Visibility Distance with Headlights: A Functional Approach

Proceedings of the Human Factors and Ergonomics Society Annual

Patton

1998

Pedestrians consistently overestimate their visibility at night. This experiment examined the effectiveness of several strategies of educating pedestrians about their own nighttime visibility. Forty-eight undergraduates were assigned to one of four groups: Lecture, Demo, Combo, or Control. Several weeks prior to data collection, participants in the Lecture and Combo groups had heard a lecture on applied visual physiology in their Introductory Psychology course. Immediately before data collection, participants in the Demo and Combo groups sat in a car and watched a nighttime pedestrian visibility demonstration. Under various clothing and illumination configurations, all participants walked towards a stationary car until they believed they were recognizable as a pedestrian. The lecture significantly reduced estimated visibility distances. This result is encouraging since it suggests public education efforts may be useful. The demonstration did not produce significant changes when participants wore either white or black clothing, but significantly increased estimates when wearing retroreflective strips.

Section: Discussioncontrasting

confidence: 60%

The Effectiveness of Educating Pedestrians about their own Nighttime Visibility

Proceedings of the Human Factors and Ergonomics Society Annual

Patton

1998

“…These values were chosen to cover a broad range of luminances from photopic to scotopic, with luminance values in the intermediate conditions typical of those encountered during the dimmer periods of civil twilight. 12 Luminance was always tested with maximum image clarity (i.e., no blurring lenses).…”

Section: Methodsmentioning

confidence: 99%

The Effects of Severe Visual Challenges on Steering Performance in Visually Healthy Young Drivers

Brooks

Optometry and Vision Science

Frank

2005

In healthy young drivers, steering performance is remarkably robust to severe blur and to extremely low luminances. These results support a key element of the selective degradation hypothesis advanced by Leibowitz and colleagues--that steering abilities are preserved at night even when the ability to recognize objects and hazards is not. Additional research should address the other element of this hypothesis--that drivers fail to appreciate the extent to which their visual abilities are degraded at night.

“…The changes in visual performance are most dramatic during civil twilight. In clear atmospheric conditions, ambient illumination during civil twilight ranges from approximately 330 lux down to about 3.3 lux . This range of illumination corresponds to the transition between photopic (cone) and scotopic (rod) vision.…”

Section: Vision In Twilightmentioning

confidence: 99%

“…Design standards limit the total amount (luminous intensity) and the spatial distribution of light . While detailed photometric descriptions of headlight characteristics are available, a spatial analogue of civil twilight provides a holistic description of the useful range of headlight illumination . This ‘twilight envelope’ method involves measuring the spatial extent over which a pair of headlamps provide illuminance of 3.3 lux or more (that is, bounded at the dark limit of civil twilight).…”

Section: Headlightingmentioning

confidence: 99%

“…In clear atmospheric conditions, ambient illumination during civil twilight ranges from approximately 330 lux down to about 3.3 lux. 11 This range of illumination corresponds to the transition between photopic (cone) and scotopic (rod) vision. Civil twilight lasts approximately 30 minutes at mid-latitudes, although the exact duration varies with latitude and time of year.…”

Section: Vision In Twilightmentioning

confidence: 99%

See 1 more Smart Citation

The conspicuity of pedestrians at night: a review

Clinical and Experimental Optometry

Wood

Owens

et al. 2016

Drivers' visual limitations are a leading contributor to night-time traffic crashes involving pedestrians. This paper reviews the basic changes in vision that occur at night for young and old visually healthy drivers, as well as those with common ocular pathology. To maximise their safety at night, pedestrians should be conspicuous. That is, beyond being simply visible (detectable as an ambiguous object), they should attract the attention of drivers and be readily perceivable as pedestrians. Research has established that the conspicuity of pedestrians can be optimised by attaching retroreflective markings to the pedestrian's extremities. Doing so highlights the pedestrian's 'biological motion,' which facilitates the accurate perception of a person; however, retroreflective markings on the torso (for example, vests) are less effective. Importantly, behavioural evidence indicates that most road users -drivers and pedestrians alikeare not aware of the limitations of night vision. For example, drivers typically 'overdrive' the useful range of their headlight beams and under-use their high beam headlight setting. Further, pedestrians overestimate their own conspicuity at night and fail to appreciate the extent to which their own conspicuity depends on their clothing. The widespread misunderstanding of the challenges associated with night driving reflects a lack of awareness of the fundamental limitations of night vision. Educational interventions are needed to ameliorate these dangerous misunderstandings and to improve the safety of all road users at night.