Uses
The PTAL is used as a development planning tool in London, to determine both permitted parking standards and development densities. Large site developments (those the London boroughs refer to the Greater London Authority) must follow planning guidelines that allow more parking in areas with low PTALs (i.e., poor public transport) and vice versa—and that also relate the allowed density of development to PTAL (i.e., areas with better public transport may have higher density housing or offices).
TfL also have software to calculate PTALs across wide areas using GIS and timetable data, the typical result being a map with coloured bands relating to PTAL grades.
Read more about this topic: Public Transport Accessibility Level