In the new Châtel-St-Denis (Fribourg) train station, what makes the bridges special is big – but almost invisible.
The old station was a dead-end, the new one is connecting Palézieux to Bulle. The project consisted of two bridges, each 100 m long. One is rectilinear, made of reinforced concrete and composed of six spans supporting two railway tracks and the platforms. This bridge' piers cross an underground car park with 120 spaces and two side staircases in reinforced concrete, allowing the access between the parking and the platforms. Following the first, the second bridge is curved, in prestressed concrete, and has four spans. The behavior of the two bridges is distinct: for example, under the effect of thermal expansion, one can lengthen while the other tends to a banana-like shape. The challenge is to maintain the alignment of the rails undisturbed.
BG engineers were up to the task and designed a single horizontal foundation, the largest that the supplier has ever delivered. This enormous steel element is placed at a pier in the junction of the two bridges. It can withstand up to 900 tons of horizontal load, a feat invisible to the users of the Fribourg Public Transports, but essential to their safety.
Conclusion of our engineers : "It is a solution with interesting statics, an architectural project signed by EMA with a beautiful aesthetic and many railroad requirements, which we were able to fulfill by coupling the straight and the curved bridges."
BG was in charge of all technical studies and the construction management of the new train station, part of a big urban restructuring.