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Between Hinojal and Cáceres, Spain's A-66 motorway crosses the Rio Almonte, a tributary of the River Tagus. Two arched bridges are being built here side by side, with each arch to carry a two-lane carriageway deck on its apex. The Spanish contractor Necso has turned to Doka's innovative forming-carriage technology to help it construct both arches. Doka system formworks are also in use for the piers of both the bridge itself, and of its approach viaducts.
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In this region, the Rio Almonte has been dammed to create a reservoir. This called for a very large bridge structure that also incorporates approach viaducts. The overall length, from abutment to abutment, is 432 m; both arched bridges have a 184 m span. The project got underway with the initial foundation work in mid-2002; construction of the first of the superstructure arches began in March of last year.
Advanced Doka forming-carriage technology makes the tight schedule viable
The Technical Department of Deutsche Doka in Maisach liaised closely with Doka España Encofrados S.A., Madrid, to elaborate a functional forming-carriage
concept for the two 47 m high arches on behalf of clients Necso. According to Heinz Hobmeier of Deutsche Doka's Technical Department: "The forming carriages have an extremely lightweight design, and - depending on the desired workflow - they even make it possible to pour the entire crosssection."
Pouring is being carried out in a weekly cycle, working from both banks. In total, each half of the arch involves 17 casting sections, each of them 5.85 m long. The big advantages for the Necso team are the low weight of the Doka cantilevering forming carriage and its cost-saving design, based primarily upon rentable system components and upon tried-and-tested SKE automatic climbing technology. Another plus-point is the adaptability of the forming carriage.
Good marks for customer care and swift response times
Raúl García Eickelberg of Doka España Encofrados S.A has been servicing this project right from the outset: "Above all, the Project Superintendent's team are very satisfied indeed with the swift response times and with our package of services. For example, problems with the back-stay anchoring and extreme weather conditions caused delays in the construction sequence, putting a big question mark beside the scheduled completion deadline. We were able to arrange a second forming-carriage set within a short period of time, thereby ensuring that the deadlines could be kept. No mean achievement, and one that earned us quite
a few extra plus-points from those in charge on this site."
Climbing using a sophisticated formwork system
The piers are spaced at uniform intervals, with a clear gap of 22 m between piers. The tallest pier measures 40 m and has a cross-section of 2.50 x 4.50 m. A total of 36 piers are to be erected for the two arched bridges, with a separate set of formwork being commissioned for each different type of pier. Each
such set comprises MF 240 climbing units and Doka large-area formwork Top 50 modules. The wide working platforms of the MF 240 offer ample workspace, while its sturdy design permits large gangforms. This saves time and cuts costs on the site.
"With the MF 240, safety climbs with you all the way"
This is a platform system that is well thought-out right down to the last detail. Together with the high
load-bearing capacity of the formwork, this ensures a very high standard of safety. In short: A versatile system formwork for custom assignments that have to be tackled quickly and safely.
The 432 m long bridge superstructure is being constructed with steel trusses. These serve as supports
for the Top 50 elements and are attached to the piers by brackets. Load-bearing towers d2 are being used for each of the closing cycles. Around 5000 m² of this Doka
falsework system are in use on the site. The actual carriageway deck consists of a single-web T-beam cross-section. The carriageway slab is being cast in-situ, also using Top 50 large-area formwork elements.
The Rio Almonte Bridge will be completed during 2005. The Spanish government's latest estimates expect a traffic load of between 9500 and 10,000 vehicles per day. High time, then, for the "Motorway of Silver" (Autovia de la Plata) to be completed - although unlike its predecessor in Roman times, it is intended
not so much for hauling away the region's mineral wealth as for facilitating the transportation of goods between Northern and Southern Spain.
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| Alongside the innovative Doka forming carriage for the arches, various different sets of climbing formwork MF 240 were used for forming the piers. |
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Special Projects Director Oscar Pailos, Doka España Technical Manager
Michael Jentsch, Spain General Superintendent
Jose Luis Aldecoa, NECSO Export Dept.,
Heinz Hobmeier, Maisach Managing Director Gerhard Werner, Doka España Export Dept.
Helmut Schaurhofer, Maisach |
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