Unexpectedly soft soil conditions are slowing down work on installing the Dyers Pass Road safety barriers, pushing completion of the project out by about two months.
The work to install the 3km of safety barriers is now expected to be completed at the end of August.
The safety barriers (or guardrails) are being installed at high-risk locations to help reduce the severity of crashes where vehicles would have left the road.
Christchurch City Council Acting Head of Transport Lynette Ellis says as contractors have dug up the ground, they have encountered unexpectedly soft soil conditions at a depth that was not encountered when ground investigations were completed during the design phase of the project.
“As a result they are drilling anchors into the rock under the road in order to achieve the required retaining wall strength to support the safety barriers.
“Five hundred anchors are required across the all of the retaining wall sites. This additional work is the reason that construction is taking longer than expected,’’ Ms Ellis says.
Work is expected to continue with similar road disruption to what is currently in place – night works, and around three work sites where the road is reduced to one lane during the day.
“We’re working to speed up the work where possible,” says Ms Ellis.
“We’ve successfully trialed an alternative retaining wall design using a Magnumstone concrete block system that is quicker to construct and requires less excavation, but this has been built into the end of August timeframe.
“We understand that this work is highly disruptive to the Banks Peninsula community and we are working with the contractor to complete construction as fast as possible.”