As cities grow and develop over time, changes take place that impact on the accessibility to various services and activities for the population living within and around the city. Land use changes such as the establishment of shopping mega-centres, which provide cheaper prices and a wider range of goods have precipitated the demise of the local store. But has access to opportunity and choice improved? These mega-centres provide a greater level (and range) of services, but there are less of them in a city and they are more sparsely located, yet local facilities often find they cannot compete and close. This increases travel distances for the majority of the population. The increased distances travelled may also result in transportation mode shifts, reducing accessibility and possibly magnifying inequalities for at-risk members of the community.
Urban sprawl typically increases the distances the population needs to travel and therefore increases travel times. Some cities have addressed urban sprawl through the provision of high-speed arterial roads and motorways, but this encourages a reliance on private motor vehicles and results in an increased dependence on oil, increased air pollution and other negative impacts. It also increases inequality in accessibility, as it does nothing to provide for sectors of the community that do not have access to a private motor vehicle. Another approach to containing urban sprawl is to enact polices to limit expansion of urban boundaries and increase population densities around key services. This reduces travel distances and can encourage modal shift towards more sustainable modes of transport such as walking, cycling and public transport. This can in turn reduce transportation congestion and pollution.
So which of these approaches does more to increase accessibility? In order to improve and measure the progress towards any goal, the first step is to be able to objectively measure what one is setting out to change.