00464597

Component

http://onlinepubs.trb.org...trr/1987/1111/1111-008.pdf

https://scholar.google.co...shov&publication_year=1987

An additional yardstick to evaluate the quality of fixed highway lighting is proposed, specifically, the contrast of a critical-size standard target object, such as a 20 x 20-cm (8 x 8-in.) square middle-gray card placed vertically on the road surface perpendicular to the road axis. The proposed measure of standard target contrast would be used in conjunction with other currently used yardsticks, such as luminance and glare. The concept of a standard target contrast is demonstrated with reference to a test section of conventionally designed luminaires. Although luminance levels meet the standards for uniformity, spots of unsafe low contrast are clearly revealed by the new yardstick. Contrast has been defined in such a way that values for silhouette vision range from no contrast at zero to a maximum contrast of -1, representing a comfortable range for all practicable evaluation work. The prospect of more effective nonsymmetrical luminaires for one-way traffic is also investigated. It is shown that about half the light output must be widely and uniformly distributed to meet luminance requirements and that the remaining light can be effectively directed toward the driver for enhancing contrast values. Conventional symmetrical luminaires need a distinct overlap of main beams to provide sufficient contrast for silhouette vision at all points along the road.

Publication of this paper sponsored by Committee on Visibility. Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved

00496549

pp 62-71

1987

Transportation Research Record

0-309-04463-4

Print

Figures (10) ; References (5)

Contrast; Evaluation; Luminaires; Measurement; Quality control; Street lighting

Silhouette Vision

Quality

Design; Highways; Safety and Human Factors; I85: Safety Devices used in Transport Infrastructure

TRIS, TRB

Dec 31 1987 12:00AM

• A METHOD OF CALCULATING THE EFFECTIVE INTENSITY OF MULTIPLE-FLICK FLASHTUBE SIGNALS
• A STUDY OF ROUTE SELECTION FROM HIGHWAY MAPS (ABRIDGMENT)
• ADVISORY SPEED SIGNS AND CURVE SIGNS AND THEIR EFFECT ON DRIVER EYE SCANNING AND DRIVING PERFORMANCE
• ALTERNATIVES TO ENFORCEMENT IN MODIFYING THE SPEEDING BEHAVIOR OF DRIVERS
• ANALYSIS OF HIGH-HAZARD LOCATIONS: IS AN EXPERT SYSTEMS APPROACH FEASIBLE?
• CRASH REVISITED: ADDITIONS TO ITS CLARITY, GENERALITY, AND UTILITY
• DEMONSTRATION OF REGRESSION ANALYSIS WITH ERROR IN THE INDEPENDENT VARIABLE
• EVALUATION OF ALTERNATIVE SIGN-LIGHTING SYSTEMS TO REDUCE OPERATING AND MAINTENANCE COSTS (DISCUSSION AND CLOSURE)
• EVALUATION OF OPPORTUNITY-BASED ACCIDENT RATE EXPRESSIONS
• EVALUATION OF THE EFFECTIVENESS OF CRASH CUSHION DELINEATION
• EXCESS TRAVEL: CAUSES, EXTENT, AND CONSEQUENCES
• RELATIONSHIPS BETWEEN VERTICAL AND HORIZONTAL ROADWAY ALIGNMENTS AND THE INCIDENCE OF FATAL ROLLOVER CRASHES IN NEW MEXICO AND GEORGIA
• SAFETY IMPLICATIONS OF TRUCK CONFIGURATION
• SPECIAL TRAFFIC CONTROL TO MEET MOTORIST INFORMATION NEEDS ON LONG, STEEP GRADES (DISCUSSION AND CLOSURE)
• VALIDATION OF A NONAUTOMATED SPEED DATA COLLECTION METHODOLOGY
• VIDEO COLLISION RECONSTRUCTION USING PHYSICAL EVIDENCE