Load-shedding traffic nightmare — why batteries for robots don’t work
Rampant theft and vandalism are the main reasons why some of South Africa’s biggest metros don’t offer backup power for their traffic lights.
Among the many negative impacts of load-shedding is its ability to frustrate motorists by disrupting the flow of traffic.
This is particularly problematic in major cities like Johannesburg, Pretoria, and Cape Town, where a single offline robot can significantly increase commuters’ travel times.
However, traffic intersections are not heavy power consumers — with the largest LED-powered installations consuming around 450W of power.
That could theoretically be supported by a battery backup costing less than R10,000 at retail, including VAT.
GeeWiz sells 1.5kWh lithium-ion batteries for R6,995 that you can pair with a Mecer inverter for under R3,000.
While that might be expensive when multiplied across all the intersections in the country’s biggest cities, it could curb the impact of load-shedding on productivity if placed strategically at the worst-impacted locations.
Managing director at Innovative Transport Solutions, Jan Coetzee, told MyBroadband that there were already uninterruptible power supplies (UPSes) at many traffic lights in Johannesburg and Pretoria.
“It is normally installed at intersections with high traffic volumes — typically where two major arterials intersect,” Coetzee said.
Unfortunately, most of these were missing, as criminals know the high street value of this equipment.
“The challenge is theft and vandalism,” Coetzee said. “Typically, the steel boxes to protect the batteries cost more than the batteries.”
Having no power running through cables to traffic lights during load-shedding also presents an opportunity for copper cable thieves.
The City of Joburg (CoJ) told MyBroadband that the Johannesburg Roads Agency (JRA) had installed approximately 1,000 UPSes at traffic lights.
However, about 91% of these units were no longer in operation.
“[The] majority of them were unfortunately vandalised, and there are approximately only 90 currently working,” the CoJ told MyBroadband.
The city said the JRA has published a tender for UPS backup systems that use super-capacitors, which would make them unsuitable for supplying backup to homes, thereby reducing their attractiveness to thieves and vandals.
The city said it would also take care to upgrade the boxes housing the equipment to include new security features.
Editorial credit: Wesley Lazarus / Shutterstock.com
Tshwane’s divisional head for transportation planning, Lourens Swanepoel, said the city had a very similar experience.
In 2012, it launched an experiment to measure the effectiveness of using a solar-and-battery system to power traffic signals at the busy Fountains Valley circle in Groenkloof.
“Within three or four days after installation, all infrastructure had sadly been stolen. Needless to say, that was the end of the experiment,” Swanepoel said.
Nevertheless, the city followed this up with an attempt to introduce UPS systems at various intersections.
“Again, most of the infrastructure — notably batteries and inverters — were stolen and/or vandalised,” Swanepoel said.
The 38 UPS systems installed along the A Re Yeng Bus System route from around 2017 to 2018 have had better luck.
“These UPS systems are secured and have not been subjected to theft and vandalism,” Swanepoel stated.
The City of Cape Town’s mayoral committee member for Urban Mobility, Rob Quintas, told MyBroadband that around 70% of all intersections on its road network had UPS systems installed.
“Unfortunately, these systems are prone to vandalism and theft, and older systems do not perform well when higher stages of load-shedding are implemented,” said Quintas.
“That said, the city is constantly upgrading, maintaining and installing UPSs.”
The city previously said theft and vandalism of UPS systems at its traffic lights had cost it R6.6 million.
In the 2020 lockdown period alone, it recorded 152 incidents of theft or damage amounting to more than R3 million.
Solar not a good idea
Notably, the CoJ is considering adding solar panels to charge backup systems in areas with a low risk of theft and vandalism.
But Coetzee has maintained his previous stance that solar-powered backup is unfeasible.
“The cost for backup batteries with an enclosure varies between R50,000 to R100,000 per site at present,” Coetzee said.
“If a real vandal-proof enclosure must be constructed, a steel vault with a cost up to R50,000 is required. The batteries, inverter and other electrical equipment makes up the rest of the cost.”
Coetzee said one option was to scale down the number of poles and signal heads at traffic intersections to reduce electrical demand and the cost of backup power.
“In Europe, there are only traffic signals on the near side of the road. We have signal heads on the near and far sides of the road,” he explained.
But he said among the most effective measures to improve traffic flows — including during load-shedding — was to remove unwarranted traffic signals altogether and replace them with mini-roundabouts.
“Often a traffic signal is erected because of a perceived improvement in traffic safety, or it is erected too early, before traffic warrants it,” Coetzee explained.
Although using pointsmen like those sponsored by Outsurance was also an option, Coetzee said this should be reserved for emergencies.
“They work well in certain cases, but result in long delays and unnecessary cost in fuel in others,” he said.
Instead, Coetzee said it was the responsibility of government-appointed traffic officials to improve flows.
“Vigilant municipal officials, Saps, and other public entities will go a long way to improve the operation of traffic signals,” he stated.
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