Flashing Yellow Left Turn Arrows Scottsdale s Experience 2013 ITE Western District Conference July 16, 2013 Todd Taylor, P.E., PTOE City of Scottsdale Senior Traffic Engineer
FYLTA Review Question NCHRP Report 493 evaluated what type of traffic signal displays for left turn control? A. Protected B. Permissive C. Protected/Permissive
FYLTA Review Question How many Flashing Yellow Left Turn Arrows (FYLTA) did the City of Scottsdale have in 2011? A. Zero B. One C. Two
FYLTA Review Question NCHRP 473 suggested which signal head should be used for the FYLTA (P/P)? Or Or Type Q-2 Type P?? G Modified
FYLTA Trivia Question Does the MUTCD allow a three section head for the FYLTA? 1. YES 2. NO
FYLTA Trivia Question In a three section head for the FYLTA where is the flashing yellow arrow and solid arrow located? Solid Yellow Arrow Or Flashing Yellow Arrow + Solid Green
FYLTA Review Question The number of collisions at the FYLTA s in Scottsdale? A. Increased B. Decreased C. Stayed the same
FYLTA Timeline 2006 2007 2008 2009
Educational Video Nevada
FYLTA in Scottsdale 2008 FHWA approval May 2008 for two sites
FYLTA in Scottsdale 2012 Ten existing FYLTA in 2012
FYLTA in Scottsdale Three new sites with FYLTA for ALL directions Scottsdale Rd & Happy Valley Rd 13 FYLTAs in 2013
FYLTA Controller 170 and ASC/3 RM
Raintree and Northsight (N/S) Heavy Left Turn Demand Peaks in PM Dual SB Left Turn Implemented FYLTA October 2008 Northsight Blvd Single NB Left Turn
Northsight and Raintree (N/S) Collision History presented AZ ITE Spring Conference 2012: 2 Collisions since 2012 ITE Presentation Prior to FYLTA: 9 Collisions in 21 months (5.1 per year) Since FYLTA: 5 collisions in 56 Months (1.07 Per Year) After FYLTA: 3 Collisions in 40 months (0.9 per year)
68 th and McDowell (N/S) Circle K Generates Pedestrian Activity Single SB Left Turn Valley Gutter Slows McDowell Through Road Movement Tempe Study of Dual Lefts Identified as High Collision Intersection Implemented FYLTA November 2008 Dual NB Left Turn
68 th and McDowell (N/S) Collision History presented AZ ITE Spring Conference 2012 2012: ITE Three Collisions since Presentation Prior to FYLTA: 6 Collisions in 22 months (3.3 per year) Since FYLTA: 8 collisions in 55 Months (1.74 Per Year) After FYLTA: 5 Collisions in 39 months (1.54 per year)
Scottsdale Road and Ashler Hills Drive Ashler Hills Scottsdale Road Implemented FYLTA ALL Directions August 2012
Scottsdale and McCormick (S) Scottsdale Road Single SB Left Turn Implemented FYLTA in June 2011 McCormick Pkwy
Scottsdale and McCormick (South)
Scottsdale and McCormick Video
Pima Road FYLTA s Pima Road & Via De Ventura Implemented FYLTA for Spring Training March 2011 Pima Road & Salt River Fields @ Talking Stick Pima Road & 7350 North (Pavilions) Pima Road & Indian Bend Road
Pima Road and 7350 North (Pavilions)
Pima Road FYLTA s Since FYLTA: 7 collisions in 28 Months (3.00 Per Year) Implemented FYLTA for Spring Training March Pima Road & Via De Ventura Pima Road & Salt River Fields @ Talking Stick No Collisions 2011 Since FYLTA Pima Road & 7350 North (Pavilions) Pima Road & Indian Bend Road Since FYLTA: 4 collisions in 28 Months (1.71 Per Year)
Frank Lloyd Wright and 100 th Street FYLTA for ALL Directions April 2012 Frank Lloyd Wright Implemented FYLTA N/S November 2008 100 th Street
70 th Street and Gold Dust (E/W) Scottsdale Road Since FYLTA: 2 Collisions 2 Pedestrian Prior to FYLTA collisions McCormick Pkwy Implemented FYLTA July 2011
Atlantic Cities Headline Flashing Yellow Turn Signal: Good for Drivers, Bad for Pedestrians.
ITE Western District Headline Flashing Yellow Turn Signal: Good for Drivers, Even Better for Pedestrians. See Chuck Huffine for more details
Scottsdale Road and Paradise Lane Paradise Lane Implemented FYLTA ALL Directions June 2012 Scottsdale Road
Frank Lloyd Wright and Cactus (N/S) Implemented FYLTA September 2011
Frank Lloyd Wright and Cactus (North)
Frank Lloyd Wright and Cactus (South)
Public Reaction Drivers recognized that FYLTA requires them to yield Number of citizen complaints of aggressive driving went down significantly Received some complaints from drivers who did not understand indication, when questioned they did the proper thing No Complaints removing Split-Phase Positive comments changing from Protected
FYLTA Trivia Question What sign needs to be installed for the FYLTA?
Lessons Learned No signs needed for FYLTA Implementation is easier with ASC 3 then it was with old 170 s which required numerous logic statements Phone calls increase with the installation, but when asked drivers always did what was required. Need to add an additional F head for through traffic since one is lost with FYLTA
Current Standard P/P Operation
FYLTA Lesson Learned
Recommended FYLTA
Conclusions Use of Flashing Yellow Left Turn Arrows has a positive impact on collision experience when used to replace Green Ball during permitted left turn phase. Growing number of agencies are adopting FYLTA as preferred indication for permitted left Need ADOT to add the four section arrow head to the standard nomenclature Scottsdale continues to be an innovator in Arizona Traffic Engineering
Proposed New Signal Head Type P TYPE P
Todd Taylor, P.E., PTOE City of Scottsdale Senior Traffic Engineer Ttaylor@ScottsdaleAZ.gov Questions?
Proposed New Signal Head Type T TYPE T
FYLTA in Scottsdale Northsight and Raintree (N/S) 68 th and McDowell (N/S) Pima and Indian Bend (N/S) Pima and Stadium (N/S) Pima and Pavilions (N/S) Pima and Via De Ventura (N/S) 70 th and Gold Dust (E/W) Frank Lloyd Wright and Cactus (N/S) Frank Lloyd Wright and 100 th (N/S) Scottsdale and McCormick (S)
Yellow Trap Example
Current ADOT Signal Head Standards
Current ADOT Signal Head Standards
Proposed New Signal Head Type P
Flashing Yellow Arrow Background NCHRP Report 123 (2007) looked at numerous field installations of FYLTA Improved safety if intersection was P/P before install Safety not improved if Protected only before install No change in safety if Permitted only before install
Flashing Yellow Arrow Background NCHRP Report 493 (2003) looked at numerous displays for P/P left turn control Report recommended use of FYLTA based on high level of driver comprehension and versatility in signal phasing Driver who did not understand indication tended to yield Numerous requests to FHWA approved for experimentation between 2004 and 2006 FHWA Issued Interim Approval for use 3/20/06 FYLTA added to current version of MUTCD
Raintree - Northsight Investigated alternatives Split phasing Protected only phasing Synchro analysis showed that these would significant increase delay and congestion Implemented FYLTA for NB/SB in October 2008
Innovation Demonstration Project: Presentation today will include: History/Background of Flashing Yellow Left Turn Arrows (FYLTA) Update of FYLTA s in Scottsdale Lessons Learned Conclusions
Proposed New Signal Head Type P
Question 30: Q: Does the MUTCD now require agencies to provide a flashing yellow arrow indication for a left-turn movement for the permissive left-turn phase? A: No, this is not mandatory, but the flashing yellow arrow is now allowed in the 2009 MUTCD as an optional alternative display for PPLT or "permissive only" left turn movements (see Sections 4D.17 through 4D.20). NCHRP Report 493 describes the results of a comprehensive research project to evaluate the use of different permissive displays for protected-permissive mode left turns (PPLT), including the flashing yellow arrow (FYA). The research found that the most easily understood and most effective permissive display is the FYA in an all-arrows separate turn signal face for the left turn. An NCHRP follow-up study found that converting circular green permissive left-turn displays to flashing yellow arrow improved safety. Flashing yellow arrow displays are also now allowed for use with permissive right-turn movements (see Sections 4D.21 through 4D.24.)
FYLTA Website Educational Video
Proposed New Signal Head Type T TYPE T
Scottsdale and Ashler Hills Since FYLTA: 4 collisions in 11 Months (4.36 Per Year) Prior to FYLTA: 5 Collisions in 36 months (1.67 per year) Implemented FYLTA ALL Directions August 2012
Scottsdale and McCormick (S) One Collision Prior to Scottsdale Road FYLTA in 24 Months (0.5 Per Year) Single SB Left Turn Implemented FYLTA in June 2011 Since FYLTA: 2 collisions in 25 Months (0.96 Per Year) McCormick Pkwy