WIT Press


Visibility Concept In Road Lighting

Price

Free (open access)

Paper DOI

10.2495/LIGHT110141

Volume

121

Pages

12

Page Range

159 - 170

Published

2011

Size

350 kb

Author(s)

M. Zalesińska

Abstract

A major purpose of road lighting is to increase the visibility for drivers and other roadway users. The visibility of a target depends on observer age and visual characteristics, observer duration, size of target, luminance of the target, luminance of the background, contrast polarity, exposure time, magnitude of the disability glare, and adaptation. A visibility formula was described by Adrian in 1989 and applied with Visibility Levels in North America as a quality criterion. According to procedures described in ANSI/IESNA RP-8-00: American National Standard Practice for Roadway Lighting the visibility of the target can be calculated when the target luminance, background luminance and veiling luminance in calculation methods are given. In European countries this criterion is still investigated as a new concept. Keywords: road lighting, visibility level, small target visibility, road lighting standards. 1 Introduction Road lighting has significant impact on road traffic comfort and safety. All participants of the traffic, vehicle drivers, cyclists and pedestrians alike, should benefit from vision conditions that facilitate the completion of visual tasks. The entire road along with its background should be well visible at all times. Cyclists and pedestrians alike should see all obstacles in their way and should be able to correctly identify the intentions of other traffic participants. The visual reliability of drivers should be suitably high to allow them to spot, quickly enough, pedestrians, cyclists and any obstacles present in their traffic lane, as well as road signs and information boards in its immediate background, in order to reduce the likelihood of dangerous situations or traffic accidents. Even though the attempts to identify direct relation between quantitative and quality parameters of road

Keywords

road lighting, visibility level, small target visibility, road lighting standards