Cantilever formwork travellers have speeded up construction of two dramatic bridges on Europe’s new high speed road network.
In the future, travelling between Budapest and Southern Dalmatia will take less time thanks to the Vc branch of the Pan-European Corridor.
The 702km long road network, also known as European route E73, connects parts of Hungary, Croatia and Bosnia-Herzegovina to the Adriatic coast near the port of Ploče. It is being created by linking and upgrading existing roads, as well as building new sections of road where the existing infrastructure is unsuitable or non-existent.
These extended 5m pouring segments reduce the number of segments and coupling joints, and therefore save time and money
The longest individual stretch of the route is through Bosnia, where it runs the entire length of the country from the northern border to the Adriatic, via Zenica, Sarajevo and Mostar, a distance of 397km.
Among the structures on the route are two dramatic concrete bridges that carry the A1 over the Studenčica and Trebižat river valleys near the southern Bosnian municipality of Čapljina.
The larger of the two structures is the 555m long Studenčica bridge, which rises to a maximum height of 81m above the valley floor.
The superstructure is supported by five piers, each made up of two columns, with each span measuring 120m. Its smaller neighbour, the Trebižat bridge, is 365m long and 59.5m high, and has three piers.
Both bridges are being built using balanced cantilever construction techniques, with the superstructure extending out from hammerheads at the top of the columns.
Formwork specialist Doka has supplied 10 cantilever formwork travellers for the job, eight for the Studenčica bridge and two for the Trebižat bridge. The equipment is being used by Hering, which is working as a subcontractor to Spanish main contractor OHL.
Doka’s travellers have been built with extended pouring sections that enable the team to pour a length of 5m at a time. This has meant that the superstructure can be built using eight fewer segments than originally planned, shaving around eight weeks off the construction programme compared.
“These extended 5m pouring segments reduce the number of segments and coupling joints, and therefore save time and money,” says Hering project manager Mario Jurisic.
Doka has also supplied equipment for the pier construction. The columns were constructed with the help of the firm’s crane-lifted MF240 climbing formwork and Framax Xlife framed formwork. Its high performance supporting construction frames were used horizontally for the hammerheads.
The company also helped to develop a creative solution to get the concrete into place at a height of 81m above ground, which involved incorporating parts of a gantry crane into the formwork.
Limited working space on the hammerheads - a maximum length of just 8m - led to another innovative solution when it comes to forming the cantilever sections.
Rather than both travellers moving symmetrically in each direction, in line with the cantilever forming principle, one of the cantilever forming travellers starts off from the hammerhead ahead of the other one. This creates enough space for the second traveller to be hitched to it to offset the balancing act.
The travellers have been designed so that they can return to the hammerhead once the width of a span has been completed, and then repositioned and used again for the next pier.
Construction of the two bridges started in May last year, and is due to finish later this month.