The Florida Department of Transportation (FDOT) installed a high frictionpavement surface system aimed at reducing the potential for run-off-road crashes along an on-ramp to northbound Interstate 75 from eastbound Royal Palm Boulevard in the City of Weston, Florida. The effectiveness of the Tyregrip surface was evaluated from a materials perspective and from a safety perspective. Due to the limited availability of crash data for the site,surrogate measures of safety were evaluated to obtain a better understanding of the effects of the surface treatment. Skid tests performed by the FDOT Materials Testing Office indicated that the friction number was much higher after application of the treatment, as expected. Speed studies revealed that the mean speeds were decreased by an average of 3.72 miles per hour under dry pavement conditions and 2.62 miles per hour under wet pavement conditions after treatment application. The speed variance and proportion of drivers exceeding the posted advisory speed were also found to decrease under both wet and dry pavement conditions with the surface treatment.Drivers were also less likely to encroach over the pavement edge lines under wet pavement conditions after the treatment was applied. It appears from this study that the use of this high friction surface treatment may bea practical countermeasure for improving safety at locations that are prone to run-off-road crashes, such as sharp curves and interchange ramps.
Samenvatting