PHOTO #1: You said "Yes"
-- GREAT! You are correct -- I timed my detection of 35 cars from this direction and was able to hear all of them far enough to know it's clear to cross that half of the street whenever it is quiet (click here for observations).



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PHOTO #1: You said "No"
-- OOPS! You were wrong -- a person with normal hearing and walking speed CAN hear the traffic coming from the left well enough to know that if it is quiet, nothing is coming that would reach him before he finishes crossing that half of the street.

I timed my detection of 35 cars from this direction and was able to hear all of them far enough to know it's clear to cross that half of the street whenever it is quiet (click here for observations).



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PHOTO #3: You said "Yes"
-- GREAT! You are correct, you can hear the traffic coming from the right far enough to know it's clear to cross whenever it is quiet.



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PHOTO #3: You said "No"
-- OOPS, you were wrong! A person with normal hearing and walking speed CAN hear the traffic coming from the right well enough to know that if it is quiet, nothing is coming that would reach him before he finishes crossing the entire street.



Click here for a video of this crossing

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PHOTO #2: You said "Yes"
-- GREAT, you are correct! I timed my detection of 36 cars from this direction and even though there is a bend to the right and the traffic often approaches at more than 50 mph, whenever it was quiet I was able to hear all of the vehicles far enough to know it was clear to cross all three lanes (click here for observations).



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PHOTO #2: You said "No"
-- OOPS, you were wrong! Amazingly, even though there is a sharp bend in the road to the right and the traffic often approaches at more than 50 mph and the pedestrian must cross 3 lanes, a person with normal hearing and walking speed CAN hear the traffic coming from beyond the bend well enough to know that if it is quiet, nothing is coming that would reach him before he finishes crossing the entire street (click here for measurements of the detection of 36 vehicles from this direction).



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PHOTO #4: You said "Yes"
-- GREAT! You are correct, you can hear the traffic coming from the left far enough to know it's clear to cross that half of the street whenever it is quiet.



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PHOTO #4: You said "No"
-- OOPS, you were wrong! A person with normal hearing and walking speed CAN hear the traffic coming from the left well enough to know that if it is quiet, nothing is coming that would reach him before he finishes crossing that half of the street.



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PHOTO #3: You said "Yes"
Oops -- you were wrong! This was one of the sites for research that Dr. Rob Wall Emerson and I did (see article), and we found that it was not possible for experienced blind people with normal hearing to hear vehicles from the right until after they appear around the bend. Even though the speed limit is 25 mph and vehicles go no more than 40 mph around the bend, some of them were not heard until they were only 4 seconds away, which is not enough time for people with normal walking speed to cross.



Click here for a video of this crossing

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PHOTO #3: You said "No"
GREAT -- you were right! This was one of the sites for research that Dr. Rob Wall Emerson and I did (see article), and we found that it was not possible for experienced blind people with normal hearing to hear vehicles from the right until after they appear around the bend. Even though the speed limit is 25 mph and vehicles go no more than 40 mph around the bend, some of them were not heard until they were only 4 seconds away, which is not enough time for people to cross with normal walking speed.



Click here for a video of this crossing

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PHOTO #5: You said "Yes"
OOPS -- you were wrong, but don't feel badly, I was fooled just like you were! (Click here for the story.) Even though the traffic is visible for a long distance, for some strange reason it is not possible to hear them until they reach the bottom of the hill, and by that time some of them are too close and/or fast and would have to slow down to avoid hitting a pedestrian who started to cross when it was still quiet (just before the vehicle could be heard).

For a modification that made it possible to hear the vehicles better from this intersection, see "Environmental Modifications to Improve Crossings with No Traffic Control")



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PHOTO #5: You said "No"
GREAT -- you were right! Hey, you did better than I did, I was fooled by this one (click here for the story). Even though the traffic is visible for a long distance, for some strange reason it is not possible to hear them until they reach the bottom of the hill, and by that time some of them are too close and/or fast and would have to slow down to avoid hitting a pedestrian who started to cross when it was still quiet (just before the vehicle could be heard).

For a modification that made it possible to hear the vehicles better from this intersection, see "Environmental Modifications to Improve Crossings with No Traffic Control")



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PHOTO #4: You said "Yes"
-- GREAT, you are correct! This was one of the sites for research that Dr. Rob Wall Emerson and I did (see article), and we found that even though there are trees blocking the view and a gentle bend in the road, whenever it was quiet, blind people with normal hearing could hear the traffic coming from the left well enough to know it's clear to cross that half of the street.



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PHOTO #4: You said "No"
-- OOPS, you were wrong! This was one of the sites for research that Dr. Rob Wall Emerson and I did (see article), and we found that even though there are trees blocking the view and a gentle bend in the road, whenever it was quiet, blind people with normal hearing could hear the traffic coming from the left well enough to know it's clear to cross that half of the street.



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PHOTO #7: You said "Yes"
OOPS, you were wrong! When tall vehicles are parked to the right of the pedestrian, they block the sound of the approaching traffic so that even when it is quiet, it is not possible to hear the approaching vehicles until they are too close. If a person started to cross while it was still quiet (just before the approaching vehicle could be heard), the vehicle would have to slow down or stop to avoid hitting him.



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PHOTO #7: You said "No"
GREAT -- you were right! When tall vehicles are parked to the right of the pedestrian, they block the sound of the approaching traffic so that even when it is quiet, it is not possible to hear the approaching vehicles until they are too close. If a person started to cross while it was still quiet (just before the approaching vehicle could be heard), the vehicle would have to slow down or stop to avoid hitting him.



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PHOTO #6: You said "Yes"
-- GREAT, you are correct! In this situation, whenever it is quiet you can hear the traffic coming from the right far enough to know it's clear to cross the entire street.



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PHOTO #6: You said "No"
-- OOPS, you were wrong! In this situation, a person with normal hearing and walking speed CAN hear the traffic coming from the right well enough to know that if it is quiet, nothing is coming that would reach him before he finishes crossing the entire street.



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The video below shows a car approaching the crossing in Photo #3:



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Oops -- way wrong!

You can go back and try again, or
click here to find the answer.































Oops -- wrong!

You can go back and try again, or
click here to find the answer.































Oops -- wrong, but you were close! As you suspected, the speed of each vehicle had very little effect on how well the subjects could hear it approaching.

If you want to see the graph of the data you can click here.

Otherwise, you can go back and guess again,
or click here to find the answer.































Correct! Can you believe it?

The factor that had absolutely no relationship whatsoever to how well the subjects heard a vehicle approaching was:

how loud the vehicle itself was!

Yeah, it blew our minds, too. You can click here to see the graph of the data --
otherwise, click here to return to the Self-Study Guide.































You probably won't believe this --

The factor that had absolutely no relationship whatsoever to how well the subjects heard a vehicle approaching was:

how loud the vehicle itself was!

Yeah, it blew our minds, too. You can click here to see the graph of the data -- it's a total scatterplot showing no relationships whatsoever.

Otherwise, click here to return to the Self-Study Guide.































Correct! As the ambient noise level increased, it got harder and harder to hear the vehicles above the masking sounds, as you can see in the chart below (click here for a description of the chart). Well, it makes sense, doesn't it? That's why people say to wait until it is quiet to cross.

You can click here to return to the Self-Study Guide.





























Oops -- wrong, but you're very close! The presence of a sharp bend in the road or a hill had a great effect on how well the subjects heard the vehicles approaching, but it wasn't the most significant factor.

You can go back and try again, or
click here to find the answer.































Oops -- way wrong! The speed of each vehicle had very little effect on how well the subjects could hear it.

If you want to see the graph of the data you can click here.

Otherwise, you can go back and guess again,
or click here to find the answer.































WAY wrong! Can you believe it?

The sound level of the vehicle itself has absolutely nothing to do with how well the subjects can hear it approaching!

Yeah, it blew our minds, too. You can click here to see the graph of the data --
otherwise, click here to return to the Self-Study Guide.































The factor that affected the subjects' ability to hear the vehicles approaching the MOST was
the level of ambient sound.
This is probably not a surprise, if you think about it -- as the ambient noise level increases, it gets harder and harder to hear the vehicles above the masking sounds, as you can see in the chart below (click here for a description of the chart). That's why people say to wait until it is quiet to cross.

You can click here to return to the Self-Study Guide.



































. . . observe and analyze how well you can hear / see the traffic in THAT situation and determine if you have enough warning!

The only way to determine if you are in a situation of uncertainty for gap judgment is to
observe and analyze how well you can hear / see the traffic in THAT situation
and determine if you have enough warning!



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