Section 4: Teaching to determine crossable gaps --
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to determine there is a crossable gap in approaching traffic
Determine when the traffic is far/slow enough by SCANNING or GLANCING left/right
As we've said before, people who use vision to cross a street need to assess the situation by looking at the traffic approaching from several directions, one at a time.
Thus, after they have practiced to become proficient with Determining Gaps in Approaching Traffic in one direction, students should learn to make that judgment accurately when scanning or glancing in that direction.
For issues that must be considered for scanning and glancing with various eye conditions, see page 7 in this section.
Procedure to train students to determine if there is a crossable gap in traffic while
scanning / glancing to each side
For this training, do NOT occlude the student's hearing
You may remember that when you are training students to scan or glance to detect the presence of vehicles, you occlude the students' hearing to make sure they can detect the vehicles even when there is too much noise to hear them.
But now you are training students to scan or glance to determine if the approaching vehicles are far/slow enough to allow you time to cross.
Research shows that judging the speed and distance of approaching vehicles involves hearing as well as vision, and you want the students to learn to make this judgment in realistic conditions, so
do NOT occlude the students' hearing for this training.
Once the students have learned to judge when the traffic in one direction is far/slow enough to allow them time to cross (as described on page 10), have them practice doing it by glancing as follows:
- Have the students face the street.
- Prepare the students by telling them that you will ask them to turn and glance at the approaching traffic in one direction and determine whether they would have time to cross.
They can report to you that either there is enough time to cross, or there is not, or that it is too close to call.
Tell them that for this exercise, they should look at the traffic just long enough to make that determination, then look forward again and report their judgment.
- Once the students are ready, wait until there is a vehicle or traffic approaching that you want them to judge.
I like to start out with situations that are obvious and easy to judge and, after they do well with those, I choose situations that are more difficult,
so the first few situations have approaching vehicles that are either much too close/fast or still plenty far/slow enough to allow the student time to cross.
When the approaching vehicle or traffic is where you want it to be, tell the student to turn and look.
- As soon as the student finishes glancing at the traffic and starts turning to face forward again, start a stopwatch, and ask the student if there would have been enough time to cross.
When the first vehicle passes the crosswalk, stop the watch and tell the student whether or not s/he was correct.
If the student reported that
For example, suppose the student's "X" is 6 seconds.
You ask the student to turn and look, and when the student has finished looking and is turning back to face straight ahead, you start the timer.
Meanwhile, the student reports that there would have been enough time to cross.
When the vehicle arrives, the stopwatch indicates it was 10 seconds away when the student was finished looking.
You report to the student that s/he was correct; there was enough time to cross when s/he had made the judgment.
- there would have been enough time to cross, s/he would have been correct if the time to arrival was at least "X" seconds, and incorrect if it was less.
- there wasn't time to cross, s/he would have been correct if the time for the vehicle to arrive was less than "X" seconds, and vice versa.
- it was too close to call, s/he would have been correct if the vehicle was "X" seconds away (give or take a second).
You may be asking, "Why start the timer when the student has finished looking and is turning to face forward again?"
It's because when the students are assessing situations and plan to cross,
they need to make sure they still have time to cross after they have made that determination, not when they first turned to look.
- If the students judged incorrectly (for example they thought it was too late to start a crossing but the stopwatch said there was plenty of time), they learn
from the feedback and try to improve the glancing next time. Usually what they needed was more time to view the approaching vehicles
before making their determination, but sometimes the problem is that they hadn't had enough practice Determining Gaps in Approaching Traffic.
- Continue until the student has demonstrated accuracy with glancing / scanning to assess whether there is time to cross.