Asphalt Reinforcement

A87 Trunk Road, Rotaflex - Portree, Isle of Skye, Scotland

Client Transport Scotland
Contractor

Bardon Contracting / ABG

Consultant Transerv Scotland
Product

Rotaflex – Glass Fibre Asphalt Reinforcement

Quantity

26,000m²

Benefits

– Extended maintenance period
– Fast in-line installation
– Reduce reflective cracking

Project Description
The 99 mile long A87 is the major trunk road for the Scottish Highlands North West Axis, running from Uig on Skye across the Skye Bridge to central Scotland at Invergarry. It is an all-purpose, mostly single carriageway trunk road which receives 2,200 Annual Average Daily Traffic vehicle movements, of which 5% are heavy goods vehicles. The road bypasses Portree and then climbs up between Loch Portree and a steep scarp. Transerv Scotland, who carry out the maintenance design for Transport Scotland, identified the need for a full resurfacing of the road from the south of Portree past the Varragill section of the Portree Forest.

The Challenge
This highly exposed area of road not only receives heavy rainfall and surface runoff from the scarp slope, it is founded on deep layers of peat. Peat by its nature is very flexible, swelling in wet weather conditions and contracting when dried. Whilst the road construction takes account of this, it is still susceptible to flexural cracking when loaded with heavy traffic. The edges of the road are particularly vulnerable and Transport Scotland have had to undertake multiple repairs with resulting traffic delays and no alternative routes for commuters.

The Solution
Transerve Scotland needed a solution to the differential movement and flexing of the carriageway which led to surface cracks. The cracks in turn allow water to penetrate from the top down, causing further swelling of the peat.

ABG Rotaflex 830 asphalt reinforcement geocomposite was selected to control cracking and produce a seal on the road surface. Rotaflex 830 comprises a high strength/low strain glass fibre reinforcing geogrid, combined with a non-woven geotextile. ABG, the installer, sprayed the prepared binder course layer with a K1-70 bitumen emulsion bond coat and applied Rotaflex to the surface. The non-woven geotextile absorbs some of the bond coat and holds fast to the road. When the hot asphalt surface course is placed, the geocomposite becomes saturated with the bitumen and then sets hard within the road surface, forming a complete seal which is reinforced against lateral movement. Rotaflex was installed to the edge of the road surface and was shaped to follow the curvature of the road as it climbs the slope. Rotaflex 830 asphalt reinforcement geocomposite can extend the average maintenance period by four times, giving substantial savings in construction and delay costs.

ABG Rotaflex 830 system for asphalt reinforcement

The ABG Service

ABG provided design advice for this highly exposed site and worked closely with Bardon Contracting to avoid any delay to the installation process.

Contact ABG today to discuss your project specific requirements and discover how ABG’s past experience and innovative products can help.

 

Additional information