Possible indicators

Prior to investigating how indicators might be delivered in New Zealand, the indicators highlighted in earlier research (Chapman and Weir 2008) provide a starting point for discussion.

Comments on international experience with such indicators is summarised in table 5.3. It can be seen that although many of these indicators have been used successfully elsewhere, there are significant limitations since they do not directly describe the opportunities available for different users to access services. It is therefore preferable that any new accessibility measurement should build up locally relevant indicators based on available data as described in the remainder of this chapter.

Table 5.3      Review of indicators previously proposed and employed

Indicator

Type of indicator

Successful examples and experiences

Access to private motor vehicles

A measure of mobility which identifies the people who are most likely to suffer accessibility problems

Many examples throughout the world allow accessibility improvements to be targeted where there is low car ownership. However, it does not help identify what improvements need to be made.

Access to public transport

An indication of network coverage, particularly where the services being accessed are categorised by frequency and destination type

The public transport accessibility levels (PTAL) methodology (see chapter 9) developed in London works well in a very densely populated area with frequent public transport and a large choice of destinations for each trip purpose. However, it can be misleading outside urban areas. Access to public transport can also be as complex to calculate as integrated accessibility measures so is losing favour relative to indicators which measure access using public transport.

Activity by cycling and walking

A measure of expressed accessibility

Generally a good proxy indicator of the health of a neighbourhood and widely used internationally. However, it does not help identify what improvements need to be made.

Transport behaviour

A measure of expressed accessibility

In a highly segmented analysis travel demand is a good indication of accessibility, ie if many low-mobility people are travelling to the shops then there is likely to be good access. This type of measure is widely used internationally. However, it does not help to identify what improvements need to be made.

Satisfaction with transport options

A measure of stated accessibility

This is an essential type of measure whether or not other quantified measures are used. In all parts of the world local people understand their accessibility problems.

Aspects of infrastructure such as the proportion of public transport fleet with enhanced access features

A transport accessibility measure

These are widely used to describe the product offered by transport providers. However, such measures do not directly indicate whether anybody benefits from the features or what people can access using the infrastructure.

Travel expenditure such as proportion of income spent on travel

A social accessibility measure

This sort of indicator is very useful, but has not been widely used since there are few places in the world where data on personal expenditure can be obtained at a level useful for accessibility planning.