With industry attention being almost universally focused on devising solutions that shorten construction programmes and use the smallest possible workforce, the falsework and formwork for the bridge over the lagoon at Ningo in Ghana at first glimpse appears to be out of step with current thinking.

Its operation called for extensive use of manpower and the timescale was measured in seasons rather than weeks or months! But this was an instance where the finance for sophisticated formwork was not available, virtually the entire village could be employed on the task, and time was simply not of the essence.

The lagoon at Ningo is prone to seasonal and sudden flooding, effectively splitting the village into two communities. The new concrete road bridge was constructed during a couple of dry seasons, utilising precast beam sections manufactured on site using local labour.

RMD Kwikform's involvement was to design and supply the formwork for the precast beams, the lifting gantries and the special low-technology beam launching trusses, and to supply components and supervise the construction of the mobilisation trolleys and runways used to transport the beams from the precasting position to the launching trusses.

The project called for the construction of 42 beams, each 36 metres long, 1.7 metres deep and 300mm wide and weighing 65 tonne. These were positioned six wide, in seven spans across the lagoon entrance. The 80 metre launching truss was manufactured in the UK and assembled on site by local labour. This was rolled out over the lagoon entrance onto the first span supports, using hand operated winches.

The beams were cast on site in steel-faced forms specially manufactured by RMD KWIKFORM in the UK. These beams were transported over 18 metres of runway beams, while being supported at both ends on yoke trolleys, to a position in line with the launching truss. Each end of the beam was lifted hydraulically using launching trolleys mounted on the launching truss, and then winched out along the truss until it was in position over the bridge piers.

The beams were then lowered into position using hydraulic rams mounted on the launching trolleys. The support frames on each pier and abutment of the bridge allowed the launching truss holding the precast beam to be moved laterally to a point alongside the adjacent beam positioned earlier, while the launching truss and its support had ample platform space to allow full access to the beam throughout the construction process.

According to RMD Kwikform's site engineer, Steve Turner, the Ningo bridge is typical of projects that abound in remote locations throughout the Third World. He says: “They demand a high degree of ingenuity and the ability to marshal the local labour force. Equipment and materials are invariably thin on the ground, so planning and pre-delivery fabrication is often essential.”

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