Source: adapted from. Giuliano, G. (1995) “Land Use Impacts of Transportation Investments: Highway and Transit”, in S. Hanson (ed) The Geography of Urban Transportation, New York: The Guilford Press, p. 307.
Transportation and land use are part of a retroactive feedback system. Accessibility is shaped by the structure, capacity and connectivity of transportation infrastructure, which is not uniform. Since accessibility differs, this attribute has an impact on land use, such as the location of new activities, their expansion or densification. These changes will influence activity patterns in terms of their distribution and level of transport demand. This change in the demand will shape the planning, maintenance and upgrade of transportation infrastructure and services such as roads and public transit. Again, these changes will further impact accessibility into a new cycle of interactions.
The interactions between transportation and land use are also part of a complex framework that includes economic, political, demographic and technological changes. Several characteristics and processes have an influence on the dynamics between transportation and land use. Changes in transportation technology, investment and service characteristics can alter overall accessibility levels as well as the relative accessibility of different locations. The recent trend towards digitalization is providing a new impetus to urban mobility such as on-demand services and the availability of large amounts of information about the characteristics of urban travel. E-commerce by itself is generating an entirely new set of patterns in urban freight distribution, particularly with home deliveries.
Land use characteristics also affect activity patterns, such as zoning patterns and regulations, the availability of land, public utilities and telecommunication infrastructure. Of special importance are the changes in trip generation, both for passenger and freight, which are influenced by economic and demographic changes. Obviously, population growth is a vector for additional transportation demand, but rising incomes as well. Trip patterns may change in a number of ways, such in terms of the number of trips, the timing of trips, their origin or destination, the mode, and trip chaining. These changes in travel demand exert considerable influence on the development of new transportation infrastructure or services. As such, the interactions between transportation and land use are often referred as a “chicken-and-egg” conundrum since it is empirically difficult to demonstrate if transportation changes precede land use changes, or vice-versa.