Applicability of mesopic factors to the driving task

Abstract

light-emitting diode technology being applied to roadway lighting, the spectral power distribution of the light source is becoming much more important. In this experiment, the detection of pedestrians at five adaptation levels under three light sources, high pressure sodium and light emitting diodes of two color temperatures, was measured in realistic roadway scenarios. The results show that while the light source type was not significant, an increase in adaptation luminance also increased the detection distance. As the offset of the object to the roadway increased, some spectral effects became more significant; however, this effect was not consistent across all angles of eccentricity. The conclusions from this work indicate that mesopic factors may not be applicable on high-speed roads.

Target visibility under mesopic vision using a driving simulator

“…Akashi and Rea 15 designed a difficult off-axis identification task with a flashing target and found that the RTs for the 15-degree target are shorter than that for the 23-degree target. Gibbons et al 16 found that at a low adaptation luminance, the detection distances decreased with increasing offset from the travel lane as expected. However, at higher adaptation luminances, the relationship between offset and detection distance changed and was less clear and more varied.…”

“…Mayeur et al 23 designed a field experiment to investigate target detection performances, comparing driver and passenger status conditions in order to specify the driver's visibility needs in a way consistent with state-of-the-art lighting engineering practice. Gibbons et al 16 designed a mixedfactors experiment to measure the effect of age, overhead lighting type, adaptation luminance, vehicle speed, visual angle and pedestrian position on pedestrian detection distances. All of them measured the detection distance to find the relationship between factors and visibility, and Mayeur et al 23 further compared the result with VL value.…”

Road lighting research for drivers and pedestrians: The basis of luminance and illuminance recommendations

“…63,64 While there is now a system for mesopic photometry still to be resolved is the situations where it should be applied. For some driver-related activities, mesopic models may not be applicable, 65,66 a result of the diminishing use of peripheral vision during driving on main roads, the ever changing adaptation luminance due to the dynamic nature of drivers' eye movements, and the simultaneous use of headlights. The CIE system has been applied, however, in pedestrian lighting recommendations, 5,[67][68][69] to characterise the illuminance reduction permitted when using lighting of greater short-wavelength content, this being of benefit for tasks such as obstacle detection 70,71 and spatial brightness perception.…”

“…It should be noted that further research indicated that in a driving environment, the mesopic effect was minimised at higher speeds do the reduction in the use of the peripheral vision and blur due to visual flow through the field of view. 65 The reaction time to detection of a target is suggested to be of direct relevance to driving performance as the speed of detection plays an important role in perceptual judgements made by the driver and can be easily translated into stopping distances. 95 Several studies 60,94,96,97 have investigated detection rate and reaction time to detection, for onaxis and off-axis targets, under different luminances and SPDs.…”

“…It should be noted that further research indicated that in a driving environment, the mesopic effect was minimised at higher speeds do the reduction in the use of the peripheral vision and blur due to visual flow through the field of view. 65…”