Transport Walkability Index The Transport Walkability Index is a relative indicator of how well the built environment in different areas supports walking for transport. The index is frequently used in physical activity research and has been validated against walking behaviours. The Transport Walkability Index can be calculated for geographical areas of interest (e.g. census areas, neighbourhoods) and has three components: dwelling density, street connectivity, and land use mix. Dwelling density is the density of residential dwellings in a given area. Higher dwelling densities are more walkable because a denser population means there are likely more destinations to walk to in the area. Street connectivity assesses how easy it is to walk from place to place and is measured by the density of intersections in a given area. Areas with higher street connectivity are more walkable for two reasons. Distances between destinations along the road network are typically shorter, and there is more route choice within a journey. The Transport Walkability Index land use mix measure is the balance of diverse types of land use in an area (e.g., retail, residential, commercial, community, recreation). A greater mix of land use is seen as being supporting walking behaviours because it indicates a greater variety of destinations available to walk to. How was the Transport Walkability Index calculated? The Transport Walkability Index was calculated for SA1s (areas of approximately 400 residents) in Metropolitan Melbourne using Geographic Information Systems (GIS). The three components were equally weighted in the index. A detailed description of the methods can be found in the short report: How Walkable is Melbourne? The Development of a Transport Walkability Index For Metropolitan Melbourne (Giles-Corti et al., 2014). Frequently asked questions about how the Transport Walkability Index was calculated are answered below. How was land use mix calculated in multistorey developments, and why are some land types considered more important that others? The GIS analyses require a single land use for each parcel. Where there are multiple land uses in a single parcel (e.g., a building with a shop on the bottom storey, and apartments above) a single land use was selected based on the following priority: retail, commercial, community, recreation (excluding public open space), residential, and other. The priority was determined by a panel of experts who considered the likelihood of the land use being treated as a destination to walk to. Are footpaths (especially good quality and well maintained footpaths) included in the Index? (and if not, why not?) While the presence, quality and maintenance of footpaths are important aspects of walkability they are not included in the Transport Walkability Index due to footpath data
being unavailable across Metropolitan Melbourne Additionally many residential areas in Metropolitan Melbourne are reasonably well-serviced by footpaths. Is traffic volume or speed included in the Index calculations? Are public transport stops included in the calculations? Are pedestrian traffic signals and controlled crossings included in the calculations? Are pedestrian amenities (e.g., seats, toilets) included in the calculations? Is safety or street lighting included in the Index? Is slope included in the Index? Are the aesthetics or the visual appeal of an area included in the Index calculations? The Transport Walkability Index incorporates fundamentals of the built environment that need to be in place to support walking: having something to walk to (land use mix, density), and a street network that supports walking (connectivity). Traffic (speed and volume), public transport, pedestrian traffic signals, safety, street lighting, slope and aesthetics, while important for walking, are not likely to matter if there is nowhere to walk to and nothing to walk on. However, we acknowledge that the built environment characteristics listed above can also contribute to the walkability of an area. They were not included in the index for a number of reasons: 1) lack of data, 2) lack of a methodology to calculate /include these measures, 3) lack of validation against walking behaviour, and 4) lack of resources to collect data and develop measures. Increased availability of consistent data on the above aspects of the built environment could help researchers create improved walkability indices that better account for all aspects of the environment that influence walking. What is the difference between walkability and accessibility? Walkability relates to how different characteristics of a place support walking. Whereas spatial accessibility refers to how easy it is to get to one place from another place via different modes of travel (including walking). If people are trying to get to a destination that is, walking for transport - increased spatial accessibility to certain types of destinations can make places more walkable and increased walkability can make places more accessible. However, when people are walking for recreation, access to destinations may be less important. Two f the three components of the walkability index - street connectivity and land use mix - are directly related to accessibility. Increased street connectivity often results in shorter distances between destinations and therefore is associated with increased spatial accessibility. Land use mix is a measure of different destinations and a higher land use mix score means that different types of destinations are closer to each other and therefore more accessible to each other.
What is the difference between the Transport Walkability Index and Walk Score? Walk Score (www.walkscore.com) is a popular measure of walkability that provides a number between 0 and 100 for any address. Walk Score is based on distances to amenities, population density and road metrics, however the methods for calculating the score are not available for public scrutiny. Both Walk Score and the Transport Walkability Index are useful measures of walkability and both assess three important components of walkability by having: 1) destinations to walk to, 2) a dense enough population to support the viability of the destinations, 3) and a connected road network that minimises the distance to destinations. However, each approach has different strengths and weaknesses and differences between the measures are summarised in the table below. Walk Score Transport Walkability Index Destinations Distance to destinations Land use mix Density Population density Dwelling density Road metrics Block length, intersection Intersection density density (for example) Relative or Absolute Absolute (value from 0 Relative (deciles) measure? 100) Clearly defined area No Yes Transparent methodology No Yes To illustrate the difference between WalkScore and the Transport Walkability index, imagine we are interested in the walkability of Carlton, Melbourne. The first thing to note is that WalkScore calculates walkability for an address entered and the address can be at a range of scales. Entering Melbourne in the WalkScore website produces a score of 57, while Carlton results in a score of 98 and 8 Little Elgin St, Carlton produces a score of 99. However, we do not know the extent of the spatial areas measured with WalkScore. We know that WalkScore calculates distance to destinations, but unless we enter the exact address we do not know where the distance is calculated from. In comparison, the Transport Walkability Index is calculated for a clearly defined area, e.g. an SA1. What can I use the Transport Walkability Index for? Comparing relative walkability across areas. An evidence source that can test proposed developments prior to development in an area An advocacy tool A research tool What should I be aware of when using the Transport Walkability Index? The results are relative. The Transport Walkability Index only indicates which areas are more or less walkable when compared with other areas. There is no optimal score. Results can
vary when the Transport Walkability Index is calculated in slightly different ways. The index is only as good as the data used to calculate it. Decisions made when calculating the Transport Walkability Index can change the results, however, in general it is generated using three stable inputs (ie street connectivity, dwelling, land use mix) which do not change rapidly across time, as such, this definition of the Transport Walkability Index can be relied upon as a general measure of Transport Walkability for the short run in the absence of major infrastructure changes. What geographic scale is the Transport Walkability Index available at? The Transport Walkability Index is available for SA1s. Are results available for country Victoria? The Transport Walkability Index is currently only available for Metropolitan Melbourne and the North West Metropolitan region. Transport Walkability Indices for Regional Centres are under development. The index will not be calculated for other areas as it is an urban tool and does not make sense when calculated for regional and rural areas. What are the strengths and limitations of the Transport Walkability Index? Strengths: Validated against walking behaviours in many studies worldwide. Able to be calculated using routine and readily available data. Transparent methodology Ability to interrogate the components of the index Can be updated easily when additional spatial data become available There are opportunities for making the index more sophisticated when better data become available Provides an easy to interpret, relative measure that is useful for comparing across regions. Limitations: A relative measure of walkability. Therefore there is no single value that means an area is walkable or not walkable. This also means that the index only makes sense when it is calculated for a number of areas. (also a strength) Does not include some aspects of the built environment that are likely to be important for walking. Not available beyond Metropolitan Melbourne at this stage. While street connectivity is relatively stable, dwelling density and land use mix can change over time, therefore the index represents a single point in time. (Also a strength)
The data for the three components of the index are as closely matched in time as possible, but there are some discrepancies i.e. VGO land use (2010), dwelling density (2011), connectivity (2012) How do I download the Transport Walkability Index for my area? Maps of the Transport Walkability Index by Local Government Area (LGA) are available from: Community Indicators Victoria http://www.communityindicators.net.au/walkability_for_transport References Giles-Corti, B., Mavoa, S., Eagleson, S., Davern, M., Roberts B., Badland, H.M., (2014) Transport Walkability Index: Melbourne. McCaughey VicHealth Centre for Community Wellbeing, Melbourne: The University of Melbourne.