Transport Scotland introduced a new standard for road surfacing in December 2010 to ensure that our trunk roads are safe and well maintained
Following issues with the quality and in-service performance of early Stone Mastic Asphalt (SMA) road surfacing, we have been working closely with the roads industry to improve the design and specification of SMA road surfacing.
The decision to develop this specification is based on SMAs proven track record in Germany, where many of the roads remain in excellent condition after more than 20 year’s service. The new Scottish specification and guidance is therefore based on the German specifications, practice and experience.
Through its four operating companies, Transport Scotland safeguards the structural integrity of the trunk road network. Our ongoing maintenance regime typically includes replacement of the carriageway (reconstruction), the surface (resurfacing) and reinstating the skidding resistance of the surfacing (surface dressing).
Improving the durability of roads offers the following benefits:
SMA surfacings can provide the following benefits:
This new specification will be rolled out to the four Operating Companies in 2011.
The surface course, or top layer of the road pavement, incurs the greatest wear and needs to be replaced on a regular basis. The surface course is also the most demanding part of the road in terms of material requirements and properties.
A good surface course will provide a smooth and quiet running surface for road users. It is also required to have a high resistance to rutting (the longitudinal channels that develop due to heavy wheel loads) and provide good friction to provide good grip.
The surface course also acts as a seal against water infiltrating and harming the lower structural layers of the road.
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