Surface dressing is a preventative treatment, to prolong the life of the roads. It is an essential part of Dorset County Council's road maintenance strategy, alongside patching and resurfacing.
- helps prevent potholes forming by providing a waterproof seal
- improves skid resistance, with a thin layer of new stone chippings spread on the finished surface
- is very cost effective; roads can be kept in good condition for longer, so that resources can be directed to fully resurface the roads that need it most. Full road resurfacing costs 12 times more per mile
A newly dressed road may feel 'bumpy' as the grip will have been restored. The surface will also be noisier initially while the chippings 'bed down'.
About the treatment
Surface dressing can only be carried out when the road is dry. When it rains, the work has to stop - changing dates across the whole programme of work.
It is a quick process - rural sites take less than a day to complete and urban roads will take 1-2 hours, depending on the length of the road.
Bitumen binder (glue) is sprayed onto the road, stone chippings are spread onto this and then compacted down with a roller. A sweeper then travels along the road the following day to clear any immediate loose chippings.
Closing the road
We have a team of 20 people, two purpose built chipping spreaders, one spray tanker, six lorries feeding chippings and two suction road sweepers. This is a lot of equipment to fit into the road, even without traffic!
Doing the work in the daytime
We cannot work overnight as surface dressing relies on the evaporation of water from the bitumen binder (glue) for it to set, and it needs traffic to travel on the new surface for it to 'bed down' and lock onto the old surface.
We also cannot work in wet weather - any amount of rain or surface water dilutes the bitumen and so doesn't hold the chippings in place - which is why our surface dressing programme runs from April through to September. In rural areas we will be working 8am to 4pm and in urban areas we will be working 9am to 4pm.
There may be loose chippings still on the road. It takes cars driving on the surface to help the stones bed into the bitumen.
This is why there will be 20mph limit after the work. Travelling at a reduced speed through the newly dressed area will prevent skidding on the loose chippings, it helps 'bed down' the material and it will save your paint work! We sweep the road the day after the work to get rid of excess stones.