Accessibility (transport)
In transport planning, accessibility refers to a measure of the ease of reaching (and interacting with) destinations[1] or activities distributed in space,[2][3] e.g. around a city or country.
In time geography, accessibility has also been defined as "person based" rather than "place based", where one would consider a person's access to some type of amenity through the course of their day as they move through space.
[6] For example, a person might live in a food desert but have easy access to a grocery store from their place of work.
For a non-motorized mode of transport, such as walking or cycling, the generalized travel cost may include additional factors such as safety or gradient.
The essential idea is to define a function that describes the ease of travelling from any origin
is a parameter defining how quickly the function decays with distance.
[17][2] This association is often used in integrated transport and landuse forecasting models.
At the same time, the accessibility of a place can not only be changed through a modification of the transport infrastructure, but also as a consequence of a changed spatial structure / distribution of destinations.
Destination-based accessibility measures are an alternate approach that can be more sophisticated to calculate.
Using destination-based measures we can calculate how many schools, hospitals, jobs, restaurants (etc..) can be accessed.
[18] Accessibility-based planning is a spatial planning methodology that centralises goals of people and businesses and defines accessibility policy as enhancing people and business opportunities.
[19] Traditionally, urban transportation planning has mainly focused on the efficiency of the transport system itself and is often responding to plans made by spatial planners.
Such an approach neglects the influence of interventions in the transport system on broader and often conflicting economic, social and environmental goals.
Using this definition accessibility does not only relate to the qualities of the transport system (e.g. travel speed, time or costs), but also to the qualities of the land use system (e.g. densities and mixes of opportunities).
It thus provides planners with the possibility to understand interdependencies between transport and land use development.
[20] For politicians, citizens and firms it might be easier to discuss the quality of access to education, services and markets than it is to discuss the inefficiencies of the transport system itself.
Despite the high potential of accessibility in integrating the different components of urban planning, such as land use and transportation and the large number of accessibility instruments available in the research literature, the latter are not widely used to support urban planning practices yet.
[21] By keeping the accessibility language out of the practice level, older paradigms resist the more informed and people-centred approaches.
The existence of accessibility instruments is fairly acknowledged, but practitioners do not appear to have found them useful or usable enough for addressing the tasks of sustainable urban management.
