Dear Johnnie >> When traveling east or west on Niwot Road at the intersection with the Diagonal Highway, the green lights on the stop lights appear to be burned-out until you get right under them, causing confusion.

Would you please ask the appropriate person the reason for this?

I enjoy your column and appreciate your research. — Dim Bulb

Dear Dim Bulb >> You’re no dim bulb. You asked a question that I hadn’t thought to ask, even though I’d noticed the same thing about certain green lights.

Your question led me to verbalize the thought that had never escaped the back of my mind: Why only certain green lights? So I started thinking about it again. Are these lights intended to combat sun glare for eastbound or westbound motorists? Or does the fact that these lights are at back-to-back intersections play a role?

I checked with Colorado Department of Transportation spokesman Jared Fiel to find out.

“These are programmable (or directional) signal heads,” Fiel said in an email. “These traffic signals are used to limit signal visibility to specific target areas and increase intersection safety. These traffic signals have a directional beam to avoid motorist confusion when two intersections are in close proximity.”

There it is. A motorist arriving from east or west on Niwot road is faced with a nearer green light and a farther green light, which do not turn green or red simultaneously. So motorists could see the green light at the far side of the intersection and ignore the red right in front of them.

And as it turns out, they did.

“Prior to their installation, there were many reports of confusion when both the near side and far side signal heads were visible — especially at night,” Fiel said. “People were confused which light they were to follow.”

Field noted that prior to the installation of those direction signals, CDOT recorded a higher than expected frequency of red-light running crashes at that intersection.

“While we haven’t done an official before/after analysis,” he said, “we have seen a drop in severe crashes at that location.”

You’re the bright one, Dim Bulb. Your question has cast a light on this situation.

— Send questions to johnnie@times-call.com.