Lichthinder zonreflectie voor weggebruikers – ontwikkeling beoordelingsmethode op basis van disability glare
report
Purpose : Road users may be hindered by sun reflections in man built objects along the road. To assess these glare situations currently an TNO developed assessment method is used which is based on discomfort glare (TNOdiscom). This report describes the development of an alternative assessment method based on disability glare, which also takes into account contextual factors such as road situation and time of day (TNOdisab). Disability glare is based on physiological glare (scattered light in the eye) and is therefore directly linked to the visibility of objects on the road.
Method : To develop TNOdisab first a suitable disability glare model was chosen. After that, an analysis was made of the visibility of the objects on the road that are critical for the driving task and to what extent they are affected by disability glare. Finally, the amount of disability glare was determined which is allowed in order to safely perform the driving task in which the context of the situation is taken into consideration. On this basis, a rejection criterion is selected.
Finally, it is examined how much disability glare is allowed in order to perform the driving task safely. The context of the situation is also taken into account. On this basis, a rejection criterion was chosen.
TNOdisab was compared with TNOdiscom and the American model SGHAT for three glare situations on the road (sound barrier, solar park, building over the road).
Using the TNOdisab method the duration of unacceptable light reflections was calculated for a few generic glare situations of a sound barrier and a solar park for different traffic directions and tilt angles of the sound barrier and solar panels.
Finally, the influence of the direct sun was compared with that of the reflected sun, for a sound screen and a solar farm, using the TNOdisab method.
Results : TNOdisab is based on the determination of the visibility of the road markings on the stopping distance. With standard models for daylight and glare disability the visibility of the road marking is determined in the glare situation to be assessed. When the road marking is not visible than the glare is not permissible when the road user is close to a curve in the road or a convergence or divergence point. On a straight road the period of invisibility of the road marking of 1.3 s to 1.8 s is allowed, depending on the maximum allowable speed.
The TNOdisab assessment method is less strict than TNOdiscom. Averaged over the three glare situations, the duration of unacceptable sunlight reflections determined by TNOdisab was 64% of the length determined by TNOdiscom. The assessment method SGHAT is on average twice as strict as TNOdiscom.
The calculations of the generic glare situations resulted in a set of tables showing the duration of unacceptable sun light reflection (hours /year), for sound barrier and a solar park, for all combinations of driving direction, location (left, right), and tilt angles, taking into account a cloudless sky probability of 1/3.
The duration of unacceptable sunlight reflections is a factor 1.4 greater when, in glare situations, both the direct and the reflected sunlight are taken into account.
Conclusion : The new assessment method based on disability glare (TNOdisab) is a suitable method for determining the glare for road users by sun reflections in objects along the road.
Method : To develop TNOdisab first a suitable disability glare model was chosen. After that, an analysis was made of the visibility of the objects on the road that are critical for the driving task and to what extent they are affected by disability glare. Finally, the amount of disability glare was determined which is allowed in order to safely perform the driving task in which the context of the situation is taken into consideration. On this basis, a rejection criterion is selected.
Finally, it is examined how much disability glare is allowed in order to perform the driving task safely. The context of the situation is also taken into account. On this basis, a rejection criterion was chosen.
TNOdisab was compared with TNOdiscom and the American model SGHAT for three glare situations on the road (sound barrier, solar park, building over the road).
Using the TNOdisab method the duration of unacceptable light reflections was calculated for a few generic glare situations of a sound barrier and a solar park for different traffic directions and tilt angles of the sound barrier and solar panels.
Finally, the influence of the direct sun was compared with that of the reflected sun, for a sound screen and a solar farm, using the TNOdisab method.
Results : TNOdisab is based on the determination of the visibility of the road markings on the stopping distance. With standard models for daylight and glare disability the visibility of the road marking is determined in the glare situation to be assessed. When the road marking is not visible than the glare is not permissible when the road user is close to a curve in the road or a convergence or divergence point. On a straight road the period of invisibility of the road marking of 1.3 s to 1.8 s is allowed, depending on the maximum allowable speed.
The TNOdisab assessment method is less strict than TNOdiscom. Averaged over the three glare situations, the duration of unacceptable sunlight reflections determined by TNOdisab was 64% of the length determined by TNOdiscom. The assessment method SGHAT is on average twice as strict as TNOdiscom.
The calculations of the generic glare situations resulted in a set of tables showing the duration of unacceptable sun light reflection (hours /year), for sound barrier and a solar park, for all combinations of driving direction, location (left, right), and tilt angles, taking into account a cloudless sky probability of 1/3.
The duration of unacceptable sunlight reflections is a factor 1.4 greater when, in glare situations, both the direct and the reflected sunlight are taken into account.
Conclusion : The new assessment method based on disability glare (TNOdisab) is a suitable method for determining the glare for road users by sun reflections in objects along the road.
Topics
TNO Identifier
573774
Publisher
TNO
Collation
69 p.
Place of publication
Soesterberg