Navigable bridge
A record-breaking bridge.
Works: Navigable Bridge
Location: Houdeng-Aimeries, Belgium
Project features: the presence of canals in a territory as vast as Belgium sometimes makes it necessary to build structures which offer navigable routes. For this reason, in the Thiria Sart valley, a 500 m bridge was built, with thirteen bridge spans each 36 m long. Working in the context of a station equipped with a boat lift, ALPI supplied equipment and assistance, placing its own experience at the service of this launching bridge project. Using ALPI equipment, fourteen pairs of piers were prepared with variable heights up to 20 m and a diameter of 3 m, built using the ALPI circular metallic formwork and covered with a rubber matrice, to create the fair faced finish demanded by the client. The impossibility of using a continuous scaffolding led to the need to design a "launching bridge". The single segments were built using the MECCANO system. The demand for high water-tightness led to the use of a minimum number of passing tie rods. The formwork was also lined with a rubber matrice. The internal formwork was raised by crane, the external formwork was set up and struck, always using a crane, but sliding in a transversal direction to the bridge. In practice, once removed the formworks after casting, the "module" was pushed using a special hydraulic system over its 12 m length. With forty one castings of 12 m each, the last push was with all probability a world record, given the enormous weight being moved. The project required vast amounts of calculations, due to the enormous load of the bridge - a waterway carries eight times more weight than a normal road - and the choice of building using reinforced concrete was the best solution, both from static and economic points of view, in addition to the fact that, contrary to steel, concrete requires no maintenance over time.The ALPI staff worked alongside the company during the moving and work phases, as well as during the positioning of the formwork.