Taking Vehicle Lighting for Granted

By: Richard C. Moakes, CEng

A recent weather event in February 2022, caused by battling warm and cold fronts after a major winter storm, had left snow on the ground, which created thick daytime fog.  This resulted in a very hazardous situation that highlighted a deficiency in the human/vehicle interface of modern vehicles with automated lighting.

The more automated systems we have become reliant upon in our present-day vehicles, the more hazardous and careless we become as drivers when unusual and out of the ordinary circumstances develop.  These days most of us can slip into our vehicles, whether it is day or night, and not think about turning on the headlights.  In fact, we have no idea whether our lights are on or off as we drive along the road sipping our favorite beverage and singing along with the satellite radio.  Practically every car on the road has what is known as daytime running headlights, which consist of the headlights illuminating as soon as the ignition is switched on, even in broad daylight conditions.  In addition, vehicles have an automatic position on the light switch which automatically switches on the vehicle’s headlights and taillights as outside ambient light levels become low.  This is just one of many options that are explained to us in the owner’s manual or by the dealership when we first purchase the car.  The significance of this simple light switch position diminishes slowly as time passes and as we indulge in the many other automated systems such as collision avoidance, smart cruise, lane departure warning, remote start, and infotainment systems that automatically connect to our smart phones so that we can make hands-free calls.  However, on this one day, the one old fashioned safety device that has been on vehicles since the days of horse and carriage was missing!  This was full vehicle lighting, or to be precise, taillights and in some cases, headlights were not illuminated.

It is essential in foggy conditions that the headlights and taillights of vehicles are on so that other drivers aren’t suddenly surprised by coming upon a slower vehicle in front of them.  It is also essential that drivers see one another at intersections and junctions to avoid dangerously pulling out in front of another vehicle.  Headlights are a means of warning at intersections, for turning vehicles and for pedestrians, of the presence of an oncoming vehicle.  And yet, on this day in February as I set out on my commute to work in bright daylight conditions, but with thick fog present, I estimated that 80 percent of the vehicles that I came across on the road either had no lights on at all, or only had some type of lighting at the vehicle front.  I say some type of lighting because not every car had their headlights illuminated and some were driving along the road with just front side lights illuminated.  “How could this be?” I ask myself, before realizing that the rear lights on my own car were not on either!  My daytime running headlights were on through the activation of the ignition, but my taillights were not.  With the headlights switch set in the automatic position, the headlights and the taillights are switched on by a sensor that senses a low light condition.  In daylight fog conditions this sensor does not sense low light and so does not turn on the complete vehicle lighting system.  To make matters worse, being a European car, it was also fitted with high intensity red rear fog lights which I had not activated separately to the main light switch.

Having discovered my mistake and being a concerned automotive safety and accident reconstruction expert, I set about flashing my lights at my fellow commuters in an attempt to draw their attention to the fact that they could not be seen easily without lights.  However, the exercise was futile because they were either oblivious of the situation or had no idea how to manually turn the headlights and taillights on, because they had never had to do it since owning the vehicle. 

I wondered to myself whether cars like the Tesla that were capable of driving themselves in auto pilot would have this weather phenomenon sorted out.  To my horror I observed five Teslas of various years and models, including the latest Model X and Model 3 on that day, and none of these cars had their rear lights illuminated either.  Now presumably none of these Teslas were being operated on auto pilot, but I doubt that it would have made any difference to the vehicle’s lighting condition if they had been.  If Tesla’s computers, sensors, and programming experts were not ready for this day in February, then where are we heading with safety in the hands of autonomous vehicles?

If you have a case where you think that the vehicle’s lights might have played a role in the accident, let the engineers and accident reconstruction experts at Consulting Engineers & Scientists investigate it for you.  In many cases from light bulb evidence, we can determine whether the rear lights, brake lights, side lights, or turn signals were in operation when the collision occurred.