The trail, following a dirt road for a long stretch (about one hour walk), begins near Tivoli along the road SP Tivoli-Marcellina, and turns right immediately after crossing the first railway bridge.
After climbing for about half an hour, go beyond a fence in location Giardinetti and a clearing (the same clearing crossed by a stretch of trail C), and you will reach a large central area of the Reserve dominated by Turkey oak woodlands. After a while you will get to location Fontana Vecchia, where you will see on the right a big trough.
After crossing Fosso di Piavola, you will notice on the left a natural arc representing the entrance of a wide collapse karstic formation. Above the doline you can see evident rock outcrops interested by karstic phenomena (limestone pavement). Farther on you will reach a crossroads where trail B meets trail E and, going ahead, you will reach a small picnic area in location Fonte Bologna. Here there is a small mountain hut, behind which there is a large rectangular reservoir buried in the ground. On the left of the reservoir, near a trough which is often without water, Valle Gelata ditch begins.