This video will explain human factors through the use of a real crash.
This real life example involves a car versus a motorcycle crash that happened on a four
lane road with a grassy median in the middle of the Northbound and Southbound lanes.
Unfortunately, this example is just one of many that happens far too often.
In this example the Biker's name was James.
It was a clear Sunday morning.
A red car is northbound, and wants to turn left to head West into a Starbucks parking lot.
The red car pulls into the middle turning area waiting for traffic to clear.
At the same time a southbound blue car enters the same median area to make a left turn.
As the two cars are in the median, they are obstructing each other's view of the oncoming traffic to some extent.
The red car thinks that oncoming traffic is clear and that he can turn left, but he
fails to see James on his motorcycle heading South at approximately 40 miles per hour.
The red car starts his improper turn, violating
James's right of way by entering into his lane.
A crash is going to happen.
Let's break it down and look at it from a human factors physics and scientific perspective.
James will Identify the threat.
He is in his lane, driving South His focus is on his lane ahead of him.
He will be aware of the other vehicles in the median.
So far, he is not perceiving or identifying any sort of threat.
However, as soon as he detects the motion of a vehicle coming
into his lane, he will immediately identify that threat.
He will be keenly aware of the motion and size of the car entering his lane.
In this case, James will identify the threat well before the driver of the car will.
The car did not see the James at all, otherwise, he
would not have begun his turn into James's lane.
At this point in time, James has Identified the threat.
Let's move to the second step and that's all motorcycle riders will experience.
And that is James must now Predict the Outcome.
He has identified the threat, and now in his mind he will predict that a collision is imminent.
He predicts that his lane will be completely blocked
by the car making a left turn in front of him.
James predicts that after considering his speed and the speed
of the turning car, that there is no way to avoid an impact.
James predicts that an impact is unavoidable.
He must now go to the third step and that is to make an instant decision
about what to do to avoid, or reduce the damages of the impending crash.
What shall James do to avoid or reduce the imminent crash that is about to happen?
He must make a snap decision about what action or maneuver to take.
Let's consider James' Choices about what he can do to avoid or lessen the damages from the crash.
He only has two choices.
First is Speed, and the second is direction.
There are no other options.
And There are essentially nine evasive actions that James can take.
Three with speed, which are to brake to reduce speed, maintain speed, or to accelerate.
And James has three choices with direction, turn Left, go Straight or turn Right.
James first option is to change his speed.
Option one, speed up, and try to make it past the car.
This choice is a tough one, and one that is not a natural choice.
The normal human reaction is to avoid a collision by attempting
to stop rather than accelerating towards the threat.
For the sake of this example, if James were to accelerate, he increases the amount of energy that
will transfer into his bike and his body if a collision happens and injure himself more severely.
This is a highly unlikely choice and is a very bad decision.
The more likely choice and safer decision is to reduce his speed
and decrease the amount of energy that the impact will have.
So in this example, James will apply his brakes as
hard as he can while maintaining control of his bike
The second maneuver option after changing his speed is to change
direction of the bike, to start a turn to avoid the crash.
This is a good decision for James if he is a skilled rider with
lots of practice of braking while turning at the same time.
His choices are to either change his direction to his left, go straight, or turn to his right.
In this example, the safest and most common turning decision would be
to turn towards the right in an attempt to avoid the whole impact.
James might get lucky and the car driver might suddenly see him and
slam on his brakes and James is able to go around the car completely.
However, this decision to swerve to the right has other risks.
There may be traffic to his right, James may be turning
into another dangerous situation by going to his right.
Does James have time to look to his right?
Not likely.
But if he is keenly aware of the traffic situation he may choose this evasive maneuver.
Back to our example, if the car does not stop, and James turns to his right, at least he will to some extent
lessen the impact by hitting the front of the car with his bike and having his body go over the hood of the car.
If James chooses instead to go straight, he will likely hit the "B" pillar of
the car with his face and his body, and likely become catastrophically injured.
If he swerves to his left, then he hits the passenger side of the car, and his face
contacts the roof rail of the car, again causing possible catastrophic injuries or death.
Now, let's go back to his decision to change his speed by braking hard.
Is braking a good choice?
If James chose to go straight, then braking is the absolute
best choice to make because it will lessen the impact.
But if James makes an evasive turn to the right, AND at the same time attempts to brake,
then he runs the risk of exceeding the laws of inertia and starting a skid or a slide
because his tires will lose contact with the road, and not reduce his speed as effectively.
If this happens he is not slowing as much as he could if he maintained full braking control,
and he is not turning away from the collision due to the lack of tire contact with the road.
Like I said, This is an extremely dangerous combination of evasive moves where he is likely to
lose control of his bike, and possibly go under the car and face catastrophic injuries or death.
The safest maneuver is to brake hard and not turn.
Braking hard and turning at the same time is very dangerous.
Now, Should James use both brakes, the front wheel and the back wheel at the same time?
Yes!
We know the front brake is more powerful than the rear
due to laws of physics caused by the weight transfer.
However, he should use the back brake at the same time to do everything he can to reduce his speed.
Sliding is the biggest risk James faces in this situation.
He is applying full brake power and taking an evasive turn to the right at the same time.
He can easily cross the 100 percent traction limit, start to skid, lose control of
the bike and go down where he is at greater risk of catastrophic injury and death.
Now let's talk about how fast all of these things happen in time.
As we discussed, James has to First Perceive the danger.
He has to see the red car coming into his lane and he must perceive this as a danger to himself.
Human perception takes time before any reaction can occur.
Reaction times for the human brain are estimated to take approximately 1.75 seconds,
depending on various factors such as health, age and time of day.
This is the time the average human brain will take after
seeing a danger, to actually react to the danger.
In this situation James will perceive the danger and one and three quarter seconds later
begin his evasive maneuvers by applying his brakes and or starting an evasive turn.
Now, we need to consider how a motorcycle turns.
A motorcycle takes about 1 second to begin a turn.
This is because you have to lean the bike first, before a turn can happen.
It takes about one to 1.5 seconds to turn 1 foot depending on your speed.
So we have a time lag of about two and three quarters of a
second from Perception, Response, to Execution of the turn.
So, let's back up 1 second to turn,
and back up another one point seven five seconds to perceive that you need to turn.
This means that it takes two point seven five seconds from perception of
the danger to taking evasive action to turn the bike away from the crash.
Remember that James could see the car before the car could see James, because the hood of the car is
coming into James path of travel, James is focusing on the unexpected intrusion of the car into his path.
It is a clear and present danger to his safety.
Now Let's switch places for a second and consider that
the car will see James in time to avoid the crash.
What is the car's perception response and execution of braking likely to be?
The perception of the car driver initiating the turn is
expected to be much slower than James's for a few reasons.
First, the red car obviously did not see James, so he is committed to his turn.
And it is unlikely that the red car will be able to perceive
the risk of collision quickly enough to slow or stop his car.
His perception time is going to be in the two second range, followed by
one and a half seconds to decide to brake and then slam on the brakes.
Let's consider the physics of speed in this example.
If James is going 40 miles per hour, he is covering 58.33 feet per second.
Let's see how far away he would have to be to apply his
brakes at a perfect 100% to stop before hitting the car.
If we assume that the roads are perfectly dry, and that his tires are in excellent condition, then we use a co-efficient
of friction factor of .7, this tells us that making a perfect 100% full stop going straight,
James can stop in 59 feet.
Now, if we back up 1.75 seconds to allow James time to perceive, predict, decide
and then to execute an avoidance maneuver,
which is going to be to apply his brakes at 100% braking,
then a perfect stop could be made in 161 feet.
What if James decides to try and turn to his right to avoid the crash, while applying his brakes.
Like I said This is a very dangerous maneuver.
If he is at 100% braking power, and he attempts to turn the bike,
he will exceed the 100% traction threshold point, and cause his bike to skid.
Once a skid starts, the coefficient of friction between the road and his bike changes.
Before with rubber on asphalt the friction was .7
Now that his bike is on its side, the bike is mostly metal
and plastic which has much less friction with the road.
This means that he won't be able to stop in less than 161 feet, but due to his skid,
he will need more distance to stop.
In a controlled skid he would stop in about 193 feet.
So how can he brake and turn at the same time?
He can only turn the bike if he is using less than 100% of his braking power.
Whatever percentage he reduces his braking power, he can use to apply to turning power.
If he reduces his braking to 75%, then in a perfect world he could use the other 25% to turn the bike.
If we assume he is braking at only 75% of the full
braking power, he will stop the bike in 201.25 feet.
And if he uses the other 25% of turning power which can only come in another
one second after James is able to: Identify, Predict, Decide, and Execute.
So one second after the perception, he begins to apply his
brakes, and starts to LEAN the bike to start to turn.
And it will take about One more second to get the bike to start to turn.
The total amount of time from the Perception of the car
of the bike to begin to turn is 2.5 seconds.
With 75% braking power and 25% turning, he will be able to stop in approximately
200 feet, and he will have turned his bike to the right by 5 feet.
If James is traveling at 50 miles per hour he is covering 73 feet per second.
So if we had him make a perfect 100% stop, it would take 93 feet to come to a complete stop.
Now let's add 1.75 seconds for perception time or 128 feet to give
James time to perceive the danger then he could apply his brakes.
He could stop in 220 feet.
If we factor in a reduction of braking power to 75% and turning maneuver beginning at 1.5 seconds,
then he will stop in 275 feet, and turn the bike to the right by 5 feet again upon reaching the stop.
Both of these examples would be virtually impossible for a rider to do.
These examples are assuming 100% effective braking and turning.
This is not possible.
However, if the bike had anti lock brakes,
then these maneuvers are going to be closer to 100% effectiveness.
But most bikes do not have anti lock braking systems.
To summarize this example, there is Reaction Distance, which is the distance
the bike travels for the driver to identify and react to the danger.
Then there is Braking distance, which is the distance traveled from the time
the brakes are first applied to the time the bike comes to a complete stop.
Then there is Total Stopping Distance which is the total distance it takes to stop the bike
from the moment the driver sees a problem to the time the bike is completely stopped.
Reaction Distance + Braking Distance = Stopping Distance.
As a trial lawyer handling a motorcycle crash case
the issue comes up whether the biker should have turned or gone straight?
I will ask the Defense Expert: "would you rather ride into the side of the car and
eat the roof rail and the B pillar, or would you rather go over the hood of the car?
Their answer is almost always that it is safer
to hit the hood of the car rather than the roof rail.
In this case,
James made an Active Decision to go over the hood of the car in this scenario,
and it probably saved his life.
I hope you have found this video informative
and I hope that you are more aware as you enjoy your bike,
so you can drive safely, and be prepared for that car that's about to come into your lane.
And please practice your emergency braking until it becomes automatic for you.