This page outlines how I typically introduce students to the concept of "Situations of Uncertainty" and the importance of being able to recognize them.
My teaching style is to ask questions to elicit a discussion and draw out the information from the student -- how you explain it to your student would of course depend on your teaching style and the needs and abilities of your student, but this page may give you some ideas of how to start.
In my experience, it makes no difference whether I introduce these concepts before or after students have learned to cross at traffic signals.
Note that throughout the discussion, I carefully avoid suggesting that I'm going to teach them what is safe to cross, or whether they should cross in these situations.
This is especially true when working with teenagers, who often are testing their limits and feel invincible -- I do not attempt to pierce that armor.
Rather, I present it as an interesting challenge -- I'm letting them in on a secret that most people don't realize (that is, the fact that there are situations where even someone with normal vision and hearing can't tell it's clear to cross!), and challenging them simply to recognize these situations.
Discussions about what is "safe" and whether they should cross come later.
Discussion with student:
"Now we are going to work on crossings where there is no stop sign or traffic signal for the street we are crossing.
Can you think of some examples of this kind of crossing?
What is the traffic like at these crossings?
Are there any patterns of traffic movement there?
How is this different from the traffic at crossings with stop signs or traffic signals, where the appropriate time to cross is usually well-defined?"
"For these crossings that have no pattern of traffic movement, when would be a good time for pedestrians to cross?
How can pedestrians recognize it's a good time to cross?"
Together the student and I come up with all 3 ways to cross these streets, as listed below but at this stage, I just cover the first two briefly and then focus on the third way to cross ("cross when it's clear to cross").
I cover the issues of yielding drivers in more detail later, when the student is learning about alternatives and learning to analyze risks.
1. Cross when all approaching drivers have yielded/stopped.
We discuss how they can recognize that all drivers have yielded.
the ability of the pedestrian to hear other vehicles.
2. Cross by assuming that all approaching drivers will yield.
We discuss how reliable it is to trust that drivers will stop for pedestrians who have the right of way.
This includes a discussion of the student's experience with yielding, if any, and my experience/observations, and research about yielding.
3. Cross when it's clear to cross (during a "crossable gap").
THIS is the strategy that I focus on at this stage.
"How could you recognize it is clear enough to cross?"
If students say they know it's clear to cross whenever it is quiet (or whenever they hear/see nothing coming), I tell them that used to be true at every crossing (60 years ago) and it is still true in some situations, but not in others.
"There are some situations where we cannot assume that it is clear to cross when we hear/see nothing coming (even when it is quiet) because we cannot hear (see) the approaching vehicles with enough warning, and these are called 'Situations of Uncertainty.'"
"All of us (even those who have perfect vision and perfect hearing!) have Situations of Uncertainty where we can't tell whether it's clear to cross, and it is very important to be able to recognize those situations."
"The purpose of our lesson is for you to learn to recognize these "Situations of Uncertainty" - situations where you cannot be certain that nothing is coming that would have to slow down for you."
If they ask what they should do in a Situation of Uncertainty (or if they ask what good would it do to know they are in a Situation of Uncertainty!), I sometimes discuss it with them but more often I am eager to take them out to discover and recognize Situations of Uncertainty and the discussion is so much more meaningful when we are there, so I assure them that we will discuss that in great detail as soon as we find a Situation of Uncertainty.
"We will go to crossings where there is no traffic signal or stop sign and analyze whether or not those are Situations of Uncertainty."
Often I ask the students to think about how we could analyze the crossings to figure out whether or not they are Situations of Uncertainty, and together we come up with some version of timing their detection of the vehicles and comparing it to their crossing time, but I sometimes I simply explain how we will use the TMAD to analyze the situations.
alternatives for situations where the risk is not acceptable.
NOTE: There are only 3 ways that I know of for pedestrians to cross streets with no traffic control:
Cross when all drivers have yielded;
Cross with the expectation that drivers will yield, and
Cross when it's clear to cross (that is, when you know that no vehicle is approaching that could reach the pedestrian during the crossing).
Other strategies that have been developed, such as crossing with a parallel vehicle, all seem to be designed to accomplish one of the 3 ways to cross that are already listed here --
that is, to help identify when it is clear to cross, or to increase the likelihood that drivers will yield to the pedestrian.