Accessibility is the aptitude of a road or rail network or any other transport network generally evaluated in time of travel or measured in distance to be covered to reach public equipment, an employment pool, arrive at the city centre, obtain a proximity service (trade, leisure, public services, social network). It is presently considered as a good accessibility if one can have access to a daily service within a period of less than 20 minutes and a weekly service within a period of less than one hour.
On the other hand, inaccessibility is considered as the impossibility to obtain a service within a socially-acceptable time frame; it is the synonym of isolation, relegation, exclusion. Accessibility comprises four dimensions that mutually overlap:
- physical accessibility,
- economic accessibility (affordability),
- accessibility of information.