An international joint venture led by Italian contractor Webuild has completed the 825m-long Senqu Bridge spanning the future reservoir of the Polihali Dam in the northeastern highlands of the Kingdom of Lesotho in southern Africa.
The bridge, which reaches 90m in height, maintains the road connection from communities in the Drakenberg Mountains to Lesotho’s capital Maseru, necessary because the reservoir will submerge the A1 Trunk Road when filled.
The Polihali Dam is part of the ongoing Lesotho Highlands Water Project being undertaken by Lesotho and South Africa, which completely surrounds the kingdom, to harness the water resources in Lesotho’s highlands. It’s the biggest water transfer scheme in Africa.
The client was the Lesotho Highlands Development Authority. Local contractors Enza Construction, Raubex Construction and Sigma Construction joined Webuild in the JV.
‘Extradosed’ bridge
With a 100m-long central span, Senqu is the region’s first “extradosed” bridge, meaning it contains both cable-stayed and girder bridge elements. It was designed to resist high mountain winds.
It has 16 spans, with piers ranging from 15m to 90m in height.
The team had to work in very steep and rugged conditions.
Measures included work platforms reaching up 88m, access roads carved into rock faces and temporary structures adjusted daily to meet changing weather conditions.
Pietro Salini, Webuild’s chief executive, said: “The Senqu Bridge is a concrete response to an epochal challenge.
“With this bridge, we have overcome a natural barrier to secure Lesotho’s water and energy future. Major infrastructure projects are enablers of development worldwide and an act of care for communities: they overcome geographical barriers to establish vital connections, supporting economic progress and social well-being.”
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