The Queen Salote Wharf upgrade climate proofs a lifeline for Tonga’s future

PROJECT FILES: Consulting engineers Haskoning in partnership with the government of Tonga, Asian Development Bank , Australian Infrastructure Financing Facility for the Pacific and contractor McConnell Dowell managed a $70 million upgrade for the Kingdom of Tonga completed this year. This is why the project was so important to our Pacific neighbours.

When the Tongan Royal Family blessed the newly completed Queen Salote International Wharf this year in the Kingdom of Tonga, it signalled more than the completion of a $70 million infrastructure upgrade. It marked the start of a new chapter for the Pacific nation’s future.

The project transformed the country’s only international port into a modern, climate-resilient facility designed to last generations to come.

The project was one of the largest infrastructure investments in Tonga’s history.

A critical gateway under pressure

As a lifeline to the rest of the world, the wharf at Nuku‘alofa handles around 95 per cent of Tonga’s imports and exports, from food and fuel to medical supplies. Originally built in 1967, decades of exposure to the sea and cyclones had left the concrete deck and fender systems deteriorated. Rising seas and storm surges caused frequent flooding.

The site had reached a tipping point. The wharf had become worn from exposure over the decades, cabling ran through pools of water and piles of corroded scrap metal sat along the quay. Its condition wasn’t just an operational issue, it had become an environmental and safety risk.

When Cyclones Tino and Harold, followed by the Hunga Tonga-Hunga Ha‘apai eruption, disrupted trade routes, the vulnerability of the port was exposed and became impossible to ignore. Upgrades were now a necessity.

However, the project faced a significant challenge: closure for critical rebuilding wasn’t an option as it would have cut off the nation’s lifeline.

Community-centric construction plans

Keeping the port open during construction became the defining challenge.

Every shipment of food, medicine and goods passes through this port.

Shutting it down simply wasn’t an option. We had to work closely with our project partners and the community to create a plan that allowed for construction while the country kept trading, this was something that hadn’t been done on this scale before.

The solution was a phased delivery strategy that enabled one wharf to operate while the other was rebuilt. Detailed hazard modelling for cyclones, earthquakes, storm surge and sea-level rise informed every element of the new design. The firm’s engineers worked side-by-side with local authorities and contractors to coordinate construction sequences, vessel scheduling and safety protocols.

Building for future generations

The redevelopment focused not only on increasing capacity but incorporated climate adaptation to ensure the port stood the test of time against the elements. Key components included:

• Rebuilding Wharf 1 with a suspended reinforced-concrete deck and upgraded fender and mooring systems
• Extending Wharf 2 by about 50 metres to accommodate vessels up to 220 metres long
• Adding four mooring dolphins and two navigation markers for safer berthing.
• Reusing 2160 tonnes of demolished concrete in rock bags for erosion protection along the foreshore
• Installing modern stormwater, firefighting and energy-efficient lighting systems

The upgraded port has doubled operational efficiency, increasing throughput to roughly 45,000 twenty-foot equivalent containers a year. But the achievement is measured in longevity, not just numbers.

The wharf is designed for the next 50 years. The aim wasn’t to simply patch it up, but to deliver a rebuild that was climate resilient and built to last.

Environmental restoration was woven into the construction plan. Decades of debris of scrap metal and waste machinery of roughly 100 tonnes was removed and exported for recycling. Concrete and steel were repurposed wherever possible.

The project diverted 85 per cent of materials from landfill, a level of circularity considered rare in small-island infrastructure. It demonstrates you can deliver high-performance engineering and reduce waste at the same time, something that it’s hoped will set a new standard for the industry moving forward.

Keeping it focused on local

Community was placed at the centre of delivery. Over 80 per cent of the workforce came from Tonga, including 11 per cent women, supported by more than 3000 hours of training in safety, construction and environmental management.

The upskilling outcome was as important as the engineering itself, as the best resilience is considered to be primarily about people and this project built capability for future generations to operate and maintain the port effectively.

The design met international codes comparable to those applied in Europe or Australia and the emphasis on risk-based planning and adaptive design has already influenced new port initiatives in Nauru and Tuvalu.

The project completed on time and within budget, despite pandemic delays and material volatility.

Asian Development Bank in fact said the project was one of the region’s best-performing infrastructure programs, praising its environmental management, gender inclusion and local-skills development outcomes.

Lessons learnt on the project included:

• Build local capability – training and inclusion turn a project into a legacy
• Close the loop on materials – reuse and recycling reduce both cost and carbon

The new wharf secures Tonga’s maritime lifeline for decades to come and sets a new standard for how small-island nations can build bigger and better.

Climate resilience and design challenges

• The port design focused on balancing future climate risks with cost and usability to build lasting resilience
• The main challenge was designing for future conditions like sea level rise and stronger storms
• The port uses open piled deck structures to let water ?ow through during storms, reducing structural damage
• Structure orientation was planned to minimise wave impact and maximise durability
• This approach re?ects a “worst case” scenario to ensure practical resilience
• The design also accounted for storm surge height and cyclone strength to set appropriate structure elevations

Material selection and environmental technologies

• Materials and technology choices aimed to withstand harsh marine climates and reduce environmental harm
• New lighting towers were installed with downward-facing, controlled lighting to limit disturbance to people and marine life
• These towers were built with materials suitable for strong winds and saltwater exposure
• Foundation design considered cyclone-force winds for stability
• Rock bags were placed around the port edges to reinforce coastal resilience against erosion and storms

Waste management and sustainability practices

• The project prioritised minimising waste through reuse and careful disposal to achieve near zero waste status
• Scrap metal and steel from old infrastructure and new construction waste were separated, stored, and shipped to New Zealand for recycling
• Concrete and other hard materials were crushed and reused as ?ll for rock bags, road bases, and reclamation areas
• Special containers collected used oils, which were exported for treatment to prevent local contamination

Construction challenges and risk mitigation

• Unexpected site conditions and weather events required ?exible responses and strict safety protocols during construction
• Strong storms forced multiple site shutdowns with quick equipment securing and evacuation protocols
• A tsunami warning during a regional event triggered a site clearance within 30 minutes to ensure worker safety
• The need to adapt quickly to weather was a constant operational factor
• Unforeseen underground issues included unstable old structures and contaminated soils
• Teams found historical contamination such as oil spills that required containment or removal
• Some old structures were reinforced or encased instead of removed to maintain stability.

The details

Client: Government of Tonga, Ministry of Infrastructure, Ports Authority Tonga

Lead consultant: Haskoning (engineering, environmental management, design leadership)

Contractor: McConnell Dowell

Funding partners: Asian Development Bank; Australian Infrastructure Financing Facility for the Pacific

Value: USD $70 million

Duration: 2019-2025

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