Sani Pass upgrade

The road less travelled

Built in the 1950s, the Sani Pass is the only road that crosses the summit of the Drakensberg Mountain range, which transects the uKhahlamba Drakensberg Park World Heritage Site.

The problem, however, is that this iconic 33km gravel pass has become treacherous for travellers (even those using 4x4 vehicles) and especially in extreme weather conditions.
It often had to be closed for expensive maintenance, which hampers trade and mobility between Underberg on the western side of the KwaZulu-Natal province in South Africa and Mokhotlong in Lesotho. Closures not only cut off the surrounding impoverished communities from essential services but also result in a loss of tourism revenue.

In 2005, Lesotho and South Africa signed an agreement to upgrade the Sani Pass. 

Restoring the beaten path

The KwaZulu-Natal Department of Transport wanted a cost-effective, aesthetically pleasing upgrade of the Pass that would improve accessibility in most weather conditions.

What’s more, construction had to take place without restricting the movement of people or traffic. This included upgrades to improve road drainage, prevent gravel loss, and limit erosion caused by high-intensity storms and flooding.

The innovative design presented by Royal HaskoningDHV and its partners — Semenya Furumele Consulting, Ndizani Civil Works, and Leomat Construction — not only met these requirements but went beyond the brief. The new Sani Pass was designed to look like it “fits in” with its surroundings to preserve the unique heritage of the area.

Challenging environment

Construction took place in challenging conditions, with some sections of the Pass reaching altitudes of 2.876m above sea level, with grades as steep as 1:4 on the upper sections.

The environmental constraints imposed by the route's location within a World Heritage Site also had to be considered and addressed. Because of the rugged terrain and narrow width of the Pass, the road had to be designed and built in half-widths to ensure that the work activities stayed within the footprint of the already-built road.

Another challenge was constructing a switchback section – known locally as a “Nip and Tuck” – with continuously reinforced concrete pavement. For this switchback section, gabion and terramesh retaining walls up to 7m high were built.

Special care was taken to make sure the road's alignment was optimised at places like Yellowwood Corner, where a scenic boulder formation and old yellowwood trees had to be carefully avoided.

Beyond the brief

At Royal HaskoningDHV, we’re always looking for ways to “go beyond the brief” to ensure our projects enhance society.

For the Sani Pass upgrade, this included:

• Cleaning up the ruins of the old Good Hope Trading Station and turning it into a tourist attraction.
• Incorporating small access "hedgehog holes" at various points along the barrier wall to help small creatures cross the road.
• Carefully removing specific plants, trees, and sods from the site before construction began for replanting and curb-side rejuvenation.

The project will enable more tourists to experience the beauty and wonder of the uKhahlamba Drakensberg Park World Heritage Site. It has set the benchmark for the next phase of construction, which will complete the route to the Sani Top.

The Sani Pass upgrade received the SANRAL SAICE 2022 National Award for Most Outstanding Civil Engineering Project.