Design update
The team has been busy working on the detailed design for the new motorway and recently reached the point in the design where we've developed the overall layout and key features of the new motorway. This includes things like the alignment (where the road will go), major structures (like bridges and interchanges), and how the motorway will connect with existing roads. It confirms the big-picture approach before we dive into the details.
We’re looking to reach the 50 percent design milestone in late September, which is where the design is more refined. Engineers have worked through many of the technical details, such as drainage, earthworks, and structural components. This stage is used to check that everything is working together as planned and to identify any issues before finalising the design.
Geotechnical investigations are mostly complete and have shown a lot of variation in soil conditions across the project area, with silt, sands, and dense gravel all present in different locations.
Results have given us important insights into the soil conditions and potential liquefaction risks in the area. This information is helping engineers design foundations for the new bridge structures and plan ground improvement work needed to support the new road embankments.
As part of this, we’re planning the work needed to strengthen the SH1 Kaiapoi River Bridge. This upgrade will ensure the bridge can safely carry an additional southbound lane between the Lineside Road intersection and the Ohoka Road southbound slip lane. This lane will provide the capacity needed between the Lineside Road onramp and the Ohoka Road off-ramp.
The bridge strengthening is part of the Early Works Package and will involve strengthening the bridge columns by wrapping them with a special material called CFRP (Carbon Fibre Reinforced Polymer). This helps improve the bridge’s resilience and safety. Work is expected to get underway in early 2026.
The consents for this work have been approved. Next, we’ll engage a contractor and confirm timing for the work to start. The addition of the southbound lane will be carried out later, during the main construction works.
Image below: Drill core samples packed and ready for geotechnical testing
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