Pad ontwerp - Hoekom so?

[Jan Horn]

Another one of those abandoned projects that cost the tax payer millions of Rands. That funny road construction is at the approach to the Theo Martins Poort through the Magaliesberg. It was obviously part of a planned greater road works as the overpass was designed and build with a major road system in mind which would have been able to accommodate up to 4 roads. Looking closely at the screenshot one can still see the remnants of the original road which seem to have stopped at the overpass. The DEM screenshot the area highlight the pass through the Magalies mountain. I noticed a High Accident area warning approach the overpass using google street view.
This is what Wilkipedia has to say on the subject :

The R80 is a Regional Route in South Africa that connects Pretoria with Soshanguve. It is a dual carriageway freeway, with 2 or 3 lanes in each direction at different points.

It passes through the Theo Martins Gateway (Afrikaans:Theo Martins Poort), a mountain pass over the Magaliesberg mountains, and the northbound carriageway has an infamous rising hairpin bend, approaching the pass, as the freeway abruptly switches an from east-west to a south-north direction.

[Jan Horn]

The clue as to the reason for the road design emerge when you look at the road profile.There is a 1 in 20 meter gradient to be negotiated and the hairpin bent would prevent taxi's speeding around a normal bend to negotiate the gradient at speed.
Ironically given the destination the road is called the John Vorster Drive.