Road delineation often causes traffic to follow the same wheelpaths, which creates a wide disparity of trafficking effects transversely across the road. Where the wheelpaths are concentrated, there is more compaction of the chipseal, reorientation of chip, more embedment and more wear, so less binder is required to fill existing voids in the wheelpaths, compared to the centreline and shoulders. Spraying bitumen at application rates that vary transversely across the width of the road provides a solution to both repairing sites with binder imbalance and preventing the excessive build up of binder in the wheelpaths by applying the appropriate rate of binder transversely across the road rather than the inappropriate averaged application rate. This paper presents results from seals (up to seven years old) constructed using variable application rates, showing the improved performance for texture and seal design strategies to ensure extended life for chipseals. As there is no recognised application rate design method that takes into account the texture variation of the surface and the different traffic loadings that vary transversely across the road, various design procedures for calculating variable transverse binder application rates are proposed and discussed in this paper. (a) For the covering entry of this conference, please see ITRD abstract no. 0612AR242E.
Samenvatting