Public participation geographic information system as a tool to study outdoor lighting and urban experiences after dark

The quality of outdoor environments after dark is as crucial as during daylight hours, especially in regions where long autumn and winter seasons limit daylight availability. Outdoor lighting plays a central role in shaping after-dark environments, yet it is often treated as a secondary or purely technical task rather than a multidimensional design responsibility that integrates social, environmental and economic goals. People, along with their experiences, are the primary beneficiaries of outdoor lighting. Various methods exist to capture and explore these experiences. Among them, participatory mapping, particularly Public Participation Geographic Information System (PPGIS), has gained increasing attention in both academia and practice and is widely applied in urban and environmental research. However, the application of PPGIS to outdoor lighting and after-dark experiences remains limited. Little is known about its capacity to capture lighting perceptions, and, to the author’s knowledge, no studies have yet integrated lighting-specific spatial datasets with PPGIS data to examine after-dark experiences. This gap motivates a more dedicated exploration of PPGIS for lighting research. The objective of this thesis is to evaluate the applicability and limitations of the PPGIS methodology as a tool for studying outdoor lighting and urban experiences after dark by: (i) synthesising existing research on urban experiences to support the use of PPGIS for lighting research, (ii) testing whether PPGIS can capture and spatially represent perceived overall quality of street lighting (POQ) and brightness in ways consistent with actual lighting conditions, and (iii) applying PPGIS to explore reassurance in relation to outdoor lighting in real-world settings. Two literature reviews were conducted. Furthermore, a campus-scale PPGIS survey collected place-specific reports of reassurance, POQ and brightness, which were analysed alongside three lighting GIS layers: a map of road lighting features, a map of road lighting classes, and nighttime aerial imagery, supplemented by targeted on-site investigations. Existing literature highlights that outdoor lighting influences experience on multiple, interconnected levels, ranging from direct visual perception to psychological effects and behavioural responses. This evidence supports the use of participatory, experiential methods such as PPGIS in lighting research and practice. In the campus study, PPGIS successfully captured and spatially represented POQ and brightness. Specifically, areas rated high versus low in POQ corresponded to observable differences in lighting conditions, reported POQ and brightness ratings differed significantly across the three defined lighting groups, and brightness ratings showed a moderate correspondence with relative luminance derived from nighttime aerial imagery. Furthermore, reassurance explored through PPGIS was positively associated with perceived lighting attributes and with spatial indicators of lighting infrastructure. The thesis also discusses limitations and further developments of PPGIS for lighting applications. Overall, PPGIS emerges as a promising method for exploratory, large-scale assessment of afterdark environments, offering researchers and planners a scalable way to incorporate public perspectives into lighting research, strategy and design.