Why blinding car headlights are becoming a bigger problem

New lighting technology and increased adoption of vehicles that are higher off the ground are two possible factors causing more cases of car headlight “blinding” than in previous years.

Many South African motorists will know the feeling of having an oncoming vehicle’s headlights temporarily distorting their vision while driving at night.

This glaring issue can sometimes be due to an oncoming driver forgetting to switch off their high-beams (“brights”).

In other cases, however, they are met with even brighter high-beams when mistakenly signalling to the oncoming driver that their “brights” are on.

Blinding headlights creates serious issues because research has shown it can take the human eye several seconds to recover from exposure to them, influencing their ability to drive safely.

Even when travelling at a relatively slow 60km/h speed in the city, you will cover nearly 17m every second, during which time you can easily hit something in the road or veer off course with potentially disastrous consequences.

It is easy to shrug off instances of headlight glare as being due to a person’s unique sight or a particular situation — like the fact that the surrounding area was in complete darkness due to load-shedding.

However, the RAC Limited, a major automotive services company in the United Kingdom, recently called on the country’s government to launch an independent study into what appears to be an increasingly glaring issue.

In a recent RAC survey of motorists in the UK in November 2023, 89% of drivers thought at least some headlights on the road were too bright, while 28% believed that most cars’ lights were too bright, the highest number yet.

74% of the survey participants complaining about being dazzled by headlights said it occurred regularly, while 7% said they avoid driving at night specifically over this issue.

“While the RAC has been surveying drivers on dazzling headlights since 2018, these new findings show more drivers than ever appear to be suffering from them, with 85% of those affected stating they believe the problem is getting worse,” the RAC said.

There have been similar reports out of the US, but seemingly little action from regulators or authorities in investigating the validity of the claims.

A Change.org petition launched by the Soft Lights Foundation in 2016 has amassed over 56,000 signatures in support of its call for US authorities to “seriously and properly” regulate LEDs as spatially non-homogeneous, directed energy radiation.

South Africa’s headlight regulations

South Africa has a set of regulations governing the maximum strength, beam patterns, angles, placement, and colours of vehicle headlights.

These are contained in the SANS 1046:1990 specification, also called SABS 1046, enforced through the Standards Act of 1993.

Among these regulations, high-beams must be able to see pedestrians 100 metres ahead of the vehicle but cannot strike the road more than 45 metres ahead.

The standard also determines that a headlamp emitting a dipped-beam (when the car’s brights are off) shall be adjusted and maintained so that it does not cause a dangerous glare to oncoming traffic on a reasonably level road.

The graph below shows some of the requirements for dipped-beam lights on cars driven on South African roads.

Diagram showing guidelines for headlamp design on cars in South Africa

The RAC reckons there are two major contributors to more complaints of blinding headlights than in the past.

The first is the switch from headlights that use halogen or high-intensity discharge (HID) bulbs to light-emitting diode (LED) bulbs, which started happening around 2006.

LEDs are much more power efficient than halogen and can cast a brighter and wider beam of light, benefitting the safety of the driver using the car with LED headlights.

However, testing by Consumer Reports in 2019 found that although LED headlights improve side-of-road visibility, they did not help improve the view on the road.

When these bulbs are tested for approval in automotive use, their brightness is measured in lumens.

Although the objective measured strength of the lumens of the light might be similar or within range of halogen, the perceived brightness of LED to the human eye could be substantially higher.

LEDs tend to generate more blue light than halogen bulbs, which can put additional strain on the human eye.

LED lights emit more blue light waves than halogen lights.

The second factor is that there are bigger differences in ground clearance between various car models with ranging body types, where there was previously more consistency between conventional sedans.

Consumers have generally started preferring cars with higher ride heights in recent years.

In South Africa, this is made all the more necessary by worsening road conditions, with motorists leaning toward vehicles with greater ground clearance to avoid undercarriage damage.

Data from Lightstone Auto showed that sports utility vehicles (SUVs) or so-called “crossovers” grew their share of new sales in the passenger vehicle segment from 21% in 2014 to 38% in 2023.

In addition, one-tonne double-cab bakkies also saw substantial growth — from 9% in 2015 to 16% in 2023.

These “high-risers” made up 54% of new vehicle sales in 2023, compared with 30% for hatchbacks and sedans, which accounted for 53% of sales in 2014.

Among the other factors that could be contributing to more “blinding” are people fitting illegal LEDs with higher brightness than regulations allow and automotive workshops not adjusting the angles of beams correctly when fitting aftermarket bulbs or conducting services.

In addition, the plastic covers on headlights can become scuffed over time, which can cause them to distribute light at a higher or skewed angle.

While South Africa’s vehicle headlamp standards may have been sufficient when halogen lights and low-riding vehicles were the norm, this might no longer be the case.