Impact of Macrotexture Depth and Its Variation on Safety on Rainy Days

Pavement macrotexture depth proves to be both a significant factor affecting the pavement adhesion coefficient on rainy days and a regular data for freeway maintenance routine testing. Based on a comprehensive consideration of the road conditions, weather and daily traffic volume, this paper analyzes the impact imposed by road macrotexture depth and the discontinuity of changes upon accidents on rainy days with 500m as a computation unit and the average macrotexture depth per 100m and daily traffic volume as indicators. Those fitting results by inverse function have indicated that accidents on rainy days show an upward tendency along with the decrease in macrotexture depth. What’s more, studies on the continuity of changes in macrotexture depth have shown that accident rate on rainy days will increase as the rate of reduction in mean macro texture depth within 100meters dose. By means of the test of significance of the average rate of accidents on rainy days on different macrotexture depth and its change, it is found out that accidents rate on rainy days increases noticeable as the is lowered below 0.4mm and the change rate of macrotexture depth is higher than 0.3mm within 100m, on which occasion maintenance of the road is strongly recommended.