This trail gets its name as it was formerly used to bring heavy artillery up the mountain to the fortifications on the summit. Today, this section has "deteriorated" into a singletrack, making it perfect for pedestrians.
The route starts at the Assietta Road (Unpaved Section)
near the Gran Costa summit and is 100% downhill in this direction. Here, you're above the tree line so you've got great views of the mountains on the opposite side of the val Susa (valley) on your way down. At about 2 km (1.2 mi) after 150 m (500 ft) of descent, you'll enter into the forest. Shortly thereafter, the grade levels off somewhat and you can meander down to the intersection with the Col Blegier
Of course you can also climb this trail, but it's a difficult climb. It's better to integrate it into the Gran Costa dal Sauze d'Oulx loop so you can catch this segment on the downhill.