Client name: North Canterbury Transport Infrastructure Recovery (NCTIR)

Duration: February 2017 - December 2017

Location: Kaikōura, NZ

Bringing specialist geotechnical expertise to the Kaikōura Earthquake Recovery project.

On November 14th 2016, Kaikoura earthquake was felt around New Zealand. It caused extensive damage to the area leaving communities stranded by slips, critical infrastructure and rail and road network severely damaged, including State Highway 1 (SH1) and the Main North Rail Line between Picton and Christchurch, which both had to be closed.

In response the North Canterbury Transport Infrastructure Recovery (NCTIR) alliance was set up to rebuild the SH1 and rail network north and south of Kaikōura (between Picton and Christchurch). The NZ Transport Agency, Kiwirail, Downer, Fulton Hogan, HEB and Higgins form the alliance.

A Coffey team has been seconded to NCTIR to provide specialist services for geotechnical and seismic design of new seawalls, bridge foundations, abutments, cut slopes and mechanically stabilized earth walls (MSEW).

State of the art detailed geotechnical design for new structures

After the earthquake, where realignment was necessary, new seawalls, bridge foundations, abutments, cut slopes and mechanically stabilized earth walls (MSEW) needed to be built for both the SH1 and the inland route SH70.

Coffey is providing specialist geotechnical design for those new structures, incorporating 2D static, pseudo-static and time history analyses using FLAC. This is a departure from the Bridge Manual requirements. The team also applied the AASHTO 2014 allowance for reduced seismic demands for the MSEW design by allowing for deformation of the new structure.

Our team is also providing construction monitoring for safety during slip stabilisation and design verification.

Cost saving innovative design 

The Coffey team delivered realistic, state of the art detailed designs that eliminated over conservative design which helps to reduce material costs and construction time

The use of computer models to predict the response of the engineered system to earthquake events has led to an optimised design without any reduction in the quality of the final product.

An example of this was by reducing the geogrid lengths our solution has provided significant cost savings.  By utilising locally available material and optimising the amount of geogrid required for the seawalls material costs construction times have been reduced.  

Assessing and restoring existing assets 

By conducting a thorough investigation of existing structures with less significant damage – roads, bridges, retaining walls and embankments – we were also able to determine they could be reinstated safely. 

Bold and innovative ideas 

Our team is applying their expert geotechnical knowledge to conduct field based construction inspections and geotechnical assessments and is disrupting the current thinking on prescribed codes on investigation and assessment of seismic affected structures.

In the absence of site specific seismic hazard assessment our team is providing technical advice on the formulation of recommended spectra for seismic design. 

Assessment of strong motion data

We are also conducting on-going assessment of strong motion data to help understand the complexities of the project and carefully select the appropriate analytical tools based on specific site requirements.