Technical Reports

Rear-End Train Marker Light Evaluation

  • 07
  • Sep
  • 1990
AUTHOR: Denwood Ross III, Daniel Griser, Delia Treaster, Louise Tijerina
SUBJECT: Human Factors
KEYWORDS: Train Rear-End Markers, Light Intensity Distribution, Marker Color Distribut, Human Factors Test
ABSTRACT: All rear-end train marker lights until recently were incandescent bulbs of almost identical design. With the advent of cabooseless trains and battery-powered end- of-train devices, new technologies using low-power LED and xenon flash tube lights were developed. Because of uncertainties in off-axis light intensity distribution, the FRA sponsored this research study to evaluate different types of markers in the context of current Federal regulations (CFR Part 221 ). Laboratory tests were conducted on the train rear-end marker devices from four manufacturers. These included incandescent bulbs, LED arrays, and two different xenon flash tube devices. Both red and amber lenses were tested on two of the devices. Chromaticity (color) measurements were made over a .range of 380 to 780 mil 1 microns wavelength. Peak intensity measurements were then made using a telephotometer at distances of 25 and 100 feet, both at the geometric center and up to t90 degrees vertically and horizontally from center. Effective intensity values were calculated based on time integration of the pulse shape, using standard IES formulae. A field test was then conducted to assess the visibility to human observers of the test markers differing in lamp type, color, cycle (pulsed or steady) and intensity. Both subjective assessments and visual detection data were collected, using a population of 24 volunteers. Tests were set up on a 1000-ft stretch of dark road at Battelle's West Jefferson facility* Point of angular detection was measured by slowly rotating each device. On-axis assessment was done by an "A-0" comparison of different marker combinations. Field test data did distinguish among markers.