Scottish Trunk Road NMC - North West - A9 Tummel Wall Replacement

Description

A section of the Tummel riverbank adjacent to the A9 Pitlochry South slip road has been subject to fluvial erosion, leading to a part failure of the A9 South 530 W1 Tummel LB wall. The failed gabion basket wall supported an access track which was located between the slip road and riverbank.. The failure resulted in the loss of a section of the access track, and one lane of the adjacent slip road is now being used to facilitate continued access to adjacent fields. An emergency rock bag revetment was installed in November 2023 to prevent further erosion. This scheme will involve the construction of a replacement wall approx. 120-130m in length. The new wall will consist of continuous steel tube piles with a reinforced concrete capping beam and a rock armour revetment above. Following the installation of piling, a 1V:1.5H slope will be formed (3.75m width) using the reclaimed rock bag material and this will be capped with imported rock armour blocks. This will allow the farm access track to be reinstated back to the original level with engineered back fill. In addition to this, vehicle restraint system is required at both the slip road and farm track. The existing river banks comprise of gabion mattress system and gabion retaining wall. Repairs will be required for some of the sections of remaining gabion mattress and wall system.