Trucks and traffic-light tragedies

A possible solution to reducing accidents involving heavy-duty trucks at traffic lights

Serious and fatal collisions that occur at traffic-light intersections in South Africa often involve heavy-duty trucks that are unable to stop in time once the traffic lights change to caution (orange).

Recent media reports have unfairly criticised reckless truck drivers after fatal collisions at intersections where traffic lights are in operation. However, what many drivers of light motor vehicles do not realise is that heavy-duty trucks that are fully loaded require a longer stopping distance – and truck drivers often have no choice, when they are in close proximity to the traffic light, but to continue through the intersection when the lights turn to caution.

There are many roads in city areas of South Africa that are used by large, fully loaded trucks; where the speed limit varies between 80 and 90 km/h and intersections are controlled by traffic lights. Truck drivers using these roads travel at the displayed maximum speed limit and often cannot stop when they are close to the intersection and the lights change.

A good example is Hendrik Potgieter Road in the Little Falls area of Gauteng. The road is used day and night by many large trucks, some transporting building material from a nearby quarry, going to and coming from Botswana and Namibia.

There are 16 traffic lights in operation along this section of Hendrik Potgieter Road between the N1 Gordon Road exit and the N14 Krugersdorp/Pretoria Highway, a distance of approximately 18 km.

The displayed maximum speed limit on this section of the road varies between 80 and 90 km/h.

Research has shown that a large, fully loaded truck grossing at 56 t takes approximately 140 m to stop when travelling at 88 km/h, provided that the brakes on the truck and trailer are working correctly. (This allows 60 m for the driver’s reaction time once he or she sees the traffic light change.)        

Minibus taxis and impatient drivers who use the emergency lane to get ahead of the traffic that is stopped at the traffic light intersection, and then race ahead before the lights have changed to green, also contribute to the high incidents at the intersections. It is no wonder that there are so many accidents involving trucks at intersections that are controlled by traffic lights.

To overcome this problem, the Australian authorities appear to have found a solution.                                                                           

They are presently testing a system in Sydney, which signals the traffic light to remain green when a truck is in close proximity to the intersection.

The system appears to be relatively simple. As the truck approaches the intersection a transmitter fitted to the truck sends a signal to the traffic light to keep the green light on for a few seconds longer, allowing the truck to pass through the intersection safety.

Hopefully the South African traffic authorities are aware of this Australian trial and are monitoring the results, as this may well be a solution to reduce the unacceptably high accident rate that we witness every day.