Client: Commune de Bellevue

Location: Bellevue, Switzerland

Date: 2024

Type: Landscape

Length: 145m

Budget: Undisclosed

AZPML

Alejandro Zaera-Polo, Maider Llaguno-Munitxa, Ivaylo Nachev

Walter Bieler AG

Enrico Fromm

Amstein + Walthert

Dirk Bandemer

Topography, Comfort, Durability
Our proposal for this gateway pursues three main objectives:

1. Create a bridge that integrates with the landscape characteristics of its two ends, strongly differentiating them, both by their landscape conditions and by making them specific to the activities that users will develop near the landing sides.

2. Create a comfortable and warm structure for users, and easy to maintain.

3. With good wood protection, using wood as the main material creates a sustainable and environmentally friendly solution.

Static System
The footbridge is constructed as a trough bridge, spanning three fields of different span lengths. On the east side, the system is connected to the spiral ramp, which permanently rests on the ground. By using a continuous beam, the main beams can be used more efficiently and deformations can be reduced. However, as the deformations of the central span are still relatively significant, they must be compensated by means of cambered beams.

An important advantage of a viaduct bridge is that the superstructure can be placed not under the bridge, but next to it. In the case of the Orchidées footbridge, this eliminates the need for a counter-slope to cross the clearance profile of the road with a uniform slope.

Two Distinctive Sides
Our proposal is to build a footbridge with two very different ends:

On the Vergeron side (+377m), the landing arrives 3.15m from the ground and descends with a helical ramp built like a topographical berm that produces supports allowing people to sit and look at the lakeside or to use the space inside the helical ramp. as a small auditorium for events and shows, located between the existing trees.

On the Champ-du-Château side (+384m), the footbridge is placed at ground level and opens to embrace and welcome people coming from the residential complex, thus providing seating for meetings and protecting from the noise of the N1 highway.

Côte Champs du Château : The Embracing Footbridge

On the Champ-du-Château side, the bridge is located near the southern limit of the plot in order to maintain a distance of 10 m from the gas pipeline. This would avoid any interference during the installation and maintenance of the bridge.

Access to the bridge will be defined by a small meeting/waiting area. The outer edge is raised to protect visitors from the N01 motorway (direction Lausanne) at the nearby point. The inner edge will open towards the stairs connecting the Route de Lausanne.

The metal fence of the gazebo will be replaced by an oval wooden fence to increase the quality of the public space.

Côte Vengeron : The Forest Theatre

On the Vengeron side, the bridge will descend along a spiral ramp inclined at 6% and will land inside the lawn delimited by the existing trees. The exterior radius of the ramp will be 12 m and will be located to avoid disturbance to larger, more established trees.

The ramp will land at the top of a relief made up of gabions filled with local molasse sandstone. The gabions will be used to stabilize the ramp and provide an outdoor auditorium/seating area allowing people to enjoy the view of Lake Geneva. The gabions will be covered with an upper deck surface to provide a comfortable seating area. On the interior side, it will create an amphitheater that will also serve as a more private retreat.

Materials and Maintenance
The walkway is designed to be made from timber to provide a low-carbon, low-maintenance solution. In addition, the choice of materials complements the recreational space at the lakeside, accessible by the footbridge.

The footbridge will be made with glued laminated wood beams. Two large beams of 1760x360mm will support the longitudinal loads (GL32h & GL40h in the curve) while the slab will be supported by GL24h 160x360mm at 2m.

The supporting structure will be clad on all sides by a 60×40 mm ventilated wooden rain screen to protect it from bad weather and allow easier maintenance.

To reduce cross-sectional dimensions and material usage, we will specify higher strength wood types in certain areas. Thus, the freely suspended and torsionally loaded section of the spiral ramp must be made of ash laminated wood (GL40h). Other areas of the walkway where high strength is not required will be constructed from spruce wood, as it is much cheaper.

The entire wooden structure is protected from humidity, road salt and pollution thanks to a cladding surface: the main beams are surrounded by vertical battens where the 60×40 mm horizontal slats will be fixed, thus creating vertical ventilation chambers. The longitudinal arrangement of the slats aims to emphasize the directionality of the bridge. In addition, a drainage system was installed along the side beams to channel rainwater towards the two column beams and towards the Vengeron side.