Mammoet has assisted the Dubai Roads and Transport Authority (RTA) in the widening works for the Mirdif City Center bridge, which included lifting and installing 24 long and heavy precast concrete girders in place.
The global engineered heavy lifting and transport specialist said the bridge improvements will ease traffic flow for road users, meeting the current and future needs of commuters and alleviating traffic congestion. The project, located at the interchange along Dubai’s Sheikh Mohammed Bin Zayed highway and Al Rebat Street, consisted of the construction of additional lanes between two existing two-lane bridges, converting them into one high-capacity flyover comprising six lanes.
The project entailed the installation of the 24 precast girders, connecting the two bridges together, on supports from the top of the bridges. “Installing them from the ground wasn’t possible due to space constraints and the busy highway is too crucial to the city’s transport infrastructure to allow time for a stick-built methodology,” said Mammoet.
“The project’s main contractor – Afcons Infrastructure Ltd. – contacted Mammoet to develop a solution for this installation challenge. After detailed design engineering and risk assessment, Mammoet developed a novel approach for installing the girders using a tailored mobile gantry system that could straddle the two existing bridges. This system would comprise custom-made beams with two 100t strand jacks and skidding system, sitting on top of SPMT trailers. The strand jacks would lift the girders vertically, the skidding system would allow side movements, and SPMTs would transport the girders from pick up location to the installation spot.”
Mammoet added that the mobile gantry was positioned above each precast girder, measuring 30m long and weighing up to 68t. With rigging connected to the girder’s lifting points, it was raised using the strand jacks until it was at sufficient height for transport. The mobile gantry travelled over the existing bridges with the girder until it reached its setting point. The girder was then skidded above its final position and lowered down before being secured onto supports. The mobile gantry then returned to the pick-up location for the next girder.
In close coordination with the client and the RTA, the operation took place overnight to avoid disruption to local businesses and residents. Each girder installation activity was performed within a 30-minute road closure 2-3 times each night. All precast girders were successfully and safely placed into position two days ahead of schedule.
Michel Bunnik, commercial director, Mammoet Middle East & Africa, said: “We are pleased to have been entrusted with this challenging installation by Afcons Infrastructure Ltd. By partnering with Afcons, we have ensured swift and efficient installation of the girders for one of the key interchanges in Dubai, that will soon enable a smooth flow of traffic. This non-conventional, innovative method of installation proves once again that Mammoet can offer an intelligent and efficient solution to any challenge, no matter how complex.”