Time Geographic Analysis

Glossary Authority constraints Regulation of access to activity places in the form of social rules, laws, financial barriers, and power relationships Base locations Activity places in which activities are conducted that act as pegs around which the rest of the activity and travel pattern is organized Capability constraints Biological, mental, and instrumental limitations Coupling constraints All limitations which arise when people, equipment, and materials are joined together at given times and places Potential action space The area which encompasses all activity places that can be visited in a certain time window Prism Three-dimensional space-time construct which contains all potential paths a person may choose given that person's spatiotemporal constraints Project Entire series of tasks necessary for the completion of any goal-directed behavior Relational string A threadlike connection between actors in which impressions, perceptions, attitudes, ideas, emotions, and other types of information emerge and are transmitted in different rhythms and intensities. Space-time cube Three-dimensional representation of space-time in which the horizontal axes represent geographical dimension and the vertical axis the time dimension Station Activity places with diverse physical extensions Time window A block of time in which travel and nonbase location activities can be conducted Authority constraints Regulation of access to activity places in the form of social rules, laws, financial barriers, and power relationships: Travel time ratio: a share of travel time in the sum of travel time and activity duration in a certain time window The origins of time geography can be traced to the mid-1960s. It forms a part of the human ecological tradition in human geography. The founding scholar in this area Torsten Hägerstrand (1916-2004) sees it as a four-dimensional view of the world. Although there are various versions of time geography, the main developments occurred in the 1960s, 1970s, and early 1980s. Hägerstrand defined the domain of time geographic analysis on the basis of his observations of approaches in human geography in the 1960s. His main problem with the typical geographer's thinking and practices at that time were that these were unable to catch the conditions that circumscribe human action. His criticism of human geography was largely driven by his strong motivation to make geographical knowledge and skills more useful for policy makers and planners. For that purpose, it was necessary to develop a conceptual and instrumental framework that could capture the connected human activities that are taking place in time-and space-bound situations. To address these shortcomings of human geography, Hägerstrand proposed a new theory based on three pillars: space, time, and the identity of mankind. Hägerstrand reproached quantitative geographers, asserting that they were more interested in the distribution of human beings and other material entities across space than in their space-consuming properties and the consequences of these for their ordering in space. Space is not only a matter of distance between material entities but also of the room taken up by these entities. A housefly needs just a tiny piece of three-dimensional space, but an international airport consumes a relatively large amount. This notion of space as provider of room implies, at least in some relationships, competition for available room between human beings, animals, plants, roads, buildings, and other entities. Some sites in space offer better opportunities than others for reaching one's goals. Once a site has been occupied by a certain entity that space is no longer available for other objects, which are then forced to search for another site in space. In addition to this constraining notion of space, the time dimension also sets limitations on relationships between entities. Time is not a budget like money that can be saved up for later use. Just like a clock, time in an individual's life ticks away. Moreover, at every moment in time, an individual is located somewhere in space. As a consequence, events in time, like the birth of a child, calling a dentist, buying groceries in a store, and traveling to a destination, are not discrete but are located and connected within space-time volumes. Consequently, one event might have consequences for another event, like the birth of a child that triggers the move to another, larger dwelling, which in itself might disconnect the household from the local community. The third pillar of time geography forms the identity of humankind. Hägerstrand stated that a human being is treated as a "divid-ual" rather than an "individual." By this definition, he means that in human geography a human being can be studied as shopper, husband, father, colleague, or sportsperson separately, without taking account of the fact that a person has to integrate the activities that belong to these various roles in space and time. Many of these activities have specific durations, and times and places at which