DISMANTLING OF LAUNCHING GANTRY
Dismantling a launching gantry is a delicate operation, that VEXA carries out with great attention regarding the safety factor. In autumn 2022, our Innovative Solutions Department dismantled the launching gantry which had been installed at the new bridge on Ticino, in Vigevano. In this article we will explore together the different actions which made it possible to dismantle this launching gantry. Among the special equipment pieces that are involved in the making of infrastructure, a launching gantry is one of the most useful when it comes to building big-size bridges and viaducts.
To better understand how the dismantling operations of the launching gantry took place, it is useful to start from the features of the equipment and from the peculiarities of the bridge. Framing the project of this launching gantry helps to make a more precise idea regarding the importance of its dismantling. The launching gantry whose removal VEXA took care of had been made for the construction of a bridge on river Ticino. Compared to others, this bridge has two specific features:
- 2 main spans of 150 m each and
- 2 ways for every direction (then reaching a considerable width).
Moreover, the bridge had been built with a suspension technique, which means without temporary bearings in the riverbed. The installation included these steps:
- installing the upper “rhombuses” hooked to the head-pier,
- preassembling on the ground the formwork for the casting of the bottom,
- lowering the DIWIDAG bars from the rhombuses,
- hooking, with specific jacks, the whole bottom frame,
- the progressive uplifting up to the established height.
Once understood the installation steps of the launching gantry and of the making gf the bridge, it is simpler to follow also the dismantling operations. Dismantling a launching gantry entails the removal of two pieces of special equipment. Each of them weighs about 250 ton and it made it possible to build 4.5 m of viaduct with precast elements that were built simultaneously. For what concerns the metal structures, they are made of these components:
- upper “rhombuses” to support the load,
- beams to support the bottom (under the scaffolding)
and DIWIDAG bars to support the bottom formwork.
In 5 weeks and involving 6 people, VEXA took care of all dismantling operations of the launching gantry, including the removal of also other special equipment on construction site. Working with a crane, our workforce dismantled the double couple of wagons, lowering the whole bottom formwork and then proceeding with the dismembering on the ground. In particular, VEXA was in charge of the operations of:
- lowering the lower frame (of 80 ton) on a paddock in an active riverbed by using 4 12,000-millimeter DIWIDAG bars,
- dismantling the lower frame,
- dismantling the upper frame from the viaduct,
- dismantling the inner formworks,
- dismantling the panels and the beams in h20 wood and the iron plates,
- dismantling every other related element,
- further dismantling operations on the ground to get to pieces suitable for road transport,
- packaging and loading on means of transport,
- transporting, subdivided into almost 15 loads, to clients’ stores.
As also mentioned in the introduction, dismantling a launching gantry requires a solid background in the field of special equipment. To accomplish all operations, VEXA used a crane, safety lifting platforms and a telescopic wagon to move the pieces. During the work, we were especially careful with:
- safe handling of considerable loads,
- safe working at height,
relieving the tie-rods in the right order.
It was thanks to its long experience, gained over the years, that VEXA managed to brilliantly face the difficulties in this work of dismantling the launching gantry. A kind of experience that can ben seen in the skills that our company has acquired and in the competence of the workforce involved. Because of these qualities, even though we had not been directly involved in the construction of this specific structure, it was possible for us to dismantle it with no complications. Remaining in the field of special equipment, our Innovative Solutions Department has also gained experience in the construction of steel railway overpasses, templates to install precast elements falseworks, balances for productive plants.