Truck on R80 nosedives onto N4 highway near Pretoria — what went wrong?

A truck plunged off the R80 Mabopane highway north of Pretoria on Monday, nosediving into the embankment of the N4 highway below, in what has been described as “an exceptionally rare occurrence”. 

Tshwane emergency services said the driver had sustained only minor injuries and refused transportation to a medical facility.

The crash at the N4 Eastbound and R80 South bridge caused heavy traffic delays for motorists travelling on the R80 Mabopane highway, they said.

Forensic engineering, accident reconstruction and investigations consultant Konrad Lötter, asked by TimesLIVE to assess a photograph of the accident, said the incident was “most uncommon”. 

“The number of locations where one road crosses over another are extremely limited, so the number of such incidents will also be extremely limited. When you then consider the number of incidents where vehicles leave the road, that would make this specific incident interesting, in the sense that it is such an irregular occurrence,” he said.

On what might have caused the accident, Lötter spoke on condition that we clarified that his views are based on general perceptions and not an actual inspection.

“Due to the fact that I have very little useful detail at this stage, all possible causes and factors still need to be assessed. That means that all possibilities at this specific stage would need to be considered and analysed, if necessary.

“It is evident that the vehicle would need to deviate from its line to end up in this position. While the event in this case was irregular in terms of the one vehicle falling onto another road below it, vehicles leaving a road in general are reasonably common and there are various possible causes, where one would look at the more common causes first and one would then also need to investigate all other factors that may lead to such an event ... driver fatigue, general loss of concentration, driver travelling at a speed that may have been too high ...

“Actions of another driver or drivers which may have swerved or suddenly changed lanes in front of the truck (which may include the previous points, such as fatigue, concentration or speed). This is possible, as it occurred at a location where traffic merges.”

Possible mechanical failures are also a factor, with a common occurrence being burst tyres.

Lötter said damage to the road due to poor maintenance, and if there is a lack of warning signs or proper guidance to detours and deviations at roadworks are also assessed.

Factors not likely in this case are poor design and features of the road (uphill or downhill).

A lack of barriers is also not applicable in this case. “There are W-guardrails at the location and the deviation of the vehicle would need to be reasonably extreme at this location for it to move through the barriers.”

All these factors should be investigated by examining possible marks on the scene, and information from any witnesses, if available, and one should also do research relating to the scene itself. 

“An actual investigation of the vehicle and the scene may even give clues to alternative possibilities which may increase the scope of such an investigation.”

According to Lötter, in most incidents they investigate, most of the truck collisions on national roads occur at times when drivers are likely to be fatigued. 

He said this was mostly late in the evening or very early in the morning.

“It also often occurs when one driver makes an error and the other driver fails to react, which is normally also related to fatigue.” 

Lötter said a second common type of incident is where there may be a mechanical breakdown and a truck driver stops the broken down vehicle in a dangerous location and also fails to warn other road users of a stationary vehicle in an unsafe location at night. 

“From our investigations, it is also evident that the drivers are not properly informed about the necessary steps that should be taken to safeguard a broken down vehicle and the steps that need to be taken to warn other road users.”

TimesLIVE