Stage 1: Assessing the Travel Characteristics of a Development: Measurement of accessibility to and from the site
Determining the accessibility of a site will require calculating the travel time (at peak and off-peak times) by different modes of access: walking, cycling, public transport and car. Travel time assessments determine the catchment area of a development by different modes; areas within which one can reach a development within set times or time-bands (e.g. 30 mins). Catchment areas can be shown by lines on maps (isochrones) which connect points equal in time from a given location. The choice of time-band may vary, in line with the use and scale of the development: people may be prepared to travel further for some activities, for example, to a regional shopping centre than to a local shop.
- Walking and cycling: these seek to establish the catchment area for walking and cycling - the places from which pedestrians or cyclists can reach a development within a set time. Journeys of up to 1 kilometre for walking and up to 4 kilometres for cycling are normally appropriate. A two-stage process is recommended: estimating time by analysis of maps; then checking the actual times of people travelling these routes, which will help take account of factors such as the time required to cross roads or walk/cycle up hills.
- Public transport: can be calculated by a combination of analysis of timetables and maps. However this should be complemented by observation of walking times to actual (or potential) bus stops. A 30 minute door to door travel time (including the walk, wait, journey time, and walk to the destination) is an appropriate choice of time-band by public transport for most types of development although it may also be helpful to consider a 45 minute door to door travel time. For developments of regional importance 1 hour may be appropriate.
- Car (or other motorised vehicles) access: can be calculated in various ways, including analysis of maps and route planning software. It should include estimates of the in-vehicle travel time: walking to the vehicle; searching for a parking space; and walking from the vehicle to the site entrance plus likelihood of known congestion on route. Time estimates for other motorised vehicles - motorcycles, mopeds, light vans, HGVs - can be assumed to be the same.
For housing developments a different approach is needed since it is a generator of journeys rather than an attractor. The travel time assessment should measure the time taken to reach services (e.g. shops, schools, employment centres etc.) from the housing development, but the basic methods used will be the same. Travel times across the development site for larger housing developments may be significant, and separate analyses may be needed for different parts of a very large development.