A82 – Tarbet to Inveraran
It is proposed to widen the existing A82 carriageway from Tarbet to Inverarnan and add the provision of hard-strips, verges, cycle/pedestrian facilities and laybys. Proposed construction works include replacing existing structures such as retaining walls, bridges and culverts, and the construction of new structures including viaducts, shoreline works and drainage improvements.
The £3.4M ground investigation for the A82 upgrade had to contend with steeper slopes, deeper bogs and narrower access than many other projects of this scale. Whilst it was one of the largest and most challenging ground investigations undertaken by Soil Engineering in Scotland, it was also one of the most varied with a wide range of both geophyscial and intrusive techniques required.
At the peak of work, Soil Engineering had a team of 35 people on site with two overwater pontoons undertaking both Rotary and Cable Percussive drilling and a land-based team also undertaking Rotary and Cable Percussive works. A total of almost 150 boreholes were completed during the works, to depths of up to 40m below ground level. Also completed within the scope were 38No. machine and hand excavated trial pits, 208No. pavement cores and in excess of 1400 peat probes. In situ testing included geophysical surveys, televiewer surveys, dynamic cone penetrometer tests, variable head tests, hand vane tests, and soak-away tests. Due to restricted access times and conditions on areas of the site Sonic Drilling and Slope Climbing rigs were employed to minimise works impacts on stakeholders.
The challenging terrain, combined with complex Ecological and Archaeological restrictions, ensured that tight control of all resources was required, along with open and clear communication with all stakeholders. Facilitated by Soil Engineering’s experienced Land Liaison team, stakeholders were kept up to date throughout he works with any changes. Access management was undertaken by dedicated team members, responsible for delivery of all protection packages, and handover of reinstated sites on completion.