Source: New Zealand Transport Agency
Underslip and rockfall repairs are now finished at State Highway 6 Dellows Bluff, south of Murchison.
Contractors have been on site since 2022, fixing an underslip and mitigating rockfall dangers. Substantive repairs are now finished, and the highway is restored to two lanes, operating 24/7 through the area.
SH6 Dellows Bluff rockfall, July 2022.
Rob Service, System Manager Top of the South, says a major rockfall in July 2022 had a big impact, closing the road at the time, and required significant effort to fix.
“We had to make the road safe, with shipping containers brought in to protect traffic while the cliff face was stabilised. This involved scaling and rock blasting, the use of drill rigs, and installation of hundreds of rock bolts into the cliff face.”
Setting steel work at underslip site, SH6 Dellows Bluff.
Mr Service says the nearby underslip, which was triggered by heavy rain in February last year, also required complex engineering and construction to fix.
“Contractors installed around 850 metres of steel piles and 563 metres of horizontal anchors while working to restore and stabilise this part of the road. 58 vertical piles were put in place to build a 60-metre retaining wall. New drainage was also installed to help stabilise underground areas.”
“A lot of work has had to go into fixing this site. We appreciate it has taken a while to complete. But it hasn’t been a simple job, and it was important contractors took the time needed to get design and construction right.”
“I want to thank the community and road users for their patience and understanding while this project has been underway. The result is a road that will be much more resilient and resistant to future bad weather events,” Mr Service says.
Meanwhile, the protective container wall and a temporary speed limit of 70 km/h will remain in place at the rockface until a permanent rock fence is built. The entire site will continue to be monitored to ensure it is stable and functional.
SH6 Dellows Bluff rock fall and underslip repair sites.
State Highway 6 rock fall and underslip repairs – facts and figures
Underslip site
- Vertical steel piles totalling 850 meters in length were installed.
- Horizontal anchors measuring 563 meters were implemented.
- Approximately 18,000 litres of grout were used around the anchors for stabilisation.
Rockfall site
- Two drill rigs were used during construction.
- A total of 1,200 meters of rope was used.
- 280 rock bolts, each 6 metres long, were installed.
- 80 kilograms of high-explosive material were used.
- Transporting materials required 29 helicopter lifts.
- 840 bags of cement were used for various construction tasks.
