Customer: Christchurch City Council
Contract Type: Design and Construct
Construction Period: 2.5 years
- 15 km of road corridor remediated
- 30 retaining walls built and reinstated – the largest of which is 132 metres long and seven metres high
- 100,000m3 of hard rock removed and transported to Gollans Bay Quarry for reuse in Christchurch City Council’s Coastal Pathway project.
- 420 m of bluffs engineered/blasted
- 150 m maximum drop for rope access
Sumner Road is a vital link between the Lyttelton and Sumner communities, an important strategic connection between the Lyttelton Port and Christchurch city, and a popular recreational space for tourists and locals. But significant rockfall from the surrounding cliffs during the February 2011 earthquakes left a 2.6 km section of the road impassable, forcing it to close.
Christchurch City Council engaged McConnell Dowell to undertake vital geotechnical remediation works to reopen the road for the first time in eight years. We carried out scaling and ground support of the bluffs above Sumner Road, excavated a large 407m long, 18 m high, 15 m wide catch bench below the bluffs to catch any falling rocks, and constructed a 50m long 7 m high rock bund in the gully to the west of the Crater Rim Bluffs to capture rockfall from the bluffs. Our work also included repair and reinforcement of 30 retaining walls below Sumner Road and remediation of the road itself.
Working 300 m above sea level and within the Port Hill’s rugged landscape provided a number of logistical constraints for accessing the site and transporting equipment. Further, the complex nature of the works required specialist input across a number of disciplines including ground engineering, drilling, blasting, earthworks and roading, all of which had to be carefully coordinated to ensure the safety of personnel working across multiple faces along the narrow roadway. The proximity of Lyttelton Port Company’s coal yard operations and infrastructure works directly below required strong stakeholder management to minimise disruption without impacting on the programme.
Safety was a key driver informing both our design and construction methodology and giving Christchurch City Council confidence that the high profile works, subject to public interest and scrutiny, would be delivered in a safe manner, as well as ensuring the long-term safety for future maintenance of the road.
Key to success
McConnell Dowell gathered a team of experts to bid and deliver the project. We built a collaborative, open culture which enabled the development of a robust design and construction methodology and a sense of ownership in project outcomes. This open approach also enabled Christchurch City Council to be heavily involved in project delivery. This strong relationship with the client enabled further collaboration on design, resulting in a change of temporary design elements into permanent works – delivering beneficial time and cost savings. These works were integrated into the programme of the original scope to accelerate the reopening of the Sumner Road for the benefit of the community.