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OCR for page 21
21 Different analyses were conducted for daytime and night- intensity of the light source leads to a higher glare experience time; because glare is not evident during the day, it does not by the approaching observer. provide an upper limit to the photometric rating of the light Flash Pattern. The results show that the use of a flashing source. Therefore, a dual level of light source should be consid- light provides both high conspicuity and reduced glare. In ered. A nighttime range and a daytime range of light intensities particular, the use of an asynchronous flashing light seemed should be considered to provide adequate attention-getting to provide an increased benefit over the synchronous pattern. while still limiting glare. Proposed values based on a discom- The frequency of the flashing seemed to have a minimal im- fort glare level of 6 and an attention-getting rating of 5 for both pact on the response (a lower frequency seemed to provide the daytime and nighttime were developed and are presented only a slightly higher response). in the guidelines (see the attachment). Light Type. The use of halogen or LED sources seemed to not be significant in the analyses. However, in some limited applications, the LED seemed to provide a higher response, Discussion likely due to the color purity for this type of light. The results from this static experiment were specifically Retroreflective Tape. The results indicate that the retro- analyzed to enable the development of guidelines for the reflective tape is not suitable as the only marking option application of warning lights to maintenance vehicles. These re- on maintenance vehicles; however, this tape seemed to pro- sults support specific recommendations relevant to the lighting vide an additional benefit at night, with regard to attention- design. The possible areas of consideration are lamp color, getting. effective intensity, flash pattern, lamp type, retroreflective tape Lamp Location. There was an improved benefit during use, and lamp location: the daytime to have the light source appear against a black background by providing a contrast that can be con- Color. The results indicate that amber and white are the trolled by the agency operating the vehicle. Having the lighting colors that should be considered for maintenance ve- lamp appear against a non-black background may not be as hicles. These colors provided the highest conspicuity in the effective. peripheral detection task and the best attention-getting rat- ings and were most closely linked to maintenance vehicles Preparation for Dynamic and construction activities in the participants' minds. Performance Testing Effective Intensity. The effective intensity of the light source needs to be balanced between the higher conspicuity pro- To more fully explore the requirements found in the static vided by a higher effective intensity and the experience of screening experiment, the performance experiment was under- glare by the driver. The results show that a higher effective taken with four lighting arrangements. These were rotating intensity of light source provides a greater conspicuity both beacons in two different locations and panels lights in both during daytime and nighttime. However, the higher effective LED and strobe configurations.