GOVERNMENT CAUSES
TRAFFIC SIGNAL TRAPS

In many cases, government officials make bad decisions that endanger drivers through hidden traps. Here are some of these traps:


LEFT TURN TRAFFIC TRAPS

TRAP
TYPE
TRAP NAME
AND CAUSE
SIGNAL
SEQUENCE
MUTCD
VIOLATION
PROPER
REMEDY
DEFICIENT
REMEDY
T
U
R
N
S
 
O
N
 
C
I
R
C
U
L
A
R
 
G
R
E
E
N
YELLOW TRAP (CLASSIC)
Circular greens end at different times, tricking a left-turn driver into thinking the other circular green ends at the same time.
1. Greens 2. Change 3. Trap
circular greens changes to yellow crash
4D.05.03.B4
Steady
Circular
Yellow
Rules
Flashing Yellow Arrows yellow trap prevention Anti-backup circuitry (limits signal sequence)
CHEAP YELLOW TRAP
Flashing Yellow Arrow wrongly installed in only one direction on the street with the flashing yellow arrow. This was done to save money. Yellow trap is not prevented.
1. Green & FYA 2. Change 3. Trap
circular green & FYA changes to yellow crash
4D.05.03.B4
Steady
Circular
Yellow
Rules
Install Flashing Yellow Arrow signal face for oncoming left turn Anti-backup circuitry (limits signal sequence)
GREEN TRAP
Circular greens with permissive turns start at different times, tricking driver into thinking left turn is protected.
1. One Green 2. Two Greens 3. Trap
1 circular green 2 circular greens crash
4D.20.01.B
4D.20.01.C
Protected/
Permissive
Left Turn
Display
Use single phase unit for both directions Force concurrent phases to display together
LITTLE YELLOW TRAP
Circular yellows end at different times, tricking driver into turning across other clearing vehicle.
1. Yellows 2. Change 3. Trap
circular yellows one yellow ends crash
(none) Use single phase unit for both directions Carefully adjust times to be equal.
SCG PRE-EMPTION YELLOW TRAP
The start of a signal pre-emption was not designed with yellow trap in mind. It causes yellow trap when the oncoming circular green is wrongly terminated early.
1. Greens 2. Pre-emption 3. Trap
circular greens Pre-emption starts Yellow trap
4D.05.03.B4
Steady
Circular
Yellow
Rules
Install flashing yellow arrows
Don't inhibit flashing yellow arrow on pre-emption
All-way all-red clearance before pre-empt approach emptying
TRAP
TYPE
TRAP NAME
AND CAUSE
SIGNAL
SEQUENCE
MUTCD
VIOLATION
PROPER
REMEDY
DEFICIENT
REMEDY
T
U
R
N
S
 
O
N
 
F
L
A
S
H
I
N
G
 
Y
E
L
L
O
W
 
A
R
R
O
W
SECOND YELLOW TRAP
Right-turn overlap does not end when flashing yellow arrow ends, causing yellow trap.
1. FYA Turns 2. Trap 3. Next Phase
circular greens with FYA second yellow trap next phase
4D.05.03.E5
Steady
Yellow
Arrow
Rules
Remove right-turn overlap phase
Channelize right turn
(none)
THIRD YELLOW TRAP
Start of flashing yellow arrows is delayed to protect pedestrians. Reservicing the pedestrian phase causes yellow trap.
1. FYA Turns 2. Trap 3. Illegal Next
circular greens third yellow trap illegal next phase
4D.05.03.E4
4D.05.03.E5
Steady
Yellow
Arrow
Rules
Don't delay flashing Yellow Arrow beginning Anti-backup circuitry to prevent pedestrian phase from being reserviced (limits signal sequence)
FYA PRE-EMPTION YELLOW TRAP
The start of a signal pre-emption was not designed with yellow trap in mind. It causes yellow trap when the oncoming left turn is wrongly terminated early.
1. FYA Turns 2. Pre-emption 3. Illegal Next
circular greens Pre-emption starts Yellow trap
4D.05.03.E4
4D.05.03.E5
Steady
Yellow
Arrow
Rules
Don't inhibit flashing yellow arrow on pre-emption Fire the politician who thinks that the lives of government employees are more valuable than other people's lives.
STUPID YELLOW TRAP
Flashing Yellow Arrow signal faces wired to the circular greens facing the same way by people who don't understand FYA or yellow trap.
1. FYA Turns 2. Change 3. Stupid Trap
circular greens illegal next phase Stupid yellow trap
4D.05.03.E4
4D.05.03.E5
Steady
Yellow
Arrow
Rules
Install the Flashing Yellow Arrows the correct way Fire the politician who made this decision
OVERLAP YELLOW TRAP
Flashing Yellow Arrow signal faces are wired to the circular greens of one oncoming overlap phase, but not the other. Could be a problem of double clearance timing.
1. FYA Turns 2. Trap 3. Illegal Next
circular greens overlap yellow trap illegal next phase
4D.05.03.E4
4D.05.03.E5
Steady
Yellow
Arrow
Rules
Remove the overlap or connect FYA to both overlaps Anti-backup circuitry (limits signal sequence)

MORE TRAFFIC TRAPS

TRAP
TYPE
TRAP NAME
AND CAUSE
TRAP
DIAGRAM
MUTCD
VIOLATION
PROPER
REMEDY
DEFICIENT
REMEDY
O
T
H
E
R
 
T
R
A
P
S
OFFSET INTERSECTION YELLOW TRAP
Circular greens end at different times, tricking driver into thinking other circular green ends at the same time.
offset intersection 4D.05.03.B4
Steady
Circular
Yellow
Rules
Flashing Yellow Arrows yellow trap prevention
Exclusively Protected left turns
Prohibit the left turns
RIGHT TURN ON RED MUST YIELD TO U-TURN
It is impossible for a driver turning right on red to know in advance if a driver coming from the right is turning left or making a U-turn. The sign tells of the traffic rule, but does not remove the hazard.
RIGHT TURN
ON RED
MUST YIELD
TO U-TURN
(none)
See
2B.54.08
Channelize the right turn Prohibit the right turn on red
BIKE BOX TRAP
Bike box rules trap driver if bike hidden by vehicles when signal turns green. Cyclist trapped if moving when signal changes.
bike box Bike Box Not
Permitted
By MUTCD
Remove bike box Remove politician who wants bike box.

WHAT MUST GOVERNMENT DO?

THE QUESTION THE ANSWER VIOLATION RESULTS
When must the flashing yellow arrow be flashing? ANY time the oncoming circular green is displayed Yellow trap crashes
When must right green arrow overlaps be avoided? When oncoming permissive left turns are allowed Yellow trap crashes
When must anti-backup logic be installed? When permissive turns are made on circular greens Yellow trap crashes
Can a pedestrian phase inhibit a flashing yellow arrow? NO! Use flashing yellow arrow as circular green was used. Yellow trap crashes
How can I fully protect pedestrians from turns? Use exclusive protected mode or exclusive all-walk phase Yellow trap crashes
When must signal protected-permissive mode change? The change must occur when the phases involved are red. Yellow trap crashes