The Kaikoura M7.8 earthquake caused widespread damage to the road and rail corridor for approximately 20 km North and South of the Kaikoura township. Over forty major slips inundated the road and rail with more than 750'000 m³ of material from source zones up to 500 meters above sea level. The highly fractured Grey Wacke means frequent future rockfalls and debris loads. The high rockfall frequency created the requirement for a geohazard solution at Site 1-2.
The original design and installation was a 50 meters long 3 meters high GBE-500A barrier. After installation, the decision was made to install an additional 50 meters of barrier to protect the highway further. The system was easily extended by upgrading the northernmost post to a support rope separation with no material wastage.
The GBA-500A is a hinged post system. The barrier has upslope anchors, which reduce the post foundation forces and therefore minimise impact to the precast concrete wall and shotcrete retaining walls below. The rockfall barrier used a 10 meters post spacing, had two downslope anchors due to a curved alinement and as previously mentioned was split into two sections with a support rope separation. Due to the highly fractured rock mass, self-drilling anchors were required. Geobrugg type II flex heads transfer the loads to the bar anchors. The mesh was ultra-coated due to its proximity to the sea.