Southern Main Road, Chatham

The PURE Unit of the Ministry of Works and Transport conducted slope stabilization works along the Southern Main Road Chatham between LP #1983-1986. It was found that the landslip developed in 2015 from a ruptured 16 inch water main which eroded one lane of the road structure. The landslip spans approximately 140 meters (m) long and approximately 5 meters high.

The solution entailed the construction of a geo-grid reinforced earth embankment which utilizes compacted fill material reinforced with geo-grid at specified intervals to stabilize the structure. The stabilized embankment will also contain a vegetated surface on the face of the slope to prevent further erosion from occurring while providing a more green aesthetic design.

The purpose of the project is to:

  • Eliminate traffic congestion,
  • Prevent further erosion from occurring,
  • Reinstate the existing pavement structure to dual lanes and
  • Create a smooth riding surface for commuters.


The PURE Unit found it necessary to incorporate these designs into the project as it is a more cost effective and time consuming solution compared to the traditional reinforced concrete structure. 
The completed stabilized slope was then covered with top soil and a reinforced turf mat. The turf mat is a vegetated surface which consists of fibre and plastic mesh and is a natural method that provides a green aesthetic surface and prevents further erosion from occurring.

The geo-grid reinforced earth embankment is a compacted sand fill embankment that contains layers of geogrid used as reinforcement to stabilize the structure. Geogrids allows the structure to become stable by interlocking the particles in contact with it within its mesh. The type of geogrid required for stabilizing the structure depends on the type of reinforced earth structure, grade of the slope, height of the slope and the loading imposed on the slope. For the purpose of this project, a layer of triaxial 140 geo-grids was embedded between layers of sand for a maximum height of five (5) meters.


Project Commencement Date: 24th October, 2016
Completion Date: 20th February, 2018