1. Flashing Yellow Arrows for Permissive Left Turns – Is It for You?

2. Presented by:
Bruce E. Friedman, P.E., PTOE
Kimley-Horn and Associates
Cary, NC

3. Flashing Yellow LT Arrows
What is its history?
How does it operate?
What is its current status?
What are its advantages?

4. What is the history of the flashing yellow left-turn arrow?

5. Traffic Signal Displays
Innovations are rare in vehicular signal displays
Pedestrian signal innovations:
Solid symbol messages
Countdown displays
Accessible ped signals

6. Traffic Signal Displays
The last significant innovation in vehicular signal displays was the red left-turn arrow that was introduced in the 1971 MUTCD

8. Research Project Requested
The Signals Technical Committee (STC) of the NCUTCD had concerns in the mid-1990s about the effectiveness of the circular green as the indication for permissive left turns

9. Research Project Requested
The STC was also concerned about the wide variety of permissive left turn displays being used around the nation, such as the flashing circular red in Michigan or the flashing circular yellow in Washington State

10. Shared Face: Permissive Only LTs

11. Shared Face: Permissive Only LTs

12. Shared Face: Protected/Permissive LTs

13. Shared Face (with sign): Protected/Permissive LTs

14. Shared Face: Permissive Only LTs

15. Separate Face: Protected Only LTs

16. Research Project Requested
Left-turning driver confusion about the meaning of circular green led the STC to request a research project to take a new look at protected/permissive LT displays

17. Research Project
NCHRP Report 493 documents a comprehensive, national research study to evaluate operational advantages and safety aspects of various left-turn displays at signalized intersections

18. Research Process
Studied a wide variety of types of left-turn displays, including:
Flashing circular yellow
Flashing yellow arrow
Flashing circular red
Flashing red arrow
Flashing green arrow (Canada)
Steady circular green

19. Research Process
Still Photograph and Video Studies (approximately 2,500 drivers)
Driver Simulation (more than 400 drivers)
Field Implementation in 4 States

20. Research Results
NCHRP Report 493 found that the flashing yellow arrow permissive left-turn indication had significantly more correct responses than the steady circular green permissive left-turn indication

21. Research Results
NCHRP Report 493 found that a flashing yellow arrow (FYA) permissive indication is well-understood by drivers and recommended its application for permissive left turns

22. Other NCHRP Report 493 Recommendations
A 4-section, all-arrow signal face should be the only FYA display allowed
The FYA left-turn signal face should be placed over the left-turn lane

23. Other NCHRP Report 493 Recommendations
A supplemental sign is not needed with the FYA display
The FYA should be tied to the opposing through green indication

24. What does the new FYA operation look like and how does it work?

25. Shared Face Sequence: Leading Protected/Permissive LT

26. Shared Face Sequence: Leading Protected/Permissive LT

27. Shared Face Sequence: Leading Protected/Permissive LT

28. Shared Face Sequence: Leading Protected/Permissive LT

29. Shared Face Sequence: Leading Protected/Permissive LT

30. Shared Face Sequence: Leading Protected/Permissive LT

31. Left Turn Trap with Shared Faces: Protected/Permissive LTs
Northbound
Southbound

32. Left Turn Trap with Shared Faces: Protected/Permissive LTs
Northbound
Southbound

33. Left Turn Trap with Shared Faces: Protected/Permissive LTs
Northbound
Southbound

34. Classic Left Turn Trap with Permissive LTs
Northbound
Southbound

35. The separate signal face (“Dallas Phasing”) solution for the LT trap

36. Separate Face (“Dallas Phasing”): Protected/Permissive LTs

37. Separate Face Sequence: Leading Protected/Permissive LT

38. Separate Face Sequence: Leading Protected/Permissive LT

39. Separate Face Sequence: Leading Protected/Permissive LT

40. Separate Face Sequence: Leading Protected/Permissive LT

41. Separate Face Sequence: Leading Protected/Permissive LT

42. Separate Face Sequence: Leading Protected/Permissive LT

43. The flashing yellow arrow signal face solves the LT trap problem and offers other advantages as well

44. A New Idea: A Flashing Yellow Arrow (FYA) Signal Face for LTs

45. Simultaneous leading protected/permissive
LTs in both directions

46. FYA Sequence: Simultaneous Leading Protected/Permissive LTs

47. FYA Sequence: Simultaneous Leading Protected/Permissive LTs

48. FYA Sequence: Simultaneous Leading Protected/Permissive LTs

49. FYA Sequence: Simultaneous Leading Protected/Permissive LTs

50. FYA Sequence: Simultaneous Leading Protected/Permissive LTs

51. FYA Sequence: Simultaneous Leading Protected/Permissive LTs

52. FYA Sequence: Simultaneous Leading Protected/Permissive LTs

53. Leading LT Phase with FYA

54. Lagging left-turn when the opposite direction has a leading left-turn

55. FYA Sequence: Lagging Permissive/Protected LT when Opposite Direction Has a Leading LT

56. FYA Sequence: Lagging Permissive/Protected LT when Opposite Direction Has a Leading LT

57. FYA Sequence: Lagging Permissive/Protected LT when Opposite Direction Has a Leading LT

58. FYA Sequence: Lagging Permissive/Protected LT when Opposite Direction Has a Leading LT

59. FYA Sequence: Lagging Permissive/Protected LT when Opposite Direction Has a Leading LT

60. FYA Sequence: Lagging Permissive/Protected LT when Opposite Direction Has a Leading LT

61. Lagging LT phase with FYA

62. Leading left-turn when the opposite direction has a lagging left-turn – the solution to the LT trap

63. FYA Sequence:. Leading Protected/Permissive LT when
FYA Sequence: Leading Protected/Permissive LT when Opposite Direction Has a Lagging LT

64. FYA Sequence:. Leading Protected/Permissive LT when
FYA Sequence: Leading Protected/Permissive LT when Opposite Direction Has a Lagging LT

65. FYA Sequence:. Leading Protected/Permissive LT when
FYA Sequence: Leading Protected/Permissive LT when Opposite Direction Has a Lagging LT

66. FYA Sequence:. Leading Protected/Permissive LT when
FYA Sequence: Leading Protected/Permissive LT when Opposite Direction Has a Lagging LT

67. FYA Sequence:. Leading Protected/Permissive LT when
FYA Sequence: Leading Protected/Permissive LT when Opposite Direction Has a Lagging LT

68. FYA Sequence:. Leading Protected/Permissive LT when
FYA Sequence: Leading Protected/Permissive LT when Opposite Direction Has a Lagging LT

69. FYA Sequence:. Leading Protected/Permissive LT when
FYA Sequence: Leading Protected/Permissive LT when Opposite Direction Has a Lagging LT

70. FYA Sequence:. Leading Protected/Permissive LT when
FYA Sequence: Leading Protected/Permissive LT when Opposite Direction Has a Lagging LT

71. FYA Sequence:. Leading Protected/Permissive LT when
FYA Sequence: Leading Protected/Permissive LT when Opposite Direction Has a Lagging LT

72. Permissive only left-turn when the opposite direction has a lagging left-turn – the solution to the LT trap

73. FYA Sequence: Permissive LT when Opposite Direction Has a Lagging LT

74. FYA Sequence: Permissive LT when Opposite Direction Has a Lagging LT

75. FYA Sequence: Permissive LT when Opposite Direction Has a Lagging LT

76. FYA Sequence: Permissive LT when Opposite Direction Has a Lagging LT

77. FYA Sequence: Permissive LT when Opposite Direction Has a Lagging LT

78. FYA Sequence: Permissive LT when Opposite Direction Has a Lagging LT

79. Use of the FYA signal face for permissive only left-turns at times of the day when the LT volumes are low

80. FYA Sequence: Permissive Only LT

81. FYA Sequence: Permissive Only LT

82. FYA Sequence: Permissive Only LT

83. FYA Sequence: Permissive Only LT

84. Perhaps the ultimate signal operation during low traffic volumes – lagging left-turns in both directions with set-back detection

85. FYA Sequence: Simultaneous Lagging Permissive/Protected LTs

86. FYA Sequence: Simultaneous Lagging Permissive/Protected LTs

87. FYA Sequence: Simultaneous Lagging Permissive/Protected LTs

88. FYA Sequence: Simultaneous Lagging Permissive/Protected LTs

89. FYA Sequence: Simultaneous Lagging Permissive/Protected LTs

90. FYA Sequence: Simultaneous Lagging Permissive/Protected LTs

91. FYA Sequence: Simultaneous Lagging Permissive/Protected LTs

92. The flexibility of the
4-section FYA signal face:
Protected/permissive operation

93. FYA Sequence: Protected/Permissive LT

94. FYA Sequence: Protected/Permissive LT

95. FYA Sequence: Protected/Permissive LT

96. FYA Sequence: Protected/Permissive LT

97. FYA Sequence: Protected/Permissive LT

98. FYA Sequence: Protected/Permissive LT

99. FYA Sequence: Protected/Permissive LT

100. The flexibility of the
4-section FYA signal face:
Protected only operation

101. FYA Sequence: Protected Only LT

102. FYA Sequence: Protected Only LT

103. FYA Sequence: Protected Only LT

104. FYA Sequence: Protected Only LT

105. The flexibility of the
4-section FYA signal face:
Permissive only operation

106. FYA Sequence: Permissive Only LT

107. FYA Sequence: Permissive Only LT

108. FYA Sequence: Permissive Only LT

109. FYA Sequence: Permissive Only LT

110. 3-Section FYA Signal Face: Permissive Only LT

111. What is the current status of the flashing yellow left-turn arrow?

112. MUTCD Revision This Standard was deleted in the 2003 MUTCD:
A traffic control signal shall be operated in either a steady (stop-and-go) mode or a flashing mode at all times.

113. Interim Approval – Issued 3/20/2006 Optional Use of FYA Display for Permissive LTs

114. Interim Approval Status
The following are among the agencies that have received approval to implement FYA under the Interim Approval:

115. Interim Approval Status
11 State DOTs:
Colorado, Iowa, Michigan, Minnesota, Missouri, New Hampshire, North Carolina, Oregon, Utah, Washington, and Wyoming

116. Interim Approval Status
22 Cities and Counties
(representing a total of 18 States)

117. Current Status
During experimentation and as a result of the Interim Approval, the FYA has now been approved for installation and/or installed at approximately 500 signalized intersections across the U.S.

118. Implementation Results
The FYA display has been successfully implemented in the field with relatively little or no technical or safety issues
The field data supports a high level of driver understanding of the FYA display

119. What are the advantages of the flashing yellow left-turn arrow?

120. Advantages of FYA
The FYA display is better understood by drivers than the circular green display
Allows for the display of different LT modes at different times of the day

121. Advantages of FYA
Eliminates the LT trap situation, thus allowing the display of leading and lagging LT phases at different times of the day to improve signal progression, while still providing permissive left turns to improve capacity

122. Advantages of FYA
No louvers or other special optical features are needed to shield the display from adjacent through traffic because the face is comprised of arrows only, thus allowing for span-wire mounting and eliminating the need for precise aiming

123. Advantages of FYA
No sign is needed as drivers find it easy to understand that the FYA display means that left-turn drivers must yield to oncoming traffic
Can be used to prevent a permissive LT movement from turning during RR preemption

124. One Caution About FYAs
Steady LT yellow arrow to clear the permissive mode is on at the same time as the opposing direction’s circular yellow
This requires a conflict monitor modification and will require revised text in the MUTCD

125. One Caution About FYAs
FHWA has released Official Interpretation #4-320(I) to cover this situation and has recommended that the MUTCD text be changed accordingly in the next edition

126. Innovative flashing yellow arrows for permissive left turns – are you ready to give them a try in your jurisdiction?