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Transport modes can also be classified on the basis of power, i.e., man and animal, mechanical power driven like automobiles, trains, ships, aero planes, etc., and physical power like wind or running water, facilitating movement of goods. The form of one transport mode differs from that of another because of the technological differences between them.
Transportation fundamentally involves two aspects:
(a) A vehicle or unit of conveyance, and
(b) A medium upon which to move.
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The choice of medium determines the type and design of the vehicle. In the study of transport one is concerned with the manner in which transport takes place and, looking at the various modes, two obvious methods of analysis exist:
(i) From a geographical point of view, there are distinctions between land, sea and air transport; and
(ii) From an operational point of view, there is a distinction between the transport of goods and passengers.
Transport modes can also be classified on the basis of power, i.e., man and animal, mechanical power driven like automobiles, trains, ships, aero planes, etc., and physical power like wind or running water, facilitating movement of goods. The form of one transport mode differs from that of another because of the technological differences between them.
The most obvious example is basic difference in morphology between those modes which require a continuous infrastructure – roads, railways and canals, and those which require only discontinuous infrastructure at terminals – shipping and airways. Within the modes themselves, morphology also differs with the differing functions they are expected to perform in different geographical situations. Form and function are thus closely linked in transport geography.
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The four necessary requirements of any mode of transport are:
(i) Route,
(ii) Vehicle,
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(iii) Motive power, and
(iv) Terminal.
1. Route:
All modes of transport require some form of route, the way; course or track on which to operate, but having distinction between land transport on the one hand and air/sea transport on the other, the requirement of construction of a route way or track is a necessity for land transportation, which requires large investment before journeys can take places. Both roads and railways, the basic forms of land transport, cannot take place without the construction of suitable route ways. In comparison to roads, rail transport requires a more specific route in the form of a special track as well as other operational infrastructure like signaling equipment, etc.
Sea and air transport are comparatively free from the construction of route ways and may be said to operate in a natural rather than a man-made environment. But for inland water transport, the route requirement is for the construction of canals or the improvement of the existing natural waterways. Air transport is almost as free as a bird and in theory the route can operate anywhere and in any direction.
Pipelines have been used to carry mineral oil as well. Their construction involves heavy initial investment and maintenance. The land transport is one-dimensional, therefore, restricted by physical factors like relief, rivers, other water bodies, waterlogging, forests, etc. On the other hand, sea and air transport operate in different dimensions. Air transport is the most versatile of all and operates in three-dimensional space where altitude and direction can be adjusted.
2. Vehicle:
This is a requirement for the carriage or conveyance of persons or goods by any means of transport. The history of transport shows on ever-increasing complexity in the character of the vehicle, largely as a result of man’s increased technological knowledge and expertise and his demand for increased speed and improved carrying capacity. There is an enormous difference in the complexity of vehicles among main mode of transport.
The animal driven vehicles are still popular in developing countries, so is the bicycle. The auto-vehicles have now become an integral part of our transport system. The railway locomotive, ships and aeroplanes are the principal vehicles of the modern times serving the entire world community.
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The size, shape and speed of these vehicles are changing day-by-day with the changing technological pattern. There is a vast variation in the carrying capacity of different vehicles. The railway can carry much greater loads than motor transport. On the other hand, air transport has limited carrying capacity and is costly too. Water transport is especially suited to the heavy, bulky nature of many commodities where waterways are available.
3. Motive Power:
Motive power is necessary to propel or drive the vehicle. The early modes of transport relied upon the natural power of wind, gravity, animals or even human muscle for the movement of people and goods. For inland transport man relied on horses, mules, asses or oxen for transport of goods; on the other hand sea transport relied upon the vagaries of the prevailing winds. While most of the contemporary transport relies almost exclusively on man-made rather than natural power.
There are two main sources of power for transport: coal and oil. The most important revolutionary step affecting transport was the invention of the steam engine and the harnessing of steam power to the locomotive and certain other forms of road and water transport. With this development transport became available on a mass basis. In the latter part of the nineteenth century, the railway really was the king, but with the development of internal combustion engine, using oil, this supremacy was changed.
The air transport system is exclusively based on oil products for their source of power. The use of electric driven engines in railways now has enhanced the speed. In economic terms, the cost of motive power is a determining factor for the user; as such air transport is the most expensive of all forms of transport because of the higher cost of motive power per tonne-kilometre. For road transport, however, the weight and cost of fuel are both low in relation to the total weight of the vehicle and total operating costs vehicles among main mode of transport.
4. Terminal:
The fourth essential requirement of transport is the terminal, which initially was defined in terms of providing access on to the transport route or network. The terminal is also a point to which motion ends. For example, in terms of rail transport, the terminus is the station at the end of the line; while for bus, the normal bus stop is the terminal. But for car, a parking place either at the home or a specially designed park may be considered as terminus, although in car transport there is nothing like terminus since the route is virtually endless.
The terminals are always designed according to the mode of transport, their location, capacity and importance in relation to overall transport network. The bus stop is the simplest of terminals having some shelters or sometimes is open spaces. On the other hand, rail terminals have several infrastructures.
Even more complex are the sea terminals, viz., ports with their docks, wharves, warehouses, custom offices, etc. For air terminals, there are certain requirements which have to be fulfilled for the take-off and landing of aircraft. The ownership of terminals may be private or government. But, for an efficient network, good terminal facilities are essential.
Modes and Means of Transport:
Transportation fundamentally involves two aspects:
(a) A vehicle or unit of conveyance, and
(b) A medium upon which to move.
The choice of medium determines the types and design of the vehicle. Transportation can be classified conveniently on the basis of power, route and vehicles.
Taking power into account, the following categories are significant:
(i) Man and animal power used as a force in transportation,
(ii) Mechanical power in the form of force driving automobiles, trains, ships, aero planes, etc., and
(iii) Physical power like wind or running water facilitating movement of goods.
The classification on the basis of nature of routes includes:
(i) The land routes including transportation by path or track, road, rail and pipeline;
(ii) Water route, inland as well as sea and oceanic routes; and
(iii) Air routes.
Similarly, according to mode of transport, it can be classified into:
(i) Man and animal,
(ii) Wheeled vehicles driven either by man or animal,
(iii) Automobiles,
(iv) Railway and
(v) Ship or plane.
In fact, modes and means are interrelated and integral part of any transport system. Therefore, these brief characteristics are necessary for proper study of the regional transport network. With the dawn of civilisation and man’s first appearance on the surface of the earth, some form of device must have been employed by human beings to carry materials from one place to the other.
Men own body served this purpose and he used to carry loads himself. ‘Human portage’, thus, was the most universal as well as the most primitive means of transportation and still man works as a beast of burden generally under two sets of conditions:
(i) Geographical, and
(ii) Economic.
In certain hilly and forested areas, movement of vehicles is rather impossible and naturally man’s own head or back is used to carry goods. In developing countries including India due to economic considerations ‘hamali’ is a common source of livelihood of labourers carrying bags of grains or other commodities from market and godowns to the residences of consumers as well as of shifting goods from markets/godowns to trucks and/or goods trains. Similarly, animals are still used as mode of transport in all parts of the world especially in developing countries. Common pack animals such as bullock, horse, donkey and camel are used to carry man and material either directly or in non-power driven wheeled vehicles.
Roads:
A road is a symbol of motion. Truly it is said that if the community is stagnant, roads will indicate the fact. In the reconstruction of a region or a nation, roads invariably play a positive part. Outside home, most of our activities be it individual, regional, or national, greatly depends on cheap, smooth and quick means of road transport. As Jeremy Bentham points out, roads are the veins and arteries of a country through which channel, every improvement circulates.
The vast importance of contemporary road transport is very much a reflection of this unrivalled convenience to the user, especially in the conveyance of persons. No other form of transport is able to provide such a comprehensive door-to-door or origin-to-destination service nor does any other mode have such an extensive route network. Apart from this, road transport also provides a feeder or connection with other modes.
The outstanding characteristic of road transport is its flexibility. Motor vehicles can supply services over public highways between any two points in the country, if necessary from door-to-door on even or uneven terrain or on poor roads. Businessmen and traders value very much the convenience afforded by road transport in loading their goods from their premises and unloading them directly in their own godowns. In case of road transport, the vehicles go the goods, while in case of other means of transport; goods have to be carried to the vehicle.
Speed and certainty of timely delivery, which are essential in the marketing of perishable and semi-processed materials, is one of the important considerations in favour of road transport. Traffic in ‘smalls’ can be sent daily and easily by road service.
The earliest roads doubtless began as hunting trails and game tracks that were trodden out by the foot of man and beast. These rough tracks were made more distinct and durable as restless man used them to satisfy the various needs related to transport of goods and passengers and now every country of the world is having a dense network of roads. The efficiency of a road depends on its maintaining a surface on which wheels will run without undue friction. The relative cost of road as compared with rail transport depends on a variety of circumstances.
The principal factors are:
(i) The length of the haul,
(ii) Possibility of obtaining return loads,
(iii) The liability of the goods carried to damage or pilferage,
(iv) The class of commodity to be transported,
(v) The volume of traffic offering, and
(vi) The service rendered.
In brief, roads are most suitable means of transport in the present state of economy.
Railways:
A railway is defined in the shorter Oxford Dictionary as:
1. A way or road laid with rails (originally of wood, subsequently of iron or steel), on which the wheels of wagons containing heavy goods are made to run for ease of transport; also the way composed of rails thus laid.
2. A line or track consisting of iron or steel on which carriages or wagons conveying passengers or goods are moved by a locomotive engine. Hence also the whole organisation necessary for the working of this and the company or persons owning or managing it.
In fact, railway was, in a real sense, a product of the Industrial Revolution and afterwards became a predominant mode of inland transport. Railways solved two important needs:
(i) The economic carriage by land of (a) materials in bulk, (b) bulky commodities, and
(ii) The relatively rapid movement of large numbers of people as well as goods.
The rails always revolve around its fixed track. This provides guidance for the wheels and also enables very heavy loads to be carried. The opening of public traffic on September 27, 1825 of the Stockton and Darlington Railway is among the great events of history, and one of greater importance than most of so-called ‘decisive battles’. The date marks the inauguration of the railway era in which we now live.
Railways have the following obligations to meet:
(i) The cost of capital expenditure on tracks,
(ii) The cost of maintenance of tracks,
(iii) The cost of rolling stock, and
(iv) The cost of additional restrictions for the safety and convenience of the public.
Railways are providing both long distance as well as short distance mode of carrier. There are national and international railways, while some intercontinental railways are also in function. Rail’s main contemporary function especially in developed countries lies as a provider of inter-urban travel. Railways are able to achieve higher speeds and also easier access into the heart of cities. Their disadvantage lies in being tied to a fixed track and a published service.
New technology has further helped railways to perform their function more effectively. The trains of today are usually powered either by diesel oil or electricity. The changes to the track have been much less significant. In recent years, in order to achieve increased speeds, a continuous welded track has replaced the traditional rail.
Advance has also been made in improving the design of carriage units which, along with track changes, have promoted a better ride for passengers. Consequently, train speeds of up to 200 k.p.h. are now being achieved by high-speed trains. Railways are providing goods service in all the countries of the world. The main advantage of rail is for the-movement of heavy, bulky goods and of coal and mineral ores in particular.
Because of the heavy capital investment, the railway must be used up to capacity if it is to be economic. Capacity depends on a combination of train load, average speed of the trains and the frequency of the service. There is no need to elaborate the importance of railways to a nation and/or a region. In fact, road and railway are complimentary to each other and together they control the entire inland movement of both goods and passengers.
Ocean Transport:
The sea offers a ready-made carriageway for ships which, unlike roadway or railway, requires no maintenance. Water surfaces are two-dimensional and although sea-going vessels frequently keep to shipping lanes, ships can travel, within a limited numbers of constraints, in any direction. Because of floatability and reduced friction, ocean vessels are capable of carrying far greater loads and far greater weights than can be handled even by the longest railway train.
Ocean going vessels have fewer physical obstacles to surmount than those which, so often handicap overland transport. Terminals (i.e., ports) are necessary and control the entire ocean transportation and these normally entail heavy investment. Although movement of ships is free and are capable of going virtually anywhere on the ocean surface, they trend to keep certain ‘lanes’ because of (i) physical conditions, and (ii) economic considerations.
The construction of ship canals, primarily to shorten certain sea routes is also an important feature. The cutting of Suez and Panama Canals revolutionalised the pattern of sea trade and after the North Atlantic route, the Red Sea-Suez-Mediterranean route became the most important in the world. Ocean shipping now has become a landmark in heavy load transportation between all parts of the world.
Inland Waterways:
Transportation through inland waterways has been a common feature not only in contemporary times but from ancient times as well. Inland movement by water is undertaken by either natural waterways (rivers) or artificial waterways (canals). Such movement is governed by depth, width and direction of waterways and by such physical impediments as rapids, waterfalls, swiftness of flow and seasonal freezing.
In earlier times waterways was frequently used, because at that time the volume of traffic was limited. But during the eighteenth century, ships began to grow in size, trade began greatly to expand and speed of carriage came to be of greater importance and accordingly technical changes have been made.
The chief advantages of water transport are:
(i) There is no problem of maintenance in case of natural waterways;
(ii) The movement is swift and rapid, thus energy is saved; and
(iii) Waterways, under favourable conditions, provide cheap transport for heavy, bulky, imperishable commodities such as coal, ore, timber, cement.
The principle disadvantages of inland waterways are:
(i) Rivers may involve devious journeys and may flow in the wrong direction from the point of view of trade;
(ii) Navigable rivers may be interrupted by falls or rapids;
(iii) Change in river levels and freezing may occur in winter causing stoppages in navigation; and
(iv) Canal construction involves heavy capital investment as well as regular maintenance.
Although water transport is carried out in some way or the other in all parts of the world, but six major navigable systems of inland waterways are: the rivers of the western and central Europe, the Volga-Don system, the North American rivers, the Amazon system, the Panama-Paraguay system, and the Chinese waterways.
Airways:
The use of aircraft and the development of air communication belong to the twentieth century. During two world wars, much of the accelerated development in the design, size, propulsion and use of the aero plane has occurred. Air transport differs from all other forms of transport in that it is three-dimensional; as a result it is the only one to enjoy the advantages and suffer the disadvantages of the third dimension.
Air routes are purely theoretical and aircraft are not tied to the surface, although, for commercial purposes air routes are channeled along carefully prepared routes. The air transport is generally controlled by terminals as well as by weather conditions. Air transport needs terminal facilities in the shape of airports. The airports are always designed according to the landing capacity of the aircrafts.
An airport needs a large area of flat land on the suburban fringe of a city. In addition, there is a requirement for a public safety zone beyond the airport perimeter and under the glide path. With the development of hovercraft services, a new type of terminal is needed.
In the early days of air transport, when aircraft had a relatively restricted range of flight due to their size, speed and limited fuel-carrying capacity, air routes were so designed as to avoid extensive ocean crossings, high mountains, deserts and vast forest areas. However, as a result of the greatly improved performance of aircrafts and their greater reliability, physical features in themselves now place no limit upon the choice of routes.
Air routes are now determined by:
(i) Adequate ground facilities for operation, and
(ii) Availability of traffic for economic working.
Air transport is still, in general, costly and this limits its use. Air transport is best suited for the carriage of commodities which are low in bulk but high in value.
Nowadays, air services are of two main kinds:
(i) Short-distance services which are operating between important centres within a country, and
(ii) Long-distance services such as the trans-continental and trans-oceanic flights.
The pattern of air routes in the world shows that there is a worldwide network providing very good transport service which is speedy. Most of the countries are having their own home as well as international air service organisation, either private or owned by government.
Pipelines:
A pipeline may be defined as a line or conduit of pipe of variable diameter and length and traditionally used for carrying liquid or gas from a point of supply to a point of consumption. Earlier pipes were used only to supply water and its evidence is available in ancient civilizations of China, Egypt, Mesopotamia, Greece and Rome. But, the discovery and use of petroleum ushered in a new era in pipeline use.
The first crude oil pipeline, constructed of wood, was laid down in the United States in 1861 but this proved to be unsuitable and first successful pipeline was made of cast iron in Pennsylvania in 1865. In the early days of oil industry, pipelines served local proposes but gradually the value of piping crude oil or refined products in bulk came to be recognised and today, nearly half-a- million kilometres of oil pipeline exist in the world together with a slightly smaller distance of natural gas pipeline. The increasing use of pipelines in recent years represents, wrote Manners, “one of the most notable revolutions in the history of transport”. Like other forms of transport, pipelines require maintenance, especially against external rusting and internal corrosion.
Nowadays, pipelines are used for transporting:
(i) Liquids and gases;
(ii) Solids in suspension;
(iii) Solids by pneumatic pressure; and
(iv) Materials enclosed in capsules.
Patterns of Movement:
The demand for transport is generated by individuals, groups and by industry, thus movement is necessary and an indispensable part of transport. The basic question is: why does movement take place, and how is demand for movement effected; followed by another question what are the main transport patterns? Patterns of personal movements reflect the influences of mobility and accessibility levels, and freight movements are closely associated with the relative locations of raw material sources, processing plants and the final markets.
The basic unit of movement is a trip, defined as “the one-way travel from one point to another for a particular purpose” (Powell and Smith, 1970: 39). The two end points of a trip are usually referred to as the origin and the destination of the trip (Figure 2.1).
The two trip-ends may be defined in terms of either a geographical area or in land use terms. The former refers to some classification on the basis of a known place-name which usually defines an administrative unit. The trip can also be described in terms of the land uses at the origin and destination, e.g., residential to industrial or, in terms of the individuals from home to work. The pattern of movement in urban areas is a complex one, because urban traffic is composed of two main elements, movement into the area from outside and movement within the urban area. On the other hand, land uses from which trips radiate are called trip generators and land uses to which trips converge are called trip attractions.
In-spite of complexity in patterns of movement within urban areas, the main movements tend to be either from residential areas to each of the high-density land uses. In an urban area, there is a complex mix of various land-uses. Figure 2.2 outlines the main patterns of movement, which occur within a hypothetically specified zone.
The main patterns of movement are shown by desire lines. These show two principal features: first, the direction of demand for communication as illustrated by the line from an origin to a destination, e.g., suburb Yn to Y; and, second, the width of the desire line, which is an indication of the volume of demand for movement. The largest demand, for example, is between town X and city Y and the lowest volume between villages in the rural areas.
On the basis of the foregoing diagram, one can distinguish the following general patterns of movement:
(i) High density – high density travel, e.g., Town X to City Y (inter-urban travel);
(ii) Low density – low density travel, e.g., Village R1 to Village R: (rural travel);
(iii) Low density – high density travel, e.g., Suburb Y1 to City Y (one component of urban travel);
(iv) Movement within high density zones, e.g., within City Y1 which along with (iii) combine to give total urban travel.
Problems of Route Selection:
Since there is a number of specific locations at which journey may start and finish, problem of route selection can be explained by simplifying any description of types of movement as shown in Figure 2.3.
If it is assumed that movement is a process, which seeks to minimise journey length, time and cost then it is possible for the transport geographer to study personal travel and freight transport in terms of the constraints placed upon movement. The quest for what is described as maximum route efficiency has attracted many mathematicians and has also been pursued by geographers in the context of route network.
Where several locations are to be interconnected the solution to what is known as the shortest-path problem ranges from complete inter-linkage, providing direct movement between all points, to more circuitous routing where the network is of a simple form. Between these two extremes lies the compromise solution where network building and operating cost constraints are combined to create a framework of routes where both direct and multi-stage trips can be made (Figure 2.3).
Distance can also be considered in terms of time and cost, and the choice of a particular route can be strongly influenced by its ability to offer the cheapest trip between origin and destination. Inter- and intra-urban road network suffer from various levels of traffic congestion and in consequence car drivers may often divert their journey from a direct but heavily trafficked road to one which offers a shorter trip time although involving a greater distance and higher travel costs. Urban motorists who adopt these measures are seldom popular in the residential areas through which they take ‘short cuts’, however, and traffic- calming schemes are now introduced to curb this practice.
Personal Movement Patterns:
Personal movement patterns are most complex in large urban areas where trips involving several purposes and modes are common. Travel to work is one of the most common personal movement patterns and has been studied in detail, as it involves large numbers of people, requires a substantial investment in transport facilities and presents some of the most intractable problems to the urban transport planner. In many urban areas up to 20 per cent of all trips are to and from work, and these are primarily responsible for the congestion in the two daily peak travel periods (Figure 2.4).
Up to the mid-twentieth century the concentration of employment in, or close to, city centres produced radial commuting patterns, with morning and evening flows concentrated along rail, tram and bus routes. In the modern city several factors now interact to create a much more complex situation with work trips across cities and from inner to outer areas, all counter to the traditional flows.
Decentralisation polices have led to the relocation of many older inner-city enterprises in peripheral industrial estates, a trend aided by the flexibility offered by the car. New employment sources have also been attracted to these outer zones, further reducing the need to travel into urban cores.
Freight Traffic Movement Patterns:
Freight movements are largely determined by the distribution of the industries, which generate this traffic, and industrial transport may be placed into three categories. The assembly of raw materials and power resources at the production or processing plant is an essential initial transport requirement and is followed by the second type of movement, the transfer of semi-finished goods between plants where more than one location is involved in manufacturing.
The distances covered by these trips and the mode of transport used vary with different industries. In the case of petrochemicals almost all the necessary transfers can be made by pipelines within the refinery and between associated plants, and no other transport services are required until the final distribution stage is reached. In contrast, motor vehicle manufacturing usually requires the regular delivery to the assembly plant of components drawn from a widely scattered pattern of ancillary works and both road and rail can be used.
Interaction Model:
In transport geography analysis has also been done for interaction between adjoining settlements and/or regions. For this purpose gravity models have been used to explain the movement pattern. There are two limiting factors, which determine the strength of interaction (or volume of movement demand) between two places. Distance is the first crude factor – the attraction between two areas or places of a given size will increase as the distance between them decreases, and vice versa. In terms of Ullman’s principle of transferability, the time and cost of making a particular trip are important considerations and act as a good practical measure of distance.
The second limiting factor of the relative attraction between two places is that measured by their populations. For example, the attraction between two cities a given distance apart is greater than that of two small towns the same distance away from each other. These two limiting factors of distance and population form the basis of a gravity model, which is widely used as a simple measure of interaction between two places. This model has been much used in geography and, as its name suggests, is an adaptation of Newton’s law of gravitation.
A simple example will help to explain the basis of this model. Suppose there are three settlements A, B and C, each of which has the same population of 100 persons. Settlement A is 1 km from B and settlement C is 2 km from B. Figure 2.6 represents this situation.
Assuming there are no barriers to communication, i.e., all other factors beings equal, the gravity model suggests that there will be twice as many trips made between A and B as between B and C. Distance is, therefore, a linear limiting factor, given that the populations are all equal. The above assumptions are important for in the real world there may be physical or even political barriers to travel. Furthermore, it is also assumed that in each settlement, persons have the same will or propensity to travel and that travel costs depend directly upon distance. This latter assumption, however, is not always a realistic one to make, for cost does not usually increase uniformly with distance travelled. The gravity model formulation for the strength of interaction between two zones is usually expressed in the following generalised form:
Tij = (population of i) × (population of j)/ distance between i and j = Pi × Pj/ dij
where Tij is an estimate of the total number of trips made between two zones, i and j.
The population of each of the two zones is being used as a mass variable, representing the particular attraction of each area. If one were dealing with a particular trip purpose, it may be necessary to use an alternative measure.
In terms of formulation (1) above, suing the simple example described as an illustration, the gravity model infers
TAB = 100 × 100/ 1 = 10,000
TBC 100 × 100/ 2 = 5,000
It should be pointed out that in the above example the values of T are only relative, i.e., there will be twice as many trips between A and B as between B and C. The same relationship between trip volumes may be obtained if the population or mass variables are different yet distances between zones are equal. Figure 2.7 shows such a system.
The gravity model formulation becomes:
TAB = 200 × 100/ 1 = 20,000
TBC = 100 × 100/ 1 = 10,000
Although the values of TAB and TBC differ from the first example, the important point is that the relatives are the same, i.e. TAB: TBC = 2:1 and, therefore, it can be expected that there will be twice as many trips between A and B as between B and C. In practice, this problem of relatives is overcome by adjusting the model estimate by a constant so that the basic formulation becomes:
Tij = k. Pi × Pj/dij (2)
A practical use of the gravity model is to predict the volume of trips between one zone and one or more other zones, and is therefore, an application of the Ullman’s principle of transferability.