On the banks of the River Nile, in Cairo, the most populous city in Africa, considered an open-air museum because of the mixture of ancient and modern, the works for the Extension to Metro Line 3 are underway, led by the EFJV (Egyptian French Joint Venture) Vinci, Bouygues, Orascom and Arabco.
Among the neighbourhoods, streets, buildings and traffic we find the BERD Hi-Tech LG36-S Launching Gantry, supplied on time to the EFJV, for the construction of the pre-cast deck of the 5,000-metre-long viaduct.
The use of prefabricated solutions in this type of works allows for significant industrialisation both in the manufacture of the precast segments and in their placement, using equipment such as the launching gantry. In addition to the reduced impact on the surrounding area, the construction of the deck is quick and economical.
The concept and design of the launching gantry was another challenge that our engineers overcame, in synergy with the EFJV. In addition to the pressure on planning and deadlines, this viaduct is being built in the largest city in the Arab world and Africa. Its path goes through areas of high construction density, extremely limited space, very tight curvature radius and inclinations up to 4%, which led to great dimensional and kinematic restrictions on the equipment design.
During construction, the prefabricated launching gantry will have to pass over areas of already built viaduct and also over an area where the construction of the pillars has not yet been carried out. This equipment, designed to advance using supports on the deck and on the pillars, will have to “overfly”, in the section with no permanent pillars, over temporary pillars installed on the site for this purpose.
The LG36-S is a completely autonomous equipment, allowing construction with no ground support.
A Telescopic Leg on Rear Support System was incorporated in the equipment. This system compensates the altimetric amplitude resulting from the 4% inclination and allows the precast segments to be launched with the equipment horizontal. An Automatic Spreader Beam – Connecting Beams System was also designed and assembled. This system removes the need for manual intervention and gives the equipment high productivity and enhanced safety.
The safety of all the equipment was one of the areas which was given extra care and investment. This launching gantry includes an advanced Centralised Safety and Monitoring System that allows the operator to wirelessly check the status, positioning and stability of all the equipment at all times. Considerable development work was done on the optimisation of platforms, accesses and working conditions in order to improve safety and comfort. Accessing and moving about inside this gantry is the same as doing it in the comfort of a building, something far from common in equipment of this type.
Other features of our gantry that we would highlight are its lightness, manoeuvrability and flexibility, combined with robustness. In spite of the adverse desert conditions of Cairo City, and some periods of stoppage of the Work, no corrective intervention to the equipment has yet been required.
In terms of performance, the equipment has met, and even exceeded, the initial project forecasts. The excellent work carried out by EFJV on site has also contributed to this result.
Once again, our Engineers have used all their experience, know-how and creativity to innovate and find solutions that meet the customer’s needs and the challenges of the project, which would not have been possible without the good relationship that has developed between the parties since the project development phase.
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Photo Credits: Stéphane Ciccolini