Walking is widely promoted as an effective form of physical activity associated with wide ranging health benefits for adults . Current UK guidelines recommend that adults complete at least 150 minutes of moderate intensity activity, such as brisk walking, every week . Nevertheless, the English National Travel Survey 2010 reports that walking trips have declined by 28% since 1995 .
Ecological models of health behaviour suggest that environments such as residential neighbourhoods can directly influence physical activity behaviours including walking . However, the objective measurement of environmental variables provides a substantial research challenge. Mapping technologies, such as Geographical Information Systems (GIS), have increased access to objectively characterised data on neighbourhood design and land-use. These data are now regularly utilised in physical activity research and significant associations have been found between walking behaviours and land-use mix, population density and destination proximity . Detailed street-level characteristics such as pavement quality, lighting and aesthetics may additionally be influential. Indeed, walking for both travel and leisure have been significantly associated with individuals’ perceptions of the availability of pavements [6, 7] and aesthetics . Objectively measured street-level data, however, are rarely available through mapping databases .
A number of street audit tools such as the Systematic Pedestrian And Cycling Environment Scan tool SPACES , the Pedestrian Environment Review System (http://www.trl.co.uk) and the Residential Environment Assessment Tool REAT  are available to measure the street characteristics hypothesised to influence walking behaviours. Such audit tools are completed in-person by trained researchers and are typically found to provide a valid and reliable measure [10, 11]. However, in-person audits are highly time-consuming, have safety issues for personnel and are costly due to the related travel expenditure, thus prohibiting large-scale data collection for the majority of research projects. Recent technological advancements, such as the Google Street View programme (http://www.google.com/maps), might provide an alternative mechanism to traditional in-person street auditing. Google Street View is a freely available web service using video stills of streets and neighbourhoods captured worldwide. The images are displayed to provide continuous panoramic street views that can be navigated along and rotated by 360° allowing the user to virtually walk down any available street from their computer. The use of this desk-based tool, therefore, has the potential to dramatically reduce the resources necessary to complete large-scale assessment of street characteristics.
The reliability of desk-based auditing has previously been investigated by a small number of studies all of which consistently report high levels of agreement between Google Street View and in-person measures [12–14]. Nevertheless, to date, the majority of this research has focused on somewhat homogenous urban areas within the US. Further research is therefore necessary to assess the appropriateness of Google Street View in differing countries and area types where factors such as varying road and pavement width or traffic and building density could potentially impact upon the reliability of the measurement tool.
This study aims to first, test the inter-rater and intra-rater reliability of a newly developed street audit tool designed specifically for use with Google Street View and, second, to test the reliability of this desk-based measure when compared with on-foot street audits across a range of land-use types within the UK. This research forms part of the FAST study (Forty Area STudy). FAST is examining the degree to which built environment characteristics influence adult’s physical activity behaviours across a broad range of social and environmental settings in northwest England. In FAST, we are particularly interested in capturing aspects of the street environment around our participants’ homes that may influence their walking and cycling behaviours, and the street audit tool that we present in this paper, was developed for this purpose.