Siphofaneni Bridge, Swaziland

Aurecon designs innovative features for the Siphofaneni Bridge to reduce the transportation cost for the sugar industry.

“It is humbling to be part of a project that is not only technically excellent but will help the people of Swaziland for years to come,” said Aurecon Professional Civil Engineer, Louis Steyn.

The Siphofaneni Bridge is a massive 375 metre-long incrementally launched bridge over the Usutu River, which forms part of the 23 km St Phillips Road upgrade project. The bridge will not only contribute to reduce transportation cost for sugar farmers in the industry, but will reshape and transform the local community to assist them to develop in future.

Aurecon was tasked with preliminary and detailed design, assistance with tender evaluation and construction supervision for the project.

The construction method that was used, namely an incrementally launched bridge, is a construction method that is used extensively all over the world when building bridges that cross rivers valleys and roads where formwork cannot be constructed within the river. What makes the Siphofaneni Bridge different to other incrementally launched bridges is the use of reinforced concrete instead of post tensioned concentric cables during the construction phase.  

The conventional method of building bridges follows the principle that the concrete may not be allowed to crack and concentric cables are used to avoid cracking in the concrete. The consequence is that one must have a specialist subcontractor coming to site weekly for several months to install and stress the concentric cables. While these specialist contractors are easy to source near major centres, these skills are expensive and rare when working on remote sites. Aurecon used the approach of allowing the deck concrete to crack in the construction stages by using only reinforced concrete. The specialist subcontractor was therefore only required at the end of the deck construction phase. The final stage post-tensioning closed all cracks. 

The bridge replaces an existing low-water single lane structure which necessitated stop/go traffic movement, usually with delays and sometimes long blockages. The former structure was retained for pedestrian and livestock traffic.

This bridge gives community members on both sides of the river access to schools, shops, and clinics. There are three bridges in Swaziland across the Usuthu river downstream of this one, two of which are also single lane low-water structures. The other high-level bridge is approximately 30km downstream. In the past, during flooding of the river, the community would have to take longer routes to reach their destination. The main benefit to community members is quick, safe and easy access to services and amenities. 

Engineering solutions that will boost Swaziland’s sugar industry

The new bridge, which was designed and constructed according to world best practices, will also have a large impact on the community members in the region as well as the country’s economy. School children and local community members, for example, use the bridge to access local schools and clinics. Farmers who have to transport their sugar cane to the local sugar mill will be able to safely cross the river during flooding of the river.

The project formed part of a larger agreement, between Swaziland and the European Union, to develop the transportation infrastructure for the sugar industry, which included the development of approximately 11,105 ha of smallholder sugar chain farms. The purpose of the infrastructure development was to reduce the transportation cost for the sugar industry. According to international trade agreements, the European Union needs to reduce the current quotas that guarantee the price and quantities of sugar to be exported each year from Swaziland to the European Union. To help them achieve this goal, they have committed to improving the infrastructure for the sugar industry in Swaziland.

The bridge was officially inaugurated in June 2017. King Mswati III of Swaziland, Pastor Lindiwe Dlamini, Swaziland Minister of Public Works and Transport and Nicola Bellomo, European Union Ambassador to Swaziland, attended the official inauguration.

At the South African Institution of Civil Engineering (SAICE) Awards in 2017 the project won the 'The Most Outstanding Project in Structural Engineering' award.

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