Kaikōura SR11

Initial situation

The 2016 Kaikōura M7.8 Earthquake caused widespread damage to the road and rail corridor some 20km North and South of the Kaikōura town ship. 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 Greywacke meant future landslides were expected, creating a requirement to install shallow landslide barriers in several SH1 and Rail locations. To date (2023), six SL150 barriers have been installed along the corridor. The SL150 barrier at the SR11 site required steeper upslope anchors to avoid interaction with the rail tunnel and also a rockface connection at Northern end. The barrier is 3.5 m high and 48 m long (6 x 8 m fields).

In March 2023, heavy rainfall triggered a large 600 m³ landslide at the SR11 site. Since the SL150 barrier installation (2017), only smaller 300 – 400 mm rocks had released and impacted the system. The landslide was comprised of a mixture of soil, gravels, vegetation and large blocks. The largest block was › 10 m³ and came to rest against the fourth post (South-North). The barrier was filled to approximately 0.5 m from the top in the centre two fields and had 1.25 - 1.5 m elongation, just touching the roadside barrier. Overall, the barrier performed exceptionally well.