Vanstone Precast (Pty) Ltd

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Practical Problems with SANRAL Median Grid Covers for U-Channels:
SANRAL precast concrete Median Grid Covers are generally used on top of U-Channels adjacent to new jersey barriers and similar positions.
The shape of the product is unique in that both the water slots and ends are sloped at 45°.
Practical Effects:
When a wheel drives onto the high sloped end of a Median Grid, the Grid tends to slide foward and tip up. Only friction keeps this from happening. Under breaking or acceleration this action is exacerbated. Median Grids are moved out of position creating up-stands and gaps. Once the vehicle has driven away, the grids are left out of position complete with obstacles and holes.
Median Grids are light-weight and are easily disturbed by vehicle wheels.
The concrete cracks and chips off at the sharp angles. Although the corners are rounded and there is reinforcing, the sharp ends are points of specific weakness where the first breakages occur.
Because of its intricate shape, Median Grids are notoriously difficult to cast. Moulds are complicated and demoulding is difficult. This often results in manufactuting defects.
Conclusion:
The problem is in the design and not the manufacturing. Vanstone no longer mass-manufactures Median Grids for new projects. A few are kept in stock to serve as spares.