Visibility & Lighting Conditions Flashcards
7 cards from real ACTAR practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Visibility & Lighting Conditions flashcards as text
High-beam headlights on a standard passenger vehicle typically illuminate the road to approximately:
Answer: 350–450 feet
Standard high-beam headlights illuminate approximately 350–450 feet ahead, providing greater available sight distance at higher speeds compared to low beams.
The term 'maintained illuminance' in road lighting, as defined by the Illuminating Engineering Society (IES), refers to:
Answer: The average illuminance sustained over the life of the luminaire accounting for light loss factors
Maintained illuminance accounts for lamp lumen depreciation and luminaire dirt accumulation, providing a realistic lighting performance value applicable to accident reconstruction analysis.
In the context of visibility during accident reconstruction, 'threshold contrast' refers to:
Answer: The minimum luminance difference required for an observer to detect an object against its background
Threshold contrast is the minimum luminance difference between a target object and its background that allows a driver to detect the object, critical for analyzing pedestrian and obstacle visibility.
What is the primary function of retroreflective sheeting on traffic signs in relation to nighttime accident reconstruction?
Answer: To return light from vehicle headlights back toward the driver, making the sign visible at night
Retroreflective sheeting on signs returns headlight beams toward the driver, enabling sign visibility at night without requiring external illumination.
A traffic accident reconstructionist analyzing nighttime visibility would use photometric data primarily to:
Answer: Determine how road lighting or headlights illuminate the scene and affect driver visibility
Photometric data provides information about light distribution and intensity, allowing reconstructionists to model how roadway lighting or headlights illuminated the scene and assess driver visibility.
Which of the following best describes 'disability glare' versus 'discomfort glare'?
Answer: Disability glare reduces visual performance; discomfort glare causes annoyance without necessarily impairing vision
Disability glare reduces a driver's ability to detect objects by scattering light within the eye, while discomfort glare causes pain or annoyance but does not necessarily impair visual performance.
When evaluating a nighttime accident scene, a reconstructionist measures the 'effective perception distance' as:
Answer: The distance at which a driver could first have detected and identified a specific hazard under the prevailing conditions
Effective perception distance is the distance at which the specific hazard—given lighting, object conspicuity, and driver factors—would first have been detectable, forming the basis for calculating avoidance feasibility.