Title

INFLUENCE OF PAVEMENT MARKING ANGULAR SYSTEMS ON VISIBILITY PREDICTIONS USING COMPUTER MODELS

Document Type

Journal Article

Publication Date

2001

Subject Area

operations - traffic, planning - methods

Keywords

Traffic markings, Road markings, Road marking materials, Retroreflectivity, Pavement markings, Night visibility, Measuring methods, Luminance, Computer models, Carriageway markings, Angles, Accuracy

Abstract

Computer models like CARVE (Computer Aided Roadmarking Visibility Evaluator), which predict the nighttime visibility of pavement markings, require quantitative information about the coefficient of retroreflected luminance (R sub L) for selected pavement marking material and selected dimension parameters. To specify the coefficient of R sub L, four angles are necessary (observation, entrance, presentation, and orientation). However, R sub L values for pavement marking materials are measured as a function of two angles only, whereas the other two are held constant. This two-angle-only approach makes the R sub L data-collection procedure and subsequent computer models significantly less cumbersome. The objective was to determine the angle-ranges in real-world driving situations for the International Commission on Illumination's goniometer, intrinsic, application, and roadmarking four-angle system to measure R sub L values of different pavement marking materials for sets of the observation, entrance, presentation, and orientation angles and to compare these R sub L values with R sub L approximations calculated by using two-angle intrinsic and roadmarking angular systems. R sub L approximations using the two-angle intrinsic system (based on observation and entrance angles only) overestimate the actual R sub L values by between 4 and 10%. On the other hand, the R sub L approximations based on the two-angle roadmarking system (taking into account only illumination-elevation and the observation-elevation angles) overestimate the actual R sub L value by between 25 and 82%. Under retroreflective conditions, it is suggested to use the two-angle intrinsic system rather than the two-angle roadmarking system for modeling pavement marking visibility problems because the abridged intrinsic system yields more accurate and more conservative R sub L approximations.