Selection and Application of Warning Lights on Roadway Operations Equipment (2008) / Chapter Skim
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NCHRP Project 13-02 was conducted to address this need. Objective The objective of this research was to develop guidelines for selection and application of warning lights to improve the conspicuity and recognizability of roadway operations equipment (i.e., vehicles and mobile equipment)
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Literature Review Currently, there is a wide disparity in the design of warning lights used on roadway maintenance vehicles. The Manual on Uniform Traffic Control Devices (MUTCD)
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The characteristics affecting warning-light conspicuity include contrast brightness, flash effective intensity, flash color, flash frequency, flash duration, flash shape, flash type, flash pattern, flash size, number of elements, and apparent motion, and steady-burn light color. Contrast Brightness Contrast brightness refers to the direct comparison of one reflecting surface with another.
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Disability Glare Disability glare occurs when a bright light source impairs an individual's ability to see objects. The effect of disability glare caused by warning beacons, as stated by Cook et al.
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Lights flashing in the center of the visual field are more likely to cause an eleptogenic response. Also, drivers of emergency vehicles reported that strobe beacons cause more visual discomfort than rotating beacons.
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Incandescent Filament Bulb There are two types of flashing lights that use incandescent filament bulbs: rotating beacons and 360° flashing lights. The pulse width and shape of a rotating beacon are determined by the reflective optic because the bulb is on continuously.
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From page 11... ...
Any measure that increases the distance at which motorists are informed about the presence of maintenance vehicles will increase the time available to react. Because signs are stationary countermeasures and the operation of shadow vehicles is expensive, the use of more conspicuous warning lights is desired.
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