Scores of traffic lights have malfunctioned in heavy rains in Cape Town in the last couple of months, causing a series of serious traffic jams.

Last Monday, 20 traffic signals were reported to be “out” or “flashing”, according to Peter Sole, manager of the City of Cape Town’s Transport Network Operations.

Last month, 139 of the 1 300 traffic signal installations in Cape Town stopped working on different days.

“Traffic signals are more complicated, complex installations than most people realise,” said Sole.

More than 360 individual electrical connections arrive at each signal aspect; each pole can have up to 28 individual electrical connections.

“Although these connections are protected from water, they are subject to natural deterioration, particularly in moist-air conditions.”

Additionally, earthworks or pegs being driven into the ground can destroy underground cables. This unseen danger will only be noticed when water seeps into the cables during a heavy downpour, thus causing a fault.

Theft of cables and equipment, and wear and tear, especially in exposed areas near the sea, sometimes lead to power outages, and cause traffic lights to stop functioning.

“We continually strive to improve our preventative maintenance schedule,” said Sole.

One example is low voltage installations that will be less prone to cable damage and are being developed at the moment.

Sole said nearly every traffic light fault reported last Monday had been repaired on the same day and no accidents due to the faults were reported.

“Power outages caused by cable theft can take longer to repair, due to the more complex logistical arrangements.”

Merle Lourens, principal inspector of the Cape Town Traffic Services, said that whenever there were traffic light faults at intersections, repair teams prioritised the ones at important intersections first.