Transportation Geography, also Transport Geography, is the branch of geography that investigates spatial interactions; letting them be of people, freight, and information. It can consider humans and their use of vehicles, or other modes of traveling. And how markets are serviced by flows of finished goods and raw materials. It is a branch of Economic geography.
“The ideal transport mode would be instantaneous, free, have an unlimited capacity and always be available. It would render space obsolete. This is obviously not the case. Space is a constraint for the construction of transport networks. Transportation appears to be an economic activity different from others. It trades space with time and thus money” (translated from [Merlin, 1992]).
Geography and transportation intersect in terms of movement of people, goods, and information. Over time, accessibility has increased and led to a greater reliance on mobility. This trend can be traced back to the industrial revolution, although it has significantly accelerated in the second half of the twentieth-century, for various reasons. Today, societies rely on transport systems to support a wide variety of activities. These activities include commuting, supplying energy needs, distributing goods, and acquiring personal wants. Developing sufficient transport networks has been a continuous challenge to meet growing economic development, mobility needs, and ultimately to participate in the global economy.
Transport and urban geography are closely intertwined, with the concept of ribbon development closely aligned to urban and transport studies. As humans increasingly seek to travel the world, the relationship transport and urban areas have often become obscured.
Transportation geography measures the result of human activity between and within locations. It focuses on items such as travel time, routes undertaken, modes of transport, resource use, and sustainability of transport types on the natural environment. Other sections consider topography, safety aspects of vehicle use, and energy use within an individual's or group's journey.
The purpose of transportation is to overcome space, which is shaped by both human and physical constraints, such as distance, political boundaries, time, and topographies. The specific purpose of transportation is to fulfill a demand for mobility, since it can only exist if it moves something, whether it is people or goods. Any kind of movement must consider its geographical setting, and then choose an available form of transport based on cost, availability, and space.
Transportation modes 
In terms of transport modes, the primary forms are air, rail, road, and water. Each one has its own cost associated with speed of movement, as a result of friction and place of origin and destination. For moving large amounts of goods, ships are generally used. Maritime shipping is able to carry more at a cheaper price around the world. For moving people who prefer to minimize travel time, and maximize comfort and convenience, air and road are the most common modes in usage. A railroad is often used to transport goods in areas away from water.
" Transportation modes are an essential component of transport systems since they are the means by which mobility is supported. Geographers consider a wide range of modes that may be grouped into three broad categories based on the medium they exploit: land, water and air. Each mode has its own requirements and features, and is adapted to serve the specific demands of freight and passenger traffic. This gives rise to marked differences in the ways the modes are deployed and used in different parts of the world. Recently, there is a trend towards integrating the modes through intermodality and linking the modes ever more closely into production and distribution activities. At the same time; however, passenger and freight activity is becoming increasingly separated across most modes." 
Road transportation 
Road transportation networks are the type of transportation that is connected with movements on constructed roads; carrying people and goods from one place to another by means of lorries, cars, etc.
Maritime transportation 
Water transportation is the slowest form of transportation in the movement of goods and people.
Problems with transportation geography 
Traffic and transportation on existing streets, highways, and rail facilities no longer match demands created by a recent population growth, and new location patterns of economic activity. Besides an increase in population, another problem is vehicles overloading the network of highways and arterial streets. See Traffic congestion, Transportation network, and Population densities
See also 
- Dr. Jean-Paul Rodrigue, Dept. of Economics & Geography, Hofstra University