What is micro-trenching?

When a telco installs cables of any sort between one point and another, there are a limited number of ways of doing so.  Cables, copper or fibre can be installed underground or overhead between poles.  Overhead (or aerial) cable is quick and cost effective to deploy, but it is unsightly and at the mercy of both the elements and wayward vehicles.  Underground cable is usually installed in ducts or pipes which connect manholes where the cable can be accessed, split and joined as needed.  The conventional method of burying these pipes involves digging trenches with pick and shovel, positioning the pipes and then backfilling over the pipes and restoring the surface to its original condition.  These trenches are usually routed along road verges and pavements, but can also be positioned across or at the edge of the roadway.

Over the years, alternative methods of deploying underground cable have evolved; one of these involves using storm water drains and sewers (as Link Africa do), while another involves using a machine the size of small car to cut a slot in the road surface.

Depending on the type of road and the depth of existing services such as electrical power and water, this ‘micro-trench’ can be 20mm to 60mm wide and 300mm to 500mm deep, usually near the edge of the roadway.  The machine has a blade in front (much like a giant angle grinder) which cuts into the road surface. Depending on the terrain and the experience of the team, a 4-man team and a machine can conceivably complete between 200m and 400m of trench per day.

The benefits of micro-trenching are:

*Less disruption of roads and sidewalks.
*Faster deployment.
*More cost effective trenching.

Micro-trenching machines come in various shapes and sizes, depending on the make of the machine and the purpose of the trench. The machine makes about the same noise as a lawnmower and the dust resulting from the cutting blade is managed with the use of water.  All in all, far less disruptive than a small army of workers with picks and shovels.

This method of trenching is used extensively in Europe and the USA, but has yet to become widely accepted by municipalities here in SA.  Frogfoot are in the process of setting up a Proof of Concept projects with both Tshwane and Cape Town municipalities.

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