VKE Namibia Consulting Engineers, part of the SMEC Group, was contracted by the Namibian Roads Authority to carry out the design work and to supervise the construction phase of the Main Road 118 upgrade. The SMEC Group is a global consultancy delivering engineering excellence, design innovation and advisory to clients worldwide.
Background to the project
The lack of a road transportation link between the !Kharas Region town of Oranjemund in the far south of Namibia and the rest of the country has been a controversial issue since the 1990s. Residents of Oranjemund have had to drive across the Orange (Gariep) River via the border post on the B1 at Noordoewer (past Port Nolloth and Steinkopf in South Africa) in order to access routes onwards to the major centres of Namibia. This increased the travel times to and from Oranjemund to anywhere else in the country by a significant amount.
Following pre-feasibility and feasibility studies undertaken prior to 2000, the Namibian Government decided that a bitumen road link to the national road network between Oranjemund and Lüderitz would suit neither the operation at Rosh Pinah nor at Skorpion some 20 km to the of Rosh Pinah. The government also decided that a road via Lüderitz would not improve the road conditions for traffic using the national gravel road along the Orange River between Noordoewer and Rosh Pinah which serves the Rosh Pinah/Skorpion mines and the commercial grape production unit at Aussenkehr, as well as various tourism lodges and canoeing recreational facilities along the Orange River.
A subsequent fact finding study to investigate a direct link between Rosh Pinah and Oranjemund, so that people could avoid travelling through the diamond mining deposits along the Orange River, once again favoured the upgrading of the existing Namdeb private road along the north bank of the river, rather than the construction of a whole new route altogether.
The overall rationale for this conclusion concerned the tourism potential of the extremely beautiful scenery along the Orange River; the potential practical difficulties in crossing the very high Obib sand dunes and other parts of the pristine Namib environment; and – importantly – the fact that diamond mining in the area will one day be phased out leaving the country with the responsibility of maintaining the existing gravel road in addition to any new direct bitumen road.
A decision was ultimately made to upgrade the ‘river route’ to a bitumen surface which would be known as Main Road 118.
Upgrade design and construction
In January 2014 the Roads Authority contracted Raubex Namibia Construction to undertake the road works and VKE Namibia Consulting Engineers to carry out the design work and supervise the construction phase. The Roads Authority had been compelled to accelerate the planning and construction of the road, which led to the initiation of a ‘design-under-construction’ approach. Under this strategy VKE Namibia found it was quite a challenge to provide timely design information to the contractor, who was placed under pressure to comply with a programme that could not be planned for accurately in the absence of a completed design.
Challenges relating to road construction in sandy environment
During sandstorms, public traffic became stuck in thick sand deposits on the temporary route diversion, with visibility limited to only tens of metres at times. The strong winds occurring in the area also added thick layers of sand over half-completed work, which at times delayed progress, since corrective measures were needed to address the damage caused by the sand.
A temporary water storage dam ended up being partially filled with wind-blown sand and had to be reconstructed. Buried PVC pipelines were exposed by wind and damaged, causing disruptions in the supply of pumped construction water to the work site. During construction it required nearly daily cleaning of each pavement layer and bitumen application prior to the contractor continuing before the wind speed picked up again in the afternoon. The contractor not unnaturally, reported endless frustration with sand removal over sections of the road.
Additional challenges included high risk rock which had to be removed using extensive drilling and blasting and on occasion by applying high-pressure water jetting to soften up the inter-layers to reduce internal friction, followed by secondary blasting. The road height along the Orange River needed to be raised above the highest water level recorded in 1974 when both the Orange and Fish Rivers came down in full flood.
The southern part of the Namib Desert has become much more accessible with the upgrading of the 99 km main road between Rosh Pinah and Oranjemund. The project significantly reduces time and travel costs for the residents of Oranjemund, increases potential tourism growth and has been designed to withstand sandstorms, flooding and other challenges. The road, now completed, is of a very high geometric standard with an excellent riding quality, and complements the beautiful natural scenery of southern Namibia.