Catching a Bowling Ball at 200kph

Whenever you see a racing crash you often see the car crumple into pieces as it dissipates the energy generated from the impact.

Debris fences were originally designed to stop these small pieces from flying into grandstands, and as more crash data has become available this evolved into being able to catch an entire race car upon impact.

But what happens when large (and heavy) pieces of debris from these crashes hit these fences at high speed? 

To answer this Geobrugg worked in close collaboration with the Dynamic Test Center, an FIA approved test house located in Switzerland, to carry out the first tests of this nature.

Two high-speed assessments were performed pitting our high tensile wire mesh against a normal steel chain-link mesh using objects that have an impact mass of 15kg (the equivalent of two bowling balls) at a speed of 216kph. The setup consisted of a high tensile ring net, with a second layer of mild steel chain-link mesh. The ring nets featured an opening of 350mm, with the secondary mesh designed to stop smaller debris from penetrating.

In the video above the tests were recorded in real-time and at high-speed at 1,000 frames per-second, so you can see the impact clearly and the effect it has on the debris fence systems.

In the first shot the debris hit the fence easily penetrating the steel chain-link mesh. We then changed the barrier setup slightly, adding in a Geobrugg mobile debris fence element in an elevated position to stop potential flying debris.

Although a stronger secondary mesh was used, it was easily penetrated, and the object was only stopped by the high tensile wire mesh debris fence panel. Spectators situated behind the debris fence would have been safe from a hazardous object!

While this test series demonstrated that high tensile wire meshes, and our Geobrugg debris fences, can stop high speed debris impacts, we also realized that the size of the mesh opening plays a crucial role in stopping debris. The FIA guidelines specify that mesh openings must be square at 90x90mm to stop debris from flying into the grandstand, in combination with a cable spacing of 25cm supporting the mesh. It is really important that these dimensions are not exceeded.

Geobrugg is using a high tensile wire mesh with a 4mm wire and a mesh opening of 80mm, which should stop most of the debris caused from a crash. Having demonstrated what can happen with a high-speed debris impact into the debris fence, we strongly recommend using our high tensile wire solution with an opening that is no larger than these dimensions to keep everybody safe around a circuit.