Upgrading Tonga’s Queen Sālote International Wharf

The challenge

The Queen Sālote International Wharf (QSIW), built in 1967, is the Kingdom of Tonga’s only international port and handles 95 percent of the nation’s imports and exports. After more than five decades of operation and limited maintenance since 1999, the port faced serious structural deterioration, safety limitations, and capacity constraints.

With much of the infrastructure sitting less than three metres above mean sea level, the facility was increasingly exposed to storm surges, tropical cyclones, and sea-level rise. The wharf’s ageing deck structures, pavement failures, and inadequate mooring and fender systems created significant safety challenges for workers and vessels. In addition, the port no longer met international environmental and security standards, while inefficient cargo handling and constrained berth space hindered operational efficiency and expansion.

As Tonga’s main maritime gateway, the QSIW upgrade was critical to ensuring the nation’s trade resilience and long-term economic stability. The challenge lay in modernising aging port infrastructure, improving safety and environmental performance, and enhancing resilience to sea-level rise and extreme weather events — all within a constrained budget, limited local resources, and without disrupting essential trade operations. This was a complex challenge requiring innovation, precision, and close stakeholder collaboration.

The solution

In 2019, the Asian Development Bank (ADB) engaged Haskoning to deliver the detailed engineering design, technical assistance, feasibility studies and site supervision for the Queen Sālote International Wharf upgrade project.

Our team developed an integrated plan to modernise, climate-proof, and expand the port’s capacity while maintaining operations throughout the five-year program.

Our approach began with a comprehensive climate and disaster risk assessment, combining scientific analysis with local insights. This four-stage process included:

• Port operations and asset condition assessments
• Hazard modelling and seismic, tsunami, and resilience forecasting
• Stakeholder consultation workshops
• Multi-criteria evaluation of adaptive design options

Based on the findings, Haskoning designed a port expansion plan centred on efficiency, safety, and long-term sustainability:

• Rebuilding Wharf 1 with a new suspended deck structure using locally produced concrete.
• Extend Wharf 2 by 45 metres to accommodate larger vessels.
• Construct four new mooring dolphins and two navigation markers for improved berthing and safety.
• Reuse demolished concrete for coastal protection works.
• Install firefighting systems, lighting, HV/LV, stormwater drainage.
• Reorganise container yards and upgrade access roads and pedestrian routes. 

Our assignment included the establishment of a comprehensive asset management and maintenance framework to ensure the port’s long-term operational and environmental sustainability. 

During implementation, 80 percent of the workforce was local, with 14 percent female participation supported by gender equity policies and training programs in safety, operations, and environmental management.

The result

Despite unprecedented challenges that included Cyclone Harold, the COVID-19 pandemic, a volcanic eruption, and global supply chain disruptions, the QSIW Upgrade project was delivered on time and within budget.Environmental outcomes have been equally transformative:

• More than 100 tonnes of waste and scrap metal were removed from land and sea, with most recycled offshore.
• Contaminated areas were rehabilitated, reducing long-term environmental risk.
• Recycled construction materials reduced carbon footprint and costs.

Beyond physical infrastructure, the project has strengthened local capability — empowering Tonga’s port authority and workforce to manage and maintain critical maritime assets sustainably.