Lower Beam Headlighting System Visibility Confirmation Test – Test Procedure Assessment

This report summarizes an assessment of a draft test procedure for confirming the visibility performance of lower beam headlighting systems. Headlighting system performance in this procedure is determined by activating the lower beam headlamps on a production vehicle and measuring the amount of light cast onto the forward roadway over an array of specified locations. Performance levels are then calculated based on measured values for the specified locations.In this assessment, three vehicles were subjected to three repetitions (sets) of the test procedure. Results showed measured values for visibility and glare measurement locations to be consistent across the three test repetitions. Calculated performance levels based for these same measurement locations were also consistent across the three measurement sets (2015 Cadillac ATS: 5; 2014 Infiniti Q50: 25; 2016 Volvo XC90: 15). Measurement results for an expanded array of measurement locations showed higher coefficient of variation values for the center and left lanes than were seen for the right lane. Performance levels based on the center and left-lane locations were consistent across the three test repetitions for two vehicles, but were not consistent for the third vehicle because one of the measured values was very close to the 3.0 lux cutoff for visibility scoring. An alternative test procedure was considered that would involve measuring illuminance at only the rearmost points and then calculating the remaining values using the inverse square law of light. Performance levels based on calculated illuminance values matched measurement-based performance levels for two of the three vehicles tested. For the third vehicle, differences resulting in a lower performance level based on calculated illuminance values. Overall, the test procedure presented no difficulties to execute and was effective in characterizing lower beam performance levels. This test effort also provided valuable information on headlamp illuminance consistency and indicated good test repeatability. The inclusion of center and left lane measurement points to augment the right lane measurement points was informative, but also showed more variance in measured values which may result in different performance level values across multiple test repetitions. The use of alignment aids such as those used in this test effort can help to achieve accurate and repeatable test vehicle and receptor head positioning.


  • English

Media Info

  • Media Type: Web
  • Edition: Final Report
  • Features: Figures; References; Tables;
  • Pagination: 41p

Subject/Index Terms

Filing Info

  • Accession Number: 01720891
  • Record Type: Publication
  • Report/Paper Numbers: DOT HS 812701
  • Created Date: Oct 29 2019 9:32AM