developers lean on ptal as the indicator in such assessments for london projects as it helps them evaluate how new development would affect accessibility to public transport in a selected area and determine the acceptability of the impact while it provides a useful indicator of local accessibility and allows easy comparison of areas across the city one criticism is that it assumes access to a public transport network includes access to reasonably wellintegrated rail and bus services and by implication to a range of final destinations but ptal does not in fact measure access to final destinations that said the access to opportunities and services atos indicator a complementary tfl measure that does reflect access to destinations and is described below shows that in the case of london a city with a comprehensive and relatively dense public transport network ptal is a good proxy for access to services and opportunities in areas of lower density however the ptal method may not be applicable as they usually have a sparser public transport network with poor connections and interchange facilities nor does it account for availability of cycling lanes or quality of walking environment