Use of high intensity reflective sheeting in lieu of external lighting of overhead roadway signs.
-
2013-06-01
-
Details:
-
Creators:
-
Corporate Creators:
-
Subject/TRT Terms:
-
Publication/ Report Number:
-
Resource Type:
-
Geographical Coverage:
-
Corporate Publisher:
-
NTL Classification:NTL-HIGHWAY/ROAD TRANSPORTATION-HIGHWAY/ROAD TRANSPORTATION;NTL-SAFETY AND SECURITY-Highway Safety;
-
Abstract:Effective highway signing is an important component of driver decision making, comfort, and
safety. Like many agencies across the country, overhead sign lighting has been used by the Florida
Department of Transportation (FDOT) to improve visibility. However, the availability of newer and more
efficient retroreflective materials has created a new challenge for state transportation agencies going
through sign upgrade programs and considering the need for sign lighting. FDOT initiated this study to
investigate whether high intensity reflective sheeting can be used to replace overhead sign lighting.
Field data was collected to assess the conditions of Florida signs in terms of the MUTCD
minimum maintained retroreflectivity levels. In addition, a luminance computation model was developed
to calculate sign legend luminance under various situations, including different sign lighting technologies,
different geometrics and sign locations, and different amounts of sign dirt and sign aging. By comparing
the calculated luminance of a specific sign at a specific situation with the legibility luminance levels
required by older drivers, sign lighting needs were assessed.
A life-cycle cost spreadsheet was developed and used to calculate the cost of replacing the current
sign sheeting in Florida with high reflective sheeting and the cost of installing/upgrading sign lighting.
Based on this analysis, we found that under the conditions considered (either on straight and flat
roadways or horizontal curves, in rural areas or urban areas), the most cost effective approach to maintain
overhead guide luminance is to use (installing or replacing with) induction or LED luminaires. The results
also indicate that a viable alternative (in terms of maintaining luminance and being cost effective) would
be to use either Type VIII or Type XI legend sheeting materials and forgo sign lighting. For Type XI
sheeting materials, sign lighting would be needed along horizontal curves in rural areas with radii of 880
ft and horizontal curves in urban areas with radii of 2500 ft or less.
-
Format:
-
Collection(s):
-
Main Document Checksum:
-
Download URL:
-
File Type: