On 11/28/2015 9:24 AM, Arthur Conan Doyle wrote:
Don Y wrote:

Tell the factory that! Car rides up higher than a
regular car -- should all truck drivers deliberately
point their lights at the ground (instead of "aiming"
them as required?)

The height of the lamp isn't the issue. As you noted, it's the aim point and the
coverage area. Misaimed headlights are frequently too high and stray into the
oncoming lane.

There are two different issues at play. One is left to right aiming:
the driver's side (inner) headlamp is supposed to point "right" instead
of straight ahead. This keeps your lights out of the "other lane".

But, height/elevation also plays a role. If you're lights are higher up
off the roadway, they will cross a given point of elevation that lower
mounted lights won't. E.g., an 18-wheeler's lights are more likely to
be up *above* my eyes, pointed downward, than a MiniCooper's.

In each case where "oncoming" drivers "flashed us", they were parked
(at a light) directly across the intersection from us. I.e., close
enough that our light cone hadn't fallen to a point BELOW the driver's
eye level.

Living in a world of pickup trucks, we had noticed this early on:
"Why are everyone's headlights so bright?" But, you'd only notice
when the offending vehicle was very close -- not "down the road a
bit and headed in your direction". The "solution" is to get your
vehicle *up* and out of the downward aimed lights sooner.

Should folks not be allowed to use halogen and HID lights
because they're brighter??

They aren't. The DOT regulates how bright a standard headight can be.

http://www.ecfr.gov/cgi-bin/text-idx...e49.6.571_1108

Table XVIII and XIX - note the Maximum Photometric Intensity column. People
think High Beams means brighter - it doesn't. It means the aim point is higher.

Exactly. "High" and "low" aren't synonyms for "bright" and "dim".

People also think some lamps are brighter because the color temp is different -
more blue than incandescent or halogens. That's also regulated, but not as
tightly.