|Surface Dressing on road in Leicestershire|
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Surface Dressing is a process of routine maintenance by which bitumen is sprayed across the surface of the road's carriageway before covering it with stone chippings. The chippings are subsequently rolled and stick into the bitumen.
The road is subsequently opened to traffic, usually with a 10-20 mph recommended maximum speed limit for a short period to allow the moving traffic to further roll in the chippings. The final stage is to sweep the excess chippings and remove temporary road signs, as well as re-lining and replacement of cat's eyes where appropriate. The process usually occurs between spring and late summer, with work being carried out when weather conditions are good.
The advantages of the process are that it allows cracks in the road to be filled, to prevent freeze-thaw damage in winter, as well as providing an extension to the life of the carriageway by providing a new surface layer. Arguably, it also may reduce spray from vehicles in wet weather, and, when the process is complete, provide higher resistance to skidding than a "shiny" tarmac surface. It is also a relatively cheap process, which means that where surface dressing is applied appropriately highways authority funding can be more equitably targeted.
The principal disadvantage is that the process is unpopular with the public, as the dust and speed limits imposed while the passive rolling process is ongoing make driving less pleasant and less safe, as there is a higher skid risk on roads with many loose chippings. The effect is worse for cyclists and motorcyclists. In cases (usually where drivers ignore the speed limit), stone chippings have also been known to damage vehicles. The bitumen used in the process is sticky and may also stick to footwear and clothing. The dressing may also increase road noise, particularly in the early stages after application.
Other disadvantages are present where the dressing may be used inappropriately, such as where:
- conditions are too cold or wet
- conditions are too hot
- there is a very high volume of heavy goods traffic
- the road itself needs rebuilding, as surface dressing will not resolve structural issues such as rutting or potholes
Highways Maintenance.com - Surface Dressing Guide: 
The Road Surface Treatments Association produce a Code of Practice for Surface Dressing in nine parts:
- Types and Design
- Surface Preparation
- When to Surface Dress
- Use of Spray Tankers
- Quieter Surface Dressing
- Direct Binder Delivery to Sprayer
Design guide for road surface dressing (7th Edition):
- http://www.trl.co.uk/reports-publications/road-notes/report/?reportid=7034 D Bateman [ISBN 978-1-910377-50-5]