Les Tourniquets is the name given to the series of twists and turns that the departmental road no. 1 makes as it crosses the rocky barrier formed by the Jurassic limestone that closes off the Sasse basin to the north. This road connects the Bayons valley, its forests and alpine pastures with the Turriers basin and, via the Garcinets pass, with Seyne and the Blanche valley.

The Astoin turnstiles are the successor to the mule track on the other bank of the Eau Amère, which predates it by a long way. In fact, it already appeared on the Cassini map in the 18th century.