Fig. 1 shows the relationships between these components
and accessibility (as defined above), and relationships
between the components themselves: here, the
land-use component (distribution of activities) is an
important factor determining travel demand (transport
component) and may also introduce time restrictions
(temporal component) and influence people’s opportunities
(individual component). The individual component
interacts with all other components: a person’s
needs and abilities that influence the (valuation of) time,
cost and effort of movement, types of relevant activities
and the times in which one engages in specific activities.
Furthermore, accessibility may also influence the components
through feedback mechanisms: i.e. accessibility
as a location factor for inhabitants and firms (relationship
with land-use component) influences travel demand
(transport component), people’s economic and social
opportunities (individual component) and the time
needed to carry out activities (temporal component).
Following our definition of accessibility, an accessibility
measure should ideally take all components and
elements within these components into account. In
practice, applied accessibility measures focus on one or
more components of accessibility, depending on the
perspective taken. Four basic perspectives on measuring
accessibility can be identified.