Natura 2000 - Techno Piers for a 55-meter footbridge, over the Estrigon Stream situated within the Brocas-Les-Forges Commune (Landes Department), France.

Description:

This project connects the village of Brocas to a hiking trail within the Landes Forest.  The 55-meter long (1.5-meter wide) steel and wood footbridge, was installed on site by a 350 ton crane.

The location is difficult to access because of a slope to one side, and the Landes Forest on the other side of the stream.

Year: July 2022

Dealer/Installer: Techno Pieux Landes

Client: Brocas Town Hall- work completed by Techno Pieux Landes in collaboration with ID Verde Messages and DL Aquitaine.

Location address: Impasse de la passerelle, BROCAS 40420 (France).

Project objectives:

The infrastructure must be able to withstand the tension, compression and lateral forces of the 55-meter long steel and wood footbridge.

Special challenges:

The site, which is classified as a "Natura 2000" natural zone, must not be disturbed or damaged.  The trees bordering the stream are to be preserved, so the helical piers were installed close to the edge, to avoid disrupting the area.

The 24 piers were augured in, at a depth of 6 to 10 meters, into a sandy area.

Access became difficult due to the natural zoning, slopes and constricted conditions.  The EM2 known as Techno Metal Posts' drilling machine, is equipped with special traction which allows it to access the most difficult places.

The quality control office approves the loads to be absorbed, along with the type of piers to be installed.  To successfully carry out the project, some of them were screwed in at a 45-degree angle to withstand the pressure.

Each helical pier can support up to 15 tons.

Soil type: sandy

Installation time: 10 days

Number of people on site: 1 installer and 1 welder

Materials used:

For the foundations- galvanized piers and concrete blocks

For the footbridge- galvanized steel and wood

Equipment used: EM2

Load-bearing capacity:

The footbridge weighs 20 tons (weight over its entire length).  Torque power per pier-between 1300 and 2100 psi.

Engineer's recommendations:

The project is approved by the internal design office which recommends-

• 4 TMP piers-model P4-12 and 8 TMP piers-model P5-12 (compression / tension)
• 12 TMP piers model P3-16 (lateral forces)

Driving depth: 6 to 10 meters

Details of the structure resting on the piers:

The structure is a galvanized steel footbridge boarded with wood at the bottom and on the railings.

Brocas-les-Forges : une spectaculaire opération (sudouest.fr)

https://www.youtube.com/watch?v=EC7ox95Bidk&t=2s