The longest bridge in Lesotho, and a critical component of the Lesotho Highlands Water Project (LHWP) Phase II, is officially being inaugurated by King Letsie III, along with South African President Cyril Ramaphosa and Lesotho Prime Minister Sam Matekane on Wednesday.

The 825 m Senqu bridge, along with the Mabunyane and Khubelu bridges, ensures that communities in Mokhotlong district retain access to the national road network as the Polihali reservoir fills to its full supply level.

Construction of the Senqu bridge, the largest of the three major bridges constructed in Phase II, started in 2023 and was completed in February 2026. The bridge was opened to traffic at the end of March this year.

The Senqu bridge is an extradosed structure, a hybrid design that combines the principles of a box girder bridge and a cable-stayed bridge.

The bridge deck, constructed in 50 m sections cast from both ends simultaneously, is supported by 17 piers ranging in height from 15 m to 90 m.

At 87.8 m, Pier 7 is the tallest. Fifteen of the 17 piers will be submerged to depths of up to 85 m once the Polihali reservoir reaches full supply level.

The bridge's longest span, 100 m between Piers 7 and 9, crosses the deepest section of the Senqu valley.

An integrated bridge monitoring system will continuously track tilt, temperature, movement and structural stresses in the piers, deck and cables throughout the bridge's operational life.

Construction of the Senqu bridge employed a peak workforce of 1 200, averaging 800 over the three-year construction period, the majority of whom were Basotho nationals.

About 150 000 m³ of rock were excavated, 10 000 t of steel were used and 40 000 m³ of concrete were placed in the structure.

The contract met all socioeconomic targets for Basotho employment across all categories, women and youth participation and the involvement of Lesotho and South African enterprises.

Lesotho national enterprises accounted for 29.6% of total expenditure on goods and services. Firms within the project area accounted for 7.9%; and South African black-owned firms accounted for 16.6%.

Zutari, formerly Aurecon Lesotho, with Lesotho’s White Life Consultants and South Africa’s Leporogo Specialist Engineers were responsible for the design and construction supervision of the Senqu bridge.

The Senqu bridge was constructed by the WRES Joint Venture, which includes Italy-based Webuild, South African firms Raubex Construction and Enza Construction, and Lesotho’s Sigma Construction.