CONCEPTS, MODES AND THEORIES
CONCEPTS
concept is our perception of reality to which we have attached some word labels for the purpose of identification A concept expresses an abstraction formed from our generalization of different forms of reality.
Concepts can be regarded as assumptions, principles, fundamentals, features or conventions which provide the unifying character to the theory, concepts serve as 'building blocks' for theories, explanation and predictions.
Concept is used in research and science because of its function which include:
1. Concept helps in the articulation of communication and thoughts.
2. Concept introduces a view point as a way of looking at empirical events and activities.
3. Concept functions as a means of classification and generalization, as well as enables ideas not onIy to have sharp focus, but also to introduce an order into the arrangement of thought arising from empirical observations.
Concepts are used in transport researches and in transport operations, some concepts have been developed. The concepts are:
1. The concept of safe arrival.
2. The systems concept.
3. Total distribution concept.
4. Through Transport concepts.
5. Productivity concept.
6. Profit maximization concept.
7. Optimum port capacity concept, etc.
BENSON D and WHITEHEAD G (1975) stated that "Transport provides the means of bridging the geographical gaps between producers and consumers. but it's function will not have been carried out properly unless the goods and passengers arrive safely at their destination. They noted that" the concept of safe arrival as an essential element in the carriage of goods and passengers has therefore been recognized from very early times as an essential element of transport.
The system concept examines the system as a 'whole body' made up of different components. In transport, system concept applies. BENSON and WHITEHEAD G (1975) noted that "Every mode of transport uses four major components or essential elements of transport. These are the way, the terminal, the unit of carriage and the unit of propulsion". These sub-systems must work effectively and efficiently, separately and collectively to produce result. Also, all modes must be inter-linked and coordinated for effective services and efficient operations in terms of smooth movement, safety, time, comfort and cost effectiveness.
Concept is necessary in distribution activities. BENSON D and WHITEHEAD G (1975) noted that in total distribution concept. factors such as market forecasting, material handling, space utilization, inventory control, natural wastages, damage during handling or storage, employee fatigue, employee motivation, safety, protective packaging, security, speed of transit, depot location, inter-modal handling, order processing and documentation as well as customer services will become part of the overall strategy, and the plan will aim to overcome the difficulties envisaged"
In social and scientist researcn, concept enables me researcher to carry out interactions with his own environment. The researcher indicates to himself what a concepts means as well as the designation of that meaning.
MODELS
A model is a representation and simplification of reality. Models are expressions which can be in mathematical form, in blocks, arrows and combination of others. Models are construction of abstraction which sometimes involves conceptual transparency with specific reference to concepts and theories. Models are two major classes. These include:
1. Models which are based on their level of abstraction and they are;
a. Analogue models, which are reduced to scale models
b. Symbiotic models, which have mathematical relations
c. Icons models, which use scale representation like maps.
2. Models which are based on the functions including;
a. Normative models, which are deterministic and can make accurate and unyielding predictions. As well, it is optimizing and can maximize objective function subject to a number of constraints.
b. Stochastic models, which are based on probability theory and can accommodate the probabilities and unknown inherent in human spatial and locational behaviours.
In research, models are used and instead of discussing the situation directly models are used to simulate such situation mathematically or with phvsical object. Models in transport research are used to perform a multiplicity of functions and they are use as tools to understand, explain and predict phenomenon or any event based on empirical observations.
Model building is a very important part of the transportation planning processes. Because model building is an essential element of the transportation planning process, it is useful to highlight here, that its importance has been recognized by transport researchers and planners.
Trip generation models can use mathematical relationships to describe trip- making behaviours and complementary linked systems of relationships, such as the transportation planning process.
In its application, a transport researcher or planner may make observation of the situation in an urban area in which journeys are made. He then defines certain variables which he might accept to describe the situation he is observing, such as the total number of journeys and the population of the area. He may further suggest that the number of trips made is directly proportional to the number of peopie in the area. He can therefore state that:
Ti is the number of trips
Pi is the population in the area
He can then put the relationships in a model by using the equation
Ti=gPi
This form of model is useful in the sense that:
A. It is a form of communication in directing numbers of trips (Ti) number of people (P) and a constant (G)
B. It scales down the situation to manageable proportions, using the equation to represent many people, many vehicles and movements.
C. It may be able to help illuminate some particular problems. The model may be used not only to describe the number of trips made by a particular population but also to calculate the new number trips made by a new population. In doing this the observer may measure population Pi and the number of trips Ti and by division establish gi knowing a new population Pk, a forecast can be made of the trips that would be made. Tk using the model and making the assumption that the vaIue of the constant g, measured in one case, may be applied to other cases.
Models can be used to predict future events and scaIe down the size of the problem; they are of particular values in the repeated testing of new policies. For example varying environmental conditions, various transport facilities and other variabies can be tested by repeated use of the model.
Models are in general not easy or simpIe to use because some transport models are complex. Transport models attempt to describe the travel patterns of large number of people, using a series of linked sub-models and can be considered a deception of decision making process the average person might be expected to use when he considers making a journey.
THEORIES
A theory is a generai statement that defines and explains the interrelations among a number of variables. A theory is a statement of invariant relationship among measurable phenomenon with the purpose of explaining and predicting the phenomenon.
Theories are therefore statements consisting constructs and concepts. Theories are statements of facts, which provide the framework to understanding what has happened, what is happening and what is likely to happen based on empirical observations. The basic function of theories in empirical research is to guide and provide explanations.
Theories are very important in transport research. A lot of theories have been developed in transportation.
Ullman E. L. (1973) in his Geography as Spatial Interaction Studies in Regional Development, Cities and Transportation, stated that the interactions involving transportation involve complementarity, intervening opportunity and transferability. This statement gives birth to Ullman's principles of transport, adopted by ROBINSON H and BAMFORD C. G. (1978) That is to say for any transport service, there must be demand on one side and supply on the other side there must be journey purpose, need and demand that will warrant the supplier to complement. As transport takes place and movement involved, occasions may warrant intervening opportunity. Again the principles of transferability does not mean movement of goods or transfer of people rather explains that transport supply attracts costs of production to the supplier. Therefore, these costs must be covered by transferring them to the users who pay for the services.
Discussing the need to Keep all forms of transport moving, BENSON D and WHITEHEAD G. (1975) stated that "Any form of transport earns revenue only when it is doing the job for which it was designed for; carrying people and goods. At all other times. it is generating costs". This theory he called the first principle of successful transport operation.
Other transport theories include:
1. Queuing theory
2. Management theory
3. Stakeholders theory
3. Performance analysis, etc.
There are lots of theories in transport studies. Theory is highly used in research work. Theories are also adapted in many other disciplines such as economics, geography, engineering, physical planning, sociology and psychology.
THE RELATIONSHIP BETWEEN CONCEPTS, MODELS AND THEORIES
In transport studies, concepts, models and theories are used to a great extend, and they form the basic language of communication.
The relationship between concepts, models and theories is glaring. While concepts express abstraction formed from our generalization of different forms of reality they can become the basis for scientific testing which if proved and accepted, can form a body of theory. The concept which is subjected to scientific testing forms the basis for theorisation and from this theory models can be developed. In transport research many researchers use mathematical equations, matrices as well as algebra to translate theories to the extent that mathematical theories and models in form of abstractions are commonly used. Models cannot be well developed without concepts and theories, because in addition to abstractions, model building sometimes involves a conceptual transparency with specific reference to concepts and theories while concepts develop the ideology, theories formalize and models simulate the ideas mathematically. For a good research work, there must be concept giving rise to theory and finally model and research.