Situations of Uncertainty for gap judgment -- What exactly are they?
Situations of Uncertainty for gap judgment (or simply "Situations of Uncertainty")
are situations at uncontrolled crossings where
you do not have enough warning about approaching vehicles to know whether or not it's clear to cross, even when it's as quiet as it can be in that situation.
It's very simple, really -- that's all there is to it:
Situations of Uncertainty are situations where you cannot hear / see the vehicles with enough warning to know whether something is coming that could reach you during your crossing, even when conditions in that situation are optimal!
All people find themselves in Situations of Uncertainty sometimes, whether they use vision or hearing, and whether they are walking or driving across the street.
Sometimes a crossing is a Situation of Uncertainty for hearing but not for vision or vice versa, and sometimes a crossing is a Situation of Uncertainty for both hearing and vision, and sometimes it is not a Situation of Uncertainty for either.
Examples of what happens at Situations of Uncertainty are:
In all of these cases, if they start to cross when it's quiet and they hear or see nothing coming, there could be a car coming just beyond their ability to detect it -- a car which would have to slow down to avoid hitting them.
- pedestrians using hearing may know that there is a gap in traffic whenever it gets quiet, but they don't know if that gap will be long enough to allow them time to cross.
There could be a vehicle that is close enough to be able to reach them during their crossing, but not close enoug for them to be able to hear, even though it is as quiet as possible for that situation.
- pedestrians and drivers using vision, because of something blocking their view, or something like fog, or glare, or impaired vision, are unable to see far enough to have sufficient warning about the approaching vehicles.
Situations of Confidence -- we CAN still be confident it is "clear to cross when quiet" in many situations today!
Situations of Confidence are situations at uncontrolled crossings in which you DO have enough warning about approaching vehicles
so that you can be confident about whether or not it's clear to cross.
People who use hearing to cross are in Situations of Confidence
whenever they can hear all the traffic with enough warning when it's quiet (or as quiet it gets in that situation)
that they can be confident that if any vehicles are coming that could reach them during their crossing, they'd be able to hear them.
Yeah, I know what you're thinking!
You had assumed that there are no longer any Situations of Confidence today for people who rely on hearing to cross, especially with the presence of quiet cars.
In Situations of Confidence for hearing, you can be confident that it is clear to cross ONLY WHEN IT IS QUIET, so you must be able to recognize when it is quiet!
This is covered in Section 4, which is about preparing your students to be able to cross in Situations of Confidence.
It discusses teaching them to recognize when it's quiet enough in Situations of Confidence to be confident that it is clear to cross.
But that is not true, according to my experience and our research.
We studied people's ability to hear approaching vehicles from both directions at 3 different crossings, including the one pictured here, which we called the "Straight" crossing
(for obvious reasons!).
This crossing was a Situation of Confidence for all our subjects at the time that they were there.
The subjects listened for 144 vehicles approaching from both directions at the "Straight" crossing when it was quiet, and
they heard ALL the vehicles with enough warning to know that whenever it is quiet, they can be confident that it's clear to cross.
If you want to read the data, Table 1 of our report shows that all vehicles were heard at least 7 seconds away, and since the crossing time for the average pedestrians is 7 seconds, if they had started to cross just before hearing those vehicles, they would have made it across before the vehicle reached them.
** Many crossings are Situations of Uncertainty at certain times and Situations of Confidence at other times.
This is true for everyone but it is especially a problem for people who use hearing to cross because, as will be explained later, the characteristics of sound that can change crossings from Situations of Confidence to Uncertainty may not be noticeable.
For example a crossing may temporarily be a Situation of Uncertainty because parked vehicles are blocking the sound of traffic, or the sound level of "quiet" is high (this will be explained later).
At other times, that same crossing is a Situation of Confidence because the circumstances allow you to hear the approaching traffic with enough warning (such as when the roads are wet, or it's at night when the sound level of "quiet" is lower).
Therefore blind pedestrians should always observe the situation before crossing to determine if it is a Situation of Uncertainty or Confidence.
They should not assume that it's "clear to cross when quiet" just because that was the case at another time.
Whether they use hearing or vision to cross, our students need to be able to (1) recognize and (2) deal with Situations of Uncertainty and Situations of Confidence.
Section 2 is about teaching them to recognize the situations, Section 3 is about teaching them to deal with Situations of Uncertainty and Section 4 is about teaching them to deal with Situations of Confidence.
This will help them gain the life-saving "A" skills for "A"-students, as explained below.
Life-Saving "A" Skills
Our students need the following skills:
ALERT -- be Alert to recognize Situations of Uncertainty;
ANALYZE -- be able to Analyze the level of risk in Situations of Uncertainty;
ALTERNATIVES -- know about Alternatives and be able to use them when the risk of crossing is unacceptable;
ASCERTAIN -- be able to Ascertain crossable gaps in Situations of Confidence.