Lesotho Highlands Development Authority Launches Tender for Senqu River Bridge
The tender for the largest of three bridges that will span the Polihali reservoir was released on March 4th.
The construction of this bridge is part of the Lesotho Highlands Water Project (LHWP) Phase 2. This bridge will be the first extradosed bridge in Lesotho, with its design combining pre-stressed box girders and cable-stayed elements.
Work on the design of the bridge started in 2018 and was led by Zutari. Zutari was formerly known as Aurecon Lesotho. The company also designed the Khubelu and Mabunyaneng bridges and is responsible for supervising all three bridges.
This bridge will be 825m long and 100m high. Interested construction firms have up and until the 18th of June 2021 to submit their tenders for consideration. Any interested parties who would like more information can visit the LHDA website, where there is specific information on the tenders’ conditions and requirements.
The construction of the Polihali dam will form the Polihali reservoir in the valleys. It will also create the tributary catchments of the Senqu and Khubelu rivers with a total surface area of 5,000 ha.
The Senqu bridge deck will be built incrementally from both abutments because of the valley’s depth and the inaccessible nature of the area the bridge is being built. There will also be a continuous deck formed from the in-situ segment midspan of the center span connecting both parts of the bridge.
An advantage of this design is that it will increase the construction workers’ safety and minimize the disturbance to the surrounding area. The LHDA reports that the pier shape is perfect to be constructed with sliding formwork.
LHDA Chief Executive Tente Tente states, “Experience and expertise are crucial in delivering a sophisticated, technically challenging project of this kind, which will be one of the few for the LHWP and Lesotho. Based on our experience with other major works tenders, we are confident that our call for tenders will attract the right mix of expertise and experience.”
In addition to these three major bridges, there will be the construction of new approach road sections to the bridges to tie into the existing A1 road. This A1 road is the main road that lies between the Mokhotlong district in the northeast of the country and the capital city of Lesotho.
The LHWP Phase 2 also entails constructing the Polihali dam, which is a 38-kilometer long transfer tunnel, and its associated infrastructure and hydropower component. Phase 1 was completed in 2003, and the LHWP currently delivers water to the Gauteng province of South Africa.
Phase 2 will now allow the increase of the current supply rate of 780 million cubic meters to over 1.27 billion cubic meters annually. This phase will also lead to increased electrical energy generation in Lesotho, thanks to hydroelectric power generation.
Top Photo: Bridge across part of Katse Dam in the Lesotho Highlands (Adele De Witte | Dreamstime)
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