Headlights

Better vehicle lighting can improve driver recognition of objects and therefore increase vehicle safety. Vehicle manufacturers have addressed this issue by fitting new vehicles with higher output headlights, as well as new lighting technology such as high intensity discharge lamps.

But excessively glary headlights can dazzle other road users and create dangerous situations. Queensland’s road rules prohibit drivers using lamps that dazzle other road users and the police can issue fines for this. The Australian Design Rules for Road Vehicles (ADRs) set out the design criteria and safety and performance standards for headlights that vehicle manufacturers must meet.

However, some drivers continue to raise concerns about the blue coloured headlights that appear to be becoming more common.

In Queensland law, blue lights are reserved for the police and certain emergency services vehicles and their use on non-approved vehicles will quickly attract the attention of authorities, and a hefty fine.  However, headlights with a certain amount of blue colouration are permitted.

These bluish headlights fall roughly into three groups - high intensity discharge (HID), aftermarket HID conversions, and halogen lamps that have had some types of  aftermarket globes installed. 

High Intensity Discharge lamps

HID headlamps are becoming increasingly popular as original equipment on new cars. They are a gas discharge lamp that produces light by means of an electric arc between two electrodes housed inside a transparent quartz envelope. They are electrically more efficient and have a higher light output compared to conventional incandescent lights because a greater proportion of their radiation is in visible light as opposed to heat.  The light they emit may appear to have a blue tinge, particularly around the peripheries of the beam, but it is actually whiter than that produced by a standard halogen lamp.

Due to their higher light output, HID lamps must comply with a specific set of Australian Design Rules.  These include specifics as to light colour, proportions of specified light wavelengths (including blue wavelengths) and ultra violet (UV) emissions.

Self levelling systems and headlight washers are also required to off-set the increased risk of dazzling other drivers. 

Vehicle manufacturers sometimes refer to HID lamps as Xenon or Bi-Xenon lamps. However these should not be confused with conventional incandescent bulbs that use xenon gas in their glass envelope.

Aftermarket HID conversions

Aftermarket halogen to HID conversions are available however their use on a road registered vehicle will generally result in contravention of the relevant ADRs. Typically these ‘conversions’ comprise ballasts, wiring and HID globes that plug straight into the existing lamp.

Halogen lamps and their globes must comply with ADRs 46 and 51, while HID lamps and their globes must comply with a different set of requirements within ADRs 77 and 78. Interchanging globe types (such as putting HID globes into a lamp designed for a halogen globe) prevents continued compliance of the lamp/globe assembly.

In addition, ADR 13 requires that all vehicles fitted with headlamps (including HID) producing over 2,000 lumens (a measure of light output) have a self-levelling system and headlight washers. These simple retro conversions don’t provide these features and are therefore illegal for road use and are likely to be excessively glary to other road users.

If the vehicle manufacturer offered optional HID lights for a particular model then retrofitting the complete system including lamps, globes and the features required by ADR 13 to that model should be acceptable. But ‘grafting’ a full system between models or makes would impose performance certification requirements in the new application and is unlikely to be viable.

Aftermarket lamp globes

Replacement headlight bulbs frequently claim to offer improved light output and whiter light. Many have mild blue colouring of the glass envelope, are marked as ADR compliant and are legal for road use. However others emit significantly more blue spectrum light, and are not ADR compliant. These are usually marked for off-road use only and represent a potential hazard to other drivers.

Colour aside, care should be exercised when choosing aftermarket bulbs that claim increased light output as they may have a higher current draw than the vehicle’s electrical system is designed for.  In some cases the increased current draw is disproportionate to the actual increase in light output, with much of the additional power consumption merely generating extra heat in the headlight. 

UV cut globes

With polycarbonate plastics almost entirely replacing glass for headlight lenses it is important to only use globes that are suitable for this application.  Globes with high UV output will rapidly discolour the inside of polycarbonate lenses. Reduced UV or ‘UV cut’ bulbs are specially designed to reduce this affect. 

 Headlight protectors

Headlight protectors are a popular accessory, however their value in protecting headlights from damage is questionable. Most modern cars use polycarbonate plastic for headlamp lenses instead of easily damaged glass.  Polycarbonate is very strong and offers good shatter resistance and in this respect is superior to glass lenses, and the acrylic used in lamp protectors.  Lamp protectors may offer some protection against scratching of the lens though.

Queensland Safety Certificate requirements state that clear headlight protectors are acceptable provided they don’t affect the light intensity on high or low beam. Tinted covers are also acceptable but must be removed when the high or low beam headlights are operated.

Hazy/discoloured headlights

Polycarbonate lenses on older car’s headlights can go dull and cloudy due to the effects of naturally occurring UV radiation.  This can affect the vehicle’s roadworthiness as it reduces the light’s output.

 Replacement with new or good second-hand lamps are options, however there are also special lens polishing kits available from auto accessory/parts shops that can be used to restore the lamp to an acceptable condition.  These kits are not suitable for removing discolouration from the inside of lenses caused by the use of incorrect lamp globes.

Headlight alignment

Incorrect headlight alignment is a prime cause of dazzle for drivers and is a common source of complaint. 

A quick test of headlight alignment can be made by parking the car on a level surface (a driveway will do) at right angles to a wall or garage door. Reverse back approximately 4 metres from the wall and with the lights switched to high beam the spread of the two beams should be at about equal heights and roughly straight in front of the vehicle.  When low beam is selected the light beams should drop and move slightly to the left.

If the beams are wildly out of alignment it may be necessary to temporarily cover each light in turn in order to determine in which direction they need to be adjusted. 

Owner’s handbooks usually provide instructions on adjusting headlight alignment, or alternatively you may wish to have your local repairer do it for you.