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The National Academies

NCHRP 20-07/Task 081 [Completed]

Effect of Headlamp Design on Retroreflective Signs and Pedestrian Safety
[ NCHRP 20-07 (Research for AASHTO Standing Committee on Highways) ]

  Project Data
Funds: 75000
Research Agency: Westat, Inc.
Effective Date: 4/14/1997
Completion Date: 4/13/1998
Comments: Completed

Task 81, FY 1997, "The Relationship Between Headlamp Design and Retroreflective Sign Visibility" (Westat, Inc.). The visibility and legibility of unlit signs at night are fundamentally linked to the characteristics of vehicle headlamps. Headlamps also illuminate pedestrians, with the light above the plane of the headlamp being particularly important for viewing the head and torso. The light above the horizontal plane, however, produces glare for oncoming motorists and, through mirror reflection, to downstream motorists. Headlamps also provide a visual cue at night to other road users that helps them locate the approaching vehicle's relative position and decide whether it is safe to enter or cross the roadway. Headlamp designs impact the styling and cost of vehicles. Balancing these disparate interests is a complex task. The objective of this project was to recommend headlamp intensity requirements above the horizontal plane of the headlamp. The report has been delivered to AASHTO. (NCHRP Staff: B.R. Derr)

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