Existing transport demand models

Traditional transport models have focused on travel demand, yet demand is rarely a major influence on walking and cycling access. Demand has the greatest impact on accessibility by car so, maybe unsurprisingly, currently it is car accessibility (or mobility) that is modelled in most detail.

Many transport models have not kept pace with current technology. Automated data feeds from electronic public transport journey planners have yet to be incorporated into many software products. Until about 2005 this left a gap in the market for software that could read in the various journey planning file types and represent public transport travel times geographically.

Traditionally, demand model segmentation of the population did not reflect the fact that access for some travellers was of greater policy importance than for others. Analytical skills were poorly developed in drilling down within transport model results to look at target groups of people and access for particular trip purposes.

Cost and time have generally been the focus of most analysis, and other barriers such as access to information, physical access, safety, security and level of comfort have not generally been modelled.

For these reasons, modelling tools available internationally are undergoing further development. Some of the improvements include:

·         Pedestrian demand models (previously only used in congested locations such as entrances to stations) are being developed to be able to read in digital maps and map access by walking.

·         Tools to read in data from public transport journey planners are evolving, with the worldwide Google Transit project being the largest software development in this field.

·         Various local software tools have been developed to help segment travel markets and calculate accessibility indicators relevant to local policy needs.

However, these represent only a few of the gaps in traditional transport modelling. A New Zealand accessibility assessment tool has the potential to close all of the gaps by guiding users through all the steps including ‘Will the person at this address have the necessary information?’ to ‘Have they the physical capabilities to travel to the bus and board it?’, ‘Is this a safe route?’ when linked with other tools, eg community street reviews (Abley 2010), and many other similar questions.