Transcript Document

Managing Time, Space,
and Visibility
Characteristics/Visual Fields
Central Vision
Visual Lead, Targeting,
Signs, Signals
Central Vision
Fringe Vision
Referencing, Path of
Travel, Sightlines
Fringe Vision
Peripheral Vision
Motion and Color
Changes
Peripheral Vision
Factors
Affecting
Field of
Vision
Normal 190°-200°
30 MPH 142°- 160°
45 MPH 100° - 90°
60 MPH 10° - 20°
PRINCIPLES OF VISUAL
PERCEPTION
FINAL FILES ARE THE RESULT OF
YEARS OF SCIENTIFIC STUDY COMBINED
WITH THE EXPERIENCE OF YEARS
Basic Requirements for Driving
Driver Requirements
An average driver makes 50 to 60
decisions per mile traveled …...
Visibility … Space X Time = Speed … Traction
… most such
decisions relate to
visibility, space,
time, and
placement ….
Vehicle Requirements
… all must be accomplished
within the range of available
traction!
Judgmental Abilities Required To
Manage Time/Space Adequately
• Space Relationships
• Speed Estimates
• Evaluation of Roadway
• Prediction of Others’
Actions
Space Management System
• Search for objects or conditions
• Evaluate the planned travel path
ahead(visibility, traction, space, traffic
flow, topography, legal requirements)
• Identify alternate paths of travel(look for
an out)
• Prepare to make adjustments in speed
and/or position(learn to read the route -it’s
the smooth move - safer & economical)
F rni ge V si oi n
C en t ra l
V si oi n
20 -30 se c V S A
12 - 1 5 se c V C Z
4 - 8 se c S top Z o ne
3 - 4 se c F o lol w ni g D si tan c e
Visual Habits
• 20 – 30 sec search (VSA)
• 12 – 15 sec path of travel (VCZ)
• 4 – 8 sec immediate path (Stop Zone)
• 3 - 4 sec following distance
• Mirrors (rear interval) [10x minute]
• Head checks [ any lateral movement]
• Speedometer [1x a minute]
20 sec VSA at:
35 mph = 1022 ft (0.2 mile)
55 mph = 1773 ft (0.3 mile)
3 - 4 se c F o lol w ni g D si tan c e
S di e
M ir row
R ea rv ei w
M ir ro r
S di e
M ir ro r
65 mph = 1898 ft (0.4 mile)
Visual Process
• Search roadway & off road areas 20 - 30
secs ahead to plan path of travel
• Identify conditions 12 - 15 secs ahead that
could interfere with path of travel
• Predict conditions on/near road that could
increase risk
• Decide at least 4 - 5 seconds ahead what
actions to take to reduce risk
• Execute decisions
Visual Process: Following Distance
• Continually monitor the 3-to-4 second
following distance
• Adjust as required by
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Atmospheric conditions
Roadway and off-road surface and condition
Traffic conditions
Visibility
Following traffic
Visual Process: Mirror Use
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Proper adjustment required
Monitor traffic to sides and rear while traveling and
stopping
Not for detail(objects in side mirror closer than they
appear)
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Are vehicles present?
Where?
Size?
Speed?
Mirror blind areas(head check)
Driving Process
SIPDE
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Search
Identify
Predict
Decide
Execute
Visual Search Categories
Traffic
Controls
Roadway
Features
Motor
Vehicles
NonMotorized
Users
Aggressive Visual Search
Aim high
Get the big picture
Keep your eyes moving
Look for an out
Aggressive Visual Search
An aggressive visual search involves:
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Searching 20-30 seconds ahead
Identifying an alternate path
Identifying other highway users
Assessing the consequences of alternate
responses
• Adjusting speed or position, and
communicating adjustment
Manage Risk By Adjusting
Time/Space/Visibility
• Increase Vehicle Control
• Increase Response Time
– increase space
– adjust speed
– increase visibility
A
B
REMEMBER YOU HAVE MORE TIME TO CORRECT
A SITUATION AT A SLOWER SPEED AND IF YOU
ERR IT WILL BE LESS EXPENSIVE!
Manage Risk By Increase Distance
From Hazard (Separating)
Reduced
traction,
vehicle, curve
Vehicle on side of
road
Pedestrian vehicle conflict
Adjust Time/Space For the Least
Harmful Result When Multiple Risks
Present (Compromising)
Resolve possible responses
into a single adjustment of
speed and road position
resulting in the least
consequence for the greatest
risk.
Three highway conditions that
require speed adjustments are
visibility, traction, and space.
How Fast is Too Fast?
It is not how
quickly you can
get there if
everything goes
well, but how
quickly could
you respond if
something goes
wrong?
d feet
tminutes 
S fps
60sec onds
Time saved by going 10 mph faster for 10 miles
Min/ MPH Min
10mi
saved
24.1
25
17.2
35
6.9
13.4
45
3.8
11.0
55
2.4
9.3
65
1.7
8.0
75
1.2
•Each 10 mph speed increase doubles chance of
fatal injury if involved in a crash
•10mph over speed limit is 3 point violation
IS IT WORTH IT TO SAVE 2 TO 7 MINUTES ?
52800
 251.46
60
 24.1min utes