Ensuring hydraulic transparency in the Seine floodplain with Nidaplast RA blocks
As part of the Grand Paris Express project, a lightweight and hydraulically transparent embankment was built using Nidaplast RA honeycomb blocks for the redevelopment of the platforms of the future Ardoines station, located within the major floodplain of the Seine.
This solution ensures free water flow during flood events while providing high mechanical resistance for railway structures.
2600 m3
lightweight fill volume
Seine floodplain
regulated flood zone
RER C
platform widening
Project Context and Challenges
Building infrastructure in a flood-prone zone: a technical challenge
The future Ardoines station, connecting RER C with Line 15 South of the Grand Paris Express, required construction of a new underpass and the widening of platforms (from 4 m to 10 m).
Located in the active floodplain, the project had to comply with strict hydraulic transparency requirements defined by the PPRi regulations.
Objectives Defined by the Project Owner
The specifications required a solution that would:
- preserve the natural flood expansion area,
- avoid obstructing the free flow of the Seine,
- prevent the blocking effect of a traditional soil embankment,
- guarantee long-term mechanical stability under railway structures.
Solution Implemented with Nidaplast
Nidaplast RA honeycomb blocks: lightweight, hydraulically transparent fill
A total of 2,600 m³ of Nidaplast RA blocks were installed instead of a traditional soil embankment.
Their honeycomb structure (95% void) allows water to circulate freely inside the embankment, ensuring complete hydraulic transparency.
Advantages in this context:
- Hydraulic transparency: water fluctuates through the cells without creating pressure
- Structural lightening: far lighter than soil or GNT fill
- High compressive strength
- Excellent drainage and temporary water storage capacity during floods
- Fully compliant with regulatory requirements for flood zones
Technical Characteristics of the Installed Product
Block dimensions:
2400 x 1200 mm.
Cell height:
520 mm.
Permeability:
≥ 95 %.
Material:
Polypropylene with 60% recycled content
Nidaplast RA
Nidaplast RA lightweight embankments are extremely light and resistant. These honeycomb structures are the recommended solution for constructing landscape embankments, road embankments, or building embankments.
View product sheetInstallation Process
1. Preliminary construction works
Relocation of the underpass beneath railway tracks (May 2018)
2. Installation of Nidaplast RA blocks
Progressive placement of RA blocks to build a transparent embankment under the future platforms
3. Finishing works
Completion of access arrangements (June 2018 – January 2019)
Full widening of the RER C platforms (October 2018 – August 2019)
Commissioning of the new underpass and removal of the temporary footbridge (early 2019)
Watch the installation video
Results and Benefits Observed
- Fully compliant hydraulic-transparent structure
- Efficient flood management thanks to the honeycomb void system
- Stable platforms meeting railway performance requirements
- Durable and homogeneous finish appreciated by local stakeholders
