This comes after it was revealed that 48% of the roads have been classified as being in “poor” or “very poor” condition.
The agency said the lack of maintenance had allowed the roads to deteriorate, but to get the percentage down to single digits, it would cost R13.8bn over the next 10 years.
However, the budget for the 2016/17 financial year for resurfacing and reconstruction was only R262 million.
The backlog of resurfacing and rehabilitation was R3.8bn and R2.3bn in 2013.
In total, for the maintenance and rehabilitation of 891 bridges, new installations, maintenance and rehabilitation of stormwater infrastructure, rehabilitation and resurfacing of roads and upgrading gravel roads to tar, R19.5bn is needed, with the current capital expenditure allocated being a mere R1.4bn.
Speaking about the state of the roads, JRA managing director Sean Phillips said the cost of construction of a two-lane urban road was between R4.5m to R6m per kilometre, upgrading from gravel to tar cost R4m per km, reconstruction R2.5m per km and resurfacing R1.2m per km.
He explained that every road had a design life -the number of years that it was designed to remain functional with regular maintenance before it required reconstitution - but with good maintenance, roads could often last longer.
“If regular maintenance is not carried out, then its life reduces rapidly. Many roads in Joburg have not been regularly maintained and have therefore passed their reduced design lives.”
Phillips said 21% of roads - or about 2500km - had failed structurally and required construction, and a further 27% - about 3000km - required resurfacing.
Tar roads, he explained, were made up of a number of layers. The structural strength of the road was provided by the lower layers which were usually built out of compacted gravel or crushed rock.
The tar layer at the top had no structural strength, but provided a smooth driving surface and kept water out of the lower structural layers. If water got into these layers, it loosened the crushed rock and the road became weak and started to break up.
Once a road had lost its structural strength, potholes would keep reappearing no matter how well they were repaired, he said.
Regular resurfacing, crack sealing and maintenance of stormwater channels were essential to prevent water from getting into the structural layers, he added.
However, Phillips said there was cause for cautious optimism.
“Management has put a lot of work into developing improved budget motivations to the city, which has indicated that it does intend to give the agency increased funding to address these backlogs with improved revenue.
“In the meantime, the planning department must prioritise the very limited budget across all backlogs by considering risk to life and property, traffic volumes and economic importance.”
At the end of March, City of Joburg mayor Herman Mashaba announced that he would be giving the JRA R88 million from its 2016/2017 adjustment budget allocation to fight what he called “ the scourge that has put the safety of many motorists at risk”.
He said R60 million would be spent on materials and equipment, while the rest would be used to start addressing the 40% staff capacity shortages in the roads maintenance teams.
Mashaba pointed out that pothole repairs were a short-term solution to ensure the safety of the motorists and said resurfacing remained the long-term response to the challenge.
He said the time taken to repair potholes remained a challenge, but the JRA was working on improving its turnaround time for general repairs.