Chapter 14 Existing conditions and data

An understanding of existing transport conditions is essential in being able to understand current problems and to assess how conditions may change in the future. This understanding is gained by obtaining a variety of transport data, for example, bus, traffic, pedestrian and cycle flow counts; bus passenger numbers; traffic speeds/network journey times; trip origins and destinations, trip distributions; modes of travel and accidents.

These data may be obtained from a number of sources, including existing data and new bespoke surveys. Data does, however, have a shelf life and existing data should be assessed to ensure it is still valid, particularly if there have been major changes to the transport networks, such as the introduction or removal of bus services; the introduction of a new mode of transport, such as light rail; or changes to the highway network, such as new junctions or improved highway links. The scale of the data collection exercise will depend on a number of factors, but it should be carefully planned to ensure the best use of existing data and the most efficient use of resources, both personnel and financial. This will take into account the sample size required.