Determine and Develop Intuitive Understanding of Crossing Time
Determine Crossing Time
If this is for assessing a crossing situation with two-way traffic, you will need two measurements:
the time to cross the first part of the street (for traffic coming from the left) and
the time to cross the entire street (for traffic coming from the right).
You can determine the time needed for the crossing by timing several crossings of the street (or an equivalent length) and use the longest time (if you want to read an example of using an equivalent length measured in a parking lot, click here).
To time the crossing:
Start the timer when the student is committed to the crossing.
Normally this means when the student starts to move into the street but in some instances, once students commit to the crossing they have to do something before stepping into the street.
For example some students may be committed to crossing once they
determine that it is clear to cross using a monocular (crossing time includes time to put down the monocular and get the cane ready); or
give a command for their guide dog to move forward (crossing time includes time for the dog to start crossing).
For students using vision, the crossing time for traffic from the right might have to include time to look for traffic from the left (teaching students to look for traffic right and left effectively is covered in Section 4).
Stop the timer when the student steps out of danger for that traffic.
For traffic from the left, this means when the student has stepped out of all lanes that can be used by that traffic, including turning lanes.
For traffic from the right, you and your students will need to determine where they are out of danger.
For example, in some situations they may be out of danger when they reach the parking lanes or the shoulder of the street, in other situations they are not out of danger until they cross those also.
Develop an "intuitive understanding" of crossing time
It took me more than a decade to realize that most people have difficulty recognizing Situations of Uncertainty unless they have an "intuitive understanding" of their crossing time -- a functional, gut-level cognitive understanding of the passing of time that they need to cross.
This intuitive understanding of crossing time also helps students who are learning to judge gaps in traffic (covered in Section 4)
and I've discovered that it is helpful for learning to cross signalized intersections as well (if you want to see an example, you can click here).
So before teaching students to recognize Situations of Uncertainty, I help them develop that untuitive understanding of their crossing time.
I was amazed that students do not develop this "intuitive understanding" of crossing time by crossing the street, even if you tell them how many seconds the crossing time is!
Isn't that astonishing?
The story of how I discovered that is shared in Vignette #1, and
my observations were supported with research by Dr. Shirin Hassan.
However, students can develop this intuitive understanding with the following exercise, which normally takes only about 5 minutes.
When / how to apply this skill:
Students should develop an intuitive understanding of their crossing time for streets of various widths.
With this skill, they'll understand (on a "gut" level) how much time they need to cross any street, once they determine how wide it is.
They should realize that they may naturally walk faster across streets that seem dangerous than they do at quiet residential streets.
Some students seem to retain this skill indefinitely, but some need to renew it.
I've found that if students have trouble in subsequent lessons comparing warning time of approaching vehicles with their crossing time or recognizing Situations of Uncertainty, it is helpful for them to review their intuitive understanding of crossing time for streets of that width.
Exercise for Developing Intutitive Understanding of crossing time
This is the procedure I use to help students develop an intuitive understanding of their crossing time:
Once the student knows how wide the street is and how much time is needed to cross it (or to cross the equivalent distance, such as in the parking lot shown in the photos to the right),
ask the student to imagine crossing the street, beginning when you start a timer.
Report when the student would have completed the crossing, based on the student's actual crossing times.
That is, when the time that the student needs to cross has passed, tell the student that is when s/he would have reached the other side.
For wide crossings, it often helps if you report to the student when she would have reached the second lane, the third lane, the middle of the street, the last lane, etc.
Next, ask the student to imagine crossing the street, reporting to you when she starts her imaginary crossing and when she thinks she would have reached the other side (mske sure she actually is imagining the crossing, not just counting! **).
Start a stopwatch when the student reports that the imaginary crossing has begun, and stop the watch when the student predicts she would have reached the other side
Tell the student whether she was accurate.
The exercise continues until the student can consistently measure the time needed to cross (give or take a second).
This may be reversed and the instructor asks the student to imagine starting to cross, then interrupts and ask the student to report where in the crossing she would be at that time.
The ability to determine this will be helpful later, when the student is listening/(looking) for approaching vehicles -- the student can predict where in the crosswalk she would have been if she had started to cross just before detecting an approaching vehicle and the driver hadn't slowed down for her.
** IMPORTANT NOTE: When students are learning to judge the time needed to cross, they should not be simply counting the seconds, just as they should not be counting steps when they are learning to judge distances.
Although some students enjoy the challenge of accurately measuring the passage of time and seconds (and doing so can be a fun additional exercise for these students), it is more important that they develop an intuitive understanding of the passing of time during their crossings.
This will allow them to make crossing judgments naturally and spontaneously, as most people do, rather than having to concentrate on counting or timing.
EXAMPLES OF DEVELOPING AN INTUITIVE UNDERSTANDING OF CROSSING TIME
Excerpts of this training are in the videos below. The first video shows the training being done remotely, while the student and I are each in our own homes and sharing a screen that shows the student's crosswalk.
The second video shows the training at a corner of a two-lane street.