Services: Infrastructure Engineering

CentrePort Berth and Upgrades

Holmes has been providing ongoing professional engineering advice and support to CentrePort for more than a decade. The key skills we bring are typically in civil, structural, geotechnical, fire and construction engineering. We are regularly involved in activities that encompass new build, inspection and condition reporting, structural assessment, strengthening and refurbishment, public spaces, asset management planning and more. This experience has equipped us with an in-depth understanding of the working port environment and the ability to contribute our knowledge and expertise across all levels from high level planning through to providing technical advice and design to asset management.

Holmes, alongside Tonkin + Taylor, were engaged to deliver this programme of projects that included:

  • Berth modifications to RFT2 & RFT3 to accommodate ferries
  • Upgrades to Kings Wharf to maintain an important coastal shipping facility, and
  • Post-quake temporary works to the Thorndon Container Wharf to resume operational continuity following the Kaikoura earthquake in 2016
  • Wharf modifications to accommodate for Kaitaki and Aratere, including new linkspan, berthing, mooring, fenders and strengthening works

Working in close proximity to a major fault line had a significant impact on the designs. Seismic risk reduction was factored in to reduce impact in the event of an earthquake. The harsh marine environment demanded project-appropriate constructability, and a genuine understanding of engineering close to and beneath the ocean.

Perry Bridge

Te Awa walk and cycleway stretches along the Waikato River in central Aotearoa, running from Ngāruawāhia in the north to Karapiro in the south. The Perry Bridge was the final link in the chain, completing the path and opening up a fantastic activity for locals and visitors to the region. The original plans didn’t even include a bridge—but the client wasn’t able to secure permission to build the path on the west side of the river. The solution was a detour across to the east side of the river, by way of a new bridge, which was put out for competition.

Holmes and Emmetts Civil Construction submitted an alternative solution for the bridge involving a visually stunning, innovative network arch. The efficiency of this form of structure kept its costs within a practical budget, but the client also recognised the opportunity to create a visually compelling focal point to help attract people to the cycleway. Drawing on a concept conceived in the 1950s by the brilliant Norwegian engineer, Per Tveit, the project team delivered a visually stunning, innovative network arch bridge. The bridge is very long and thin, spanning 130m at just 3m in width—presenting a number of complex technical engineering challenges. It’s New Zealand’s fourth network arch bridge and the first of its kind in the country designed specifically for pedestrians and cyclists. It’s also the longest network arch bridge in the country.

Moving into the construction phase, it became evident that the proposed launch sequence, involving barges on the river, had a high level of risk and uncertainty. We devised an innovative and efficient alternative launch sequence, pulling the bridge across the river on cables. The launch went smoothly, and the outcome is exceptional. Our alternative tender design helped to capture the public’s imagination, and involved local schools, artists and other stakeholders to ensure relevance to the local community.

Omāroro Reservoir

Holmes worked alongside contractor Heb to produce an alternative design for the Omāroro reservoir in 2019. This offering was ultimately successful, and the detailed design was completed for this critical Wellington Water project over the second half of 2020.

The Holmes structural and geotechnical design team created efficiencies through a number of means, saving the asset owner millions of dollars in capital expenditure. The alternative design drew on a thorough assessment of soil-structure interaction to demonstrate performance under service, ultimate and maximum credible earthquake events. This was particularly important for the reservoir as it is buried in its final state and a lifeline asset. We reduced material use and accommodated the contractors preferences by not adopting key elements of the original design.

We sought input from Wellington Water during the design process, and adapted aspects of the specification to suit their longer term needs. A simple example is the adoption of certain roughness requirements on the tank floor to reduce risk of slips for personnel inspecting or cleaning in future.

The team completed construction staging checks for precast walls and for different backfilling scenarios. Our structural modellers and civil designers performed a number of staged construction modelling exercises to assist the Heb team in communicating with their own staff and with external stakeholders. This enhanced safety outcomes and overall understanding for both project contributors and other interested parties.

With permanent works design complete, the team continues with temporary works, construction monitoring and technical support through 2021.

Waipapa | Christchurch Hospital

The new Acute Services Building at the Christchurch Hospital is a vital piece of infrastructure for the city, and a project demanding some clever engineering in a tight programme. Holmes was brought in for structural and civil engineering on the strength of our extensive healthcare expertise and our ability to deliver a robust, resilient design appropriate for Christchurch’s extremely challenging seismic environment.

We applied the principles of Low Damage Design to underpin the continuity of this Importance Level 4 structure which is base isolated—providing the necessary post-disaster resilience for the region and local community. Particular care was taken to ensure the appropriate seismic detailing was consistently applied to the building services, fit-out and contents, to mitigate damage during earthquakes.

The redevelopment is being undertaken within the context of a busy working hospital campus—putting extra emphasis on designs that are easy to construct, creating minimum disruption. The steel moment frame structure was designed to be prefabricated in sections and bolted together on site. The requirement for site welding and work on site has been minimised, meaning the onsite programme is far more efficient. The steelwork has also been designed such that elements can be easily transported by road or ship. This has given the contractor flexibility in the location of fabrication, allowing the structural cost to be minimised—an important saving in a big ticket, high profile project.

We’re delighted to have had the opportunity to make such a strong contribution to a building so critical to Christchurch’s future.

Commercial Bay | Te Toki i te Rangi

Commercial Bay is the largest mixed-use development ever undertaken in Tāmaki Makaurau (Auckland) CBD. The project combines two existing office towers with a new three level high-end retail complex and a new 39 level commercial tower—all above three levels of basement car parking and two train tunnels, with associated major complexities and structural transfers. Holmes was the Lead Structural Engineer on this important project, as well as providing fire and infrastructure engineering.

Structural Engineering 

The architecture of the flagship 39 level Commercial Bay tower in downtown Tāmaki Makaurau celebrates and showcases the structural form of the building. Working closely with the architect and the wider project team, Holmes designed visually striking columns and diagonal braces, which are clad to express and accentuate the structure. The structural system of the tower consists of a diagrid structure, featuring composite concrete filled hollow section steel tube columns and braces and long span beams.

In a large complex project with many stakeholders and challenges, the Commercial Bay tower is an example of a well-coordinated structure, underpinned by great BIM execution and a willingness for project partners to work through challenges collaboratively. This result was achieved through excellent continuous ongoing collaboration and communication between project stakeholders—particularly the architect and the structural engineers. Weekly exchanges of Revit files via a shared FTP site ensured well-coordinated Revit models and delivered a clear accurate picture of progress.

The penetrations through the floor slab were modelled in the structural slab, and penetrations for building services were incorporated into the structural steelwork floor beams. Across the project, regular meetings, ongoing communication and open, positive discussions ensured alignment and synergy through the design process.

With a premier site overlooking the harbour, Commercial Bay is already an iconic landmark on the Tāmaki Makaurau foreshore and skyline.

Fire Engineering

Holmes provided fire engineering advice for the entire development, including master-planning to allow for future subdivision of the entire block into four discrete separate properties. The fire engineering allows for separate phased evacuation and independent commissioning and ownership of fire protection systems serving the retail centre and the office tower. Holmes was also engaged to provided advice to almost all of the retail and office tenants, to integrate their specific tenancy fitout design with the overall base building fire engineering strategy.

Holmes was also engaged to provide specialist structural fire engineering services to rationalise the passive fire protection requirements of the entire tower. Advanced finite element modelling was undertaken to analyse the response of the whole floor and megaframe in fire. The analysis demonstrated the robustness of the whole structural frame in resisting a full burnout fire. The resulting analysis showed the composite columns and secondary beams did not require passive protection and a reduced FRL could be applied for the primary beams. The analysis was peer reviewed by Professor Jose Torero who is a renowned international expert in structural fire engineering.

This resulted in major savings on site with regard to project timeframes, labour and material costs, and the improved aesthetic and air quality within the space. The costs savings in fire proofing alone was estimated to be approximately NZ $4M.

City Rail Link Tunnels

The City Rail Link (CRL) runs beneath the Commercial Bay site on the Auckland CBD waterfront. Holmes, as part of a Fletcher Construction Design and Build Team, were responsible for the structural engineering design and documentation of the portion through the Commercial Bay site for the owner Precinct Properties and key stakeholder Auckland Transport. This separate CRL tunnel portion ties into the two adjacent enabling C1 contracts, C1 (Britomart Station) and C2 (Albert St).

The two box tunnels are on a curved alignment and merge into a twin tunnel box within the site. Separation of the tunnels from the surrounding development and the transfer of loads from the multi-storey office tower above were among the considerable challenges involved. The CRL box tunnels are constructed within the Commercial Bay basement area, with the structure of the development forming an enclosure over the top of them. Tension piles resist hydrostatic pressures on the base of the tunnels. The cast insitu tunnel base, walls and roof were formed using moveable formwork. The tunnels were designed for IL3 loads, with a 100-year design life.