Engineering Heritage Week: papers and presenters

The tale of two bridges – how understanding heritage significance can guide the treatment of our country’s unique structures

The Rakaia Gorge No.1 Bridge is an internationally unique Bollman-style truss bridge built 1880-82. The Opawa Bridge in Blenheim was the first bowstring arch truss bridge built in reinforced concrete to be constructed in New Zealand in 1917. Both are Category 1 listed historic structures. Increasing traffic weights and volumes, and ongoing maintenance challenges, mean that these bridges have both been required to adapt in different ways. This paper will discuss (from the Conservation Architect’s perspective) two different approaches taken to finding solutions that balanced heritage and engineering constraints in accordance with Conservation Management Plans, and with a little compromise on both sides.

Chessa (Francesca) Stevens: MA Cons. Stud. (Dist.); BArch (Hons); BA; ANZIA; ICOMOS NZ Co-Secretary Principal Conservation Architect & National Built Heritage Lead at WSP
Chessa is a Conservation Architect specialising in assessment, preservation, restoration, management and maintenance planning for heritage and historic structures. She is a Registered Architect, and has a Master's degree in Conservation Studies (Historic Buildings) from University of York, UK. Chessa has been with WSP since 2015, managing a national portfolio of projects as the company’s sole built heritage expert, and now leads a national built heritage team.

Dunedin Law Courts seismic strengthening and refurbishment

The Dunedin Law Courts is a Category 1 Heritage Building that holds an essential civil function. Following the devastating Canterbury earthquake sequence the Crown opted to seismically strengthen the building to a level well in excess of the minimum for heritage buildings.

Substantial strengthening was required for the tower, building foundations, diaphragms, masonry walls and support of the tourelle features. Each of the structural solutions was carefully engineered and located so their effects on the heritage fabric were minimised and the work was hidden from view. The end result reflects careful coordination with all design team members, including incorporation of its iconic heritage value.

John Finnegan: BE (Civil) ME (Civil), CPEng, CMEngNZ, IntPE, MIStructE, Member SESOC, NZSEE, NZIOB
John is an award-winning Technical Director with 35+ years of international structural engineering experience. He is currently based in the Wellington office of Aurecon. John has successfully delivered complex multi-storey design projects in New Zealand and internationally, including Australia, England, Hong Kong and China. These include projects with complex interfaces and live operating environments. Seismic engineering and innovation are a passion for John, as well as delivering projects on time, to budget and quality.

Strengthening Wellington's Town Hall - maintaining heritage in a complex seismic retrofit

This is a case study based on the Wellington Town Hall refurbishment, highlighting the complex engineering nature of the work and the extensive need for temporary works. It touches on the Heritage Fabric vs Structural requirements and the use of modelling to assist with building and heritage management and the need for intrusive survey to help manage risk.

Greg McFetridge
Greg is the General Manager – Operations for Naylor Love. He is a Chartered Professional Engineer and has spent over 35 years in the construction industry mostly working for construction companies. He has a history in temporary works design and has worked many projects involving retrofitting of base isolators into unreinforced masonry Heritage buildings.

Eoin Norton
Eoin is Naylor Love’s Project Engineer for the Wellington Town Hall project. He has been resident on site since the project began in 2019. He is a Chartered Professional Engineer with prior experience working as a consulting structural designer including some temporary works design. Eoin has been responsible for the verification and/or correction of our tendered construction sequences, and the detailed design of the associated temporary works on site. He has responsibility for ensuring the temporary works are installed correctly as well as providing general engineering advice to our site construction team for all engineering related issues on site from piling to reinforcement and structural steel detailing.

Simple Strengthening: an outline of a non-specific design approach for unreinforced masonry buildings in Aotearoa/New Zealand

The Earthquake-prone Buildings Amendment Act requires individualised performance assessment and fully-quantified strengthening of earthquake-prone buildings to occur within set timeframes. For many earthquake-prone unreinforced brick masonry (URBM) buildings, the cost of assessment and design is disproportionate to their asset value and rental return. In this paper we investigate a simpler approach to strengthening URBM buildings employing standard details and explore the key elements that would be required. We then discuss how a simpler strengthening approach could be used to the benefit of regional New Zealand centres.

Hamish Tocher
Hamish is a graduate engineer at Holmes Consulting, based in Auckland. While at engineering school, Hamish ran a heritage society, connecting engineering and architecture students and undertaking site visits to retrofit projects on heritage buildings in the Auckland region. Hamish and his co-author Matt Cutfield have worked on a number of assessment and strengthening projects for historic buildings, including projects based in the Netherlands.

Matthew Cutfield
Matthew is a design engineer at Holmes Consulting, based in Auckland. Matthew has undertaken a number of design and strengthening projects on masonry buildings, including projects based in the Netherlands. He has also had a leading design role in assessment and refurbishment works at the Auckland Museum. Prior to engineering work, Matthew completed a PhD in seismic risk assessment, including a one-year post-doctoral research project looking at the risks, costs and benefits of strengthening New Zealand’s unreinforced masonry buildings.

Historic wharf restoration using modern materials

This paper looks at some of the challenges faced by communities when trying to preserve structures with heritage value. It recognises an increasing desire to preserve historic structures because of their significance to the communities they served and educational value for future generations. The paper identifies some of the conflicting requirements with preservation projects: preserving the heritage value; meeting the needs of the community; and complying with modern standards. Trial repairs to the Tokomaru Bay Wharf have shown the potential for an engaged community group using modern materials to preserve the structure and add to its heritage value.

Mark Dyer
Mark is a Civil Engineer originally from South Wales. He worked in numerous commercial and academic roles prior to his 2017 appointment as Dean of Engineering at the University of Waikato where he was instrumental in establishing the degree in Civil Engineering. Mark is a promoter of the urban narrative to better understand the links between engineering and communities.

Ray Hudd
Ray was born in England. He is a Civil Engineering graduate with a PhD in concrete permeability testing. He worked on projects in the UK, Europe and Asia developing specialist concrete products before moving to New Zealand in 1998 working for Sika (NZ) Ltd developing self compacting concrete. He is currently a senior lecturer in Civil Engineering at the University of Waikato. He has a keen interest in concrete technology and sustainability in the construction sector.

“Reality Capture” and its place in digitally preserving the past

Knowledge of the position, size and shape of a historic structure or site is a fundamental part of any project related to the conservation of cultural heritage. Simple photographs and 2D drawings are quickly being replaced with rich, photorealistic 3D data for analysis and visualization as well as serving as an enduring digital asset of the structure or site.

This paper will provide guidance on the use of 3D laser scanning and photogrammetry across the heritage sector and should assist cultural heritage professionals making the best possible use of this now highly developed technique. Local New Zealand examples will be used to demonstrate the results achievable.

Lennon Bedford
Lennon is a Technical Specialist for Global Survey, a New Zealand owned measurement technology provider. Lennon helps professionals adopt and maximise the value of the latest Reality Capture technologies (including 3D Laser Scanners and photogrammetry) on offer. He enjoys finding innovative uses for new technologies and has a personal interest in heritage preservation. He often spends his weekends 3D scanning historic buildings.

'Bottled Lightning' – New Zealand's first public electricity supply

Dunedin electrical engineer, Mr Walter Prince, promoted a hydro-power scheme for Reefton at public meetings in 1885. He suggested an upstream off-take of the Inangahua River be fed through a rock tunnel and a timber-lined water flume to a power house close to the town.

Two subsequent replacement power stations were built on the same site before generation ceased altogether. After decades without a power station local enthusiasts formed the Reefton Power House Charitable Trust to raise funds to reinstate hydropower for the town. Commissioning a 250kVA turbine is anticipated in early 2022.

Ian Bywater, BSc(Eng), FEngNZ
A graduate of Queen Mary College, London, Ian began work with the Eastern Electricity Board before joining New Zealand Electricity in Invercargill (Southland Electricity Power Supply). He then held positions in Christchurch (Heathcote County Council electrical engineer, Port Hills Energy manager, SouthPower business development manager) before working for environmental companies (Convertech and Natural Systems). Ian represents the hydro-turbine company Turab.

Dunedin's cable car system – a bold venture in the antipodes

In 1882 a cable car service opened from central Dunedin to the elevated suburb of Roslyn. As such, Dunedin became the third city in the world after San Francisco and Chicago to inaugurate this form of street-based public transport. A year later, another cable car system extending 1.6 km to serve similarly hilly suburb of Mornington was opened.

The paper reviews the evolution of cable tramways and the engineering challenges and solutions adopted for the early Dunedin systems. The paper then focuses on the construction, operation and maintenance of the Mornington cable car service and its steep Maryhill extension. Includes recollections and archival images.

Ian MacGregor BE (Civil), MHKIE, MIET, CEng, CMEngNZ. Retd.
Civil, Production, Geotech Investigations Engineer. Materials Engineer Ministry of Works and Development. HKIE Materials Division Assessor & Assoc Prof City University of Hong Kong. Published research papers include: precast white concrete formwork, properties of stone flooring, pressuremeter & dilatometer test analysis. He is a member of Heritage New Zealand, and the Tramway Historical Society. Lived 80m from the Maryhill cable car line.

Miles Pierce BE (Elec), FIE Aust CPEng Retd.
Miles spent most of his career with GHD Consulting Engineers where he was for many years Principal Electrical Engineer in their Victorian practice. He has had a long-term interest in engineering and industrial history and heritage, particularly in relation to electrical and mechanical engineering disciplines, and has authored a range of papers in the field. He is a committee member and a past chairman of Engineering Heritage Victoria.

A series of most fortunate events – bringing new life to old technology at Mandeville Railway Trust

Twenty-two years ago, a rail heritage trust was established in Southland with the vision of becoming a working museum. Having a restored locomotive from 1878, the hunt was on for other treasures.

A turntable was located on a farm nearby, having avoided scrapping. It was traced back to one of the eight turntables imported with the loco. Some bowstring trusses were acquired, little knowing that they were part of an original Hillside Railway Workshops building erected in 1876.

This paper documents the journey to understand the heritage significance of these items, now forming part of the Trust’s facilities at Mandeville.

Robert Storm
Robert is a semi-retired career railway man. While always based in Dunedin, he has had extensive involvement with track throughout the South Island. In the last 20 years Robert has assisted with the development of an Infrastructure asset management system plus associated track GIS data, recovery work after the Kaikoura earthquakes, and mentoring young engineers. He is now focusing on various aspects of rail heritage.

Refurbishment of Ross Creek reservoir dam, Dunedin's first major water supply scheme

The Ross Creek Reservoir is retained by a puddled clay core embankment dam constructed 1865-67 to provide municipal water supply for Dunedin founded some 20 years earlier. This dam has undergone extensive refurbishment to enhance impoundment security and integrate the reservoir into the water supply resilience project for the city. Various deficiencies have been addressed, including construction of a rockfill buttress zone to enhance earthquake and flood resilience. While the engineering works have needed to satisfy modern dam safety requirements, efforts have been made to capture the archaeological record, retain heritage features wherever possible, and to sympathetically detail affected features.

Principal author Ian Walsh
Ian is a Technical Principal with WSP, specialising in the fields of dam engineering and risk management. He has a long-term interest in the safety management of ageing dams and was design leader and Engineer to Contract for the Ross Creek Reservoir Refurbishment Project.

Co-author Sam Kurmann
Sam is a section 45 approved archaeologist with 8 years’ experience in professional practice. Career contributions have included working on the Kaikoura and Christchurch Earthquakes recovery and rebuild, and other large-scale infrastructure projects around the South Island. Sam was the lead consultant archaeologist with WSP on the Ross Creek Project.

Co-author Scott Kvick
Scott has been closely involved with the Ross Creek facility since starting his engineering geology career with WSP in 2014. The opportunity to witness 150-year-old features being exposed during refurbishment earthworks operations has been a feature of his contributions to dam safety management, geotechnical investigations, construction supervision during the refurbishment, and the staged recommissioning of the reservoir.

Dunedin Law Courts - campaign for restoration

The Dunedin Courthouse was built in 1901 and is a Category 1 listed historic structure.

In her presentation, Anne Stevens QC will discuss the campaign to strengthen and restore the Courthouse following the 2011 Canterbury quake.

Anne Stevens QC
Anne Stevens QC attended University of Canterbury and Canterbury Teacher’s College before studying law at the University of Otago. She began practicing as counsel at the Dunedin Courthouse in 1988.

In 2001, Anne was involved in the relocation of the Otago District Law Society from the Courthouse to the former BNZ building in Princes Street while the Courthouse was upgraded. She was also on the committee that oversaw the upgrade. It was a $14 million investment that saw earlier internal modernisations removed and archways and spaces returned. Some earthquake strengthening took place. The work was done beautifully, and the Courthouse looked stunning and was very functional when the Law Society returned to it a year later.

The building was damaged in the 2011 Canterbury earthquake and Anne was again involved in advocating for the building and leading the campaign for its restoration.