A Steep Challenge

The A93 Perth to Braemar road runs through a twisting and steeply wooded gorge, a mile north of Blairgowrie. The single carriageway road follows the path of a river and clings to the valley side with precipitous drops. The need to carry out improvement works to this section of the A93 was identified in 1985 after the collapse of a section of retaining wall, when a Bailey type bridge was erected. Recently engineering assessment of the area around the bridge has concluded that the slopes were not sufficiently stable to support new carriageway construction, and the decision was taken to build a new road which would by-pass the bridge. Maccaferri won the tender for the design of the reinforced earth structure, comprising a hybrid reinforced-earth geogrid-wrap around structure in conjunction with a hard stone-faced Gabion Terramesh wall. The Gabion Terramesh system creates a rigid outer face and provides additional mass gravity reinforcement to the ensemble. One of the requirements of the project was to keep the road open during the construction. Consequently contractors had to develop strategies to carry out the work while allowing the traffic to use single lane working. The project started in October 2007 and the new road opened in September 2008.