Maccaferri’s rockfall protection fences can be adapted to a series of rockfall scenarios as proven by a 2015 project in Maybille Bay, New Zealand
Maccaferri’s Rockfall Barriers are used to mitigate the dangerous effects caused by rockfall. They are Certified in accordance with ETAG 027 and are supplied in a difined kit of components. The certification rates them with a particular energy absorption capacity and also the deflection that occurs under impact. For situations that do not require such certification and reassurance, hybrid fences are used. Also known as suspended drapery, these fences collect falling rocks and progressively slow them down over a distance. Therefore, there has to be sufficient space available in which to slow the falling rock down. A hybrid fence is not a barrier and cannot be certified with an energy absorption capacity.
Rather than being secured to a lower support cable, the fence mesh is longer and drapes down the slope. A project that aptly exemplifies how such barriers can be applied is the Meybille Bay project in New Zealand.
Meybille Bay is located along State Highway SH6 in the Punaikaki Coast of New Zealand West Coast. SH6 is the only route linking Greymouth and West Port along the coast. Furthermore, its scenic view attracts many international tourists to travel along the coast to use the path to the destination. The New Zealand Transportation Agency (NZTA) appointed Opus International, an engineering consultant, to identify potentially hazardous rockfall sites along the SHnetwork in the South Island region.
Under the current hazard rating system, the area qualifies for exponential protection works. After numerous field visits during which
– the most likely boulder size from the source area was identified and,
– rigorous detail trajectory analysis were undertaken,
Opus International decided for the rockfall protection structure (RPS) to be a Hybrid Fence.
This Hybrid Fence is proposed to measure 5.0mpost in height with the base plate founding to be built onto the existing slope face approximately 10.0m from the road level. Unlike standard rockfall dynamic catch fences Hybrid Fence’s do not stop the falling rocks but dissipate their kinetic energy by intercepting them in the suspended panel across the posts. The rocks are then guided down to the toe of the drape for collection/maintenance. They are often used in conjunction with other collection mechanisms, such as ditches.
Together with its NZ partner, Geofabrics – Maccaferri assisted with the preparation of the layout drawings and supplied the entirety of the fence kit system for the project. During the installation stage, the Maccaferri-Geofabrics team visited the project site and provided installation tips and advice in addition to delivering the installation drawings. The installation took the contractor’s three-man team approximately four weeks to complete.
For more details, please contact us.