Source: adapted from Wegener, M. (1995) “Current and Future Land Use Models”, Paper presented at the Land Use Model Conference, Texas Transportation Institute, Dallas.
The complexity of urban dynamics is expanded by different temporal rates of change among its main components. Usually, land use and transportation networks are very slow to change, their associated movements can change and adapt very quickly. As a result, the pace of change in an urban area will range according to the element concerned:
- Very slow changes concern transport networks and land use, which are the most stable elements of the urban spatial structure. Infrastructures, such as highways, roads transit systems, ports, and airports take years to be constructed and will remain operational for decades. The same process applies to land use as residential, commercial, and industrial functions change in a very slow manner.
- Slow changes concern workplaces and housing. Urban infrastructure such as buildings (e.g. apartment complexes, warehouses, offices) have a life span that can stretch for centuries depending on the construction techniques used and their perceived significance (historical value). However, activities occupying them (enterprises or households) are of less duration.
- Fast changes concern employment and population. Enterprises are part of business cycles where they are created, expand, and often dissolve. Market opportunities and their related demand will also evolve with technological changes. With these changes, employment opportunities will vary. Households also have a life cycle where they are formed, expanded, and are eventually dissolved with the related population changes.
- Very fast (immediate) changes that concern freight transport and commuting. Although passengers and freight mobility tends to be stable in time and space within a metropolitan area, they have the potential to change very quickly. For instance, congestion or fluctuations in the demand can be coped with rapidly by rerouting vehicles.