May 27


Minnesota’s First HAWK Pedestrian Signal System/Crosswalk

By Mike Spack

May 27, 2010

HAWK Signal, Pedestrian Safety

HAWK System
The Minnesota DOT (Mn/DOT) installed its first HAWK Pedestrian Signal on Highway 23 at 12th Avenue in St. Cloud, MN during October 2009.  (jargon alert: HAWK = High-intensity Activated
crossWalK… creative).  Here's more info on Mn/DOT's website.  The City of Tuscon, Arizona pioneered this system and is now operating about 60 of them.

The HAWK System stays dark until a pedestrian activates it by pressing the push button.  Then the signal starts flashing yellow, then steady yellow, then double red lights.  The pedestrians get a walk signal with a countdown timer when the double red lights are activated.  When the pedestrian gets the flashing hand symbol, the red lights start flashing for the vehicles.  Once the pedestrian phase ends, the signal goes dark again and traffic goes back to free flowing.

Tom Dumont, Mn/DOT's District 3 Traffic Engineer, gave a presentation about the system to the City Engineers Association of Minnesota.  The HAWK System is still in experimental mode and is not part of the Minnesota Manual on Uniform Traffic Control Devices yet.  Mn/DOT developed criteria for when these systems could be installed based on roadway speed, crossing width, mainline traffic volumes, and pedestrian crossing volumes.  This device fits a niche where full blown traffic signals aren't needed, but pedestrian safety at a high volume crossing is a concern.  The system cost about half what a normal signal would (it cost about $80,000) and has limited effect on traffic since it is dark the vast majority of the time.

According to Tom's presentation, here are some of his observations –

  • Vehicles did not stop for the dark signal (this was a major concern – vehicles historically have a tendency to stop at a dark signal, but the system is signed to encourage motorists to stop only on the red light).
  • Its use was intuitive for pedestrians – there wasn't a learning curve.
  • Some vehicles have a tendency to drive through on the beginning of the red light.
  • The flashing red lights at the end of the phase caused some confusion.  Mn/DOT is changing from both lights flashing red at the same time to a wig-wag flash (like the red lights at a railroad crossing).

I applaud Mn/DOT and St. Cloud for testing this innovative device!

  • Hey Mike, huge fan of the blog. I’m designing a HAWK signal right now for a town in Virginia. Did the folks at Mn/DOT explain how to calculate walk and flashing do not walk intervals for a HAWK signal? The MUTCD doesn’t offer any guidance on this…

  • Here’s Tom’s Presentation –
    You may want to call him directly. I think the flashing don’t walk is based on 4 feet/second full with crossing, but I don’t know that for a fact. Here’s the sequence from the presentation:
    Traffic signal dark/Don’t walk active
    -Ped pushbutton activated
    -Flashing yellow begins (7 seconds)
    -Solid yellow (4.0 seconds)
    -All red (3.0 seconds) prior to walk indication
    -Walk indication (10 seconds)
    -Flashing Don’t Walk/Flashing red traffic signal
    -Dark signal/Don’t walk

  • Dear Mike: I have never been to your blog before; I only found it by searching for info on the HAWK signal. I am encouraged by your subtitle, “Views From a Licensed Engineer,” because I truly hope a licensed engineer can explain to me why this signal isn’t a horrible idea.
    New signals should be based on old signals; that is, based on signals that drivers are already used to. Thus, established signals should always mean the same thing in every situation. So…
    1) Double-red? I don’t think this is a common signal. So the double-red means the same thing as the usual single-red, “STOP.” The double-red just seems more serious about it. It conveys the same message, but why tell drivers to stop by any message other than the single red?
    2) MOST IMPORTANTLY – alternating red signals at the HAWK intersection means “Stop, then proceed with caution when safe.” WHO DESIGNED THIS?? Can you think of another example where you see alternating red lights? I can think of two. The first one is a railroad crossing. In this case, it means “STOP! OR YOU’LL BE HIT BY A TRAIN.” The second example is a school bus, which means “STOP! OR YOU’LL RUN OVER A CHILD.” In both cases, drivers MUST stop. WHY would you design this signal to use alternating red lights to indicate “Stop, then proceed.” This is NOT CONSISTANT.
    3) I’m just spit-balling here, but if you want a signal that saves electricity… put up a STANDARD TRAFFIC LIGHT. (This also saves money by not requiring the production of special signals.) It stays OFF under standard conditions. When a pedestrian pushes the button, it turns on the GREEN light for vehicle traffic. That’s a signal everyone is used to. Then, it turns yellow… and then red… LIKE A NORMAL TRAFFIC LIGHT! Traffic stops, pedestrians cross… and then it turns green again, and after a few seconds, shuts off until the next button-press.
    Yeah, MUTCD doesn’t like “dark” signals that aren’t bagged – but I’m sure you could get around it with signage. It would make a lot more sense than the HAWK.
    …and just to add to my disdain… who came up with that name? “High-intensity Activated crossWalK” ?? I can accept “Activated crossWalK”, but I think they just added “High-intensity” to get the H in… is there a low-intensity version? Obviously not.
    AWK just isn’t a good name because it makes you think of “awkward,” which describes this signal perfectly.

  • CH,
    It’s clear you’ve done a lot of research on HAWK (and yes the acronym is a stretch). I think we come from different perspectives on this. I’m an experimenter by nature, so I see nothing wrong with testing out new traffic control and see where the data leads us. The presentations I’ve seen on the HAWK show it is a useful, safe tool that seems to work. There are no silver bullets, but I for one want more feasible options not less.
    That said, it’s a very expensive tool so it needs to be used to solve a very significant problem.

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    Mike Spack

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