Before works began it was necessary to provide worksite access roads - 32km of country roads were widened and improved and 18km of new roads were built. For one road, it was necessary to construct a viaduct 618 metres long in Verney pondage.

In view of the altitude, construction work was seasonal (5 months a year only). The nineteen-hundred strong workforce was largely drawn from neighbouring Départements. The project received extra funding in order to provide the infrastructure needed by the area’s new residents (social housing, schools, roads, drainage, etc.). These improvements have assisted the subsequent development of the valley which has been based on tourism - winter sports, water sports on the lakes, and mountain sports.