Engineering the Senqu River Bridge and the Polihali Transfer Tunnel
Infrastructure engineering consultancy, Zutari, is contributing to some of the most technically complex components of the Lesotho Highlands Water Project (LHWP) Phase II: the 825 m bridge across the Senqu River, and the 34 km Polihali Transfer Tunnel beneath Lesotho’s mountainous highlands.
the Polihali Transfer Tunnel. These projects are being undertaken in the Kingdom of Lesotho by the Lesotho Highlands Development Authority (LHDA), the implementing and management authority of the LHWP, on behalf of the governments of Lesotho and South Africa. The Senqu River Bridge The Major Bridges Project, which includes the Senqu River Bridge, is being delivered by Zutari Lesotho, together with the Lesotho sub-consultant, White Life Consultants, and a black-owned South African sub-consultant, Leporogo Specialist Engineers. This reflects Zutari’s collaborative engineering partner- ship and a long-standing commitment to infrastructure development in the Kingdom of Lesotho. Spanning 825 m across the Senqu River valley, the bridge is the longest and highest in Lesotho, rising more than 90 m above the valley floor. Designed as an extradosed cable-stayed structure, the bridge has been engineered to withstand the extreme condi- tions of Lesotho’s mountainous terrain while
ensuring uninterrupted connectivity along the national A1 route. The new crossing forms part of a series of major bridges required to maintain road access once the future Polihali reservoir is filled. Sections of the existing A1 route will eventually be submerged as the dam reaches full capacity, making the Senqu Bridge a vital long-term replacement that safeguards re- gional mobility and economic activity. The bridge was designed to address the complex environmental and geographic chal- lenges associated with infrastructure devel- opment in Lesotho’s highlands. Construction required foundations anchored on rock, as well as advanced construction techniques to navigate the steep valley terrain. The deck was incrementally launched from both sides of the valley, with precast segments pushed outward until the two sections met at mid-span. This method allowed contrac- tors to construct the bridge safely across the deep gorge while minimising environmental disturbance. Work on the bridge continued throughout challenging mountain conditions, includ-
M ultinational, buildings and infrastructure engineering con- sultancy Zutari has played a leading role in the design and construction supervision of the Senqu River Bridge, one of the most ambitious high- altitude infrastructure projects undertaken as part of the Lesotho Highlands Water Project (LHWP), Phase II. In addition, through its role in the Metsi a Senqu-Khubelu Consultants (MSKC) Joint Venture, Zutari is responsible for design and construction supervision of Tlhabeli Ralebitso, CEO of Zutari Africa.
The 825 m Senqu River Bridge spans the Senqu Valley at a height of over 90 m.
42 ¦ MechChem Africa • May-June 2026
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