Footbridges over the Seine River

Dietmar Feichtinger’s new soft mobility bridge over the Seine linking Mantes-la-Jolie and Limay is an invitation to embark on a veritable urban promenade. In the crook of one of the loops of the river that define the southern limit of the French Vexin, he has created a subtle staging for urban space and the natural landscape to meet. In the wooded shade of the hills that dominate the valley, between the high silhouette of the collegiate church of Notre-Dame and the streets of the ancient city on the north bank, the new pathway crosses two arms of the river, pausing only to rest on the wooded slope of the Ile aux Dames.

For this first crossing, which is now completed and runs alongside the road bridge, Dietmar Feichtinger chose to place the new structure at a distance from the existing bridge deck. When you stand on the bank, the footbridge looks as if it is flying over the river: fine steel curves undulate between the two banks in a three-dimensional motion, continually changing shape, rising and almost imperceptibly separating the pedestrian path from that of the two-wheelers, which is positioned closer to the car bridge. Whether crossing on foot or by bike, one almost immediately forgets the noise of the traffic. A difference in level is established between the decking of the two routes to form a bench seat. In the middle of the crossing, where the footbridge rises well above the roadway, the levels meet and the passage widens to offer passers-by a view over the river where they can linger to admire the beautiful landscape.

A ribbon of steel and wood linking the two river banks

Dietmar Feichtinger enjoys diverting, softening and twisting his structures, as he did in Paris with the Simone de Beauvoir footbridge; he never passes up an opportunity to twist the wise rules of traditional construction. Beneath the buttresses of the collegiate church, he casts a double ribbon of steel and wood which brushes against, rises above, gets closer to and then moves away again from the road. The all-steel structure is supported by the bridge abutments on either side of the river. A central caisson with a variable trapezoidal profile forms the main framework, like a spinal column to which a series of T-shaped brackets are fixed 3 meters apart from one another. The watertight box girder is composed of welded metal sheets whose torsional strength enables the asymmetrical forces generated by the profile of the bridge to be transferred to the supports. In the middle of the river, the two concrete pillars of the Pont Neuf serve to carry the intermediate supports. Thus, the new structure does not encroach on the riverbed. In each case, an inclined cross-sectional leg, fixed to the stem of the pier, takes up the vertical force, while a connecting rod ensures the stability of the entire structure. These connecting rods, embedded in the caisson, are articulated at the head of the pillars. The variable profile of the brackets makes it possible to support decks of varying widths and to absorb the differences in elevation of the decking between the two-wheeler path on the bridge side and the pedestrian path on the river side.