Abstract
Various patterns of longitudinal grooves have been installed at high accident locations to increase roadway friction. The California State Division of Highways has experimented with pavement grooving on both PCC and AC pavements. Widths and depths of grooves vary from 1/4" to 1/8" and spacing of cuts vary from 3/8" to 1" center to center. Results of these tests indicate that grooves 1/8" wide and 1/8" deep are satisfactory. At locations where wider grooves have been used drivers complain that their vehicles tend to "track" giving a sensation similar to driving on railroad tracks.