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Immediate response to stop lamps when driving is crucial to roadway safety. Previous research has demonstrated that neon and light emitting diode (LED) stop lamps that have a dynamic sweeping luminance distribution can be just as or more effective than standard stop lamps. Sweeping neon and LED lamps with sweep-up times equal to or less than 100 ms resulted in reaction times equal to or shorter than those obtained with a conventional, non-sweeping incandescent stop lamp. At the same time, an LED stop lamp having the same far-field luminous intensity characteristics as the neon lamp, resulted in shorter reaction times than the neon lamp. The LED stop lamp differed from the neon lamp in two important ways. First, its color was different; the LED lamp had a dominant wavelength of about 630 nm, in comparison to the neon lamp with a dominant wavelength of about 615 nm.

Vehicle headlamps are essential for driver safety at night, and technological evolution of headlamps over several decades has brought substantial improvements to driver visibility and comfort. Nonetheless, glare remains an important concern among many in the driving public, perhaps even more so in North America, where requirements for headlamps differ from those in much of the rest of the world. In most of the world, headlamps producing higher luminous flux are required to have automatic leveling and cleaning systems, thought to help reduce glare. The arrival of headlamp systems in the worldwide marketplace with luminous flux values just below those triggering requirements for leveling and cleaning systems will bring new questions about the causes of and countermeasures for glare.

Rear automotive lighting systems employing dynamic features such as sweeping or flashing are not commonly used on vehicles in North America, in part because they are not clearly addressed in vehicle lighting regulations. Nor is there abundant evidence suggesting they have a substantial role to play in driver safety. The results of a human factors investigation of the potential impacts of dynamic rear lighting systems on driver responses are summarized and discussed in the context of safety, visual effectiveness and the present regulatory context.

The advent of light-emitting diode (LED) technology for automotive lighting allows flexibility of the spectral distribution of forward headlighting systems, while meeting current requirements for “white” illumination. As vehicle headlights have become whiter (with more short-wavelength light output) over the past several decades, their potential impacts on visual discomfort for oncoming and preceding drivers have been hotly debated. It is known that a greater proportion of short-wavelength energy increases discomfort glare, and that increasing the background light level (e.g., through roadway lighting) will decrease perceptions of discomfort. More recently it has been demonstrated that the visual system exhibits enhanced short-wavelength sensitivity for perceptions of scene brightness.

To ensure adequate visibility without excessive glare, vehicle headlights are designed to use a specific source of illumination. The optical designs of headlights gather the luminous flux produced by the light source to produce a useful beam pattern that meets the relevant requirements and standards for vehicle forward lighting. With the advent of solid state, light emitting diode sources for general illumination, an increasing number of LED replacement headlight bulb products has emerged over the past decade. In most cases, these LED replacement bulbs are not permitted for legal use on public roadways, but some countries have begun to permit specific LED replacement bulbs to be used legally on the road for specific makes, models and production years of certain vehicles. If they can be demonstrated to produce a beam pattern that meets the photometric requirements for a legal headlight, they are permitted to be used legally for on-road use.

Recent technological developments have begun to add a number of new configurations for vehicle forward lighting to the realm of possibility, including high-intensity discharge and light-emitting diode headlamps, and adaptive forward-lighting systems. These systems can offer substantial differences in performance and appearance from conventional filament-based headlamps that have been ubiquitous for many decades. These differences have not gone unnoticed by the U.S. driving public. A review of newspaper articles published during the past several years was conducted in order to assess public perceptions of vehicle headlamps in terms of their ability to support visibility and their impacts on headlamp glare.