Boxing Clever Yas Island Bridge
Constructing the 10 structures along the route of the Shaham to Saadiyat Island Freeway is not only creating an essential link from mainland Abu Dhabi to the site of the planned new Formula One Grad Prix in the Emirates, but has also brought about a huge boost to RMD Kwikform Middle East’s business in the region.
Tony Madden is the Regional Manager for RMD Kwikform in Abu Dhabi and comments: “This is the first of the civil infrastructure projects to be started on Yas Island to give people access to the Formula One track, though there is a lot more to come. We have enjoyed a very good working relationship with the contractor, Taisei Abu Dhabi, and been able to keep up with the schedule for what is a very demanding contract. Basically our involvement with the new freeway has acted as a springboard, the base from which we have grown the business here in Abu Dhabi. Our operation in Abu Dhabi is becoming more impressive by the month.”
RMD Kwikform is partnering with the Taisei Corporation (Abu Dhabi) on the vast project that involves the erection of seven box cell bridges as well as three extensive culverts. With rapid completion being imperative for the essential transportation scheme, and with major waterways having to be temporarily diverted to facilitate the erection process, RMD Kwikform has had to provide intelligently designed formwork systems together with a number of specially fabricated steel shutters to keep the contract on programme.
Five of the seven bridges, including the 250 metre long, parallel BC7 and BC8, are being erected using Rapidshor, along with GTX beams. This falsework structure and the accompanying RMD Kwikform Rapidshor stair-towers for safe personnel access are all being supported off the infill where the river/canal bed has been temporarily raised.
Tony Madden explains: “The external webs to the bridge box cells are being built up first - forming a slab and side walls - with the Rapidshor and GTX beams being used to cast the deck element. Then the side walls and central walls are assembled using Superslim Soldiers plus GTX beams. Finally for the top slab to the boxes we have supplied Kwikstage, again with GTX beams.”
The RMD Kwikform formwork has to continue to carry the dead loads of the reinforced concrete, plus all the construction equipment and manpower, until the mix has gained sufficient strength, for the specialist sub-contractor, VSL to carry out the post-tensioned pre-stressing of all the cables that run within ducts in the box walls. The decks to both BC7 and BC8 are being built with a 1:40 super-elevation to respect the curve of the road-line, meaning that the box cells vary in depth up to a maximum of 4500 mm. Each of the two bridges will carry six lanes of traffic in opposite directions, while a further structure between them supports the two tracks of Abu Dhabi’s new rapid transit system.
Prior to the deck construction beginning, RMD Kwikform supplied Alform and Superslim Soldiers to cast the vertical walls of the bridge piers. These rise some nine metres between ground level and the pier- heads where the bridge bearing plates are inserted. They also display bull-nosed vertical edges with a 900 mm radius for which RMD Kwikform’s designers and special fabrication unit produced bespoke steel shutters which are being re-used along the contract.
Such are the demands of the timetable, however, that the Taisei Corporation has purchased a staggering 60,000 cubic metres of Rapidshor for the contract. The formwork specialist also provided some initial training of the contractor’s operatives, as well as continuing site supervision.
The last two bridges for the freeway are additionally making use of RMD Kwikform’s Paraslim system to enable the in-situ concrete element to the composite decks to be cast up to one metre in cantilever beyond the line of the precast concrete beams that span between each abutment and the pier-head. The hanging soffit support system can be built up in modules of six metres and then craned into position without relying on staging rising from ground level.
Health and safety issues have been strongly emphasized throughout the pre-planning and contract phases of the project with RMD Kwikform ensuring all outside perimeter edges to the Rapidshor platforms are fitted with double handrails; while netting has been suspended beneath the primary and secondary beam lattice.
Although the first deliveries to Taisei on the site only began in December of 2007, the majority of the bridges are scheduled to be completed by March next year. The longer, BC7 and BC8 bridges are expected to be structurally complete by May