The Fageole Summit near juction 27 1100m re below
The Fageole Summit, at an elevation of 1,107 m, is one of Europe's highest motorway passes. In addition to the constraints caused by its altitude, this area features various characteristics that promote the formation of snowdrifts, namely vast snow-covered zones (given the expanse of surrounding barren plateaus) and excavation profiles. The northern exposure and steep slope serve to exacerbate conditions whenever driving over the pass proves difficult. Two incidents involving snowdrift formation in 2005, both lasting 3 days (January 26-28 and February 15-17), resulted in the closure of this motorway (the A75) to all traffic. In response, it was initially decided to install snow fences. The layout of such fences, whose impact is highly sensitive to wind direction, entailed an analysis of meteorological data provided by the weather monitoring station located right at the Fageole Summit, combined with results from a field survey conducted among personnel with the Regional Roads Directorate (DIR). This effort led to a draft proposal calling for the installation of fences along a length of over 2 km. For 6 years, this design was closely monitored and improvements were introduced. However, since the efficiency of snow fences is so highly dependent on wind direction, it quickly became apparent that in light of past experience, the planting of wooded strips would offer a better solution in terms of winter serviceability at this site, where winds vary from northwesterly to northeasterly. Back in 1990, a 260-m wide wooded strip had been set up along the then RN9 national highway (since upgraded to the A75). This strip, positioned today 25 m from the pavement, performs its function exactly as intended, though its lower branches have started to die and thinning out the growth has become necessary. Encouraged by this experience, the present article will discuss the A75 case study, in providing an assessment of the specific practices adopted to control snowdrifts. Focus will also be placed on the current project to replace existing fences by woodlands as a more durable solution with greater capacity for integration into the landscape.