2003
KENT COASTLINE - KENT - United Kingdom
English Heritage
O&L Construction
Cameron, Taylor - Bedford
LISTENING MIRRORS HISTORIC SITE
LISTENING MIRRORS HISTORIC SITE
After Construction
Green TerraMesh installed after construction
Challenge
The historic Listening Mirrors at Romney Marsh, early acoustic detection structures and forerunners to modern radar systems, were facing significant structural risk due to ongoing coastal erosion. Built in the 1920s, the site comprises three reinforced concrete structures: two circular dishes measuring 20 ft and 30 ft in diameter, and a 200 ft long parabolic wall.
Over time, extensive gravel extraction in the surrounding area dramatically altered the landscape, forming a lake and leaving the mirrors isolated on a narrow peninsula. The surrounding ground level was reduced by approximately two metres, increasing exposure to wave action. This continuous hydraulic impact accelerated erosion, progressively undermining the foundations and threatening the long-term stability of these historically significant structures.
As part of an English Heritage conservation programme, overseen by consulting engineers Cameron Taylor Bedford, a sustainable and durable ground stabilisation solution was required to protect the site while maintaining accessibility and preserving its heritage value.
Solution
A phased coastal stabilisation and access improvement scheme was implemented, using Maccaferri’s Green Terramesh® system to provide a robust, long-term erosion control solution.
The initial phase involved reshaping the existing peninsula into a more stable island formation, reducing exposure to further erosion. A swing footbridge was constructed to maintain safe and controlled access from the mainland. In addition, the existing causeway was widened and reinforced to support both construction activities and future visitor access.
Green Terramesh® reinforced soil structures were installed to stabilise the island perimeter and protect the foundations of the Listening Mirrors. Working with main contractor O & L Construction, specialist divers were deployed to assist with the installation of submerged units, highlighting the importance of a system that performs effectively in challenging marine environments.
The Green Terramesh system offered significant buildability advantages. Its modular design, incorporating integral triangular steel brackets and welded mesh panels, allowed for fast and accurate installation without the need for temporary formwork. This was particularly beneficial given the restricted access and water-based working conditions.
Each unit is manufactured from a single sheet of double-twist hexagonal steel mesh with an additional polymeric coating, ensuring durability and corrosion resistance in aggressive water environments. The design integrates soil reinforcement, facing, and structural support into one system, improving efficiency and reliability.
With a face angle of 70 degrees and a standard unit height of 600 mm, the structures were constructed in layers up to seven courses high. The final design left only the top layer visible above the waterline, delivering an effective erosion protection solution while maintaining the visual integrity of the historic site.
This project demonstrates the effectiveness of reinforced soil solutions for coastal defence, heritage conservation, and erosion control in complex environments.
Used Products
