SMIE is a French company which in 1985 developed and marketed the first anti-collision system for tower cranes in a bid to ensure safety without decreasing work-site output.`Digital technologies for computation and data transmission have since been used in the systems. On the Paris urban renewal project, SMIE has had to upgrade the software on its AC243 systems to enable up to 14 cranes to work on a single network. Even then, such is the density of cranes that will eventually be onsite, two or more networks will be required. “Fortunately, on this project, although there are various manufacturers, all the cranes being used are saddle-jib or flat-top,” said SMIE engineer Lionel Loisy. “The plans do not allow for any luffing jib cranes,” he said. “There is also a height restriction for the building – under 40 metres – which means there will be no climbing cranes. “The most complicated area is where two cranes overlap networks. These will have to be fitted with two systems – the additional cost being shared by all contractors,” Loisy said. The AC243 constantly measures the position, speed of the jib and trolley for each crane. The unit calculates status at a rate of three times per second and takes into consideration the braking capacity of each movement in determining the collision risk. Without operator intervention, the system implements a braking procedure as, and only if, a collision risk is identified. SMIE said it has sold thousands of safety systems for use on every type of crane around the world.
