Excavation work has been completed on the catch bench that has been built to reduce the risk of falling rocks bouncing onto Sumner Road.
The completion of the bench excavation is a significant milestone as, excepting drainage works and tidying up the Gollans Bay Quarry area, it marks the end of stage one of the multimillion-dollar project to get Sumner Road reopened to the public.
The stage one work has focused on reducing the rock fall risk along Sumner Road.
The next stages involves repairing and reinforcing the retaining walls below Sumner Road and rebuilding the road itself.
Christchurch City Council and the NZ Transport Agency are jointly funding the work.
Sumner Road, which links Sumner to Lyttelton, has been closed to the public since tonnes of rocks came tumbling down onto it from the surrounding cliffs during the 22 February 2011 earthquake.
The new catch bench sits between Sumner Road and the Crater Rim Bluffs and is literally designed to “catch’’ falling rocks before they land on the road.
“Contractors McConnell Dowell and their subcontractors have excavated about 100,000 cubic metres of rock from the slope above Sumner Road to create the catch bench. It stretches for a length of about 400 metres and is 15 metres wide and 18 metres high,’’ says Christchurch City Council Senior Project Manager Peter Bawden.
It has taken about eight months to build the catch bench, which is one of a number of rock fall protection measures created along the route.
“If we get another earthquake, the intention is that rocks that come tumbling down from the bluffs will land in the catch bench rather than on the road,’’ Mr Bawden says.
Most of the rock excavated from the catch bench has been stockpiled at the Gollans Bay quarry. Over the coming months some it will be used in other Council projects.
Mr Bawden says the focus now is on repairing and reinforcing the many existing retaining walls below Sumner Road.
Sub-contractors are starting to work on repairing a 100-metre long retaining wall below Sumner Road, at its intersection with Reserve Terrace. The work involves drilling anchors into the bedrock behind the existing wall and installing new reinforced shotcrete concrete facing.
Procurement of the remaining retain walls packages and pavement repairs is under way and the target is to have Sumner Road open in early to mid 2019.