Steep slope upgrades made simple with Kaytech Geo-Cell

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Situated in the picturesque Valley of a Thousand Hills in KwaZulu-Natal is the community of KwaNyuswa. As its Zulu name suggests, the region is dominated by some extremely steep roads, which have deteriorated over the years.  It was here that Kaytech’s innovative Multi-Cell saved the day for engineers tasked with the challenge of rehabilitating these roads. Kaytech would like to congratulate the KwaZulu-Natal Department of Transport on winning the Community Based Projects section for this KwaNyuswa project at the South African Institution of Civil Engineering (SAICE) awards, held recently in Durban.

The main access road to KwaNyuswa, off the R103, is ‘black top’ but the rest are gravel roads. Due to a combination of a lack of maintenance, steep gradients with poor drainage and heavy rainfall, the gravel surface had been completely removed, exposing the in-situ, loose and slippery residual decomposed granite. Access was very difficult for private vehicles, buses, taxis and pedestrians, which make up the bulk of the traffic within the local community.
Kwanyuswa Roads - 1

The KwaZulu-Natal Department of Transport (DOT) determined that asphalting of these severely damaged sections of road would be impossible, due to the steep gradients and the prohibitive costs involved. It was therefore decided to carry out the design for an upgraded surface for the extremely steep section of District Road 1506 (D1506) as a pilot project for other similar roads and Kaytech’s Multi-Cell 100mm was specified.

In certain sections along the resurfaced 1.6km road, guardrails had to be installed due to the steep gradients and sharp corners. The 100mm thick Multi-Cell was specified for this road as it is traversed mainly by small vehicles and pedestrians, although thicker cells are available for heavier traffic loading.

Cost-effective Multi-Cell is used as an in-situ shuttering to cast interlocking concrete paving and is particularly suitable for use on steep gradients. It is manufactured by Kaytech from coated woven slit film tape strips stitched together to form a honeycomb structure of three-dimensional square cells. For this particular project, the cells were filled with ready-mix concrete, although for a vegetated embankment, the cells may be filled with topsoil.

With the help of local labour who were trained on-site by a foreman, Phambili Construction installed 9,000m2 of Multi-Cell 100mm. This was not the first Multi-Cell project undertaken by the contractor and he already had at his disposal steel frames, similar to the patented Tension Frames which Kaytech make available to contractors to ensure that they are laid to the correct line and level.
Kwanyuswa Roads - local community labour used to install Multi-Cell

On occasions, the ready-mix concrete was manufactured a little too wet, resulting in slight ridges being formed at the lower end of each cell on the steeper sections.  This was not a problem however, since it significantly improved traction and skid resistance. On a few of the panels, livestock left behind their footprints, which merely added interest to the texture.

All in all, a highly successful project with many benefits that included significant savings to the Department of Transport and creating much needed work opportunities for some of the unemployed local community. Multi-cell roads are all-weather roads, easily maintained and serviceable for many years, which will help the local inhabitants to take pride in their area.

As the breath-taking Valley of a Thousand Hills is profuse with other communities like KwaNyuswa, it is highly probable that Multi-Cell will come to the rescue of similar road projects.

SAICE WINNER OF Most Outstanding Civil Engineering Project Achievements in a Community-based project:

D1506 Upgrade (Road)

“This project, under the Expanded Public Works Programme (EPWP), saw the steepest part of District Road D1506 (located in the Valley of a Thousand Hills, KZN) – a rough, dangerous track full of deep erosion gullies – upgraded using labour-intensive methods.

The KwaZulu-Natal Department of Transport used the geo-cell system to construct a very cost-effective, all-weather road on exceptionally steep grades. The maximisation of labour-intensive activities yielded substantial benefit for local labour. The KZN Department of Transport also needed guardrails to be installed on the steeper sections of the 1.6 kilometre-long, and five metre wide road.”

Keyword: roads