On August 5th, 2018, a slope collapsed in Mianyang section of Baoji Chengdu line, with a rock fall volume of about 15 cubic meters. The flexible passive protection net designed by OST intercepted the boulder successfully, which ensured the safety of driving car and people! The falling stone was about 15m away from the passive net. A stone of about 2 square meters (1.5 * 0.5 * 0.6) fell and collided with a stone of about 8 square meters (1.2 * 2 * 3.5). At the last, the passive net intercepted them. The maximum buffer distance of the impacted cross net piece was 1.2m, decompression rings were not started, the large net was not damaged, 6 * 3 rings at the impact position of falling stones became oval (long diameter 625px, short diameter 500px), the small net was pulled across by the impact, only the nearest steel column from the impact position had about 1500px rope slip, and the steel column had no obvious tilt change.