Flashing red incandescent lamps have formed the primary motorist warning device at grade crossings for several decades, in spite of technical constraints that inherently limit the overall effectiveness possible. Tightly focused beams, necessary to obtain high intensity at lower power consumption, make perceived brightness highly dependent on precise alignment, which is difficult to achieve and expensive to maintain. In this report an examination of appropriate literature and existing standards reveals preliminary requirements of function and desirable qualities for such motorist warnings. A consideration of relevant lighting technology shows that significant improvement is possible through the use of xenon flash lamps in standard crossing mountings. The quiet flash of the xenon unit appears to be more effective, with little deviation from the applicable standards, what motorists are used to, and conventional equipment. This study includes a discussion of optimal specifications, relevant technology, field tests, and related topics including system credibility and the use of highway traffic signals. (Author/publisher)
Abstract