A new 'mega-barge' with a specially-designed overhead travel crane is being put through its paces in the Indian Ocean.
French consortium members Bouygues Travaux Publics, Vinci Construction Grands Projets, Dodin Campenon Bernard and Demathieu Bard Construction are constructing a 5.4km-long bridge for a new offshore highway for Reunion Island in the Indian Ocean. The new Route du Littoral will connect Saint Denis - the administrative capital of La Réunion - with La Possession. It replaces the existing coastal road, which is exposed to falling rocks and flooding from swells and tropical storms.
The consortium has elected to fabricate some 95% of the structure on land and the Zourite barge will be used to erect the prefabricated elements; it is designed to cope with the offshore conditions at the site.
The overhead travel crane was designed by Enerpac and comprises two pairs of lifting beams, with an overall width of 30m, and a lifting capacity of 4,800 tonnes for lifting, moving and lowering the concrete blocks for the offshore highway. The crane is classified as A5 for the structure classification and M5 for the mechanism classification and designed to operate in tropical marine conditions (IP66). Design and testing conforms to Bureau Veritas code for offshore units.
Lifting and lowering is accomplished with a reeved winch system, based on eight grooved drum winches. Longitudinal travelling of the gantry uses a trolley arrangement comprising two trolleys per lifting beam. Each trolley is propelled with hydraulic drive motors and planetary gearboxes. The wheels run on two parallel rails bolted onto the barge’s runway beams. Side shifting of the gantry hoists in a continuous movement is achieved using long stroke cylinders.
Testing of the overhead travel crane has been conducted on one of the pairs of beams and included lifting 1,100te blocks, synchronised lifting of the block with a hook from each beam, and checking the crane’s positioning, lifting / lowering accuracy to 1mm.
The new road is due for completion in 2018.
