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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.

Taking advantage of growing consumer interest in light emitting diode (LED) headlights, an increasing number of after-market LED replacement bulbs is available on the market. They are designed to have similar socket shapes and sizes as halogen bulbs, in order to fit into existing headlight housings. Although none of these LED replacement bulbs conform to present federal headlighting regulations, and some are labeled for "off road use" only, others claim to meet current regulations. Regardless, many different LED bulbs can be easily purchased and installed by vehicle owners, who may or may not be aware of their regulatory status. Several different LED replacement bulb kits, each designed to replace a conventional 55-W H11 halogen bulb, were purchased and tested in three different low-beam headlight units.

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.