Elevated metro corridor, precast segmental viaductElevated metro corridor, precast segmental viaduct

The alignment ran the length of an arterial road that could not be closed, with three signalised junctions inside the corridor and a minimum radius of 195 m through the tightest of them. Traffic management allowed a working window of six hours a night at the junctions and nothing at all during the day. A conventional ground-supported method was never viable, and the contractor had no yard within 40 km of the far end of the corridor.

Two overhead gantries were designed to work towards each other from opposite ends, each carrying its own segment feed from behind so that no delivery ever entered the live carriageway. The gantry main girders were sized for the 195 m radius by splitting the front support into an articulated pair, which let the machine steer through the curve without unloading a pier. Post-tensioning was detailed alongside the erection scheme so the stressing sequence never held up a launch.

The corridor was erected at a sustained three-day cycle per span with a best week of five spans across the two machines. No lane closure was taken outside the agreed night windows and the segment yard operated at eleven segments a day against a planned nine.