Post #268: HAWK light timing issue, fixed

Posted on May 10, 2019

In two earlier posts (Post #260, Post #225) I raised an issue about the timing of the new High-Intensity Activated crossWalK (HAWK) lights in Vienna.  These are the new lights located on Maple at Pleasant Street and at James Madison Drive.  Their purpose is to allow pedestrians to cross Maple safely at those locations.

The issue is the timing of the “walk” signal.  I thought there needed to be a longer delay between the red light, and the walk signal.  See the posts cited above if you want the full story.

This is not an issue.  I used the Pleasant Street HAWK light earlier this week, and there is a roughly 2.5 second delay between the red light and the walk signal.  So either I hallucinated the problem, or the Vienna Department of Public Works (DPW) already fixed it.  For purposes of this post, I’ll assume that I am sane and that DPW did, in fact, change it that fast.

A little more about HAWK lights follows — because I literally had to look it up to understand how you are supposed to deal with them.  The key point is that you should treat the flashing red lights like a stop sign.

The point of a HAWK light is to allow pedestrians to stop traffic, on demand, and cross the street safely.  Otherwise, when no pedestrians are present, it’s turned off and you completely ignore it.  It is specifically set up to provide the least disruption to traffic, while allowing pedestrians to cross the road.

The problem is that, in order to do that “least disruption”, the people who developed it chose an unusual pattern of lights.  I certainly was confused when I first saw one.  I had to read the entire set of rules before I knew how to use it.  I figure it’s worth laying that out here.

Now you’d think, because we all know that red means stop, they’d have done the obvious thing and … made it turn red.  When they want us to stop.  We’d stop.  And pedestrians would cross.  No confusion.

For example, you could have a traffic light that’s always green until a pedestrian pushes the button to cross the street.  Then it turns yellow, then red.  Normal traffic light, and everybody would know what to do.

No such luck.

Here’s how it actually works.

The light is completely dark until a pedestrian triggers it.  At that point:

First the light moves to flashing yellow, to alert the traffic to the fact that this light is now live, and you have to pay attention to it.

Then you get a normal yellow light followed by a red light.  Every driver knows that means stop.

Then you get a flashing red light, which means, treat this like a stop sign.  Come to a full stop, and if the crosswalk is clear, proceed.  So, weirdly enough, you are supposed to drive through the flashing red.

To me, that’s  weird because in other contexts the side-by-side flashing red lights mean “stop or die”, as in a railroad crossing.  But here just means, treat this like a stop sign.

That last part improves the efficiency of the light relative to a standard traffic light.  If nobody is crossing the street, you can proceed.

But there’s a catch:  Just because the car ahead of you drove through the flashing red light, that doesn’t mean you can.  Just like a stop sign.   Each car has to come to a complete stop, look at the crosswalk, then proceed.

This is the part that, as far as I can tell, drivers get wrong on a regular basis.  Me included.  Once traffic starts moving, people just drive right through the flashing red.  That’s wrong.

Bottom line:  Flashing red = stop sign.  If you can remember that, you can use the light properly.

You can read a full writeup of it, including history, on Wikipedia.

The best short explanation I have found is from the University of Colorado:

For drivers, if the light is not on, you can travel through the crosswalk. If the yellow light is flashing, be prepared to stop. If the yellow light is solid or the double red lights are solid, stop and wait. But, if the red lights are flashing, you may go only after coming to a stop and making sure that the crosswalk is clear.