Lighting and Conspicuity
According to the National Highway Traffic Safety Administration (NHTSA), in 2017, approximately 75% of pedestrian fatalities occurred under dark lighting conditions. A driver’s ability to recognize and perceive a pedestrian can be influenced by a number of factors such as, contrast, anticipation, pattern, lighting, eccentricity, time of exposure, and size. ARCCA engineers evaluate conspicuity issues with the use of advanced light metering equipment and the latest digital camera technology. The application of human factors and driver response research allows for a scientific approach when reconstructing collisions involving recognition and perception issues.
Headlight Illumination Mapping
Recognition for a driver is initiated when a driver is able to see an object or pedestrian. When operating a motor vehicle on an unlit roadway, a vehicle’s headlights serve as the primary source of forward illumination. An important factor when reconstructing a nighttime collision involving pedestrians is when and where a pedestrian enters the headlight beam pattern. ARCCA engineers are capable of mapping vehicle headlights to analyze their output characteristics to answer the question of when a pedestrian would likely be visible to a driver.
Roadway Illumination Mapping
When nighttime collisions occur on roadways illuminated by artificial lighting, ARCCA engineers are able to survey the roadway with three-dimensional laser scanners and measure the roadway luminance and illumination. Synthesizing these data sets allows for ARCCA’s reconstructionists to determine how much light is present.
Accidents may occur during times in which the ambient sky illumination is changing rapidly. After sunset and before sunrise there is a series of twilight periods in which the sky illumination is changing exponentially. The twilight periods, referred to as civil, nautical, and astronomical, relate to the elevation of the sun with respect to the horizon. When conducting lighting studies, ARCCA engineers utilize astronomical data and illumination metering equipment to quantify and characterize the ambient lighting levels.
A digital camera’s exposure can be adjusted by altering settings such as the aperture, shutter speed, and ISO. Adjustment of these settings allows the camera to take in more or less light which affects the exposure of the resultant digital image. Utilizing the latest in digital camera technology in conjunction with contrast panels and advanced metering equipment, ARCCA engineers are able to accurately document scene illumination with calibrated photographs.