Taking the lid off Singapore Sports Hub
In July 2014 WAN published an article on the opening of the Singapore Sports Hub which includes the largest free-spanning dome stadium in the world. The DP Architects-designed National Stadium within the wider hub project features a roof spanning a mammoth 312m.
This dramatic feat of engineering was overseen by the local firm MHE-Demag who worked with Arup Associates and Dragages Singapore to bring the project into fruition, staying in line with very strict safety standards.
The National Stadium is a highly adaptable space, capable of hosting multiple sporting matches from athletics to cricket and football, with the ability to transform the arena from one mode to another within 48 hours. Arching over this flexible playing space is a retractable roof system which can be altered according to the weather.
The moving mechanism for the retractable roof system was supplied by MHE-Demag. It carries the 2,200 tonne load of the roof (approximately the same weight as 1,830 cars) and takes approximately 20 minutes to fully open or close. This activation is issued by a single ‘start’ button in the Event Control Room.
Patrick Chin, team leader on the project, explains: “The testing and commissioning of the retractable roof was extremely demanding; as everyone was required to deploy on the roof to clear obstacles and monitor the movement of wheel bogies to ensure a smooth and accident-free roof movement. It was impressively successful and got all staff on site excited and satisfied with the positive outcome after spending numerous sleepless nights at the roof.”
Each of the two panels that make up the 2,200 tonne roof is made of a lightweight material and is highly weather resistant to create the optimum experience for the 55,000 spectators within. The panels are each seated on 20 load transferred wheel bogies, located evenly on 5 steel trusses.
The driving mechanism consists of 16 line pull winches, 32 holding storm-brakes, energy chains and an advanced electrical control systems. Each of the 16 winches is equipped with two independent inverter drive motors. The team’s greatest engineering challenge came in aligning the trusses and wheel bogies of the huge retractable roof within a tight and acceptable tolerance.
Safety features include primary and back-up sensors and an anti-skewing system that ensure a maximum skew position difference of only 35mm between any of the five trusses that support the movable roof. The brakes keep the movable roof panels locked in their desired location; designed with the fail safe principle, the claws of the storm-brake system used close automatically when power is interrupted.