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Car safety ratings have been in place for decades, covering everything from frontal crash tests to crash-avoidance technology. Only recently have headlight ratings been factored in, supplying a way to measure lighting effectiveness, especially at night. Safety ratings cover most new cars. Here’s how testing is conducted and the ratings determined.

How NHTSA and IIHS Make Roads Safer

In the US, there are two entities that measure car safety. The one that has been doing it the longest is the National Highway Traffic Safety Administration (NHTSA), a federal agency under the US Department of Transportation.

Under the NHTSA, frontal-crash, side-crash and rollover ratings are given based on a five-star rating system. The greater the number of stars, the better. The NHTSA then supplies an overall rating based on these three categories. Separately, this agency shares what recommended safety technologies are available, such as lane-departure warning and forward-collision warning. The technologies don’t affect the score, but are useful for individuals shopping for a vehicle.

The second organization performing crash tests is the Insurance Institute for Highway Safety (IIHS), an independent nonprofit. The Institute’s funding comes from insurance companies and related associations.

Like the NHTSA, the IIHS assigns an overall rating to vehicles. The IIHS scoring, however, starts with poor and rises to marginal, then to acceptable, before topping out at good. Top-performing models earn an overall Top Safety Pick or Top Safety Pick+ rating. Manufacturers that achieve top ratings use this information in their advertising, which is an important way to reach safety-conscious people.

Shedding a Light on Headlight Safety

Continual improvement in technologies means automakers have access to safety equipment that was only dreamed of a few decades ago. Lighting has helped drivers see and be seen, with Xenon high-intensity discharge headlamps and the now-ubiquitous daytime running lights playing a significant role.

But these lighting systems don’t go far enough to prevent mishaps, at least not according to the IIHS. Indeed, the Institute announced that it is now testing headlights to measure lighting reach when a vehicle travels straight and on curves. The amount of light emitted must reach at least five lux, says the IIHS; in comparison, a full moon on a cloudless night illuminates to the ground at approximately one lux.

The IIHS tests both low- and high-beam lights on five approaches. These are straightaway, gradual-left curve (800-foot radius), gradual-right curve (800-foot radius), sharp-left curve (500-foot radius) and sharp-right curve (500-foot radius). Engineers take visibility measurements, gauge illumination and measure glare from oncoming vehicles. The IIHS considers other factors, including vehicle speed and curve angle. From there, a score is assigned and listed on the Institute’s website, along with the other test score information.

You don’t need advanced headlights to drive your car, but you do need headlights that sufficiently illuminate the road ahead. As cars age, haze accumulates on the lenses, which reduces illumination. Fortunately, headlight restoration wipes do a stellar job of treating lenses with no tools required. Check your lights today, and you may quickly discover that they need your attention.

Check out all the lighting products available on NAPA Online or trust one of our 16,000 NAPA AutoCare locations for routine maintenance and repairs. For more information on headlight ratings, visit your local NAPA AUTO PARTS store.

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