Originally Posted by jeff78
What's more insidious with long life bulbs is, they start out with light output that is likely already at the 'barely legal' minimum.....which then decreases with use. After a year or two, they may still technically work, but I'd be surprised if there weren't a measurable loss of light at distance.
There's certainly a huge loss of light at distance. Tens of meters of distance are lost with aged bulbs over time. We talk about how certain brake pads help us stop like 4, 5, or 8 feet shorter, or how these stickier Michelin tires help us stop 10 feet shorter, but people don't realize that bulbs and sight distance also factor into stopping distance, and often much, much more so than just upgrading brakes or tires. High-performance bulbs have been shown to give 20 meter increases in illumination distances over long-life type bulbs. Try finding me a brake pad or tire that will help you stop 20 meters (~60 feet) shorter. You won't find any sort of brake pad or tire (unless you perhaps switch from street-legal tires to slicks!)
Originally Posted by jeff78
she responded with 'All the roads I drive on are lit at night, so the headlights aren't even really necessary'. As she drives primarily in the city, I couldn't really counter that with a convincing argument so I just dropped it.
If that were the case, there should be significantly fewer pedestrian-vehicle accidents in cities.
Street illumination can help, but it can also actually obscure pedestrians. Many times, strong overhead lamps can create silhouettes out of pedestrians. This is why researchers have been experimenting with pedestrian-height lamps that shine horizontally across cross-walks, instead of having powerful overhead lights that shine down onto a crosswalk. In the meantime, strong headlamps can help bring these people literally out of the shadows. Remember, with powerful illumination comes powerful shadows. Even in the day, there are plenty of accidents due to not being able to see something in time; that's the whole point behind Daytime Running Lamps (DRLs), which have been proven to increase visibility in the day and reduce accidents, and Canada has recently mandated rear DRLs, which is exactly what it sounds like--it increases the visibility of the rear of the vehicle.
And it's not just pedestrians one should be worried about in the city. Headlamps are critical in illuminating useful road signs, such as stop signs, which are almost never self-illuminated in the US. Stop signs in the US are all retroreflective, which means they are designed to reflect the light from your headlamps back at you. Dim bulbs can obscure stop signs, and you can end up running a stop. Disabled vehicles also rely on retroreflection for you to see them in time; that's why there are reflective amber and red bits on vehicles. Even in a parking lot, the retroreflective bits are useful in navigating the lot without hitting a car. High-performance bulbs can make the retroreflective stuff--which is prevalent throughout traffic--"pop" a little more, and therefore become more noticeable to us.
What's more insidious with long life bulbs is, they start out with light output that is likely already at the 'barely legal' minimum.....which then decreases with use. After a year or two, they may still technically work, but I'd be surprised if there weren't a measurable loss of light at distance.
There's certainly a huge loss of light at distance. Tens of meters of distance are lost with aged bulbs over time. We talk about how certain brake pads help us stop like 4, 5, or 8 feet shorter, or how these stickier Michelin tires help us stop 10 feet shorter, but people don't realize that bulbs and sight distance also factor into stopping distance, and often much, much more so than just upgrading brakes or tires. High-performance bulbs have been shown to give 20 meter increases in illumination distances over long-life type bulbs. Try finding me a brake pad or tire that will help you stop 20 meters (~60 feet) shorter. You won't find any sort of brake pad or tire (unless you perhaps switch from street-legal tires to slicks!)
Originally Posted by jeff78
she responded with 'All the roads I drive on are lit at night, so the headlights aren't even really necessary'. As she drives primarily in the city, I couldn't really counter that with a convincing argument so I just dropped it.
If that were the case, there should be significantly fewer pedestrian-vehicle accidents in cities.
Street illumination can help, but it can also actually obscure pedestrians. Many times, strong overhead lamps can create silhouettes out of pedestrians. This is why researchers have been experimenting with pedestrian-height lamps that shine horizontally across cross-walks, instead of having powerful overhead lights that shine down onto a crosswalk. In the meantime, strong headlamps can help bring these people literally out of the shadows. Remember, with powerful illumination comes powerful shadows. Even in the day, there are plenty of accidents due to not being able to see something in time; that's the whole point behind Daytime Running Lamps (DRLs), which have been proven to increase visibility in the day and reduce accidents, and Canada has recently mandated rear DRLs, which is exactly what it sounds like--it increases the visibility of the rear of the vehicle.
And it's not just pedestrians one should be worried about in the city. Headlamps are critical in illuminating useful road signs, such as stop signs, which are almost never self-illuminated in the US. Stop signs in the US are all retroreflective, which means they are designed to reflect the light from your headlamps back at you. Dim bulbs can obscure stop signs, and you can end up running a stop. Disabled vehicles also rely on retroreflection for you to see them in time; that's why there are reflective amber and red bits on vehicles. Even in a parking lot, the retroreflective bits are useful in navigating the lot without hitting a car. High-performance bulbs can make the retroreflective stuff--which is prevalent throughout traffic--"pop" a little more, and therefore become more noticeable to us.
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