Guidelines for Nighttime Visibility of Overhead Signs. National Cooperative Highway Research Program (NCHRP) has Released a Non-Edited, Pre-Publication Version of Report 828.

摘要

National Cooperative Highway Research Program (NCHRP) has released a non-edited, pre-publication version of Report 828: Guidelines for Nighttime Visibility of Overhead Signs. While the Manual on Uniform Traffic Control Devices (MUTCD) provides minimum retro-reflectivity standards for overhead signs, there are few guidelines that agencies can reference to decide how to provide sufficient nighttime performance of overhead signs in site-specific situations. This report explores legibility distances for drivers in controlled conditions and the effects of sign luminance and visual complexity on the distance at which a driver can read overhead signs and street signs. The report presents proposed guidelines for nighttime overhead sign visibility, formatted as a potential replacement for the current Chapter 10, Roadway Sign Lighting, in the 2005 AASHTO Roadway Lighting Design Guide.