In July 1998 a 4,500 tonne rock fall blocked the A83 Trunk Road, at Artilligan on the Kintyre Peninsula in South West Scotland (Figure 1). The rock fall caused severe disruption to the local community, and raised concerns about the stability of other rock slopes in the area. This paper describes the investigation of the failure, a risk assessment of other rock slopes in the area, and the design and implementation of the remedial works; all of which were undertaken in an area of structurally complex geology, and within extremely tight time scales. In addition, significant observations with regard to difficulties encountered and the solutions implemented are highlighted.
At approximately 20:00 hr on Sunday 18th July 1998 a 4,500 tonne rock fall blocked the A83 at Artilligan, on the shore of Loch Fyne. The A83 provides the only trunk road access to the entire Kintyre Peninsula. This measure proved to be a major concern to the local community, which is heavily reliant upon fish farming, shellfish production, farming and forestry. The Transport Research Laboratory (TRL) and Argyll and Bute Council were appointed by The Scottish Office Development Department (SODD) National Roads Directorate (NRD) to undertake an emergency inspection of the Artilligan failure site, design remedial works, and undertake a rock slope risk assessment of the entire A83.
The emergency inspection took place on Monday 19th July. It revealed that the rock fall was a plane failure, with a band (dipping to the south-east) of moderately to highly weathered mica schist acting as the basal failure plane, and a fault acting as a side release on the south side of the failure (Figure 2). The majority of the rock fall debris, however, consisted of fresh very strong quartzite.