Using street lighting to support pedestrian safety at night
Street lighting can make us feel safer when walking at night. Lighting after dark helps to reveal the way ahead and to reveal potential refuge if faced with an unwanted situation. It can help us to ‘suss out’ a situation such as approaching other people – is it safe to carry on or should I walk the other way?
But the use of road lighting can have unwanted consequences like light pollution, a detrimental impact on the nocturnal environment, and energy consumption. While it is important to support pedestrians, there is also a need to protect these elements.
Professor Steve Fotios and his colleagues from the Lighting Research Group (in the School of Architecture at the University of Sheffield) are researching ways to enhance street lighting, in order to support the visual needs of pedestrians while protecting the night sky and natural environment.
“Current research suggests that road lighting is beneficial to pedestrians. What is not yet known is the optimal light level to support pedestrians’ needs, if indeed such an optimum can be established, and the compromise between lighting to support active travel at night versus the need for dark skies,” said Professor Fotios.
The UK Government’s drive to promote walking and cycling aims to reduce emissions from vehicle use, to create a more physically active society, and to do so safely. Research conducted by Professor Fotios and his team shows how we can use lighting after dark to make walking a safe travel choice.
The focus of research in the Lighting Research Group is the benefit of lighting for pedestrians. This is done through field studies, laboratory experiments and data analyses. Providing evidence of the effect of changes in lighting conditions can help to inform lighting engineers faced with pressure to reduce light levels (or even to switch off lighting late at night) to mitigate sky glow, energy use and impact on the natural environment.
The Lighting Research Group investigates how lighting can be used to support the visual needs of pedestrians (and cyclists) and provide lighting designers with knowledge about the likely impact of reducing light levels in response to environmental pressures.
“Reassurance is a key consideration when targeting optimal lighting,” Professor Fotios added, “but we also consider how lighting helps to detect trip hazards, and to see and evaluate other people when deciding ‘do I feel safe to continue and approach the person or people ahead?’ We also investigate lighting in relation to crime and road traffic crashes.
“The basis for current recommended light levels is uncertain. We do not know if they are about right, lower than optimal or higher than optimal. Our research aims to address this.”
“What we’ve found is that while brighter lighting, or higher illuminance, may be beneficial, there is usually a point at which further increase in brightness brings no further benefit. For example, you might not detect a trip hazard even under the brightness of daylight. And of course, the brighter the light the more energy consumption, light pollution and so on. That point gives an estimate of the optimal brightness.
This focus on lighting for pedestrians has been running for about 20 years during which Professor Fotios and the team have finished four EPSRC (Engineering and Physical Sciences Research Council) funded projects, and are seeking funding for further research into pedestrian reassurance and cyclist conspicuity (helping cyclists to grab driver’s attention so that they are more easily seen.)
“We have used our findings to update National and International standards for lighting,” said Fotios. “Our research has had a direct impact on the bodies that set lighting standards and the practitioners who use them, including the International Commission on Illumination (CIE), the Institution of Lighting Professionals (ILP), the British Standards Institute (BSI); and the Illuminating Engineering Society of North America (IESNA). These bodies have used our research findings to define best practice, through new and modified technical standards.”
“We have a better idea about how changes in lighting affect the benefits to pedestrians, but we’re still a long way from reaching the complete picture. Lighting and visual response are complex issues, and it’s a difficult feat to measure perceived safety. But we’re making progress,” said Professor Fotios.
For his work on pedestrian lighting, Professor Fotios received the quadrennial Distinguished Services Award from the International Commission on Illumination in 2015.
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