The level of earthquake damage to the road and rail networks between Picton and Christchurch was unprecedented in New Zealand. The scale of the event and the quick restoration of this economically important narrow coastal corridor, created the great challenges for the recovery project.
To restore these transport networks, design and construction had to happen simultaneously, and quickly. From the start, design and contracting teams developed construction options and defined scope for both the road and rail networks. Every opportunity was considered to make the railway line and roads safer and more resilient. However, the first step in the process was to tackle the mountains of material dislodged by earthquake and obstructing the transport corridor.
- Multiple slips
- State Highway 1 – a broken corridor
- The Inland Road – an essential link for Kaikoura
- The alternate Picton to Christchurch route
- Rail – getting the line back on track
- Kaikoura marina – keeping the town afloat
Multiple slips
About 40 primary slips were identified along SH1, blocking both the road and rail networks, between Clarence to the north of Kaikoura and Oaro Bay in the south. Immediately after the earthquake, work was underway to clear minor slips along the transport corridor and strategies were developed to make the larger slips safe for removal.
Clearing the landslides post-earthquake was a priority but not easy. The fractured cliff faces were often unstable. Cyclones Debbie and Cook meant work was halted for some days and the already damaged slopes released more rock and material.
Slip clearance involved helicopters dropping buckets of sea water on the slopes, known as sluicing, to dislodge loose rocks and dirt. This helped to stabilise the hill faces to enable workers and machinery to move on-site down below to begin removing the slips. Abseilers also worked on numerous slips, helping remove any remaining loose material, clear trees and vegetation.
Repair on the railway and the road could only start once the slips were removed and the hillsides were made safe.
Slips – key factor for the rebuild process:
- Clean the tops of the slips.
- Clear away the slip with machinery.
- Keep the slips from blocking the road and or rail
- Repair and reconstruct the rail and road corridor.
- Make the road and rail resilient.
State Highway 1 – a broken corridor
The Transport Agency re-opened SH1 south of Kaikoura before Christmas 2016 but the network remained fragile and vulnerable to rockfall. The highway required ongoing work and was subject to short-term closures as work continued to rebuild and improve sections of the highway.
The instability of the rock cliffs had to be considered in the design and work planned to maximum safety.
In the early days, geologists assessed every slip individually to determine the safest removal option for each one.
The biggest and most complex of the nine major slips north of Kaikoura is the slip at Ohau Point.
The Inland Road – an essential link for Kaikoura
Access through the Inland Route 70 via Waiau and Mt Lyford was restored within a few days of the earthquake for NZ Defence Force convoys to get emergency supplies through to Kaikoura which was isolated by the slips.
The route remained closed to civilian access until 25 November when the first convoy of 80 vehicles, carrying 150 people, were escorted out of Kaikoura.
Restricted public access was opened on Tuesday 28 November, with 49 vehicles being escorted into Kaikoura. There was no return trip because deteriorating weather conditions closed the road.
The route remained fragile and hazardous, with restricted, escorted access only. This operation continued until single-lane controlled access for residents and essential services was restored by mid-December.
From the start, crews worked at least 12-hour days to not only re-open the Inland Route 70 but to also assess the damage to the infrastructure along State Highway 1 and to begin to clear the slips and repair the damaged road pavement. SH1 access between Christchurch and Kaikoura was restored before Christmas 2016.
The alternate Picton to Christchurch route
Immediately after the earthquake, short and medium term work was planned to ensure the alternate route between Picton and Christchurch, via the Lewis Pass and Murchison, was safe and reliable to cater for the significant increase in traffic volumes.
Traffic volumes on this route increased four-fold and initial work priorities included repairing and resealing many sections of the road to strengthen the road surface, widening it where possible and making it safer for users. This work was delivered as part of a $60 million government investment to improve safety on the route.
A safety review for each township along the alternate route was completed in February. This resulted in the implementation of new traffic measures such as speed reductions, improved signage, new guard rails and electronic real-time speed information.
To ensure the route remained safe and reliable for all road users, work got quickly underway with the installation of slow vehicle bays, widening and realigning sections of the highway.
By March 2017, several sections of the route had been widened and 36 kilometres of the route had been resealed or repaired to help the road cope with the increase in traffic. A further 22 kilometres was resealed before winter.
Two new temporary bridges opened on the alternate route in early February to improve safety and reduce travel times.
Alongside the road improvements, new technology was introduced on the alternate route such as mobile towers to reduce coverage black spots, webcams and radar to help keep people safe.
Rail – getting the line back on track
The Main North Line (MNL) railway between Picton and Christchurch was a vital link in KiwiRail’s network that provided just-in-time services, shifting freight from the North Island via the Interislander ferries, and along the MNL to Christchurch, and on to South Island customers.
By January, work was already underway on repairs along the 150kms of line damaged in the earthquake, which twisted railway tracks, sent slips over the route and caused structural damage. Major repair works started initially on four of the 20 damaged rail tunnels and six of the 59 damaged bridges.
By the end of January, the substantial work programme delivered through NCTIR involved more than 100 KiwiRail staff consultants and contractors. The first post-quake train ran from Blenheim to Lake Grassmere on 16 January 2017, the first milestone in re-opening the 347-kilometre route between Picton and Christchurch.
In March 2017 plans were underway to build a new permanent bridge to replace KiwiRail bridge 90, near Ferniehurst, in Hundalee, North Canterbury.
After almost 80 years and millions of trips, KiwiRail's Bridge 90 became the first major rail structure to be demolished as part of the earthquake recovery work.
While the Main North Line was severely damaged in the earthquake, parts of the line were easier to restore due to tunnels protecting it from slips, and through solutions such as temporary bridges.
Kaikoura marina – keeping the town afloat
The November 2016 earthquake raised the seabed below the marina at South Bay by up to two metres, making it un-usable and disrupting tourism and fishing ventures industries that are vital for the local economy.
Work on the key infrastructure got underway in December 2016 following a funding announcement by Government. The Crown funded $5.72million for the Kaikoura harbour to be restored to how it was before the earthquake, including the public slipway and the Coastguard ramp. Operators Whale Watch Kaikoura and Encounter Kaikoura put in an extra $900,000, to enable improvements to be made and allow for future expansion of the harbour for larger boats.
Initial work on the marina involved deepening the harbour – by dredging the sea floor.
Initially, a 35-tonne excavator with a two metre-long tooth raked rocks near the bottom of the slipway to break them up before collecting the debris. Further excavators lowered the seabed floor so boats could access the wharf and boat ramps at all times. About 15,000 cubic metres of material was removed from the main marina channel which was used to construct a ‘cofferdam’ across the marina basin: a watertight enclosure pumped dry, enable construction work to get underway and deepen the marina basin below the waterline within the harbour.
The next step included reinstatement of the marina, piles and wharf.
