Aquí es porqué los carros modernos apagan una de sus luces con señalización

¿Alguna vez has notado carros apagando una de sus luces delanteras para activar un parpadeo? Bueno, ciertamente lo tengo, para averiguar por qué veo los vehículos torpes de un solo ojo señalando vueltas aparentemente cada intersección. Decidí cavar en ella para averiguar qué está pasando.

Asumí que estos malos ciclops habían sido forzados a entrar en este triste estado por las regulaciones gubernamentales, así que mi primer recurso fue Stephan Berlitz, la Jefa de Innovaciones de Iluminación de Audi. Él es el hombre que ha estado luchando con los reguladores de seguridad automotriz federales en NHTSA para hacer cambios a los estándares de iluminación actuales, así que pensé que él era el tipo a preguntar. Esto es lo que me dijo:

Este fenómeno] se debe a FMVSS 108 ... Si el DRL está cerca del indicador de dirección, o incluso incorporado, usted tiene que apagar el DRL durante la indicación

Berlitz continuó diciéndome que la misma idea se aplica a las luces traseras, diciendo "si se indica que las luces de freno tienen que apagar ... La razón es una mejor percepción de la señal / [reconocimiento]".

OK, so this makes sense: the reason why so many cars look like they’ve had their eyes shot out is to prevent their daytime running lights (the eyes) from hiding the turn signals from view. Still, I wanted to learn more, so I looked up Federal Motor Vehicle Safety Standard 108 “Lamps, reflective devices, and associated equipment” (these FMVSSes are how all of car safety is regulated here in the United States), which defined Daytime Running Lamps as:Daytime running lamps (DRLs) are steady burning lamps that are used to improve the conspicuity of a vehicle from the front and front sides when the regular headlamps are not required for driving.

In other words, these are the lights that are on all the time to help other drivers see you. Though they’re technically not the same as headlamps, in some cars (like the Dodge Caliber), the daytime running lights are actually located in the same place. It’s these cars with the “optically combined” DRLs and low-beams that look especially like one-eyed monsters as they signal their turn with what looks like one headlight blown out.

Speaking of “optically combining” things, FMVSS 108 then goes on to explicitly state the rules for DRL deactivation during signaling, breaking those rules into two parts: one for cars that optically combine the DRL with the turn signal, like the Audi in the video above (you can see that the DRL and turn signal use the same LED strip), and the other for cars with that have separate DRL and turn signal light sources, like the Grand Cherokees above.

FMVSS Standard No. 108 lays it all out, starting with cars that have combined DRLs and turn signals:

Each DRL optically combined with a turn signal lamp must be automatically deactivated as a DRL when the turn signal lamp or hazard warning lamp is activated, and automatically reactivated as a DRL when the turn signal lamp or hazard warning lamp is deactivated.

So, it’s pretty straightforward for vehicles with combined blinkers and DRLs. If a car’s turn signal and DRL are separate, though, that doesn’t mean it can necessarily keep its DRL on while signaling. It all depends on how close the two light sources are. In the “Spacing To Turn Signal Lamps” section, FMVSS 108 states:

Each DRL not optically combined with a turn signal lamp must be located on the vehicle so that the distance from its lighted edge to the optical center of the nearest turn signal lamp is not less than 100 mm...

There are a few exceptions to this 100 mm rule for non-optically combined signals and DRLs, the first of which is:

(a) The luminous intensity of the DRL is not more than 2,600 cd at any location in the beam and the turn signal lamp meets 2.5 times the base front turn signal photometric requirements

In other words, if the turn signal is very bright and the daytime running lamp is fairly dim, then the DRL won’t obscure the turn signal and it’s fine if both lights are close to one another and simultaneously on.

The second exception is:

(b) The DRL is optically combined with a lower beam headlamp and the turn signal lamp meets 2.5 times the base front turn signal photometric requirements

This means that if the DRL is combined with the headlight (like the Dodge Caliber I mentioned before), and the turn signal is very bright, having the DRL and turn signal in close proximity and simultaneously on is allowed by our infinitely wise government regulators.

The final exception that allows automakers to place a DRL within within 100 mm of the center of a turn signal is:

(c) The DRL is deactivated when the turn signal or hazard warning signal lamp is activated.

So basically, if your car uses the DRL as its turn signal, the DRL—unsurprisingly— has to shut off when using the blinker. And if your DRL is separate from your turn signal, there’s a spacing requirement with three exceptions, one of which is to cut off the DRL when signaling.

Not all cars drive around like cyclopes when signaling turns (for example, the Durango above), but many do, and now you know why: it’s the pesky government making sure those daytime running lights don’t stop us noticing that someone is about turn into our path and potentially lead us into peril.