The 2016 Kaikoura M7.8 earthquake caused widespread damage to the road and rail corridor some 20 km North and South of the Kaikoura township. Over 40 major slips inundated the road and rail with over 750,000 m³ of material from source zones up to 500 m above sea level. The highly fractured Grey Wacke means frequent future rockfalls and debris loads are to be expected. The high rockfall and debris load frequency created the requirement for a Geohazard Solution that attenuated the energy to a manageable level and guided the material down to a catchment area. Due to the proximity of the Coastal Pacific rail line space is limited.
A VX080-H4 debris flow barrier was combined with a 12/3/350 ROCCO ring net tail. This system enables the rockfall and debris energy to be attenuated and guided down to a catchment area at the toe of the slope for easier clearing and reduced maintenance. Additional support ropes were also installed across the channel under the ROCCO® tail where it rested on the slope to enable the lower energy material to pass under and not get caught up. Short 0.5 m tethers were installed in the lower part of the tail to stop it from kicking out towards the rail in the larger energy events. TECCO® G65/3 was used as a secondary mesh as a robust solution was required due to the high frequency of the smaller high-velocity rocks.
Shortly after completion, the system demonstrated itself to be working well.