Development of a prediction model for wet road marking retroreflectivity
Overview
Background & policy context:
During the last ten years, dry road marking retro reflectivity has been measured by the use of mobile equipment. However, due to a growing interest in the performance of wet road markings, the use of road markings with a profiled surface is common in many European countries today. When measuring this type of marking with the use of mobile equipment in wet weather conditions, one problem arises: The measured retro reflectivity will be affected by splash from the wheels of the measurement vehicle, which can be avoided only by driving extremely slowly. Therefore, in order to carry out measurement at the speed of surrounding traffic, measurements must be accomplished on dry road markings.
Objectives:
The goal of the present study is to find an equation which describes the relationship between, on one hand, the wet road marking performance in night-time driving and, on the other hand, the performance in dry condition. The independent variables in this equation must be possible to measure at the speed of the surrounding traffic. This is important, not only for the safety of the operator, but also for traffic safety in general.
Methodology:
The work on finding a new texture factor and a better prediction model has been organized as follows:
- project management. (The Danish Road Directorate)
- theoretical considerations. (Johnson Consulting)
- development of a computer programme calculating the texture factor. (Johnson Consulting)
- field measurements. (Ramböll and VTI)
- statistical analysis. (VTI)
- 6. documentation. (VTI).
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