The Strijdom Square monument, in the city centre, was unveiled in 1972, and consisted of a shell over a bust of former Prime Minister Johannes Gerhardus Strijdom, sculpted by artist Coert Steynberg; also a statue of a group of charging horses on a marble column, created by Danie de Jager, which was not damaged during the incident.
The dome collapsed on May 31 this year – ironically on the 40th anniversary of South Africa becoming a republic.
It appeared as if the footings supporting the shell gave way, leading to the bust tumbling down, and the shell crashing through the parking garage below.
Foul play was ruled out as a cause of the incident.
Van der Merwe explains that Dynacom Constructural Engineering Consultants is conducting a forensic investigation into the reason for the collapse, but that three possibilities are currently the most probable.
These are faulty design, faulty construction, or lack of inspection and subsequent maintenance.
Maintenance on the structure would have been the responsibility of the provincial department of transport and public works.
Van der Merwe says it appears that the monument's front pillars, or 'legs' started to lift from the ground a year after it was constructed.
The then Transvaal Provincial Administration appointed consultants to remedy the situation.
The consultants decided, after an analysis of the monument, that prestressed cables should be used to strap down the shell.
One of the possibilities for the collapse at this stage is that these cables failed.
The forensic investigation on the monument will be concluded by the end of August.
Van der Merwe states the department's priority at this point is to ensure that the square becomes operational as soon as possible, particularly in light of the fact that several informal traders made use of the square's central location in Pretoria to do business.
He indicates that the State Theatre parking garage underneath the monument will be rebuilt as soon as possible.
The estimated cost of this is between R1-million and R2-million.
Van der Merwe does not anticipate the monument to be restored as the Strijdom Square again, although the future of the square is up to the provincial cabinet and the Tshwane Metropolitan Council jointly.
"My department's attitude at this point is to wait for the forensic investigation, and see what we can learn from what happened," reports Van der Merwe.
Other monuments will now be subject to inspections following the collapse of the 29-year-old dome. Gauteng Master Builders Association executive director Colin de Kock says maintenance of buildings tends to be a problem in general.
The less busy a building tends to be, and the fewer tenants reside there, the less maintenance is done on it.
In terms of State buildings, monuments not visited as such – as was the case with Strijdom Square – are often not inspected on a regular basis, while a building such as the Voortrekker monument, attracting many tourists, will have a better record of inspection and maintenance.
Monuments constructed by one generation are also often neglected by a new generation, especially in the case of Strijdom Square, where the life of one of the architects of apartheid is commemorated.
De Kock reports that State buildings are often not maintained to the desired extent, but that this is largely due to budgetary constraints.
Part of the problem is the high cost of building inspection and maintenance, as the resources to do so are expensive, and the State does not have adequate funds to ensure a high frequency of inspections, says De Kock.
One solution would be for the State to reduce its portfolio of property, as the Department of Public Works has indicated it is doing.