Accessibility planning is currently undertaken on an ad-hoc basis as there is currently no standard way that accessibility is being measured in New Zealand. Nevertheless, there are examples of projects where accessibility analysis approaches are being used.
Existing accessibility modelling tools in other countries have been developed to the specifications of those countries. The data format and exchange required by these tools is different from that available in New Zealand. This makes these tools less transferable to a New Zealand situation.
Accession, a bespoke accessibility modelling tool developed in the UK, was trialled in a Christchurch case study. The trial highlighted some of the constraints and limitations to using Accession in New Zealand, in particular, the different data exchange formats required and the fact that Accession does not consider the reach to multiple opportunities or the weight of those multiple choices.
Existing journey planning services provided in New Zealand are the closest automated tool to accessibility analysis software in New Zealand. In 2008 three regional councils provided journey planning software with varying levels of sophistication.
Local and regional councils have GIS and transport modelling resources to run a customised accessibility assessment tool, but they do not necessarily have the resources to develop or maintain one.
There is no clear leading desktop GIS application used in New Zealand. Consequently developing a product to suit one GIS software platform over another is likely to disadvantage a significant number of users. Rather it is more important to develop a clear methodology that can be implemented in various GIS software packages.
The lack of a standardised public transport exchange data format presents an issue for inputting public transport timetables and frequencies. Conversion or digital entry of this information should be simple, standardised and easy to implement. The IPTIS journey planning software that was used by all existing journey planning service providers in New Zealand in 2008 is a good source of experience when considering these issues. Latterly though, Google Transit Feed has filled this information gap and has by default, and in the absence of an alternative, become the New Zealand standard.
Where spatial data such as land use information is lacking, the collection of data will be essential for carrying out robust assessments. A factor to consider when undertaking this data collection is the intention of accessibility assessments to be an ongoing process as opposed to a one-off project. Spatial data collected for accessibility assessments will also have value in other areas. A partnership approach to spatial data collection could prove highly beneficial particularly among departments within a local government organisations and private companies.
An accessibility tool developed using an existing GIS package must be able to undertake complex calculations resulting in good quality graphical outputs. For example, the routing function included in ArcGIS Network Analyst provides functionality for optimising routes and recording deterrence variables or costs along the route. GIS packages are efficient for land use analysis and allow for the dynamic generation of OD pairs for route finding.
In order to create the very large UK national model all analysis was undertaken within a SQL server database and a bespoke routing algorithm was programmed based on AutoPTpath. The data was then managed in Accalc providing the flexibility needed to create the 568 different UK accessibility indicators. This is a much less expensive solution than purchasing licences for software but still leaves the flexibility to analyse any individual table or data set within commercial software such as ARCinfo GIS.
The requirement for customisation and other technical issues is introduced when working with public transport timetable data as frequency analysis and journey planning are not functions commonly built into GIS packages. This requires a model build within the data format created or adopted in New Zealand.
The successful adoption of the accessibility tools at a neighbourhood and local level requires as few barriers to use as possible. Server-based GIS designs, including web server designs, could be an acceptable solution to providing a tool for all users at very little or no hardware cost.