Fleet News

Special feature: Tripping the headlight fantastic

HEADLIGHTS have come a long way since the first candle lamps back in the late 1800s, getting bigger, brighter and better all the time.

Research from Mercedes-Benz shows the average volume of traffic thins to about a third at dusk and during the hours of darkness.

But the risk of fatal accidents at these times is twice as high as during the daytime and 27% of serious accidents happen after dark, so there is an urgent need for continuing improvements in lighting technology.

Leaps in technology over the centuries have resulted in acetylene, Bilux, halogen and xenon lamps, all offering varying degrees of brilliance.

But the issue is far more complicated than simply making headlights brighter. They may make vehicles more visible but can also dazzle oncoming traffic. Mercedes-Benz developed an infra-red lighting system for the new S-class and has now launched the new Intelligent Light System, developed in conjunction with Hella.

The system, which will be available in the new E-class from the middle of this year, automatically adapts to driving situations and recognises when drivers need additional light.

A Mercedes-Benz spokesman said: ‘There are strict EU guidelines on the glare allowed from headlights. The Intelligent Light System complies with all of these guidelines.’

Other manufacturers have also developed improved headlight systems.

BMW Night Vision uses a thermal imaging camera to illuminate objects emitting heat – ie pedestrians – up to 300 metres ahead. Infrared technology generates an image of the road ahead on a screen.

A High-Beam Assistant system automatically sets the bi-xenon headlights to the optimum range and brightness depending on other traffic movements. A sensor at the front of the car detects any oncoming exterior light source, allowing the car to automatically switch between high and low beam for the best level of illumination.

The Volvo Safety Concept Car (SCC) has infra-red technology which boosts night vision, while the headlamp beams automatically adjust to suit the car’s road speed and steering wheel movements.

Vauxhall’s swivelling bi-xenon Adaptive Forward Lighting (AFL) means headlamps shine into the corners as they are reached, depending on the speed, rate of turn and vehicle yaw rate.

When driving straight at high speed, automatic level control ensures the road ahead is lit further in front on low beam without dazzling oncoming drivers.

Country mode (with and without ILS)

COUNTRY Mode extends the driver’s field of vision on the right-hand side of the road. If the vehicle is fitted with bi-xenon headlamps, Country Mode replaces the dipped-beam setting.
Verdict: Country Mode makes a considerable difference to vision, especially at junctions and roadside embankments. Hazard warning cones placed at the side of the road were invisible with ordinary lights but illuminated with the new Country Mode, particularly useful when passing cyclists or pedestrians.

Motorway mode (with and without ILS)

DUE to higher output, xenon lamps and modified adjustment of the headlamp on the inside of the driving lane, the driver’s range of visibility in the centre of the cone of light increases by about 50 metres.

Motorway Mode, automatically activated from 55mph, extends the driver’s field of vision by up to 60% compared with conventional dipped headlamps.
Verdict: Probably the most notable difference. Motorway Mode improved the view ahead to give more than 100 feet of additional visibility.

Fog system (with and without ILS)

THIS lighting function has been designed to enhance the front fog lamp units. The offside bi-xenon headlamp swivels outwards and lowers its beam, illuminating a wider section of the road surface and reducing the degree of glare to approaching traffic.
Verdict: The improved fog lamps give a much clearer view. When alternating between current and improved fog lamps, the light field around the car increased in both height and depth. As the lamps swivel to the side when activated, drivers also have a clear view of the embankment at the side of the road.

Cornering

THE widely available cornering light function increases safety at crossroads and junctions. It remains activated up to a speed of 25mph. Mercedes-Benz has also modified its Active Light System to give better illumination in tight bends.
Verdict: When indicating, the corresponding corner is illuminated, improved the view to the left or right of the vehicle and helping spotlight any pedestrians crossing the road.

A dummy vehicle on a tight bend was invisible with ordinary lights until only a few metres from the vehicle. With the cornering function activated, it could be seen much earlier.

How ILS works

THE Intelligent Light System (ILS) depends on two pivoting bi-xenon modules in the headlamp housings of the E-class.

They operate on the principle of the projection-beam headlamp which focuses the beam through an optical lens.

The light of the new, adaptive headlamps must be precisely directed for different levels of light distribution, achieved by a rotating cylinder powered by an electric motor. The different lighting functions can be configured by precisely calculated and defined cylinder positions.

Part of the ILS is a feature called Active Light Function, which was introduced in 2003. The electronic control unit is integrated into the data network of the vehicle. This continuously provides information about the steering angle, yaw rate and vehicle speed and allows the bi-xenon modules to follow the driver’s steering wheel movements and pivot sideways in fractions of a second whenever the driver enters a bend.

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