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The Spokesman-Review Newspaper
Spokane, Washington  Est. May 19, 1883


Night lights

When driving at night, we need all the guiding light we can get from our headlamps. 

For years, I’ve noted how drivers are “overdriving” their headlights at freeway speed, especially when operating at the low-beam setting.  Overdriving means that objects appearing with the range of one’s headlamp illumination are seen too late by drivers in time to stop or avoid them.

More simply put — at 70 mph, the stopping distance of the average vehicle exceeds the visual range of many headlights when driver reaction time is included.  A big help in minimizing that woe is to switch on high-beams whenever absence of traffic allows.

Auto manufacturers are well aware of this night light plight and as their headlight systems evolve.  The main conundrum they face is providing enough light to safely drive while reducing glare to oncoming vehicles and those travelling ahead.

Adding to the difficulty of providing ample light, every driver suffers from diminishing “night vision” prowess as they age.  The entire topic is noteworthy, as about half of traffic deaths occur either in the dark or at dawn or dusk.  Researching potential solutions is meritorious because according to IIHS (Institute for Highway Safety) and HLDI (Highway Loss Data Institute), few vehicles have headlights that do their job well and evaluations show that the on-road illumination provided by vehicle lights varies widely.

A old feature, once named “Autolamp” by Ford and Autronic Eye” by GM, dimmed high beams for oncoming traffic and returned to high beam when that traffic passed by.  Now, there is still promise in similar but newer “high-beam assist” systems that increase high-beam use by automatically switching between high beams and low beams, depending on whether other vehicles are present. Curve-adaptive headlights that pivot in the direction of travel to improve visibility on curvy roads are also in development.  But lamp and auto makers have a long way to go.

In IIHS ratings, as of March 2019, 14 percent of headlight systems tested on model year 2019 vehicles received a good rating.  More than half were rated marginal or poor because of inadequate visibility, excessive glare from low beams for oncoming drivers, or both.

As implied earlier, headlights that are rated marginal or poor are easily overdriven in regard to safety.  It takes 1.5 seconds for an average driver to react to an unexpected event under ideal conditions.  At a speed of 55 mph, a car travels about 120 feet during this brief period. Once the driver applies the brakes, it takes more than 144 feet, on average, to stop at this speed.

The low beams of many headlight systems with poor ratings don’t provide enough light for a driver going 55 mph on a straight road to stop in time after spotting an obstacle in his or her lane, let alone the shortcoming present at 70 mph. They provide even less illumination on the left side of a straight road and when driving on a curve.

For now, drivers should reduce top speed some in low-light conditions, especially when relegated to low-beam driving.  Aging drivers, or any driver not comfortable with seeing well at night, might consider restricting nighttime driving — at least on two-lane state-routes that are curvy and lack street lighting.

For the future, we can hope that innovation in headlight system design will steadily improve the “night light” necessary for safe driving in dark conditions.

Readers may contact Bill Love via e-mail at