This method of constructing a bridge structure is used mainly for bridges spanning deep valleys or for inaccessible terrain. An optimal span suitable for free cantilevering is 60 m – 150 m, but bridges with a considerably larger span are commonly realised.
The free cantilever technology consists in developing the bridge structure by individual parts, the so-called segments. Segments are concreted into formwork fixed to a special movable steel structure – form traveller. An optimal design and weight of the form traveller is fundamental for the design and economic advantageousness of the given structure.
VSL offers the so-called modular system of form travellers, which can be applied to bridge structures with different cross-sections and lengths of segments. The lightweight system of VSL form travellers has minimal demands on lifting equipment at installation at the beginning of construction and enables at the same time an easy access to all work fronts during the construction. The typical working cycle takes five days with 12-hour shifts and with the construction crew alternating in two form travellers. In case of need, the form traveller may be equipped with a system for steam curing, which reduces the working cycle to four days.