Road Note 39 Design Guide for Road Surface Dressing, a key guide for surface dressing of roads, has been revised. The new 7th edition updates the 6th edition which was published in 2008.

The revision was overseen by an industry working group comprising both industry and clients and chaired by the Road Surface Treatments Association (RSTA). There are a number of important technical changes to the guide which are all outlined in the Document Control section. The most important change is the introduction of a new Polished Stone Value (PSV) table which in some circumstances allows a lower PSV chipping to the used on roads carrying below 250 commercial vehicles per day. The RSTA is to hold briefing sessions for members to explain the changes.

Road Note 39 provides guidance for the design of surface dressing. It has not been developed as, nor should it be used as, a specification.

Surface dressing can be used successfully on all types of roads. It provides a simple but cost-effective form of maintenance that can play an important part in a highway infrastructure asset management plan. Surface dressing has inherent advantages over other options for road surface renewal: its conservative use of material over thicker asphalt overlays and the avoidance of the need to take up, and subsequently process, existing pavement layers. Used appropriately surface dressing can be an important contributor to minimising the whole life cost of road pavements. The treatment can also help with network resilience by being designed correctly for full temperature regime and by acting as the surfacing layer to prevent water penetration and help avoid damage caused by cold weather, ice and snow.

“Surface dressing is an important road surface treatment and Road Note 39 is an important design guide,” said Howard Robinson, RSTA chief executive. “This new revised edition will provide road designers, engineers and contractors with the latest guidance to ensure the best surface dressing result.”

The revised Road Note 39 (7th edition) can now be downloaded from the TRL website Road Note 39 (7th Ed)