The trial project for Neotel involves the roll-out of 12,5 km of duct and cable, and is valued at about R4,5-million.
Muvoni Weltex sales and market- ing director Malcolm Kirby says that there is potential for additional routes to be rolled out.
The mechanised trenching equip- ment was acquired from French company Marais Group, which developed the trademarked and patented CleanFast suction road-trenching machine.
Muvoni Weltex has ordered three additional CleanFast vehicles and is expecting delivery by 2008. The vehicles, equipped with cutting wheels and integrated vacuum systems for cleaning the trench, are priced at about €700 000 each.
The CleanFast machine is truck mounted and is fitted with a cutting wheel that cuts a microtrench with smaller dimensions than can be achieved with conventional trench digging equipment.
The trench dimensions are widths ranging from about 80 mm to 120 mm, and a maximum depth of about 480 mm.
Kirby notes that, with this machine, the structure of the road is maintained and there is no associated damage to the road. Owing to the reduced trench size, the volume of waste material excavated is also reduced.
The suction function of the machine allows for the evacuated material to be removed from the trench by way of two vacuum pipes. The waste material is then stored on the vehicle and about half of it is reused as backfill for the trench.
A second vehicle then lays the cables, or ducts, and fills the trench with a locally developed backfill mix that solidifies quickly and remains flexible and pickable. Asphalt is then laid on top of this to renew the road’s surface.
Kirby notes that, at peak performance, 700 m can be completed in a day, which is significantly faster than conventional, labour-intensive trench digging methods.
An additional benefit is that the vehicles integrate with the traffic on the road, and there is less disruption to the movement of cars.
Prior to the trenching, a vehicle dubbed the Explorer surveys the route and an onboard ground-penetrating radar identifies any buried utilities that are under the road surface, for example, existing pipe systems for water or electricity.
The explorer operator marks the route along which the trench will run, and the depth to which the trench should be cut. This is intended to avoid damaging any existing underground cables or piping. At optimal performance, about 2 km of road can be checked each day before cutting takes place.
An operator walks the route with the trenching vehicle and, with the use of a remote control device, adjusts the direction and depth of the cutting wheel in accordance with the markings on the road. A camera mounted on the front of the vehicle allows the driver to view the demarcated route and follow it precisely.
Owing to a modified gearbox, the vehicles are able to travel very slowly, at about 1 m a minute.
Kirby says that the company has also ordered similar machines, and is expecting them in the next two to three months. A local company is partnering with Muvoni Weltex to develop a vacuum vehicle suitable for the required trench cleaning function. This additional vehicle is completely remote-operated and does not require a driver. It is suited for smaller-scale city jobs and is more manoeuvrable.