Applications! WORKSHEET for Teaching Crossings
Welcome and congratulations! This is the last in a series of pages recommended in the "Self-Study Guide: Preparing Visually Impaired Students to Assess and Cross Streets with No Traffic Control."
vignettes, a workshop, and frequently-asked questions that may give you ideas and insights after you have read pages 1-9 of the Self-Study Guide.
Where There Is No Stop Sign or Traffic Signal
APPLICATIONS WORKSHEET LINKS
FREQUENTLY-ASKED QUESTIONS about teaching at crossings with no stop sign or traffic signal
- Strategies for crossing:
Are strategies such as crossing with a parallel car, or timing receding cars, safe and reliable for knowing when it's clear to cross these streets?
- When to teach these skills:
Do you teach these skills early in O&M training, or are they for advanced students, or interspersed within other curriculum topics?
- Length of training:
How long does it usually take to teach the skills and concepts needed for these crossings?
- Children / cognitive disabilities:
Can students who are young and/or have cognitive disabilities learn these concepts?
What kinds of goals and objectives would be appropriate in the student's individualized O&M program for crossings with no traffic control?
Why should we avoid the word "safe" when teaching students to recognize situations of uncertainty for gap judgment?
- Why these situations exist today:
Sixty years ago it was always "safe to cross when quiet" -- why is that not always true today?
- Quiet cars:
Do quiet cars affect these crossings?
How did you get interested in this issue, and how did you figure out how to teach these concepts and skills?
- Curriculum / liability:
Are these skills and concepts in our curriculum? Won't I be at risk for liability if I teach something that isn't accepted as standard practice?
This offers hands-on, feet-in-the-street practice applying what you've learned -- you might give yourself a workshop, following the exercises that participants did in this workshop!
The workshop covers teaching students to:
Understanding crossing time
This lesson took place years ago, but I remember it vividly because it proved something that I had just started to suspect after more than a decade of teaching people at uncontrolled crossings:
Sometimes, all that students need so they can judge these crossings is a good understanding of their crossing time.
As a result of a few lessons like this, I no longer ask students to judge crossings until I've made sure they understand their need for time to cross.
This preparation, which usually takes only 10-15 minutes, has enabled students to learn to judge street crossings much quicker and, more importantly, they "get it" more reliably than they do without that understanding.
Click here to see a video of this crossing
The student (represented in these photos by my son, Stephan) was 14 years old, and had a lot of vision.
I wanted to teach him to be able to recognize situations of uncertainty for gap judgment (that is, situations where he cannot predict whether or not it is clear to cross).
I chose the crosswalk in front of his school, where the street is 4 lanes wide, and there is no traffic signal or stop sign [see photo to the left].
I asked his mother to join us for the last part of the lesson.
I didn't feel comfortable timing the student's crossing there, because I couldn't hear or see the cars from the right far enough to know whether it was clear to cross. So before I started the lesson, I measured the width of the street by counting paces across the crosswalk [photo to the right]
and then measured an equal distance from a curb in a nearby parking lot.
Luckily, it ended at a white line near a hedge that I used as a marker [below].
I started the lesson by taking the student to the crosswalk, and telling him that there are places where it is not possible for people to see the traffic well enough to know if there is something coming that would have to slow down to avoid hitting them.
I made sure he understood that this is true of everyone, and not because of any deficiency on his part.
I said I wondered if he would be able to recognize such a situation
(this kind of challenge seems to work better than talking about whether something is "safe," especially for teenage boys who show no fear of anything!).
I asked him to watch what happens with the traffic here, and tell me if he thinks it is one of those places where it isn't possible to see far enough to know whether or not something is coming, and told him we would then test his judgment.
After he watched for a few moments, we saw a vehicle from the right just appear over the horizon.
I said, "Oh, there is a good example! If you had started to cross just before you saw that truck -- that is, when you didn't see anything coming -- would the driver have had to slow down to avoid hitting you? Or would you have made it to the other side before he got there?"
The truck flew past us very soon after we saw it. He calmly said he could have made it across all four lanes before the truck got there, without the driver having to slow down.
I said "Great, thanks! Okay, now we are going to test your judgment and see if you were right.
To do that, we first need to find out how much time you need to cross the street. I have marked an area in the parking lot that is the same width as this street, so let's go there and time your crossing."
In the parking lot, he walked quickly from my marker to the curb while I timed him. I told him it took 10 seconds. He crossed back and it was the same time.
We stood at the marker and I asked him to pretend he was crossing to the curb, and tell me when he starts (in his mind), then tell me when he thinks he finishes the crossing.
He said he was starting his imaginary crossing, and I started the stopwatch. Five seconds later he said he would have reached the other side.
I told him that was only half the time he needed. I said, "I'll show you what your crossing is like. If you started NOW," [I started the timer] "you'd be crossing ..... you'd be in the middle about now, and ... [the stopwatch said 10 seconds] NOW you would be on the other side.
Okay, you try again with another imaginary crossing."
He said he was starting to cross (in his mind), and I started the stopwatch again.
This time he didn't say he was finished until exactly 10 seconds had passed. I knew he understood it when he timed it correctly a few more times.
It was not until later that I appreciated how quickly he learned it -- most of my clients have needed more practice timing imaginary crossings than he did before they "get it."
So we went back to the crosswalk again and I said, "Now that we have your crossing time, we can test whether you were right about being able to see far enough to know whether something is coming that might have to slow down to avoid hitting you. Please watch the traffic from the right and tell me as soon as you see something that might be a car coming."
He watched the traffic, and then said he saw a car coming. I started the timer, and then stopped the timer when the vehicle passed in front of us.
"What do you think?" I said. "If you had started your crossing just before you saw him, would you have made it to the other side?"
"No way!" he said.
I told him he was right -- it passed us less than 7 seconds after we saw it.
I asked where he'd be when it passed, if he had started crossing just before he saw the car (when he still thought nothing was coming). He said correctly that he would have been in the third lane, right where the car passed. It definitely would have had to slow down or take evasive action to avoid hitting him.
By this time, his mother had joined us.
The student and I talked about whether it was likely that a car would be coming just as he started to cross, and how likely that it would stop for him.
He thought it was fairly likely that a car would be coming (it was fairly busy at that time) but that it was also likely that the driver would slow down or stop for him because it was a crosswalk in front of a school, with a pedestrian sign facing the drivers from each direction.
I asked if he thought the risk of crossing there was acceptable (that is, whether he felt it was "safe" to cross). He said it was.
To my surprise his mother, who works as a school security officer, agreed.
Whenever my students and I find ourselves in a situation where it's not possible to know whether it's clear to cross, regardless of whether the risk is acceptable, I always talk about alternatives.
So I said, "Okay. There will be times in your life that you will find places where you don't think the risk is acceptable, so let's talk about what you might do then. Let's pretend, for example, that you wanted to cross the street to catch a bus, and you felt that the risk of crossing here was not acceptable. What else could you do?"
He came up with some ways he could reduce the risk of crossing there as well as some good alternatives, and then said, "Another alternative is that I could cross to the middle and then wait and cross the second half."
I said, "That alternative has some risks too -- there is no place to stand, it's just a few painted lines, so you would be standing in the middle of the street, and if you continue crossing because a car slows down or stops for you, another car might speed past it without seeing you. Are you okay with that?"
He said yes.
I turned to his mother and asked, "Would you be okay with that?"
"No," she said with her eyes wide with alarm, "I'm NOT okay with that! It is not safe to stand there in the middle of the street."
I told them about the alternative of starting to cross when it seems clear but turning around if something comes before you reach the middle, and explained that this works only when you can see well enough to know it's clear to cross at least half the street. They both felt okay with that alternative. I also explained the kinds of engineering changes that can be made to narrow the crossing and make it safer (see examples).
We continued talking about other alternatives, and then finished the lesson.
In this lesson, the student had greatly improved his ability to judge whether he can be sure there is time to cross.
The lesson also gave him some experience evaluating the risks and making decisions (which at his age are ultimately made by his parents but he needs to prepare for adulthood) as well as considering alternatives.
And of course I had learned a lesson too, about the importance of understanding crossing time!
Safety vs. confidence
I learned a valuable lesson in the use of the word "safe" one day.
This happened a year or two after I had already learned that teenage boys' idea of "safe" and my idea of "safe" were very different, so that I had to avoid using the word "safe" with them (see the Peabody Study).
But apparently I'm a slow learner and I didn't yet realize that EVERYONE's idea of "safe" is different from everyone else's, not just teenage boys -- I continued to use the word "safe" with my adult clients.
So there I was, standing with my client facing a street she'd have to cross to get to her community swimming pool.
The street looked like the one in the photo to the right -- it had two narrow lanes on each side of a wide, grassy divider, and half a block to our right the street ended at a driveway that went into her apartment complex.
We had already spent several lessons assessing four unfamiliar intersections, all of which had been recorded for my videotape. Each time, she had accurately determined whether or not she could hear approaching vehicles with enough warning to be confident it was clear to cross when quiet.
In fact, when I took her to a crossing where I was sure we would be able to hear the approaching vehicles well enough (because I could see them quite far away -- see Photo #7), it was she who pointed out that we couldn't.
And now we were assessing her own street, which again seemed to me to be a piece of cake, since it was quiet and she only had to cross 2 narrow lanes at a time.
As we listened, I realized to my dismay that for some strange reason, I was unable to hear the cars with enough warning! I said, "So what do you think? Is it safe to cross here?"
"Yes," she said.
I was horrified! I had videotaped her doing so well with assessing situations of uncertainty for gap judgment, I had already reported that she could assess them very accurately, and here she was, saying that this place was safe to cross when any FOOL could tell just by listening that you CAN'T TELL WHETHER OR NOT IT'S CLEAR TO CROSS!
I gulped and said, "So..... you think you can hear the cars here with enough warning to know that it is clear to cross whenever it is quiet?"
"Oh, no, of course I can't!" she said. "You didn't ask me that, you asked me if it was safe to cross."
She explained, "Even though I can't hear the cars until they are fairly close, the chance that a car is coming when I step out is very small and even if it does, they are going so slowly that it is highly likely that the driver would stop for me, so I feel that it would be safe to cross here.
But it wouldn't be safe at 5:30 when everyone is coming home, that would be too risky for me."
I thought to myself, "OH!"
I asked myself, "When will you ever learn, you idiot?
How many times do you need to have this happen before you realize that asking people if it's safe to cross is very different from asking them if they can tell whether or not it is clear to cross?!"
I am so grateful that this woman was so insightful, and could distinguish (and explain to me!) the difference between "safe" and "confident it is clear to cross."
I finally learned my lesson.
Ever since that day, I have avoided asking anyone "Do you think it's safe to cross?" when I really mean "is this a situation where you can be confident about whether it is clear to cross?"
When considering risks, what do you think is more important -- the likelihood that you'll be surprised by a car that will have to slow down to avoid hitting you,
or the likelihood that you'll get hit?
On this lesson, Mimi realized that she should consider both.
Mimi was learning aboutseparate right-turning lanes
at the SW corner (shown to the left)
and the SE corner (to the right)
of the intersection shown in the drawing below.
Mimi thought they would be easy to cross since they were only one lane wide, but she soon discovered that the intersection was too noisy for her to hear some of the approaching cars until they were just a second or two away.
That was too close to be sure there was time to cross even one lane, and in some cases it wasn't enough time for drivers to stop if she had stepped out just before she heard them.
I then asked her to evaluate the level of risk for crossing each, and decide whether the risk would be acceptable. The two corners are shown below:
Southeast corner -- (the inside angle of the corner is 45 degrees, so the traffic has to turn about 135 degrees to get around it).
Southwest corner -- (the inside angle of the corner is 135 degrees, so the traffic has to turn only 45 degrees to get around it).
Without thinking, she replied that the lane at the SE corner was more risky because it had much more traffic passing through it.
Traffic at that corner was congested and vehicles sometimes lined up to turn there, especially when one of them was waiting for pedestrians to cross.
At the SW corner, however, we usually had to wait several minutes before a car passed through that right-turn lane.
So at the SE corner it certainly was much more likely that a car would be coming just when we started to cross.
But when she thought about which corner had a higher risk that a vehicle would hit her, she realized it was the SW corner.
At the SE corner, we figured the drivers were much more likely to yield because:
they were going more slowly because they had to make a sharper turn (research shows that slower drivers are more likely to yield);
they were more likely to expect pedestrians there (there were lots of pedestrians crossing); and
observation bore out that most of the drivers there yielded (some of the drivers stopped for us even if we weren't intending to cross).
At the SW corner, traffic was rare but when it did pass through:
drivers were going much faster (they barely had to turn, and if they saw no traffic on the street they were turning into, drivers didn't even slow down to merge);
drivers were less likely to expect pedestrians -- we were the only pedestrians there (there was nothing but an auto dealership on the corner to attact them);
none of the drivers stopped for us.
So at the SW corner, even though it was much less likely that a car would be coming when we stepped out to cross than it was at the SE corner, it was much more likely that we'd be hit.
Mimi concluded that the SW turning lane was more risky than the SE one.
She felt that the risk of crossing at the SE corner was acceptable if she reduced the risks as much as possible (cross when it was congested and traffic there was slow, warn drivers she intends to cross before stepping out, etc.).
She did not feel that the risk at the SW corner was acceptable, and if she needed to get to that corner, she would have considered alternatives.
Using vision and hearing:
Lorraine and David both needed to learn when they can trust their vision to detect vehicles, and when they can trust their hearing.
Lorraine underestimated and David overestimated the value of their hearing, and neither of them understood the effect of masking sounds.
Lorraine's lesson was videotaped in 1990, and I was still learning as I was doing!
In that lesson, I learned that for street-crossing skills, it is much more effective to have students practice using their vision and their hearing separately than using both at once.
By the time David had his lesson a few years later, I had also learned the importance of teaching people to scan because of a frightening incident (see Journey to Understanding).
But I still had a lot to learn -- it would be another 10 years before I realized the value of having students understand their own crossing time (that is, understand at a gut level, not just in terms of numbers) before trying to judge crossings (see Vignette 1).
That is probably why I had to spend so much time working with students on these crossings before they understood -- the lesson described below is Lorraine's THIRD lesson working exclusively on these kinds of crossings.
Vignette 4 --
LESSON 1: WHEN TO USE VISION / WHEN TO USE HEARING?
Lorraine was 72 years old and recently widowed, and had lost some of her vision 3 years earlier from optic neuropathy. She wanted O&M training because she was afraid of crossing streets, especially at crossings like the one in front of her building where there is no stop sign or traffic signal (no traffic control).
We had been developing Lorraine's ability to judge crossings by analyzing 4 crossings with no traffic control, including the one in front of her building.
For this lesson, we went back to one of the places we had already analyzed and determined that she couldn't hear or see well enough to know when it was clear to cross.
This street was two lanes wide, and we figured that the reason Lorraine couldn't hear the cars far enough was because of a noisy intersection half a block to our right, and the reason she couldn't see the cars far enough was because they came over a hill very close to our left.
So we wanted to find out if she could see or hear better from the top of the hill.
It was indeed quieter at the top of the hill. To our left, the road was straight for about a block and then it had a sharp bend to the left. Beyond the bend, I could glimpse the cars between the trees.
As Lorraine started to observe the traffic, she reported seeing a car from the left, but said she actually heard it before she saw it.
When I suggested that maybe she can hear the traffic better than she can see there, she said, "I LOOK for the cars, I don't listen for them.
I want to be SURE, I would rather see than hear them. If I hear them, I don't trust it, because I'm so used to seeing.
And there are a lot of places I'll be crossing where there is a lot of noise, and I need to be able to see them."
We then talked about her vision, and the fact that it isn't as good as it was. She said that she has noticed that lately it has been getting worse.
I said that there are some places where her vision will be more helpful than her hearing, and other places where her hearing will be better than her vision.
"Just for fun," I said, "let's see which is better at this place -- looking or listening."
After watching for a while, Lorraine reported that she could hear some of the cars before she saw them, but others she could see before she heard them.
Knowing what I know now, I suspect that when she was able to see the cars before she could hear them, it was because it wasn't quiet.
Anyway, I finally figured that in order to learn to use the hearing and the vision efficiently, it would be best to concentrate on one or the other at a time.
Since Lorraine preferred to use her vision, I said, "Let's see if you can see them far enough away here and if not, let's see if you can hear them far enough."
As Lorraine observed the cars, I made a humming noise to try to mask the cars' sound so she would not be alerted to their presence before she saw them.
Now that I realize this may sometimes be necessary, I bring a tape recorder to make background noise at a steady level (I also use the recorded noise to help students understand the effect of masking sounds -- see workshop).
By isolating her vision, we learned how it works. Lorraine said, "if the car is dark, I don't see it but the light ones, I do."
We noticed that she could see the cars a block away as they moved from side to side between the trees, but after they had come around the bend and were approaching her head-on, she was unable to see them until they got very close.
I've learned since then that this is typical of people with decreased acuity and/or central scotomas -- at a distance, they can't see the cars unless they see some movement (which means they sometimes see cars from the right better than from the left because traffic from the right is not approaching them directly).
After some more observations, we concluded that Lorraine could see all the cars far enough from the left (where she only needed half as much time to cross), but could not see some of the cars from the right until they were too close.
So we started to observe how well she could hear the cars.
Again, this was a great learning experience for Lorraine -- she had been unaware of how masking sounds can reduce her ability to hear the cars,
and she had difficulty deciding when it was quiet enough.
Several times, a car snuck up without her being able to hear it because there was still sound from receding cars, and each time I had to point out that it wasn't quiet when she heard that car.
After enough of these experiences, she began to understand that in order to use her hearing, she had to wait until it was quiet.
At first, she didn't let it get quiet enough, so I asked to to please tap her cane when she thought it was quiet enough, then tell me next time she heard a car. After a while, she got the idea, and waited till it got quiet enough before listening for the cars.
When it was quiet, Lorraine was able to hear all the cars from plenty far away, such that she could be confident that it was clear to cross whenever it was quiet there.
We talked about our conclusions:
Dona: Wow, you can hear them quite a distance when it's quiet ... QUITE a distance.
Lorraine: I should listen till it's real quiet, then make a move.
Dona: Yes, when it is quiet you can really hear them far away ...
Lorraine: that's true!
Dona: ... AND it's consistent! you can hear ALL of them quite far away, but when looking, you saw some of them from far away but not all of them.
In this session, Lorraine had learned how to use her hearing effectively to determine when it's clear to cross, and gained confidence in it.
She learned in other sessions how to judge when the hearing or the vision is sufficient, and when neither is sufficient to assure her that it is clear to cross, even when it is quiet.
And I had learned that isolating the vision and hearing helps teach people to use each of them effectively!
Vignette 4 --
LESSON 2: CAN YOU USE HEARING AND VISION TOGETHER?
David saw nothing at night except lights with his 5 degrees of good acuity.
He carpooled from work but wanted to be able to use the bus instead.
To do that, he would have to cross an exceptionally busy, two-lane street where there is no stop sign or traffic signal for at least a mile.
Of course part of David's comprehensive O&M program included learning to evaluate and cross where there is no stop sign or traffic signal,
so he was eager to do it at his crossing at night.
I asked David whether he would cross by looking or by listening, and he said both; he would look for headlights and at the same time listen for approaching cars.
For example after he sees that there are no vehicles approaching from the left, he would turn and watch for a clearing on the right while listening for cars from his left.
At first David said that the left was tricky because there was a bend in the road about a block away, but after further discussion he revealed that he felt he could start to cross even if he sees a car just coming around the bend.
On the right, where he could see vehicles from twice as far away, he felt he could judge when they were far enough away that he could cross.
Oooooh, this was turning out to be a VERY interesting case! It would require almost every kind of skill needed for these kinds of crossings:
From the right we'd want to be sure he actually can judge the speed and distance of the vehicles accurately when all he can see are the headlights (TMASD);
From the left we'd want to be sure he was right that when he sees a car just coming around the bend, there is still enough time to cross before it can arrive (TMAD);
Since he is relying on being able to hear the cars from the left while he's looking toward his right, we need to make sure he understands how to use his hearing and understands the effect of masking sounds.
We decided first to test David's judgment that he could cross when a car was seen coming around the bend on his left. We timed his crossing and used the TMAD, which showed that he was right -- no car ever reached him in less than 7 seconds once he saw it around the corner, and he only needed 3 seconds to cross the first half of the street.
BINGO -- One down, and two to go!
We next tested David's judgment of the approaching cars from the right, using the TMASD.
I showed him how to use the timer, and asked him to start it at the last moment that he felt that the approaching cars were still far enough away for him to cross.
He did so for a variety of cars, and always pressed the timer when they were at least 8 seconds away.
We concluded that with his present vision, he could determine the speed and distance of those cars well enough to judge when they were far enough away that he could cross.
TWO down, only one to go!
David had said that he was relying on his hearing as well as his sight, so I wanted him to find out what information his hearing was actually providing him. I asked him to close his eyes and listen for the cars to find out if he could hear them from far enough away to detect them sufficiently.
David was amazed to discover that because there were always sounds of receding cars present, he usually could not hear the approaching cars until they were almost upon him.
David then decided that rather than depending on listening for cars from the left while he watched the right, whenever there is a clearing on the right, he should glance back to the left before starting to cross.
We then tested whether his glancing was sufficient, because by then I knew that some people cannot detect cars dependably by glancing and must instead scan slowly or hold their gaze for a moment (see "Scanning for Cars").
We tested his ability by having him turn his head to glance to the left whenever I gave the signal, then immediately look away and report whether he saw any vehicles. I gave him the signal to glance sometimes when there was nothing coming, and other times when there was a car coming.
We found that David could consistently detect the presence or absence of vehicles from the left by glancing.
So that means he can watch traffic from the right and when he judges that it's okay there, he can glance to the left and if that is clear also, he can start to cross while turning to look at the right again.
Afterwards, David said the lesson was very helpful. He had been worried about coming home at night by himself, and after this session he felt confident that he can do so.
We had subsequent lessons at this and other intersections to make sure that David could recognize when he cannot see well enough to know it's clear, and be able to judge when there is too much noise to depend on his hearing.
This session with Ammar took place after I had been teaching people at crossings with no traffic signal or stop sign (no traffic control) for only about 5 years.
I had not yet learned to avoid using the word "safe" when I actually mean "able to be certain it's clear,"
nor did I realize that students will "get it" much quicker if I first explain that there are places where even the most highly trained blind traveler will not be able to hear the traffic well enough to know whether it's clear to cross.
Nevertheless, Ammar was very intelligent, creative, and open to new ideas, so he made up for my lack of experience. It was from lessons like this that I improved my teaching strategies.
Ammar had O&M training as a teenager, when he had good functional vision, and now that he was totally blind he wanted a comprehensive review of his skills.
Of course for me, a "comprehensive O&M review" included making sure he can recognize situations where he cannot be sure whether it is clear to cross!
So we went to the busy, winding, two-lane residential street that he had crossed often as a child to get to his elementary school.
Even now, as a young adult, he often walked along it for about half a mile to get to the nearest bus stop, so he was very familiar with the street.
As we stood at the curb, I asked him to listen and consider whether he can hear the cars well enough to cross there.
He waited, and at a quiet moment he said, "I would cross now."
I explained that I didn't want to know WHEN it was safe to cross, I wanted to know IF it was safe -- that is, whether he could hear the vehicles well enough to know that whenever it was quiet, it was clear to cross.
He then listened, but apparently still didn't know what I wanted him to consider, because he failed to notice that it wasn't possible to hear the vehicles from the right until they were very close to us.
He said that he felt he could cross there safely when it was quiet.
When we used the TMAD to test his judgment, he realized that even though he could hear cars from the left almost three times as far as needed, he couldn't hear them from the right far enough to be sure it was clear to get even half way across.
He was astonished, and at first he couldn't believe it was true. He thought that with practice he could learn to hear the traffic better.
I explained that many intersections are like this, and that all the training and practice in the world couldn't enable him to hear them well enough there, because the sound of the traffic was blocked by a hill to our right.
He then suggested we try it again from about a block to our left, where we might be able to hear traffic from the right further.
After we walked to our new location, I again asked him to listen and decide if he could hear well enough there.
This time he was no longer naive and knew what to listen for, and so this time he analyzed it carefully.
He noticed that, although the cars from the left were heard less far than they were at the first corner, there was still plenty of warning from the left, and cars from the right could now be heard from further away -- just enough, he thought, to be able to cross the street during a lull.
The TMAD showed that this time he was right.
Cars from the left could still be heard about twice as far as needed, and cars from the right were detected at least a second further than needed to cross -- which was, as he had predicted, just barely enough time.
He said he learned a lot from this session that he hadn't realized, and he will listen more carefully in the future.
I felt confident that he would no longer assume that he is safe if he crosses whenever it is quiet -- he will observe and notice whether he can hear the cars well enough to be sure it is clear to cross when quiet.
What is "quiet" and why does it matter? Teaching a student with a cognitive disability
NOTE: For a discussion of what "quiet" means, see "Effect of background noise ('ambient sound level')"
Although this vignette is not about crossing a street with no stop sign or traffic control, it addresses the principles of listening for cars, identifying and avoiding or reducing dangers, etc.
The student's name is Jay. He is a young man with a cognitive disability and a visual impairment -- he can see cars only about 10 feet away.
I worked with O&M intern Eldre Boggs to teach Jay orientation and cane skills, problem-solving, dealing with the public appropriately (including safety with strangers and controlling his temper), shopping, etc.
When he was ready to work on street crossings, we needed to develop a basic understanding of intersections (he didn't even know what a "corner" is) and traffic movement.
Someone had apparently taught him some simple "rules of safety" for crossing but, as demonstrated during this lesson, rules may be useless without understanding the reasons behind them, such as what dangers exist and how to avoid them.
So we set about to teach him basic concepts of intersections, traffic movement, and the real purpose of "quiet" for crossings.
We started by using a tactile map of an intersection, with toy cars to simulate traffic movement but, not surprisingly, he didn't get much out of that exercise.
However, when all three of us pretended to be cars traveling on intersecting sidewalks that we pretended were roads, he was able to learn
what corners and lanes are, why traffic needs to stay on the right side of the road, which direction he can expect traffic from while standing on the curb and while crossing, etc.
[I've also had success teaching concepts of traffic movement by having my client and me pretend to be vehicles and pedestrians in narrow, intersecting hallways, which is often easier for students who cannot see sidewalks.]
We had some fun "crashes" when one of us was on the wrong side of the road or turned left when someone else was coming straight, and he learned why a car coming toward an intersecting street whose traffic doesn't stop would have to stop and wait for traffic on that street to clear before entering it.
Then we walked to the corner of his community entrance on a busy two-lane street called Donaldson Road (shown to the right) to observe the traffic and talk about crossings.
He said he'd be safe crossing the entrance as long as he was in the crosswalk.
We observed the traffic for a while, and he noticed that the cars coming out of his entrance all stopped, and cars on Donaldson didn't.
We talked about why they stopped, the purpose of the stop
sign, and what would happen if the stop sign was removed and no one at the intersection stopped, like we had done in our simulations.
We imagined ourselves walking across the entrance, and then imagined ourselves crossing Donaldson, and talked about which would be more dangerous.
By this time, he seemed to understand how the traffic behaves at the intersection, and what it means to cross a busy street with no traffic control, like Donaldson, compared to crossing a quiet street where there is a stop sign, like his entrance.
Next we considered the safety and risks of crossing the entrance.
He had previously said he'd be safe if he was in the crosswalk, so we observed the traffic to see which vehicles went through the crosswalk and where they came from.
Before long, Jay was able to point to the 3 sources of danger for crossing there -- traffic turning left from Donaldson to go into the entrance; traffic coming out of the entrance; and traffic turning right from Donaldson to go into the entrance, as shown in the photos below.
Jay was starting to realize that being in the crosswalk wasn't necessarily safe, so we thought about how to avoid having any cars pass through or approach the crosswalk when we are crossing.
When he was prompted to think about how he could know whether anything was coming when he started to cross, Jay remembered there is a rule that
it is safe for him to cross when he hears no cars.
Jay said he couldn't hear any cars, so it was safe to cross.
YIKES! Thank goodness this happened when a very loud leaf blower was about 20 feet away, and I realized that Jay didn't understand
the concept and reasoning behind that rule.
He could barely hear me yelling in his ear next to him, so of COURSE he couldn't hear any cars, but that
didn't mean there weren't any cars coming!
I explained that rather than cross when he hears no cars, what he REALLY needs to do is cross when he is sure that nothing is coming
that might hit him.
I pointed out that with the loud noise from the leaf-blower, he couldn't be sure nothing was coming because he couldn't hear the cars until they were very close.
I explained that the same would be true when there was any noise, such as an airplane or traffic sounds.
While the leaf-blower was still there, we watched the traffic and saw two cars flying into the crosswalk from Donaldson with no warning -- we never heard them and by the time Jay saw them, they were already in the crosswalk.
After the leaf-blower left, Jay observed traffic sounds. He noticed that when it was quiet, he could hear the cars very far away, but
if there were other noises, he couldn't hear the cars coming until they were very close.
We sometimes noticed that we could hear a car very far off and if there was another car behind it, we couldn't hear the second one until it was right in front of us.
Once Jay understood how masking sounds can prevent him from hearing the cars with enough warning, I had him guess when it was quiet
enough that he could hear the cars far enough to be sure nothing is coming. At first he was accepting too much
noise, but then he would notice that when the noise was at that level, he
couldn't hear the cars until they were too close. After enough of this experience and feedback, Jay became accurate with
judging when it was quiet enough to hear the cars far enough away.
After this training, Jay could cross the entrance safely using real-life strategies, rather than using rules that he didn't understand how to apply.
NOTE: We were very fortunate that the leaf-blower was there making a loud noise just as Jay was deciding when it was safe to cross!
You can duplicate that situation by creating a loud, steady noise (such as with a tape recording) and ask your students if they can be confident it is clear to cross with that noise there.
Having a noise that remains steady can also be useful for helping students recognize how much noise is too much; turn on the recorded steady noise and ask if they can still hear the cars well enough to know it's clear to cross,
then test their judgment using the TMAD.
Teaching hypothetical / abstract concepts to a concrete learner
Myisha, a young woman who is deaf and visually impaired, has difficulty
envisioning hypothetical situations.
So I avoid teaching Myisha unnecessary abstract concepts and, when the concepts are necessary,
I try to illustrate with examples as they actually occur, or set up situations she can experience, which isn't always easy.
- when we were at a traffic
signal and I signed, "when you cross, where do you need to be looking?" Myisha
answered, "I wouldn't cross -- the sign says "don't walk"! I had to ask again when the sign said, "WALK."
- even though she wanted to learn to travel better at night because she can't see in the dark, when I signed "let's practice finding your home without looking, so you can find it at night" she answered, "I can see fine now, I'd
find it by looking for the gate." I had to think of other ways to practice using non-visual information.
Concepts / skills needed?
One day we were walking across a busy intersection with a traffic signal. Because of construction in the street,
Myisha did not reach the last two lanes until after her signal was red.
She looked to the right, saw traffic approaching, figured they were far enough away and began to cross the last lanes.
Yeow! In my panic, I simply explained that it is against the law to cross during the red light and that we should stand by the construction and wait till it says "walk" again.
But I was not being truthful. Pedestrians who start to cross during the "WALK" signal DO have the right of way until they complete the crossing.
And I was not being realistic. All of us have crossed when the signal is red, and Myisha found herself in a situation where she had to make decisions about whether to complete her crossing or not.
So when I thought about it, I realized that the concepts Myisha needs in order to make good decisions for this situation include:
Wow! This list seemed daunting, and I was tempted to just teach Myisha some simple, concrete rules instead!
- the pedestrian laws, including when she legally has the right of way AND the fact that drivers and pedestrians don't know about those laws!
the drivers surely did not realize she would have had the right of way if she had crossed those last two lanes when they had the green signal;
- the yielding behavior of drivers, including the fact that they are less likely to yield when they are
- going fast (as those cars were);
- not expecting pedestrians (such as when pedestrians are still in the crosswalk while their signal is red).
- how to determine when the approaching vehicles are sufficiently slow and/or far away that she could cross without depending on them to yield or slow down;
- the "multiple threat" problem that exists where there is more than one lane and a driver yields, so that other drivers might pass (see the story of a child hit at a traffic signal in exactly this situation because of multiple threat at "Blind Pedestrian Killed").
But I know of no simple rules that can guide her in every situation.
And I know that the more simple and concrete the rules are, the more likely they can be dangerously misleading, like they were for Jay in Vignette 6.
And it seemed unfair to assume that there was any skill or concept on that list that Myisha could not learn. My very favorite saying is from Joanne Laurent:
"If you can't learn it, I'm not teaching it right!"
I became determined to do my very best to teach Myisha all these concepts and skills.
So I looked for a good place to teach her how to recognize when the traffic is too close or fast to allow her to cross without expecting them to stop for her.
I found a crosswalk on a one-way street with no stop sign or traffic signal for two blocks. It had a parking lane on each side of the street and one lane in the middle for traffic to move.
Why are we standing here, timing the cars?
The night before the lesson, I thought and thought about how I could explain what we are doing. How could Myisha understand why we'd be standing and timing cars at a corner where she'd never cross?
The next day, even as we got out of the car, I was still wracking my brain!
I took a deep breath, searched for some inspiration, and found myself telling the story of how my friends Dick and Lorraine Evensen had been killed 20 years ago (click here to read the story).
What a serendipity -- this true story wasn't a hypothetical situation, it was reality, and it had many of the elements that I wanted to cover:
the multiple threat (they were killed by a driver who pulled past a car that had slowed down to yield to them),
the need to be able to determine whether the cars are too close and/or too fast to start crossing;
the pedestrian laws (the driver was not charged with anything except a $40 speeding ticket because my friends were a few feet away from the unpainted crosswalk and therefore didn't have the right of way).
Myisha was very moved by the story, and kept signing how sad it was that they died. She wanted to know what happened to the driver, and so we talked about who has the right of way, about crosswalks that are not painted, etc.
We talked about the multiple threat with more than one lane, and I was gratified when Myisha clearly explained and demonstrated how she should check for cars in the next lane before walking across the street in front of a yielding driver.
So that left the issue of teaching Myisha to be able to determine when traffic is approaching too fast or too close to start a crossing when you are not expecting them to slow down for you.
I told Myisha that I was sure that Lorraine (the woman who was killed) thought the cars were all far or slow enough to cross, but that she was wrong, and I wanted to make sure that Myisha wouldn't make that same mistake.
I told her that there was a way to teach this skill, called the "Timing Method for Assessing Speed and Distance of Vehicles" (TMASD).
I smiled and told her that I myself had needed to learn that skill -- when I went to the place where Dick and Lorraine were killed and used the TMASD, I misjudged when the cars were too close to allow me to cross, just as I think Lorraine did.
But with practice with the TMASD, I learned to do better.
I said I wanted to teach Myisha to do well also. Myisha agreed, and seemed eager to learn.
Can't we avoid teaching the basic concepts?
Which brings us to the whole point of this vignette. I wanted to teach Myisha to determine when the approaching vehicles are far and/or slow enough that she can cross without expecting them to slow down or yield.
I've learned that to teach any of these concepts, you need to understand your own crossing time -- not just in terms of how many seconds (that's easy!) but understand what that time feels like (see Vignette 1).
But I despaired of being able to teach Myisha such a
So instead, I
plunged in to teach her the way I taught people before I realized they need
to understand crossing time.
Yeow! All the difficulties that I used to have came back again! It takes
her 6 seconds to cross and she thought she had enough time to cross when the bus was
only 3 seconds away! We were both tired by then, so after I expressed my
dismay about how wrong she was, we suspended till the next day.
That night, again, I thought hard about how I could teach Myisha to
understand how long she needs to cross. I have had success teaching students with a cognitive disability by modeling what I want them to understand or do. Myisha does not seem to have a cognitive disability, but I decided that modeling might help me teach her anyway.
So the next day, I explained to Myisha that I wanted her to understand her own crossing time. Then, with the help of Krista
Bulger, a Salus University student who was observing our lesson, I demonstrated to Myisha what I wanted her to do.
I asked Krista to time me, and signed that I was "imagining" Myisha starting to cross. I signed "You are walking, crossing, you're still walking, you're on the other side ... NOW!" I looked to Krista and asked how I did.
Krista said my imaginary crossing was finished a little too soon. I said I was disappointed and wanted to try it again and do better, and so I went through it all again. This time I was accurate and finished my imaginary crossing in 6 seconds. I celebrated that I had done so well.
Having modeled what I wanted Myisha to do, I asked her to try it, but she still didn't understand what to do.
After I modeled it again several times she understood, and tried it herself.
Oops! My being able to do it so well backfired! When Myisha tried it, she badly underestimated the time she needed to cross (her imaginary crossing was finished in half the time she needed), and she was too embarrassed to try it again.
So I asked Krista to try it, and she didn't do so well either.
Myisha grinned and signed "Like me! You're like me!"
Myisha got brave and tried it again, and with a lot of practice with feedback, she became accurate with estimating time to cross!
Now we were ready for Myra to guess when the approaching cars were too close to start crossing.
Again, I first demonstrated how I wanted her to indicate when the approaching cars were too close.
I stood in front of her as we both looked toward the traffic. We saw a car coming from a distance, and I signed that "the cars were still far enough that I could cross ... still can cross ... still can cross ... it's getting 'iffy' ... uh-oh! Too late! It's too late to start crossing!"
I asked Krista how much time from when I thought it was too late until the car reached us, and it was a little longer than Myra's crossing time.
Again, I had to model it several times before Myisha got it, and the first time she tried it she again thought it was okay to cross until the car was only 3 seconds away.
We discussed the mistake. "Oh," I signed, "if you had started to cross when you still though it was okay, you wouldn't have time to finish! That car would have had to slow down to avoid hitting you!"
So she tried it again, and she got it! When she guessed it was too late to cross, the approaching car was 6 seconds away.
Hurray! With that success, we called it a day.
The next lesson, I took her to a two-way street that was a little wider than the first street (she needed 8 seconds to cross it) and again she demonstrated a good understanding of the crossing time.
When we were ready for her to judge when the traffic was too close to cross, I modeled it again and then asked her to watch the traffic from the right and tell me when it was not okay to cross.
She did not do well -- she thought it was still okay to cross until the cars were only 4 seconds away.
Oops! I realized that I was asking the wrong question.
She was probably right -- because those cars were not going fast, when they were more than 4 seconds away it probably was "okay to cross" (that is, there probably was a level of risk that she felt was acceptable -- see "Vignette 2 - Safety vs. Certainty").
Drivers at that speed are very likely to stop for her if they see her starting to cross when they are more than 4 seconds away.
I clarified that I didn't want to know when it was "okay to cross," I wanted to know when the cars were still far and/or slow enough that she could start a crossing and finish before they arrived without slowing down for her.
She soon became very accurate, as verified with the TMASD.
She could even adjust for the speed of the cars -- she knew that the slower cars could get closer than the fast cars before it was too late to start crossing. Hurray!
Scanning to the left:
People with Myisha's restricted visual field often need to learn to scan more slowly or they will miss seeing cars on their left, so before we finished I used the strategy described at "Scanning for cars."
Myisha had no problem seeing the cars, I don't know if it was because her visual field is large enough that slow scanning isn't necessary or because she naturally scans slowly enough (I suspect it is the former, as she did not seem to scan slowly).
Well, while Myisha was learning how to recognize when she can start to cross when she sees traffic approaching and when the traffic is too close to start crossing, I learned some lessons too. Some of them were lessons I had presumably already learned at least once! My lessons were:
stick to the basics! You can't take shortcuts, like trying to avoid teaching students to understand crossing time;
- if you are creative and persistent, you can teach hypothetical concepts to students who learn primarily from concrete experiences;
- be very careful when asking students to judge whether they have enough time to cross, and avoid subjective terms such as "okay to cross" and "safe to cross."
Hey, it's no surprise -- if you observe and measure and listen to (and obsess about!) something for more than 20 years, you eventually notice some interesting things!
So it is with me and crossings where there is no stop sign or traffic signal.
I'll share some of the things I've noticed, but then it's your turn! I'd like to know what you notice as you teach and observe crossings with no traffic control --
if you don't mind, I'll add your observations here, crediting you of course!
Some of the things I've noticed are explained elsewhere, such as
You can't predict whether a situation will be uncertain for judgment of gaps (this took me a LONG time to figure out!);
Some people have special needs for scanning and glancing to see the traffic in both directions, such as:
-- needing to scan slowly (I learned this the hard way -- see Journey to Understanding) or
-- needing to see movement rather than clarity and details (see Vignette #4)
We need to avoid the word "safe" when we really mean "certainty that it is clear;"
I DIDN'T notice any effect of quiet cars.
What follows are some things I learned or observed that aren't covered in other sections:
Freaky Finding #1: Effect of a person's position / height
Freaky Finding #2: Effect of background noise
Freaky Finding #3: Essential concepts
Freaky Finding #4: Traffic disappears / appears
Freaky Finding #1:
Effect of a person's position / height
You're going to think, "This is so obvious, why didn't you anticipate this?" But it took me a while to realize that what can be heard while standing in one position might be very different from what can be heard when standing just a few feet away
(heck, it took me a few years to be alert to the presence of things that can block sounds, such as the parked cars that affected the sounds in photos #6 and #7!).
It all started this way. I was with a group of O&M university students, showing them how to use the TMAD. One of them agreed to wear a blindfold and stand on the curb and listen for cars. I stood in the street just a few feet in front of her, and asked her to tell me the instant that she thought she heard a car coming.
When she said she heard something coming, I started the timer but figured she was mistaken because I heard nothing. But about 4 seconds later, I heard a car coming from her right. I dismissed it as a coincidence.
But then it happened again. And then again. She'd hear a car clearly and I'd hear nothing, but several seconds later, BOOM -- I would hear a car!
So I tried to figure out why she could hear so much further than I could. I looked around and .... DUH!
There was a van parked about 10 feet to my left (the woman's right), and it blocked the sounds of cars for me.
The woman, however, was tall and standing on the curb, so her head was a little higher than the top of the van. It didn't block the sound of cars for her.
Ah HA! That experience made me aware that children will sometimes hear things very differently from their instructors or parents. And I've become more astute at noticing things that can block or affect sounds, and no longer assume that my client will hear things the same as I do.
Freaky Finding #2:
Effect of background noise ("ambient sound level")
One of the first things I noticed is that at some places, you can hear the traffic quite well even with a lot of background ("ambient") noise but at other places, the slightest noise can drastically cut back on your ability to hear the traffic.
The sound of an airplane or a distant lawnmower can have little or no effect in some places but in others, it makes you unable to hear the vehicles until they get much closer.
This observation was verified more than 15 years after I first noticed it, in the research that Rob Wall Emerson and I did, studying the ability of blind people to hear approaching cars in 6 different situations.
In four of those situations, when the background noise got a little louder (increasing ambient sound from 36 to 40 dBA),
it seemed to have no effect -- people could still hear the cars just as well (or better than!) when it was as quiet as it can get.
In two of those situations (the first two photos to the left), the road was straight and you could hear the cars at a distance even when you tried to block the sounds with a board.
In another situation (the last photo), no matter how quiet it was, you couldn't hear the cars until they came around a sharp bend in the road.
So in all these situations, making the background noise a little louder had little or no effect.
However in at least one situation (when traffic was coming over a hill, as shown in the photo to the left), that same increase in ambient sound dramatically reduced the ability to hear the cars.
Click here to see the graph showing how the level of ambient sound at each of the 6 situations affected the ability to
hear the vehicles, as measured by the average "safety margin" -- notice how the line of the safety margin is dramatically reduced for the "hill" situation between 38 and 40 db(A) (it is also reduced for the "trees" situation but that varies wildly and randomly as the background noise increases).
I began to teach people not only to notice whether they can hear the cars well enough to know it's clear to cross when quiet, but also to evaluate how much ambient sound they can tolerate (how "quiet" it has to be) and still hear well enough.
Freaky Finding #3:
I've noticed that there are two concepts that are essential for people to understand in order to be able to evaluate situations and figure out whether they can be sure it is clear to cross:
understanding their own crossing time (in terms of the passage of time, not the number of seconds -- see Vignette 1); and
understanding that there are situations of uncertainty for gap judgment.
I first had a glimmer of the importance of understanding crossing time when I started to change how I teach people to recognize situations of uncertainty for gap judgment.
Whenever students didn't seem to "get it" after my initial explanation (I STILL haven't figured out how to explain it well!), I would wait for a car to approach and then ask the students if they thought they could have finished their crossing if they had started before they heard (or saw) the car.
When some of them reported that they could get across 4-7 lanes in what was actually just a few seconds, I started to realize that the reason they didn't "get it" was not because they didn't realize that they couldn't hear (or see) the traffic well enough, it was because they had no idea how much time they need to cross.
They may be able to tell me they need 7 seconds, but they have no idea how long 7 seconds really is.
This is true of EVERYONE, regardless of vision or intelligence, including university professors with normal vision (heck, it was true of ME before I started playing around with the stopwatch!).
I found that once they have real-time experience with their own crossing time, they can easily realize when they can't hear/see the traffic far enough to know when it is clear to cross.
Situations of uncertainty for gap judgment:
Sometimes when students have difficulty learning to evaluate situations, it turns out that they believed the myth or misconception that
whenever it's quiet, it is clear to cross.
As soon as they understand that this is true in some places but not true everywhere, they quickly learn to evaluate where it is true and where it is not true (see Vignette 5).
I think the reason they don't realize that the myth is not always true is that 60 years ago, when our O&M profession was founded, it WAS always true!
Stanley Suterko, one of the first 5 orientation and mobility specialists, told me
that when the blinded soldiers were afraid to cross streets because they couldn't see, the instructors would demonstrate that the soldiers could always hear the cars far enough away that they had plenty of time to cross, even if they started AFTER they heard the car.
As a result, when our profession codified its body of knowledge, this myth was written in just about every O&M textbook. It may have been true when it was first written, but it's not true any more (see Frequently Asked Questions).
As soon as students understand their own crossing time, and understand that this myth is no longer true everywhere, they usually learn very quickly how to distinguish when it's true and when it's not.
Freaky Finding #4:
Traffic disappears / appears
I have found places where you can hear (and/or see) all the vehicles from very far away, but then as the cars approach, they disappear and you can't hear them any more.
When they get closer, they reappear and you can hear them again.
These places can be dangerously misleading because you may assume that you can hear all the cars as they approach from a distance, and you'll be surprised, as I was.
How did I notice this?
The only reason I noticed this strange phenomenon is because I was collecting data at the street in front of my community.
So there I was on a hot summer day in 1995, sitting in a lawn chair and listening to the traffic.
Whenever it was quiet (unless I was busy explaining to my neighbors what I was doing!),
I recorded how many seconds passed from the moment that I first heard a vehicle until that vehicle passed me. Then I tried to predict whether that vehicle would turn out to be one of the shortest times I would record (why on earth would I want to know that? See the Peabody study to find out).
From the left, I heard the first seven cars an average of 15 seconds away. I was doing pretty well with predicting which would be the shortest times (so far, it was 10 seconds) when YEOW!
I didn't hear the next car until it was less than 8 seconds away! That car wasn't any quieter than the other cars -- what happened? Why didn't I hear it until it was much closer than the others?
I became determined not to be fooled again, and sat on the edge of the chair. I heard the next four cars at least 14 seconds away and then OOPS!
Another one snuck up on me -- I didn't hear it until it was less than 7 seconds away! Again, the car didn't seem any quieter than the others.
So I started to observe more carefully, to find out why certain cars were getting so close before I could hear them.
I heard the next fifteen cars an average of 13 seconds away (the shortest time was 10 seconds), and then there was another 8-second surprise.
By this time, I had noticed that if it was quiet, I could hear all the cars when they first appeared at the far bend in the road,
but then they each disappeared behind some bushes. I didn't hear them again until several seconds later, when they had passed those bushes.
SO . . . if it was quiet when the cars first came around the bend, I could hear them more than 10 seconds away, and then they disappeared behind the bushes.
BUT if it was noisy when they first came around the bend, then they disappeared behind the bushes without my being able to hear them.
If it got quiet after they went behind the bushes, the first time I could hear them was when they "reappeared" from behind the bushes several seconds later.
It didn't happen often (only 3 out of 35 vehicles) but when it did, I was caught off guard. I had thought that I could hear them all from a distance and then oops! One of them snuck up without my being able to hear it.
I didn't notice another situation like this until 14 years later (March, 2009), when I was helping a woman evaluate whether she could cross a street to get to the transit station.
We stood on a wide median strip, and listened to cars coming from the right.
When it was quiet, we could hear all the vehicles when they appeared at a distance, but then they went behind some trees and we couldn't hear them until they got closer.
Photo to the left shows where we stood at the curb on the grassy median.
So, what is the problem?
The first time we heard the cars, they were all far enough away that we knew that if we had started to cross just before we heard them, we could have finished our crossing before they got to us.
But by the time the vehicles disappeared behind the trees and then "reappeared" where we could hear them again, they were too close.
So when it became quiet, we weren't sure if we had time to cross, or if there was a car behind the trees that would have had to slow down or stop for us.
The series of photos below illustrate how the vehicles move as they approach us.
The first photo shows a bus and a car passing through the area where we could hear all the vehicles.
The car remains visible throughout the approach, but the bus disappears behind the trees and then appears again.
So, what the heck can we do about these situations?
I've thought about how these situations can be handled, and how to avoid being taken by surprise when you think it's clear to cross.
The first step, of course, is to notice that after you can hear the cars, they "disappear" for a few seconds.
Once you realize the situation, find out how long the vehicles usually take from the time that they disappear until you can hear them again.
Once you realize this is happening, you'll have to analyze it in several steps.
First, figure out whether the cars are far enough away when you first hear them.
That is, if you had started to cross just before you heard the cars the FIRST time (before they disappeared), would you have had enough time to cross?
If not, there is no reason to continue -- you can't ever be sure it is clear to cross.
But if you can hear them far enough away before they disappear, then figure out if you can still hear them far enough way when they "reappear."
If so, then you know it's clear to cross whenever it's quiet.
That was the case at the street in front of my community.
I only needed 5 seconds to cross the lanes with traffic from the left, and I was able to hear the cars after they "reappeared" more than 6 seconds away.
So I knew that whenever it was quiet, it was clear to cross, even if there was a car hidden behind the bushes.
But if you can hear the cars far enough when they first appear, but not after they "reappear," then you know it's clear to cross whenever it is quiet but only if you know that there are no cars that have temporarily "disappeared."
If that is the case, whenever it becomes quiet, we need to be sure there are no cars behind the trees.
What we can do is wait for it to stay quiet long enough that, if a vehicle had disappeared just before it got quiet, it would have had time to "reappear."
So if it stays quiet long enough and nothing "reappears," then we know there are no hidden vehicles, and it is clear to cross.
Frequently Asked Questions
Q: Are strategies such as crossing with a parallel car, or timing receding cars, safe and reliable for knowing when it's clear to cross these streets?
A: No, definitely not -- in fact, these strategies can sometimes increase the risk of crossing. Be sure to read "Fallacious/Dangerous Strategies for Crossing Streets
with no Traffic Signal or Stop Sign" to find out more about these strategies that rely on erroneous assumptions.
Return to Frequently Asked Questions
Q: Do you teach these skills early in O&M training, or are they for advanced students, or interspersed within other curriculum topics?
A: The answer is .... YES! To each of these questions!
Some of the basic concepts necessary for crossing with no traffic control (as well as for crossing at traffic signals!) can be taught early -- long before the child is old enough to cross streets independently and/or the adult client is even contemplating any crossings.
Some of these basics are (in no particular order):
understanding the layout of intersections;
understanding traffic movements and where to expect traffic moving in which direction;
recognizing the edge of the street;
being able to align, avoid and correct veers, etc.
understanding the width of lanes and streets,
understanding the time needed to cross;
being able to determine the width of streets.
These basics are all necessary for crossing any street (see the outline of skills and concepts).
Until recently, I had not realized the importance of understanding time/distance and predicting crossing time before learning to cross streets with no signals or stop signs, and this understanding is important for crossing at signals too.
Some of these time/distance concepts and kinesthetic skills can be taught indoors.
Once the students have these basics, they are ready to learn to cross at signals and at streets with no traffic control.
It doesn't seem to matter which one comes first. I've taught some students first to cross at signals and then taught them to recognize situations where they cannot tell when it is clear to cross at streets with no signal or stop sign,
and for others, vice versa. It really depends on which kinds of intersections are closer or more interesting for the students, or more necessary for their travel.
At both situations (signals and no traffic control), after they learn the concepts and skills needed for crossing there, I introduce the idea of considering what kinds of dangers there are at that crossing, how to reduce those risks, figure out whether the risks are acceptable, and make decisions about whether to cross or consider alternatives (see Street-Crossings: Analyzing Risks, Developing Strategies, and Making Decisions).
Return to Frequently Asked Questions
Q: How long does it usually take to teach the skills and concepts needed for these crossings?
A: Most of the skills and concepts don't take much time to teach, as participants discovered when doing the workshop -- often concepts such as crossing time and judging distance of lanes of passing vehicles can be taught in just a few minutes.
Teaching adult students all the skills needed for streets with no traffic control (including scanning and judging speed and distance of vehicles, which is not appropriate for some students) usually takes me a total of 2-3 hours (not counting the time I needed to plan the lesson and take the student to the sites), as outlined below.
learn about the width of lanes:
learn to determine how far away (in which lanes) the vehicles are as they pass along the street: 10-20 minutes
learn to accurately predict crossing time: 15 minutes (5 minutes each for several streets/widths)
Skills necessary only for crossings with no traffic signal or stop sign:
Recognize situations of uncertainty, understand about masking and blocking sounds: 1-2 hours
(3-4 sessions assessing different streets or conditions; time needed for these sessions depends on frequency of vehicles and gaps / silence.)
Learn to judge gap length of approaching traffic (for those who can do this): 15-30 minutes
Learn to scan / glance for traffic efficiently (for those who have vision): 15-30 minutes
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Q: Can students who are young and/or have cognitive disabilities learn these concepts?
A: Yes, I believe they can. I have worked with people with developmental disabilities whose vision varied from normal to no vision, and taught them to judge when it was clear to cross at streets with no traffic control (see Vignette 6).
However I have not tried to teach any of them to analyze unfamiliar crossings to recognize situations of uncertainty for gap detection themselves.
My experience is primarily with adults so if you work with children, I am hoping you will share your experience.
I participated in a lesson with a 10-year-old child during which he learned his own need for crossing time and learned to recognize situations where he cannot hear / see the traffic well enough to know whether it is clear to cross.
Some of the other concepts, such as time/distance, can be introduced early also (see FAQ: "Do you teach these skills early in O&M training?").
One caution -- apparently sighted children do not typically develop the ability to judge the speed and distance of approaching vehicles until they are about 10 years old, although I don't know if that is because they are incapable of learning it earlier or they just don't have that much experience until that age.
If you are working with young children with functional vision, perhaps you can try using the TMASD and see how young they can learn to judge the speed and distance of vehicles.
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Q. What kinds of goals and objectives would be appropriate in the student's individualized O&M program for crossings with no traffic control?
The primary goals of instruction when preparing students for crossings with no traffic control is to achieve proficiency in
Goals such as "The student will cross correctly" may be appropriate for signalized crossings, but typically not for crossings with no traffic control.
Below are a few examples of appropriate goals, but of course there is an infinite number of possible goals and objectives to prepare students for analyzing and crossing streets with no traffic control.
This list is meant only to give you ideas to help you generate individualized goals that would be appropriate for your student.
For an estimate of time needed for adult students to reach some of these goals, click here.
- analyzing the crossings to recognize situations of uncertainty for gap judgment,
- determining risks, and
- implementing alternatives.
When presented with a crossing with no traffic control which has risk that is unacceptable to the student, student will:
- When at a street with 3 or more lanes of traffic going the same direction, student will correctly identify the lane traveled by vehicles 9 out of 10 times
- Student will correctly follow the process for estimating the width of 10 out of 12 unfamiliar streets.
- When presented with 4 streets of different widths, student will accurately indicate his crossing time (from start to finish) 5 out of 5 times for each street.
- Given 5 crosswalks at streets with no traffic control, student will identify whether or not the crossings present a situation where it is possible to determine when it is clear to cross: 5 out of 5 times.
- When presented with 6 street-crossing situations, student will correctly follow the process to determine risk level 5 out of 6 times.
- When presented with an approaching vehicle from the left at 3 streets of various width, student will estimate, to the nearest second, the point at which the vehicle is still far enough away to allow the student time to cross half the street (including a predetermined safety margin) 9 out or 10 times at each street.
[Similar goals should be written for estimating the point at which vehicles from the right are still far enough away to cross the whole street.]
For information about teaching this, click here.
- (using residual vision) When presented with a crossing situation, student will accurately determine the presence or absence of vehicles approaching from one direction by glancing 9 out of 10 times.
- Student will accurately explain the pedestrian laws for our state.
- Student will correctly identify 7 alternatives to consider for crossing.
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- plan and execute an alternative route 2 times.
- get assistance to cross at least 2 times.
- identify environmental modifications that could make 3 crossings less risky.
- find and contact the appropriate traffic engineer who is responsible for that crossing and request modifications that would make the crossing less risky.
Q. Why should we avoid the word "safe" when teaching students to recognize situations of uncertainty for gap judgment?
A. When you teach students to recognize situations of uncertainty for gap judgment, you are teaching them to objectively observe and measure their own ability to hear or see approaching traffic while considering their crossing time.
The word "safe" is a subjective term.
The dictionary defines "safe" as being "free of risk" but, since nothing is actually free of risk, we normally mean that a thing is safe if its risks are "acceptable."
How much risk is acceptable is very subjective (see "Decisions, Decisions").
I used to make the mistake of asking people if they thought an intersection was "safe to cross," when I really meant to ask if they "can hear/see
well enough to know it is clear to cross" there (see Vignette 2: Safety vs. certainty). At the time, I considered "safety" and "certainty that it is clear" to both mean the same thing. Today I cringe when I read my own writing,
like the 1996 paper in which we repeatedly talked about teaching students to "improve their ability to determine their relative 'safety' in crossing streets" -- we even titled the paper "Teaching Students to Assess Safety
for Crossing Streets Which Have No Stop Sign or Traffic Signal."
But now I realize that feeling "certain that it is clear" to cross, and feeling that a "crossing is safe," are two different things, and each should be discussed separately (see Vignette 1).
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Q: Sixty years ago it was always "safe to cross when quiet" -- why is that not always true today?
A: I have been wondering about this ever since Stanley Suterko, one of the first 5 orientation and mobility specialists, told me that in the 1940's and 1950's, they could hear all the cars well enough to know that it was clear to cross whenever it was quiet (see story).
I now believe it is because the sound of cars moving along the streets was much louder then than it is now.
Even as late as 1970, car engines made more than twice as much noise as they do today, and little or no effort had been made to reduce the sound of vehicles moving along the streets.
Today, car engines are quieter (read about the Noise Control Act of 1972) and road surfaces and tires are being designed to make less noise (read about projects to mitigate noise).
Until recently, I thought there was also another reason.
When I was traveling through the isolated fjords of Norway, it was so quiet that we could hear a car coming from more than a mile away.
I imagined that maybe the American environment in the 1950's was like that -- "quiet" was really quiet -- and maybe that is why cars could be heard so far away then.
My belief was reinforced when Rob Wall Emerson and I studied the ability to hear vehicles at streets with no traffic control (see article).
The feature that most affected the ability to hear cars approaching from a distance was the ambient sound level -- that is, how quiet it was when the car was first heard.
But it seems that the ambient sound level in America has not increased, at least not in the last 40 years.
Rob and I measured the ambient sound level when "quiet" at residential and urban intersections in preparation for our research. Later I was amazed to discover that what we found is exactly the same as it was when measured in 1971 by Wyle Laboratories ("Community Noise," U.S. Environmental Protection Agency, Office of Noise Abatement and Control, Washington, DC).
Wyle laboratories measured the sound levels of about 30 communities in 1971. They found that the "residual noise level" (the level of "quiet") varied between communities.
For example, the daytime residual noise level for cities was 62-69 dB(A) and for urban/suburban residential areas it was 42-56 dB(A).
Based on their samplings, they categorized the various communities as follows:
Ambient noise level:
The level of ambient sound also varied during the day, being quietest at about 4:00 AM and loudest at about 4:00 PM.
The following shows a sample of levels of "quiet" for one community:
- "Quiet suburban residential": 38 dB(A) (range: 36-40)
- "Normal suburban residential": 43 dB(A) (41-45)
- "Urban residential": 48 dB(A) (46-50)
- "Noisy urban residential": 53 dB(A) (51-55)
- "Very noisy urban residential": 58 dB(A) (56-60)
- The range for cities was 62-69 dB(A)
In 2006, when Rob and I prepared to do our research, we sampled the level of sound at a variety of intersections, to be sure we were using "quiet" intersections.
We found the following:
- 2:00 AM ~30 db(A)
- 8:00-9:00 AM ~42 db(A)
- 4:00 PM ~48 db(A)
- Evening ~45 db(A)
- Midnight ~50 db(A) (there was a train idling nearby)
The intersections where we collected our data were in a community that lay among country clubs at the rural border of suburban Washington, DC.
When it was "quiet" at these intersections, the ambient sound level was lower than that of average residential intersections in 1971.
Yet at one of these intersections, it was still not possible to hear all the cars far enough to be sure it was clear to cross when quiet.
- At 12 intersections in Maryland’s residential suburban DC, the average level at "quiet" was 44 db(A) with a range of 37-49.5 db(A).
This fit into Wyle's categories "quiet residential" to "urban residential" areas.
- At 7 intersections in residential/business areas in Annapolis, the average level at "quiet" was 49.6 db(A) with a range of 45.5-53 db(A).
This fit into Wyle's categories "urban residential" to "noisy urban residential."
- At two intersections in downtown Atlanta the average level at "quiet" was 66.25 db(A) with a range of 63.5-69 db(A).
This fit exactly within the range Wyle found for cities in 1971.
When Stanley Suterko and the other pioneer O&M specialists and their consumers analyzed and crossed streets in the 1940's and 1950's, they were in downtown and suburban Chicago.
I think it is unlikely that those intersections were more quiet than the quietest residential intersections today, and yet Suterko said they never found a situation where it wasn't possible to hear the cars well enough to know it was safe to cross when quiet.
It is therefore not likely that part of the reason that they could always hear the cars with enough warning to be confident it was safe to cross when quiet is that their environment was quieter than it is today.
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Q. Do quiet cars affect these crossings?
A: Well, that depends on what you mean by "quiet cars."
If you mean that all cars today are quiet, then yes indeed -- I believe that is probably THE reason we are having problems hearing them well enough at some crossings with no traffic signal or stop sign, even when it is quiet.
We didn't have these problems when our O&M profession was developed 60 years ago, because the cars were at least twice as loud then as they are now (see Quiet Cars and the Safety of Blind Pedestrians).
But if you are talking about hybrids and other unusually quiet cars, although they can be a problem in situations where drivers are moving slowly or yielding, I believe that they probably have little or no effect at crossings with no traffic control.
After more than 20 years of observing and measuring the ability to hear vehicles, and many experiences being surprised by cars that we couldn't hear, I've never noticed a problem with a quiet or hybrid car except where they are moving very slowly or yielding, such as at traffic signals, separate right-turning lanes and roundabouts.
The problem with being unable to hear cars at some of the crossings with no traffic control started long before we had hybrid / quiet cars.
I first noticed it in 1988, 9 years before Toyota introduced the Prius to the Japanese market (HybridCars.com).
In our study of the ability of blind people to hear approaching vehicles at crossings where there is no traffic signal or stop sign, Dr. Rob Wall Emerson and I recorded the detection of 805 vehicles among 6 different road features, such as straight, curved, hills, etc. (see article).
We measured the speed and the sound level of the vehicles as they passed, as well as the ambient sound level (how loud the background noise was) at the time they were heard.
The factor that most affected people's ability to hear the vehicles was the ambient sound level at the time that they heard the vehicles. Next was features such as hills or bends in the road.
The factor that seemed to affect people's ability to hear the vehicles the least was how loud the vehicle itself was!
The table to the left (click here for an accessible description of the chart)
indicates data collected for 290 vehicles at one of the sites. It compares the loudness of each vehicle with how well it was heard (its safety margin).
The safety margin is a measure of how many seconds passed from the time that the vehicle was heard until it reached us -- since the average crossing time there is 7 seconds, a vehicle that was heard 7 seconds away was defined as having a safety margin of 0.
The table shows two vehicles that were quieter than the rest. They were both actually heard BETTER than the average cars.
In fact, all 5 of the quietest cars were heard better (had a higher safety margin for detection) than cars that were louder.
But since we didn't record any cars quieter than 58 db(A), we concluded that "further study is needed to determine how the new generation of hybrid and quiet internal combustion vehicles will affect these results."
The issue of quiet cars is being studied at Western Michigan University and other places, and we hope to find out more about where the hybrid and quiet cars can be a problem and how to solve it.
Preliminary studies indicate that when cars are going fast enough, reduced engine noise (such as is produced by electric and hybrid cars) is not a factor because the sound we hear at that speed is predominantly tire and wind noise.
Meanwhile, "we have a problem, Houston!" And the problem is not because of hybrids and unusually quiet cars, it's a problem with the sound of all cars, which is being reduced even more through the development of improved road surfaces, tires and automobiles (see "Quiet Cars and the Safety of Blind Pedestrians).
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Q: How did you get interested in this issue, and how did you figure out how to teach these concepts and skills?
A: The story of my understanding this issue is one with tragedy, insight, disappointments and triumphs -- see Journey to Understanding.
For the story of sharing these insights with our O&M profession, and the struggle to have them accepted as "best practice," see the acceptance speech for the Blaha Award.
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Q: Are these skills and concepts in our curriculum? Won't I be at risk for liability if I teach something that isn't accepted as standard practice?
The orientation and mobility (O&M) profession now considers teaching these skills and concepts to be best practice.
In 2008 the largest O&M professional organization in the world (AER's O&M Division) approved a position paper that outlines the skills and concepts needed for teaching at crossings with no traffic signal or stop sign (click here to read the position paper).
This position paper explicitly states that O&M programs "must prepare consumers who are blind or visually impaired to cross at these crosswalks by ensuring that they have the information, strategies, and skills necessary to assess these situations."
These include being able to:
I think the reason that people ask this question is that very little has been published about the need to teach students to recognize situations where they cannot tell when it's clear to cross.
But the new edition of the textbook Foundations of Orientation and Mobility, which hopefully will be published by AFB Press within the next year, will have a chapter on street crossings which covers these issues.
That chapter is written by Janet Barlow, Dr. Billie Louise Bentzen, Lukas Franck and myself, and it follows the same principles as are covered in these web pages.
- determine whether they can recognize gaps in traffic that are long enough to cross;
- determine the level of risk for crossing (including the likelihood that vehicles that they didn’t detect when they started their crossing could reach them and the likelihood that these drivers will yield to them);
- make informed decisions concerning the crossing; and
- maximize their detection / assessment of approaching vehicles.
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Self-Study Guide: what next?
Have you looked through the WORKSHOP
For Teaching to Cross With No Stop Sign or Traffic Signal?
The Workshop demonstrates some of the techniques being used, and has some activities that you can try yourself to apply some of what you've learned.
If you are done with the Workshop or choose to skip it, you might want to go to the Self-Study Guide to see if you've read all the recommended pages, and look at the Study Questions to see if you understand the essential concepts.
If you've read all the recommended pages and understand all the essential concepts, then congratulations -- you are DONE!
Click here to find out how to get a Certificate of Completion.
Return to WORKSHOP
For Teaching to Cross With No Stop Sign or Traffic Signal
Return to Situations of Uncertainty for Gap Judgment
Return to Self-Study Guide: Preparing Visually Impaired Students to Assess and Cross Streets with No Traffic Control
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