The two large sinkholes that formed along the R21 highway towards O.R. Tambo International Airport in Gauteng in 2022 will cost more than R144 million to fix and will only be complete in August this year, according to the South African National Roads Agency (Sanral).
The agency recently unveiled this figure to MyBroadband as part of a report on the progress that has been made to repair the various sinkholes that have opened up around the province in the last few years.
Cost of ongoing repairs
The two sinkholes emerged on the R21 near the Olifantsfontein interchange in Gauteng in February 2022, and have necessitated the closure of several lanes ever since leading to significant congestion problems.
The lanes affected included the R21 northbound and one of the R21 offramps near the interchange, causing disruptions along the main highway that connects areas like Midrand, Centurion, and Pretoria to the airport.
This has resulted in delays during peak traffic hours, and Sanral has advised motorists to instead use alternate routes like the M18 and M57, which run alongside the R21 but are smaller roads not intended for the same level of traffic.
Despite the disruptions, the sinkholes have remained a problem for two years and are only estimated to be fixed later this year, which has to do with how the hazards were formed.
Like the many other sinkholes in the province, the cavities formed after heavy rains that dissolved the dolomite rock under the terrain’s surface, leading to large crevices that eventually caved in.
Roughly 25% of Gauteng’s land is affected by dolomite rock, and it presents an issue that necessitates extensive evaluations before any efforts can be taken to repair a sinkhole so as to avoid further collapses later on.
A specialist geotechnical engineering company, Jones & Wagener, was first appointed to investigate the sinkhole, which concluded that geophysical testing and extensive percussion drilling were needed to assess the area before plans for repairs could be drawn up.
Sanral’s northern region project manager, Oakley van Eyk, subsequently confirmed that a joint venture was formed with two construction companies – Raubex and Esor – and that work to address the sinkholes was started in December 2023.
Now, the state-owned entity, which is funded through the national treasury and toll fees, has announced that it will cost R144,245,942.80 to repair the R21 sinkholes, and that the estimated date of completion will be in August 2024 – two and a half years after the hazards formed.
Not the only ones
Sanral recently confirmed that another sinkhole along the N1 highway in Centurion will cost R280 million to fix.
The N1 sinkhole emerged in January 2022, one month before the R21 pair, as a result of the same dolomite rock conditions, and has led to existing lanes of the N1 southbound being closed with new temporary ones being drawn while the site is evaluated and repaired.
Rehabilitation on the site began in July 2023 after a contract was awarded to Jodan Construction (Pty) Ltd in June of that year, and the repairs are now expected to be finished by April 2024.
Other surface cave-ins have occurred all over Centurion, with at least six major ones being reported in the last year (not including the N1), some of which have completely destroyed roads and even houses.
One of these holes, which occurred on John Vorster Drive, led to the road agency creating a “crossover lane” cutting through the lane divider and into the opposite road, while another hole that formed nearby on Irene Main Road led to a private funding campaign from the surrounding suburb for R448,000 that saw the road completely restored in just two months.