Measurement of Pavement Treatment Macrotexture and Its Effect on Bicycle Ride Quality

Abstract

This paper summarizes the results of measurements of macrotexture on a set of California Department of Transportation (Caltrans) and local government pavement surface treatments and their correlation with survey results of bicycle vibration and ride quality on the same sec-tions. The test sections that were used for the bicycle vibration and ride quality measurements included various surface treatments placed on an existing chip seal on SR-198 in Monterey County, a chip seal on SR-1 in San Luis Obispo County, and several other sections with various textures and roughness levels on other state highway and county road sections. Macrotexture was measured in mean profile depth (MPD). Three test methods were used to measure MPD: the sand patch, the laser texture scanner, and the inertial profiler. Presented are statistical correlations between macrotexture, roughness [according to the international roughness index (IRI)], bicycle vibration, and bicycle ride quality for the surveyed treatment sections. Conclusions are presented for MPD values measured on road sections with different treatment designs and for the variability of MPD found between sections built with the same chip seal aggregate grading. Correlations between bicycle vibration and MPD are presented, along with correlations between MPD, IRI, bicycle vibration, and bicyclists’ perception of ride quality and pavement acceptability for bicycle use. This study’s results can assist Caltrans and other road owners considering gradation when continuing to use the cost-effective chip seal treatment to preserve their pavements while maintaining a bicycle-friendly surface.