Road Testing by Iain Carlile

dpa Senior Associate Iain Carlile looks at the latest papers from Lighting Research and Technology papers that range from road illumination to the non-visual effects of light.

This article was published in the Society of Light and Lighting’s newsletter ‘Light Lines’  January/February 2020 edition. To view this article in full please click here.

A paper by Fotios reviews the weightings made by the CIE in document CIE115:2010 in order to determine the P-class lighting design recommendations. P-class concerns lighting for minor roads, referred to in the UK as ‘access roads, residential roads and associated areas, footpaths and cycletracks’. CIE115:2010 gives a number of parameters (travel speed, traffic volume, traffic composition, parked vehicles, ambient luminance and facial recognition) with weighting factors, with the summed weighting factor identifying a particular lighting class with average and minimum illuminance values.

From a literature review Fotios identifies that some of these parameters are relevant due to their association with a pedestrian RTC (road traffic collision). However, the review was unable to substantiate the class selection process, due to a number of factors: little evidence of lighting needed to offset risks such as differing speed of traffic, whether weighting factors and intervals between options are relevant, and if parameter weightings are relevant.
Further, Fotios notes that if the primary aim is to light for pedestrians, since the weighting factors tend to focus on the chance of a pedestrian RTC, with other factors not being represented (for example, discerning obstacles and hazards, identifying movement of other pedestrians) then the weighting system gives false confidence to designers that their design is meeting pedestrians’ needs.

Figueiro et al present the results of a case study investigating the application of lighting for non-visual effects on a building’s occupants. The authors note that laboratory studies have shown that (depending on the time of exposure) a sufficient amount of shortwavelength light and exposure duration can entrain or disrupt the synchrony between our biological clock and our local position on Earth. They have also shown that alertness can be enhanced both day and night by light across the entire visible spectrum.

Using a novel luminaire designed to promote entrainment and alertness, field tests of light exposure were conducted in office environments. The results revealed that tailored lighting interventions can help entrain occupants and increase alertness during working hours (when properly applied). The authors note that the luminaire used in the study might not be ideal, but was practical and inexpensive to implement, helping to bridge between laboratory studies and field applications.

Siemiginowska and Iskra-Golec’s paper presents the results of a laboratory experiment investigating blue light exposure and EEG (electroencephalographic) activity, to see if a person’s chronotype could moderate the effect of monochromatic blue light. The authors note that some previous studies have reported higher alertness during blue light exposure, while other studies have failed to demonstrate this effect.
An experiment was conducted in which a group of 30 young male volunteers were exposed to two different lighting conditions of comparable luminance on room surfaces at eye level when seated. These were: monochromatic blue light (MBL) at 460nm, and polychromatic white light (PWL). After four hours of exposure, EEG measurements were taken in the morning, afternoon and evening.

It was found that the blue light effect differs depending on the length of exposure and an individual’s chronotype. From the results of the experiment it was found that the blue light effect differs depending on the length of exposure and an individual’s chronotype. MBL had a significant influence on EEG activity in the afternoon hours in morning-orientated types. The authors note that the observed effect was only based on a study of young men, limited to a particular time of the day (afternoon hours) and chronotype (morning type), and as such the results should be treated carefully.

Further editions of the Society of Light and Lighting’s newsletter ‘Light Lines’ can be found on their website


Further editions of the Society of Light and Lighting’s newsletter ‘Light Lines’ can be found on their website