Highway Engineers in the Highlands of Scotland have adopted a novel approach to reinforcing low traffic-volume rural roads in Sutherland.

01/02/2008

Much of their rural road network is single track and built on very weak ground - mainly peat. This poses no problem for light car traffic but this “floating road” construction is unsuitable for use by heavy vehicles serving the local timber extraction industry.

To reinforce the roadways and bring them up to useable standard without resorting to the importation of huge quantities of stone road-base materials, Highland Council worked with Geotechnical Specialists Maccaferri and came up with a more practical and cost effective solution.

Three trial roads serving the communities of Syre, Kinbrace and Helmsdale in Sutherland, have had bituminous overlays applied which incorporate Maccaferri Roadmesh pavement reinforcement mesh.

Roadmesh is a double twist wire reinforcing mesh which is sandwiched between the bituminous layers. This reinforcement mesh causes the pavement consrtuction to work as a cohesive mass, absorbing the horizontal tensile stresses and spreading the imposed traffic loadings over a wider footprint, reducing its damaging effect.

The pavement reinforcement work is being undertaken as a partnership agreement between Forest Enterprise and the Highland Council. The trials, which started in 2001 and run for 25 years, are also being monitored by The Roadex Project, a multi national technical cooperation which brings together Northern European countries to share knowledge on forest road construction techniques.

Norway, Sweden, Iceland, Finland, Greenland, and Scotland are all party to the project and each shares information with the others, with the objective of improving and maintaining local infrastructure.

In earlier work in 1995, a section of the nearby B873 was reconstructed using Roadmesh [see pic]. Immediately after installation, a multi wheeled tipper truck went off the single track road and became dug down in the soft verge with dramatic results. As the road was effectively floating on the surrounding peat-based sub-soil, the truck was unable to extricate its-self and had to be dragged back on to the pavement by a heavy lift recovery vehicle [see pic]. Despite the high stresses on the extreme edge of the roadway caused by the tipper the overlay held together thanks to the reinforcment function of the RoadMesh. This road is still performing as intended 12 years on [see Nov 2007 pic]