|
|
|
Title: VALIDATION OF PHOTOMETRIC MODELING TECHNIQUES FOR RETROREFLECTIVE TRAFFIC SIGNS
Accession Number: 00977230
Record Type: Component
Record URL: Availability: Transportation Research Board Business Office 500 Fifth Street, NW Find a library where document is available Abstract: Recent research in the United States has focused on the development of minimum retroreflectivity levels for traffic signs. The engineered approach uses a supply luminance versus demand luminance concept to achieve a metric that can be used to set minimum retroreflectivity levels. The supply luminance depends on reliable modeled estimates of headlamp illuminance reaching traffic signs and the resultant luminance directed back toward the driver. While the science behind the photometric modeling process is fundamentally sound, a small pocket of literature shows inconsistent relationships between measured and modeled illuminance and luminance levels. A systematic validation study of photometric modeling was done with field measurements made under conditions identical to those that were modeled. A set of headlamps were photometrically measured along with three different samples of retroreflective sign sheeting materials. Illuminance and luminance levels were then modeled for nine sign positions and three vehicle types. Then field illuminance and luminance were measured using the same scenarios, headlamps, and retro-reflective sign sheeting materials. The field measurements were recorded once on a concrete pavement and once on an asphalt pavement. Both sets of field measurements also included baffled and unbaffled measurements so the impact of pavement reflection could be considered. Photometric modeling techniques of nighttime traffic sign performance compared well with field measurements made under identical conditions. The maximum illuminance difference was 16% and was attributed to the pavement reflection properties. The maximum luminance difference was only 2.4%. The retroreflective performance of traffic signs redirects most of the pavement reflection back toward the pavement. Therefore, estimates and measurements of luminance are less affected than illuminance.
Supplemental Notes: This paper appears in Transportation Research Record No. 1862, Traffic Control Devices, Visibility, and Rail-Highway Grade Crossings 2004.
Monograph Accession #: 00977217
Language: English
Corporate Authors: Transportation Research Board 500 Fifth Street, NW Authors: Carlson, P JUrbanik II, ThomasPagination: p. 109-118
Publication Date: 2004
Serial: ISBN: 0309094542
Features: Figures
(4)
; Photos
(2)
; References
(24)
TRT Terms: Uncontrolled Terms: Subject Areas: Highways; Operations and Traffic Management; I73: Traffic Control
Files: TRIS, TRB, ATRI
Created Date: Aug 27 2004 12:00AM
More Articles from this Serial Issue:
|
