The Story Told by the Blinking Hand

Joe Rose penned an interesting Q&A yesterday that takes up one of my favorite topics: the Flashing Don’t Walk (FDW) phase. While he caricatures the consequences of the widespread non-compliance with the FDW indication just a wee bit—it may cause motorists (gasp!) delays, and in extreme circumstances may even cause (gasp! recoil!) cycle failures, where all the cars don’t get through on a single green—he is correct that non-compliance is indeed widespread in downtown Portland.

That’s precisely what makes it a favorite topic: The FDW indication, at least when it comes with a countdown clock, is in clear violation of Brian’s First Rule of Traffic Engineering.

When people are disobeying your traffic control device en masse, there’s probably something wrong with your traffic control device (See: Circle, Ladd).

So what, then, could the issue be with something as universally accepted as a FDW indication? Perhaps some insight can be gleaned from comparing how signals handle pedestrians to how they treat vehicles.

Though we claim to prioritize pedestrians above other modes, our assignment of green time suggests otherwise. Pedestrians see a Walk phase for a given movement downtown for about 9 out of every 56 seconds during daytime hours, or about 16% of the time. By contrast cars will be assigned a green for 25 seconds, good for about 45% of the overall time. On the transit mall these percentages are often more skewed, since the pedestrian signals sometimes ‘rest’ in the Don’t Walk phase to quickly serve approaching transit vehicles. So if you were to assume random arrivals at an intersection, a car (or bike) is much more likely to see a ‘go’ indication than a pedestrian.

Of course, arrivals at intersections aren’t random; we specifically time our signals so a mixture of cars and bikes can progress smoothly through downtown at about 13 miles per hour. Since this is a little faster than most people not named ‘Bolt’ tend to travel on foot, the relative chances of arriving at a green indication are skewed further. And since turning movements on the downtown grid are what we’re concerning ourselves with here, let us not forget that these are commonly allowed on reds.

To be fair, our signals do some good things for pedestrians. The quick speed at which our downtown signals rotate through the indications (cycle length, in the jargon) serves to reduce pedestrian delay at the expense of auto capacity. And a happy consequence of the 13 mph progression speed for vehicles is that, if you were to walk opposite vehicular traffic at about 4.2 mph—a nice, brisk pace—you’ll catch all the Walk signals (and incidentally, you’d make it across an intersection in just more than half the time the countdown clock thinks it takes you). Still, though, relative to their wheeled counterparts, pedestrians are asked to endure a lot of delay at signals if they’re to follow the letter of the law.

To blame, of course, is the length of the FDW phase. Since pedestrians move more slowly than other modes, the time needed to clear them of the intersection—the clearance interval— is necessarily longer and thus the Walk time is naturally limited. Moreover, as the population ages average walking speeds are getting slower, so FDW times are getting longer. Not fair, but unavoidable, right?

A fun fact about Oregon is that we’re only one of a handful of states that treat the FDW and yellow lights with consistent logic, requiring the user to stop at both. But vehicles can proceed if it is unsafe to stop at a yellow, so as long as you know how to say, “Sorry, officer, I thought it’d be safer to keep going!” then the law really just means that you’re okay as long as you’re not still in the intersection at the onset of red. Still, though, this is better than the majority of states, which give vehicles far more leeway to enter an intersection on yellow.

But a when a countdown clock is present, it provides a lot of information, and so perhaps it is a useful ally here. Former Chicago DOT head John N. LaPlante examined the effects of countdown clocks [pdf] in a 2008 presentation to the Institute of Transportation Engineers, finding that more pedestrians began to cross during the FDW phase when a countdown clock was present, but fewer began walking late in the FDW interval, and fewer remained in the crosswalk at the onset of Don’t Walk. And guess what? Crashes decreased.

So what if we applied yellow-light logic to the FDW indication, allowing pedestrians to enter during this phase so long as they were clear by the end of the countdown? Revising our crossing laws to better reflect how people naturally interact with the indications makes sense from an engineering standpoint, and would be a powerful way to reinforce our stated claims regarding modal priority. And lest our fair city’s new-found fear of solving a problem with some new thinking cripple us, we can take comfort in the fact that those wily urbanists down in Salt Lake City provide precedent:

A COUNTDOWN CLOCK (displaying time in seconds remaining in the pedestrian crossing phase) in conjunction with the flashing orange UPRAISED HAND means that a pedestrian facing the signal indication may start to cross the roadway in the direction of the signal indication, but only if such pedestrian is able to safely walk completely across the street or to a safety island before the COUNTDOWN CLOCK shows no remaining time.

Traffic laws, right-of-way allocation, and signal timing combine to tell you just about everything there is to know about the transportation priorities of a particular place. That story is on full display when the countdown clock starts rolling.

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20 responses to “The Story Told by the Blinking Hand”

  1. I see many examples around town where the countdown clock starts at 20+ seconds, way more than the time it takes a pedestrian to cross. What’s the point of that? Is it really unreasonable for me to start walking when there are still 20 seconds left in the cycle?

    • The requirement of the 20+ seconds of Flashing Don’t Walk is a function of the Access Board wanting slower speeds accomodated at each crossing.

      The answer to this is what Salt Lake City did in their ordinance to allow people to legally enter as long as they have left the crosswalk when the indication goes to solid Don’t Walk.

      I wrote about the language used in the Salt Lake city example here:

      • Peter, something I thought about when writing this: I remember you mentioning at some point an experiment where an ITS device was “looking” for pedestrians in the crosswalk of an unusually long crossing near a seniors’ residence (Sandy Blvd., maybe?), and would automatically extend the FDW phase until they cleared. Am I recalling this right? How did that wind up working? Is it feasible (both from a cost & a technological perspective) to use this as an interim solution in sensible locations until we can enact a Salt Lake-style ordinance?

    • There at least was one at NW 5th or 6th and I think Couch or Davis (pretty sure it was on the north mall) that started at a high number yet governed a crossing of only two lanes. I’m assuming this was a programming error (and yes, I should have called/e-mailed it in).

      Overall, how about just getting rid of the flashing hand and go solely with the countdown timer? The pedestrians could use the full cycle as long as they are out of the street by the time the countdown reaches zero.

  2. It is illegal, but it’s definitely not unreasonable!

    The intent of the pedestrian timer is to allow most pedestrians enough time to clear the intersection. The assumed walking speed used to be 4 ft/s, but in the latest MUTCD the speed was reduced to 3.5 ft/s to accommodate more people. So this is leading to longer countdown times as the traffic signal team gets around to implementing the new timings. But since traffic engineers deal with 85th percentiles, even these new timings might be expected to strand the slowest 15% of peds, often elderly and/or disabled people.

    That’s why I think it’s the law that needs to be addressed. The way it’s written now, we are unable to accomplish simultaneously two very worthwhile things: accommodate as many walking speeds as possible while still giving pedestrians as much bandwidth as possible.

  3. I support the idea of implementing Utah’s sensible law here in Oregon.

    I would further add that a program of upgrading all crossings to have countdown timers should be implemented. After all, as pointed out, the most vulnerable pedestrians are those who most need that additional information about how much time remains to safely cross. Could someone make an ADA-based argument that now that the technology is widespread, it actually MUST be implemented or some other reasonable accommodation?

    • One thing I’ve seen other jurisdictions do (e.g., Washington DC) is start the countdown timer with the WALK phase rather than waiting for a FDW. This has some utility to everybody, in that I can decide pretty early whether to hustle to try to make the next crossing, or resign to miss it and relax my pace. For the slowest 15%, though, perhaps this is a good way to help them avoid getting stranded by starting their crossing too late in the WALK phase.

    • This seems like a good idea, but the way the Utah law is written, once the countdown stops, you have to have cleared the intersection, regardless of whether the light is still green for cars.

      Which brings me to my question: Sometime, the countdown times reaches 0 at the exact second that the traffic light turns yellow. Other times, it reaches 0, and then… nothing happens… for quite some time. I would say that the law should stipulate that the countdown timer must reach zero at the exact second that the traffic light turns yellow. Otherwise, a reasonable pedestrian would assume to not trust the countdown timer, as it is mis-calibrated and cannot be trusted to give an accurate representation of how much time is actually remaining to safely cross.

      Any thoughts, traffic engineers?

      • There are some situations where wide streets and heavy pedestrian traffic can prevent cars from turning right at all for the entire cycle. I think the countdown-ends-no-more-walkers, but the light’s still green is sometimes meant to fix that circumstance.
        However, perhaps that could’ve been better handled by an explicit green-right-arrow phase, or a walk-all-ways phase.

  4. Nice post, Brian! I think your observation about the following happy coincidence pretty much sums it up:

    “if you were to walk opposite vehicular traffic at about 4.2 mph—a nice, brisk pace–you’ll catch all the Walk signals”

    It’s just by coincidence. Pedestrians aren’t treated as if they’re going anywhere except across the street. I wonder if a pedestrian “green wave” has ever been tried anywhere? As an aside, 4.2 mi/hr is brisk indeed. That’s more than two standard deviations above a comfortable walking speed (Bohannon 1997).

    If there are enough pedestrians to seriously impact traffic flow by blocking turns or what have you, it might be time to think about a dedicated ped phase–maybe with scramble crossing!

    • I LOVE the idea of scramble crossings. I think they’d be difficult to implement, though, but oh-so-worth it.

      I think that if you wanted to slow down the walking speed for a ped to catch a green wave, you’d have to increase the cycle length of the downtown signals. This would increase delays for peds who weren’t part of the ‘wave,’ and increase auto capacity. But maybe it’d be worth it. It’d definitely be interesting to see if it changed people’s walking patterns.

      I’m not too surprised to learn that 4.2 mph is much faster than a comfortable speed (Thanks for the link, BTW…interesting paper). I walk faster than most everybody downtown (partially due to trying to keep up with the signals), and I can only catch 4 or 5 ‘WALKS’ in a row, even in the downhill direction. The fact that I often don’t have to stop on a 17-block walk to and from work speaks to the utility of ignoring the FDW laws. ;)

      • I’ve been advocating for adding a scramble to the cycle in downtown Portland for some time, but folks who resist change are strongly opposed to this idea.

        I would still like to see it seriously studied by a qualified traffic engineer, however. It seems to me that it could work, if:

        Pedestrians could only cross legally during the scramble phase


        The other light phases were reduced in length appropriately to allow sufficient time for the scramble to occur.

        The issue in downtown is that MAX needs enough time to clear the light phase with traffic, and every train needs to have its own cycle to move with. With the sheer volume of trains moving through the system, the number of light cycles per hour is effectively limited by the number of trains per hour on each alignment in each direction, as I understand it.

        The other question is whether enough vehicles could move through on each shortened green cycle to not jam up the system far worse than it is jammed today. I would speculate that this would indeed be possible, because by eliminating pedestrian movements during the non-scramble cycles, you could move more vehicles through the intersection by virtually eliminating the delays associated with turning vehicles waiting to yield to pedestrians.

        For bicycles, it would be a double benefit, as they would be able to move through intersections on either the vehicular or the scramble cycle (though they would need to move at a pedestrian speed during the scramble cycle).

        It seems to me to just be a math problem — insert scramble cycle, reduce vehicle movement times, preserve MAX train movements & schedule, solve for x. Anybody care to attempt to pull it off?

  5. Great writing Brian. I saw that article yesterday and thought it was ridiculous. People shouldnt have to stand there at a green light just on the off chance that a car might want to turn. And isnt it a basic principle that anyone turning should yield to someone going straight?

    On another note, how do you feel about jaywalking? Personally id like to see that “decriminalized” as long as they make sure no one is coming first.

    • “And isnt it a basic principle that anyone turning should yield to someone going straight?”

      Great question! It should be, but, well, no:

      Noting that we have one of the most progressive crosswalk laws in the country (Thanks, Oregon Walks!), even here the requirement that drivers ‘stop and stay stopped’ (much stronger than a requirement to yield) comes with the caveat that the pedestrian must be in compliance with the traffic control device.

      Re: jaywalking, my opinion is that when the pedestrian doesn’t have right-of-way (midblock or looking at a DON’T WALK signal), they should be allowed to cross after yielding to any car/bike traffic. We’re probably a long way away from that, sadly. But I find it’s often more comfortable to cross that way since by definition there are no vehicles you’re delaying by crossing. When you cross legally with a WALK, you’re often delaying turning vehicles and too much of the time they let you know it…

  6. Nice post. Thank you for putting into words some of my biggest reasons for behaving like some sort of militant pedestrian downtown. If you’re driving downtown, you’re in my house. You don’t own the place, so stop driving like you do. Downtown is for pedestrians. If you chose to drive there, you made a poor choice.

  7. I think it’s ridiculous for it to be illegal to enter on a flashing orange hand; particularly for streets where the the signal transitions to an orange hand with a very high counter almost immediately.

    Here’s my question, though:

    How many tickets has PPS written for this? You see people doing this all the time, and I can’t say I’ve ever heard of anyone getting a ticket.

  8. and for any PBOT folks reading, the neighborhood is cut in half in the Pearl on Lovejoy by the obscene light timing to cross Lovejoy. The signals give cars a very long sequence racing down Lovejoy, meaning no one [but me] waits for a Walk signal to cross it. You preference the car so much that you insure jaywalking. You create a very unsafe ped environment when you force folks to jaywalk!

  9. As a newcomer, I was unaware of the illegalality of crossing while the flashing hand was on.

    This seems ridiculous in some cases. SW Broadway @ SW College is particularly offensive as there is the buffered bike lane, a parking lane and two lanes of traffic to cross and multiple times it seems as if the crossing turns green, passes only a few seconds and then begins the 12 second countdown again.

    This is anecdotal and a classic “here is what I see” story but I notice it often as my family crosses here to get to the south park blocks and I often find myself picking my 4 year old son up to get across before the flashing hand stops.

    Hardly a reasonable condition for a cross “walk”

  10. I can usually dart across a narrow downtown intersection between “0” and when the crossing traffic actually gets their green. I figured this was jaywalking but had no idea it was actually illegal to cross after it starts just flashing. How many tickets have been written for that?

    Also, really hate any intersection the streetcar participates in. There can literally be a train providing a physical barrier to anybody running me over going the same direction as me but when it was caused by preempting the signs would have me wait for it to clear the intersection like a dummy, the cycle being reset, then the cars are given a green against me, until finally my turn comes.

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