And yet another parking light aficionado...
Parking lights "needed and justified," or "a relic from the past?" Both! As defined in the SAE (Society of Automotive Engineers) in Surface Vehicle Standard J222, 2.2.1 "Parking lamps, whether separate or combined with other lamps, are located on both the front left and right of the vehicle which show to the front and are intended to mark the vehicle when parked. In addition, these front lamps serve as a reserve front position indicating system in the event of headlamp failure."
Here's a little history: The parking lamps used to work independent of the headlamps, so you could have the headlights on without having the parking lights on, too. But back in 1968, cars were first required to have "side marker lamps." The side marker lamps were to be lit up in both the "parking" mode and the "headlamps on" mode as a way of making the vehicle more visible from the side in the dark. So, to accomplish this as simply as possible, the side marker lights were wired into the parking light circuit and the parking lights were simply set up to remain on when the headlamps were turned on. So, the parking lights lost some of their uniqueness. But, as an added benefit (by design or default?) the parking lights then provided a reserve means of position indication in the event a headlamp burns out. That's what makes them still useful!
David Davis, Vehicle Lighting Systems, Phoenix, AZ
TOM: Thanks, David. I hadn't thought about parking lights as a "back up" to blown headlights, but you're right, they CAN help you figure out what you're looking at. When you see one headlight barrelling down the road towards you, the parking lights help you determine whether it's a) a motorcycle 2) a car with its right headlight out or III) a car that's driving in the middle of the road car with its left headlight out.
RAY: So if that's their only useful purpose, why don't we drop the "parking lights" name? They have nothing to do with parking anymore. Maybe we should just call them "front marker lights" and be done with this "parking light" charade. It's a ruse... a sham perpetrated on the American people!
TOM: I disagree. There's historic significance to the term "parking lights," because they used to be used for parking--before there were street lights and set-aside spaces for parking. You think we should just throw away our history because technology changes? You think we should change the term "dial the phone" to "push the phone" just because we now have push buttons instead of rotary dials? You think we should change the designation "cc" for carbon copy to "lpc" for "laser printed copy" because carbon paper is out of date?
RAY: Yes. And while we're at it, in the interests of modern day accuracy, I think they should also change the name of our column to "Ray Talks About Cars and Tom Rants and Raves About Everything Else."