Flashing Yellow Arrow Experience

Transcription

1 Flashing Yellow Arrow Experience Question 1 If you utilize the FYA, is it your standard design practice or is it used only under certain criteria? Responses: Alabama Alabama installed its first FYA in December 2014 at one intersection in the Birmingham area. Then, one month later, in January of this year, we installed FYA at 14 intersections on a corridor near Mobile. We have plans to install FYAs at 22 intersections in Tuscaloosa and 16 in Huntsville as part of corridor upgrade projects. Alaska In 2009 Alaska adopted the Flashing Yellow Left Turn Arrow (FYA) as a standard for new installations and reconstructions. Lesser retrofit projects could install the FYA, if the four section head could be positioned at least over the lane line of the left turn lane. If the mastarm was not long enough or couldn t handle the loading, the project wasn t required to install the FYA, and could retain the five-section doghouse for protected-permitted operation. (Our Chief Engineer Directive is attached. We have since incorporated the language into our state supplement with the most recent MUTCD.) Connecticut Dave, Connecticut also does not yet use the FYA. We are considering use, but have run into a couple of technical issues with some of our standard equipment. I d be interested to get a copy of what you find out from other states. Delaware We only have one FYA in DE that I can think of and it s for a right-turn, not left. Georgia FYAs are our standard design practice. For all protected/permissive left turns, we are now installing FYAs. For permissive left turns with an offset storage bay, we are installing 3-section permissive only FYAs.

2 Flashing Yellow Arrow Experience Question 1 If you utilize the FYA, is it your standard design practice or is it used only under certain criteria? Responses: Illinois In Illinois, we started implementing FYA about 4 years ago in Peoria (our District 4 area) as part of a research project. We are still in the process of collecting after-data, but so far the data has shown overall a 20%-30% reduction in left-turn crashes. FYA use has since expanded throughout most of our District 4 area and last year, was first introduced along a corridor in Springfield. FYA is not our standard practice at this time and several of our districts are still hesitant to implement it, but I do anticipate its use increasing throughout the state in the near future. Indiana Yes, per our design guidance FYA with 4 section heads are to be used for any protected/permissive left turn movement (single left turn lane). Kansas The DOT has just begun utilizing the flashing yellow arrow (FYA) for about 18 months. As an agency, we only maintain about 50 traffic signals and only one has the flashing yellow arrow. On the eastern side of the state, in Johnson County, many cities have utilized the FYA from the start. The DOT was not receptive to the FYA initially but some attended a course on signals and were told that the new MUTCD would only allow FYA as the option for protected permitted left turn phasing. I would say as of now, FYA would be standard design practice for KDOT; however, we will allow the cities the option to use or not and support whatever their decision is. Kentucky We still have option of either FYA or 5-section head, but FYA is quickly becoming our most common installation for new signals/phasing modifications. There are a few situations where our current controller (170) will not accommodate flashing yellow (such as railroad preemption, advance warning flashers, etc.). We are experimenting with 2070 controllers to overcome the limitations in these situations. Maine Maine only has two of them, we have had mixed comments regarding these, not something we are looking to do on a regular basis as of now.

3 Flashing Yellow Arrow Experience Question 1 If you utilize the FYA, is it your standard design practice or is it used only under certain criteria? Responses: Maryland Maryland does not use the FYA at this time Mass Michigan MassDOT has adopted the Flashing Yellow Arrow as our standard for protected-permissive left-turn phasing at approaches that have a separate left-turn only lane since This standard applies to all new or reconstructed traffic signals on the State Highway system and any locally-owned signal that receives state or federal aid for construction costs. At this time we are also recommending that FYA operation be used for permissive-only left turns on approaches with a separate left-turn lane at intersections or in corridors that will be using FYA for protected-permissive movements. FYA remains optional for right-turn movements, though it is occasionally recommended at intersections that have safety problems associated with concurrent pedestrian phases. If we are installing a permissive-protected operation for left turn phasing, we typically install the FYA operation. On rare occasions we will use the five section head (doghouse) for permissive-protected operation. Those are usually at T type intersections where there is left turn phasing in only one direction. If analysis indicates the left turn phasing must be protected only, we have a three color head for the left turns. Minnesota Dave, in Minnesota the FYA is now the standard design practice on our state roadways that have an exclusive left turn lane. Several other local agencies in Minnesota are also starting to install them on the local road system too. This decision was based on the FHWA studies regarding the safety aspects of using the FYA in place of the green ball for already permissive movements and for the flexibility of operation when using the FYA to allow a permissive movement where a protected movement may have been used 24 hours a day previously.

4 Flashing Yellow Arrow Experience Question 1 If you utilize the FYA, is it your standard design practice or is it used only under certain criteria? Responses: Missouri FYA is Missouri s standard left turn indication. This is implemented on any new signalized intersections installed and can be retrofitted on existing intersections if desired. Information for retrofits can be found in our Engineering Policy Guide, Article Here is a link to our Engineering Policy Guide where a lot of the information regarding Missouri's use of flashing yellow arrows can be found: %29# _Signal_Indications_for_Left- Turn_Movements_.E _General_.28MUTCD_Section_4D If you would like more information or have any questions, please contact Julie Stotlemeyer at New Hampshire We were the first state in New England to adopt the FYA. It is our standard display for any permissive left turn movements on new or upgraded traffic signals. We only have ten or so locations statewide. New York New York is just starting to use FYA. We have about a half dozen test sites in the state (mostly in Binghamton) and they were well received. So now we are moving on and are including them in new signal installations where a permissive operation is possible. Like New Hampshire, we underutilize permissive left turns as we had a point in time (20 to 25 years ago) where we began using protective phasing almost exclusively at all new signals. The following link will take you to TSMI re: flashing arrows: a=portal

5 Flashing Yellow Arrow Experience Question 1 If you utilize the FYA, is it your standard design practice or is it used only under certain criteria? Responses: North Carolina North Dakota Ohio Since becoming an approved traffic control device with the 2009 MUTCD, the 4-section FYA is currently our preferred method of operation for PPLT signal operation for new and upgraded locations. We use the 3- section FYA for permissive left turns when the face is positioned directly over an exclusive left turn lane, but still use green balls for shared lanes or when the face is not located directly over the exclusive left turn lane (in accordance with the 2009 MUTCD, this is a "should" condition). North Dakota DOT has been recommending these as part of traffic signal studies for several years. Only recently have cities within North Dakota started to install these. North Dakota DOT currently does not have any FYAs on any of our state DOT maintained signals. However, that will change for future installations. Ohio DOT currently does not utilize the flashing yellow arrow display within any state signal installation. Would be interested also in your findings. South Dakota South Dakota is installing flashing yellow arrows; we began this with the 2009 MUTCD. We are installing them on projects as we upgrade existing signals or install new ones. We are not systematically replacing all 5 section heads with the 4 section flashing yellow arrow head. Texas Flashing Yellow Arrows were made a standard by the 2009 National MUTCD and adopted in the 2011 Texas MUTCD. Many cities in Texas implemented the Flashing Yellow Arrow protected permissive operation prior to TxDOT. Attached is TxDOT guidance for implementing the operation on TxDOT signals. The guidelines do not make the operation required immediate change out for all signalized intersections. However, the MUTCD has specific standards for allowable signal displays for permissive protected left turn operation that in many cases require the use of the FYA displays.

6 Flashing Yellow Arrow Experience Question 1 If you utilize the FYA, is it your standard design practice or is it used only under certain criteria? Responses: Virginia The FYA has become VDOT s preferred signal head when using protected-permissive left-turn phasing. FYA may be used anywhere protected-permissive left-turn phasing is used. We are also considering FYA use for permissive-only left-turn phasing as well. In limited situations, we are also varying the left-turn phasing by time-of-day using the FYA. We anticipate expanding this technique to leverage all the operational improvement opportunities available from the FYA. Washington West Virginia Wyoming Flashing yellow arrow is optional for WSDOT. We typically install them to match in with a corridor where a local agency has opted to use them. West Virginia is in the same situation and carefully considering FYA use. We look forward to the survey results. Standard. All state signals have been converted to FYA. Approximately 200 movements. We have several dual left FYA installations that operate protected/permissive. Motorists have figured this out beyond my belief. Wyoming DOT has adopted the flashing yellow arrow (FYA) display statewide and has replaced almost every protected/permitted left-turn head on the state highway system to the 4-section all-arrow heads.

7 Flashing Yellow Arrow Experience Question 2 If it's your standard, what factors did you consider in establishing this standard? If used only under certain criteria, what are those criteria? Responses Alabama It isn't exactly our standard yet to go exclusively FYA but we began employing it when upgrades were needed at positively offset left turn bays with individual signal faces for the left turns, thus requiring the FYA. We decided to upgrade all other protected/permissive left turns on those corridors to FYA to be consistent in our operations. An extensive media campaign was launched in the Mobile area prior to implementation with a smaller outreach effort in Birmingham. Driver response has been positive with no reported operational problems or crash concerns. Since our 5 regions are somewhat autonomous, THEY make the decision on whether or not to convert to FYA and some have yet to embrace it. Those that have are excited about the move and are making plans to replace traditional 5-section dog house displays with the FYA (4-section heads) on future corridor projects and eventually with maintenance forces as those funds allow. Alaska We considered the NCHRP Report 493 showing the FYA: offered the highest level of safety among the permissive left turn options tested; was effective at eliminating the yellow trap; was readily understood by motorists; and showed a higher fail-safe response as compared to other indications like the circular green. (Fail-safe is a driver response to stop as opposed to go on the green ball indication). For new installations, there shouldn t be any other considerations. Delaware Historically DE has used flashing red arrow (FRA) with good success. In fact, all of the original research on this topic showed that FRA did well or better compared to the permitted circular green display, but the research panel did not like the come to a full stop message that was conveyed, in that they were looking for a replacement for the traditional permitted display. DE has used FRA as an in between countermeasure, often going to FRA when a crash problem was evident at a traditional permitted or protected-permitted operation. We stopped installing new FRA in the mid-2000s (fear of it becoming banned in the MUTCD), and only recently started installed new ones that are compliant with the current manual. Our guidelines for use are shown on page 107 (Chapter 4) of our newly adopted Traffic Design Manual:

8 Flashing Yellow Arrow Experience Question 2 If it's your standard, what factors did you consider in establishing this standard? If used only under certain criteria, what are those criteria? Responses Georgia Our main factors for going this route were operational, safety, and practical. Safety-wise, a reduction in crashes had occurred, and operationally we are able to lead-lag more intersections as well as some innovative time-of-day operation. Practically, we saw the next MUTCD revision moving towards the FYA being preferred, and made a decision to adopt early though that was primarily for safety and operations. Illinois I will point out that we have utilized lead/lag with the FYA and have still had some left-turn trap issues for locations where the left turn lane is directly adjacent to the through lane(s). Drivers were still having a tendency to see or focus on the adjacent through lane indications going yellow. We have recommended that lagging protected phases not be used with FYA unless the left turn lane is buried or separated from the through lanes for the same direction. We also recommend the use of a LEFT TURN YIELD ON FLASHING YELLOW ARROW sign as we ve seen better compliance and understanding of FYA with the sign. At this time, we are not using FYA to switch between protected/permissive and protected only. We would like to get Illinois drivers more accustomed to FYA operation before considering changing left turn modes by time of day. I would be interested if other states have had any issues with using variable left turn modes with FYA. Indiana We considered studies that showed improved driver recognition, and liked the additional flexibility in signal operation which can decrease delay. Kansas The decision to make it our standard is based on a few things: 1) a course some of us attended mentioned that the upcoming MUTCD is expected to only allow FYA for protected permitted left turn phasing; 2) a number of cities in Kansas are using FYA, particularly on the eastern half of the state; 3) many communities desire a signal head over the left turn lane. We do support having a sign to help communicate to the driver what they are to do when encountering a FYA.

9 Flashing Yellow Arrow Experience Question 2 If it's your standard, what factors did you consider in establishing this standard? If used only under certain criteria, what are those criteria? Responses Kentucky We originally experimented with locations such as the following: 1. Intersections with positive offset left-turn lanes. FYA allows us to hang a separate head over the left-turn lane as opposed to using a shared signal head. 2. Intersections with issues regarding left-turn trap and the controller setting we use to eliminate conflict. Examples include: A-Locations where you want protected-permitted in one direction and protected-only in the other direction. B-Intersections where you want lagging protected-permittted phasing for coordination purposes (not possible with current head due to left-turn trap). 3. Community wide modification involving small number of traffic signals and captive audience. We have since opened up the use of FYA to intersections outside this original criteria. Mass While MassDOT is the largest single owner of traffic signals in the Commonwealth (1,400), the majority of the traffic signals in Massachusetts are owned and operated by municipalities and state Parks and Port entities. While we cannot dictate what they do on their roadways, they tend to follow our lead, so many are starting to implement FYA on their own. MassDOT is in the middle of a 4-year project (one 2-year contract followed by several shorter contracts) to retrofit the approximately 350 signals on State Highway that operate protected-permissive left-turn phasing with FYA operation. These projects are being paid for using our statewide HSIP money. MassDOT is in the middle of a 4-year project (one 2-year contract followed by several shorter contracts) to retrofit the approximately 350 signals on State Highway that operate protectedpermissive left-turn phasing with FYA operation. These projects are being paid for using our statewide HSIP money. Michigan Which operations we use is all based on analysis of the particular intersection. We use the crash experience and sight distance for left turning traffic. We also consider the operating speeds of the roadway. This is a link to our Left turn guidelines: Scroll down to Signal Operations and the Left turn guidelines.

10 Flashing Yellow Arrow Experience Question 2 If it's your standard, what factors did you consider in establishing this standard? If used only under certain criteria, what are those criteria? Responses Minnesota Missouri We are currently working on putting together guidance to help signal operators determine how to operator the signal by time of day. Currently it really is up to the signal operator to know their intersection and what the traffic counts are out there by time of day to determine when to operate protected and when to operate permissive. While this will always be the case, we are hoping to provide some guidance to help the operator make this decision. The NCHRP research that shows it is a safer left turn operation and the flexibility it provided for time of day phasing changes. North Carolina The research that was conducted (NCHRP Project 3-54, NCHRP Report 493, and NCHRP w123) showed fewer fail-critical responses to the 4-section PPLT FYA display as compared to the 5-section doghouse style PPLT head. We wanted to experiment with this new type of operation to see if we could experience the same results in NC. Under FHWA Interim Approval, we deployed our first FYA in February, 2005 with good results. We began slowly turning out more designs throughout the state. Our Safety Evaluation Group began compiling before and after studies and we determined the crashes were showing a decline where the 5- section PPLT heads were being replaced with 4-section heads using FYA operation for PPLTs. We may elect to keep 5-section heads in place at certain intersections along corridors where adjacent intersections are still using 5-section heads. If at all possible, we are trying to stay consistent from one intersection to the next. As funding become available, the goal is to change the displays at adjacent PPLTs along a corridor to FYAs at the same time. The same would be true when coming in with the 3-section FYA for permissive left turns. North Dakota FYAs are not North Dakotas standard. However, we follow guidance of the MUTCD.

11 Flashing Yellow Arrow Experience Question 2 If it's your standard, what factors did you consider in establishing this standard? If used only under certain criteria, what are those criteria? Responses Texas The criteria used in the guidelines is basically the same criteria used to determine permissive, protected only or permissive protected operation, i.e. number of lanes, speed, geometry, traffic volumes (turning volumes and opposing volumes), crash history, sight distance. etc. There was a 2011 national study (Crash Modification Factors Clearinghouse, Study Title: Evaluation of Safety Strategies at Signalized Intersections ) that indicates a crash reduction when a green ball display is replaced with a flashing yellow arrow display. Initially, it was challenging to implement from a hardware standpoint. However, traffic signal equipment manufacturers have improved and updated their equipment to better address the operation. As you implement, public education is important. We have placed information on our website at: If you have any additional questions, please contact Henry Wickes at Virginia Originally, our draft FYA guidance noted that left-turn signal indications, whether FYA or circular green, should be consistent along a given corridor. We have since relaxed that, recognizing that it is not possible for such wholesale change to happen at once. Except in unusual circumstances, FYA deployment is currently limited only by the technical capabilities of the controller & cabinet or the structural loading limitations of existing ancillary structures (for retrofit installations). When FYA was first introduced, we did not have a consistent practice for left-turn phasing decisions. Early in our evaluation, we determined that the critical question was not where to use FYA, but how to choose the appropriate signal phasing. We determined that only when protected-permissive signal phasing was appropriate, should the FYA be used. Within the past 3 months, VDOT has released a new policy and guidance related to left-turn signal phasing decisions. This information can be found on our website. We anticipate that as we more critically evaluate our left-turn phasing decisions based on our policy and guidance, we will be using more protected-permissive left-turn phasing and in-turn morefya indications. A flashing yellow arrow is allowed for protected/permissive left-turn operations under the following conditions: The approach has a separate left-turn storage lane.

12 Flashing Yellow Arrow Experience Question 2 If it's your standard, what factors did you consider in establishing this standard? If used only under certain criteria, what are those criteria? Responses Washington At least one separate four-section signal face, in addition to the minimum of two signal faces for the primary traffic movement on the approach, is to be provided for the left-turn movement. The separate leftturn signal face is to display, from top to bottom (or left to right in a horizontally aligned face), the following set of indications: steady left-turn red arrow, steady left-turn yellow arrow, flashing left-turn yellow arrow, and steady left-turn green arrow. If the left-turn movement is always operated in the permissive-only mode, the green arrow signal section is to be omitted. During a protected left-turn movement, the left-turn signal face displays only a steady left-turn green arrow signal indication. During a permissive left-turn movement, the left-turn signal face displays only a flashing yellow arrow signal indication. During a prohibited left-turn movement, the left-turn signal face displays only a steady left-turn red arrow or a steady circular red. A steady left-turn yellow arrow signal indication is displayed following every steady left-turn green arrow signal indication. A steady left-turn yellow arrow signal indication is displayed following the flashing left-turn yellow arrow signal indication if the permissive left-turn movement is being terminated and the left-turn signal will subsequently display a steady red signal indication. The steady left-turn arrow signal indication and the flashing left-turn yellow arrow signal indication are to be separate displays for permissive left turns. When a permissive left-turn movement is changing to a protected left-turn movement, a steady left-turn green arrow signal indication is to be displayed immediately upon termination of the flashing left-turn yellow arrow signal indication. A steady left-turn yellow arrow signal indication is not to be displayed between the display of the flashing left-turn yellow arrow signal indication and the display of the steady left-turn green arrow signal indication.

13 Flashing Yellow Arrow Experience Question 2 If it's your standard, what factors did you consider in establishing this standard? If used only under certain criteria, what are those criteria? Responses Wyoming We were under a rather unique situation in that we had been using 5-section doghouse signals centered over the left turn lanes, and that was prohibited under the new MUTCD, so we had to make some changes. The positive guidance of the flashing yellow versus a green ball and overall flexibility of operation and the ability to lag the left-turn phases (and possibly lead some and lag some or lead/lag by time-of-day to facilitate progression) were the primary reasons we adopted the flashing yellow arrows. We felt statewide uniformity of all left turn displays was important. We really wanted to lag most of turn arrows to reduce intersection delay. Did not worry about complainers since we built some roundabouts.

14 Question 3 Flashing Yellow Arrow Experience Comparing FYA and circular green only displays for permissive left turns, what does your crash data indicate? Responses Alabama Given that ours have only been operational for about 5/6 months, we don t have any before/after crash data but hope to perform that analysis after sufficient time has elapsed. Alaska We haven t yet performed an in-state analysis of left-turning crashes at locations converted to FYA. We generally wait until we have three full years of post construction crash data, and we ve just about reached that point is our latest year of available crash data. We re getting to more timely data, but we re not there yet. Georgia Our crash data is still limited, but currently we are seeing a significant reduction on most intersections. We cannot yet determine if this is due to the FYA or just because of a change in display in general. Illinois We hope to have a final report for our FYA research project complete by early next year. Indiana Our first deployments were in the fall of We are completing a study through JTRP & Purdue U. that should include crash data, but the data is not available yet. Kansas The DOT has not run any studies regarding crash data and FYA. Again of the signals we are responsible for only 1 has a FYA. I am not sure what analysis communities have completed if any. The communities who use the FYA differ in the type of FYA sign they prefer or if they use a sign at all.

15 Question 3 Flashing Yellow Arrow Experience Comparing FYA and circular green only displays for permissive left turns, what does your crash data indicate? Responses Kentucky Mass Michigan Minnesota Missouri North Carolina Early studies conducted by the City of Lexington produced the following results (based on initial/limited data): Total All Collisions: Percent Reduction: 18% Total Left Turn Collisions: Percent Reduction: 18% Total Injury Left Turn Collisions: Percent Reduction: 22% The Cabinet s initial studies did not show any significant safety improvements with FYA. However, we proceeded with its use due to operational efficiencies when compared to 5-section/shared heads. To the best of my knowledge, there have been no recent crash analysis associated with FYA. At this time we do not have enough data available to us to make any qualified statements on the safety We haven t done any in-depth analysis on the crash patterns based on the different indications. The left turn type crash pattern at an intersection is part of our analysis when reviewing an intersection for dedicated left turn phasing. We have not done any crash analysis at these locations at this time. We have not completed any evaluations at this point. From a 2014 safety evaluation: where the circular R-Y-G head was replaced with the 3-section FYA for permissive left turns, target crashes were reduced by 50% (57 intersections studied). where the 5-section heads were changed to 4-section FYA PPLT operation, target crashes were reduced by 22% (105 intersections studied). [Studies conducted in 2010 at 39 sites showed a 37% reduction.]

16 Question 3 Flashing Yellow Arrow Experience Comparing FYA and circular green only displays for permissive left turns, what does your crash data indicate? Responses North Dakota South Dakota Virginia Washington Wyoming We haven t used these long enough to obtain any usable crash history. We have not performed a crash analysis of the locations with flashing yellow arrows to compare this to circular green permissive operation. We analyzed crash data for some of our initial installations and reported a 67% reduction in crashes. In fact, one of our first FYA installations was prompted to address a left-turn crash problem (32 crashes in a 4-year period). Since FYA was installed, there have been no left-turn crashes at this particular intersection. While it's unrealistic to expect this experience at all locations, we are confident in the reported FHWA FYA crash reduction factors. We have only had the flashing yellow operation for a couple years or so, so we haven t done a comparison between the two yet. On the crash data, anecdotal evidence is that we certainly didn't add to the crash picture by switching to the FYAs, and we're pretty confident that the crashes are down somewhat; but we've been too short-handed to do a thorough before/after analysis to say how much, if any, changes have happened, nor have we been able to calculate a definitive crash modification factor to associate with conversion from 5-section leading doghouse heads to 4-section lagging FYA heads. Good luck with your investigation. We're happy with our decision to change to the FYAs. It did not change much. However, no formal study has been done to date. We are focused more on high speed dilemma zone protection.

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20 Opposing traffic signal heads viewed as if transparent. Flashing Yellow Left Turn Signal Survey Results WYDOT Traffic Program

21 Executive Summary This report contains a detailed statistical analysis of the results to the survey titled 2013 flashing Yellow Left Turn Arrow Survey. The results analysis includes answers from all respondents who took the survey in the 30 day period from Wednesday, April 17, 2013 to Friday, May 17, completed responses were received to the survey during this time. 1

22 Survey Results & Analysis Responses Received: 22 1) Has your state, or any of the local agencies in your state, adopted the flashing yellow left turn arrow heads for use at intersections running both protected and permissive left turn phasing? 2

23 2) Where are they being used (check all that apply): Other Responses: New standard for protected/permissive and permissive left turn indication, where appropriate for safety (not high speed or more than 2 opposing thru lanes, etc.) We have upgraded all current signals which have PPLT left-turn phasing Changing to the FYA as locations are modernized Originally installed at locations with special situations such as: offset left-turn lanes, need for pro-perm in one direction and pro-only in other, need for lagging pro-perm, crash history, etc. Now considering everywhere. We have also mostly completed upgrading the 5 section doghouse heads to FYA on the state highway system. Upgrades to existing Prot-Perm intersections but not solely based on crashes Most of our signalized intersections utilize protected only left turn phasing, however, this FYA may be used for locations with protected-permissive phasing 3

24 3) Have you ever used the 3-section all-arrow left turn heads with flashing yellow permissive left turn arrows on approaches running permissive-only left turns? 4

25 4) If you or any of the local agencies in your state use the flashing yellow turn arrow heads, what controller standard does your state use to run them (check all that apply)? Other Responses: State uses 170. City of Lexington uses

26 5) What central server do you use to run the 4-section heads (e.g., NWSCentral/Voyage, McCain QuicNet Pro/Omni ex)? Econolite Centracs NWS NWS Central/Voyage n/a Tactics, IQ Central In-house program NWSCentral/Voyage? Varies based on the maintaing agency TransSuite MIST (2070/170) FYA operation is supported in the local controllers and MMU Naztec ATMS.now CTNET and in future, Transcore's TSMSS None 6

27 6) What local controller software do you use to run the 4-section heads (e.g., NWSCentral/Voyage, McCain QuicNet Pro/Omni ex)? Siemens Eagle EPAC M52, Econolite ASC/ NWS Voyage Seimans EPAC MOD50 controllers MARC Closed Loop Wapati NWSCentral/Voyage? Varies based on the maintaing agency NWSCentral/Voyage D4 (2070) Econolite ASC/3 with Reno 1600GE MMU, Siemans EPAC with EDI MMU Siemens EPAC Naztec TSCP (An in-house developed 2070 controller local software) EPAC controller 7

28 7) When both protected and permissive left turn phasing is used at an intersection do you (choose one)? 8

29 8) Please check the reasons for always leading the left turn phases (check all that apply): Other Responses: Driver expectancy, but may lead/lag by time of day, in limited circumstances like T- intersections or where intersection geometry requires "splitting the left turn phase". Has been standard practice and driver expectancy We do it so the motorists have something that is predictable because of the confusion that we have seen with protected-permissive phasing This has been our state's standard protocol. No problems noted that I am aware of. We are using lead/lag for three SCATS projects. The lead/lag varies with TOD for best coordination. General driver expectancy statewide is a leading LT, very few lagging across entire area, only specifc coordination cases with problems 9

30 9) Please check the reasons for always lagging the left turn phases (check all that apply): 10

31 10) Please check the reasons for leading some and lagging other left turn phases, but not changing the order throughout the day (check all that apply): Other Responses: The all red phase look funny so some drivers for leading lefts 11

32 11) Please check the reasons for leading some and lagging other left turn phases, and changing the order throughout the day (check all that apply). 12

33 12) Describe the type of agency you represent: 13

34 13) My agency is responsible for the operation and maintenance of roughly (number) (with about 20 FYA, more on the way) N/A ,600 NDOT does not maintain or operate signals 1, ,

35 Guidelines - Flashing Yellow Arrow Display For Left-Turn Operations PURPOSE To provide guidance on new requirements for the design, use and operation of signalized intersections resulting from the adoption of the 2011 Texas Manual on Uniform Traffic Control Devices (TMUTCD). These guidelines apply specifically for Signalized Left Turn Operations. BACKGROUND The 2011 TMUTCD contains significant changes from the 2006 TMUTCD regarding the requirements for traffic signal displays. These changes will affect the design and operation of traffic signals. These changes include the addition of a flashing yellow arrow display for left turn operations. While a 5-section signal face with a circular green may still be used in a shared left turn signal face, the use of a circular green indication in a separate left turn signal face has been prohibited. The flashing yellow arrow (or flashing red arrow) is now the only allowable indication for a permissive left turn in a separate left turn signal face. The same requirements also apply to separate signals for right turns. A definition of shared left turn signal face and separate left turn signal face is provided in the TMUTCD as follows: Shared Turn Signal Face a signal face, for controlling both a turn movement and the adjacent through movement, that always displays the same color of circular signal indication that the adjacent through signal face or faces display. Separate Turn Signal Face a signal face that exclusively controls a turn movement and that displays signal indications that are applicable only to the turn movement. The following are requirements set by the 2011 TMUTCD for protected only, protected / permissive, and permissive only left turn operations relating to both shared and separate left turn signal faces. For shared signal faces in a protected only operation: A four-section head with Circular RED, Circular YELLOW, Circular GREEN and left turn GREEN ARROW is required. Shared signal faces for protected only operations shall only be used if the Circular GREEN and GREEN ARROW always terminate together (i.e. Split Phasing). FYA GUIDANCE April 17, P a g e

36 The figure shown below illustrates the signal face configurations for this left turn operation: For separate signal faces in a protected only operation: Signal indications for protected only mode left turns in a separate signal face is required to be a 3 section signal face with RED ARROW, YELLOW ARROW, GREEN ARROW indications. The figure shown below illustrates the signal face configurations for this left turn operation: FYA GUIDANCE April 17, P a g e

37 For shared signal faces in a protected / permissive operation: A five-section head with Circular RED, YELLOW, GREEN, as well as YELLOW ARROW, GREEN ARROW is required. Five-section signal faces mounted overhead must be centered over (or slightly right of) a projection of the lane line dividing the through lane and the turn lane. The circular indications must display the same color as the adjacent through indications. The figure shown below illustrates the signal face configurations for this left turn operation: For separate left turn signal faces in a protected / permissive operation: A four-section head with steady left turn RED ARROW, steady left turn YELLOW ARROW, flashing YELLOW ARROW and steady left turn GREEN ARROW is required. (As a practice, TxDOT does not currently use the dual arrow signal section.) The flashing YELLOW ARROW indication is permitted to be displayed while adjacent through signals display a steady circular RED indication. The use of a RED ARROW is required to terminate a steady yellow arrow. (Past TxDOT practice to not use RED ARROW indications is now superseded by this new TMUTCD requirement.) FYA GUIDANCE April 17, P a g e

38 The figure shown below illustrates the signal face configurations for this left turn operation: For shared signal faces in a permissive only operation: A three-section head with Circular RED, Circular YELLOW, Circular GREEN is required The figure shown below illustrates the signal face configurations for this left turn operation: For separate signal faces in a permissive only operation: FYA GUIDANCE April 17, P a g e

39 A three-section head with RED ARROW, steady YELLOW ARROW, and flashing YELLOW ARROW is required. The figure shown below illustrates the signal face configurations for this left turn operation: DETERMINING LEFT TURN SIGNAL CONTROL MODE Left-turning traffic is controlled by one of four modes as follows: A. Permissive Only Mode turns made on a CIRCULAR GREEN signal indication, a flashing left-turn YELLOW ARROW signal indication, or a flashing left-turn RED ARROW signal indication after yielding to pedestrians, if any, and/or opposing traffic, if any. B. Protected Only Mode turns made only when a left-turn GREEN ARROW signal indication is displayed. C. Protected/Permissive Mode both protected and permissive modes can occur on an approach during the same cycle. D. Variable Left-Turn Mode the operating mode changes among the protected only mode and/or the protected/permissive mode and/or the permissive only mode during different periods of the day or as traffic conditions change. An engineering study should be conducted to determining the appropriate left-turn signal control mode (protected only, protected / permissive, permissive only, split phasing, or variable by time of day) for signalized intersections. The study should take into consideration left turn volumes, crash history, 85 th percentile (posted) speed, sight distance, number of left turn lanes, number of opposing through lanes, pedestrian volumes and opposing through volumes. In addition to the above considerations, intersection geometry can affect the selection of the left turn signal control mode. Intersections with wide medians, conflicting turning paths, non-standard alignments, etc. are also factors in determining left turn signal mode. FYA GUIDANCE April 17, P a g e

40 There are many sources for determining left turn control mode, two flow charts obtained from recent research projects that may be used as an aid in determining the appropriate left-turn control mode are: Figure 62: Decision-Making Flowchart for Selecting Left-Turn Signal Control Mode, FHWA/TX-09/ , Development of Left-Turn Operations Guidelines at Signalized Intersections, Authors: Lei Yu, Yi Qi, Hongxi Yu, Lei Guo and Xin Chen, Appendix A, Figure A-6. Guidelines for Determining Left-Turn Operational Mode, FHWA/TX-11/ P1, TRAFFIC SIGNAL OPERATIONS HANDBOOK, Second Edition Authors: J. Bonneson, S. Sunkari, M. Pratt, and P. Songchitruksa Development of Left-Turn Operations Guidelines at Signalized Intersections and the Traffic Signal Operations Handbook can be found at the following links: SIGNAL INDICATIONS FOR LEFT TURN CONTROL MODE Permissive Only Mode The 2011 TMUTCD allows for permissive only mode left turns using either a circular GREEN, flashing YELLOW ARROW, or RED ARROW. If a separate signal section is provided for the left turn lane, the signal face will need to be as shown in Figure 4D-7 and will require modification to the controller cabinet to provide the Flashing Yellow Arrow (FYA) operation. Alternatively, the approach can be provided with signal faces as illustrated in Figure 4D-6, without need for cabinet modification. Protected Only Mode Signal indications for protected only mode left turns in a separate signal face is required to be a 3 section signal face with RED ARROW, YELLOW ARROW, GREEN ARROW indications. Signal indications for protected only mode in a shared signal face is required to be Circular RED, YELLOW, GREEN, GREEN ARROW indications. This would be for use where the circular GREEN and GREEN ARROW indications always begin and end together (i.e. Split phasing). Protected / Permissive Mode Signal indications for protected / permissive mode in a separate left turn signal face are required to be RED ARROW, YELLOW ARROW, Flashing YELLOW ARROW, and GREEN ARROW (a flashing RED ARROW is also allowed). Signal indications for protected / permissive mode in a shared signal face are required to be Circular RED, YELLOW, GREEN, YELLOW ARROW and GREEN ARROW. TxDOT practice for protected / permissive left turn mode for standard diamond interchanges is to use a shared signal face, (Flashing YELLOW ARROW is not used for standard diamond interchanges). FYA GUIDANCE April 17, P a g e

41 Variable Left Turn Mode Variable mode operation requires signal indications as defined above for a protected / permissive separate signal face. Variable mode may be implemented by time of day or possibly by rail or emergency preemption. FLASHING YELLOW ARROW LEFT TURN OPERATION INSTALLATION Where to Install FYA is an option for permissive/protected left turn phasing. However, as with protected / permitted operation in general, careful consideration is needed in deciding on where to install the FYA. General Guidelines are provided as implementation will vary from one area of the state to another, there will be varying interest and involvement from local jurisdictions. Some have existing FYA installations others have no experience with the display. Generally, implementation should consist of an initial pilot or demonstration project consisting of a few isolated intersections or a small section of corridor. The district should obtain local buy-in and approval, providing press releases and information on where the FYA installations are being installed, what the FYA indications mean, how the motorists should interpret the indications, explain why we are changing (the benefits). In identifying pilot projects, typically, sections of corridors with signalized intersections that have the following characteristics may be considered for installation of protected permissive left turn operation (Flashing Yellow Arrow or 5 section head): Low speeds 1 left turn bay per approach 3 or less through lanes low number of left turn related crashes adequate driver sight distance to oncoming vehicles low left turn volume during peak periods low traffic volume, and signal coordination plans indicate operational improvement with the FYA permissiveprotected operation Consideration for installation of protected / permissive left turn operation (Flashing Yellow Arrow or 5 section head) on sections of corridors with signalized intersections with the following characteristics is discouraged: Corridors with multiple signalized intersections in view using solid green ball for permissive phase high speeds dual left turn lanes 4 or more through lanes high left turn crash history poor sight distance to oncoming vehicles high left turn volumes during peak periods or FYA GUIDANCE April 17, P a g e

42 high traffic volumes While it is desirable to be consistent in the application of left turn treatment along a corridor for driver expectation, it may not be practical to install FYA left turn protected / permissive mode in a consistent manner along a corridor. For example, FYA left turn operation requires a separate left turn signal face. Signalized intersections along a corridor equipped with shared signal faces that would require installation of new signal poles with longer mast-arms may be cost prohibitive to convert to FYA left turn operation. There are existing implementations of FYA that have resulted in a mix of FYA and 5 section green ball protected / permissive operation. However, it would be appropriate to install the FYA at a new signalized intersection meeting the criteria for protected / permissive left turn mode operation on the corridor without immediately modifying the other existing intersections along the corridor. Preferably, the intersection should not be within view of other intersections with 5-section green ball. FYA protected /permissive mode at a location that previously operated in protected only mode should be considered only after careful study of the intersection. Research study of locations that were converted from protected only mode to FYA protected /permitted mode saw an increase in the crash frequency 1. Do not remove protected-only left turn phasing if opposing sight distance is inadequate for permissive left turns, operating speed is too great, roadway geometry is complicated or there are too many opposing through lanes. If the protected-only left turn was installed for other safety reasons (crash prevention when under less restrictive phasing), care should be used in operating a possible FYA installation protected/ permissive. Prior to the addition of the FYA left turn signal display to the federal 2009 MUTCD, the FYA left turn operation was approved as an experimental signal display for protected-permitted mode and was studied fairly extensively. Before and after crash data indicate there is an improvement in safety over other protected-permitted left turn displays. Emergency Pre-emption Installing Permissive/Protected FYA operation along emergency vehicle preemption routes requires special study and consideration as well. It will be necessary to work closely with emergency-vehicles to provide the preemption operation that best fits their preference. Careful consideration is needed regarding whether to allow or terminate FYA for the opposing left during preemption. If the FYA is to be turned off during preemption, it will be necessary to terminate the through phases (go to all red) prior to dropping FYA for preemption. For example, if the intersection is displaying circular green and flashing yellow arrow for both approaches of an arterial when a pre-emption becomes active to provide a protected through and left turn (circular green and green arrow dwell phase) to the approach for the emergency vehicle, there are 2 possible states for the opposing left turn FYA. The FYA may be allowed to continue to flash during the preemption dwell phase or it may be terminated. If in the above scenario it is decided to terminate the opposing left turn FYA, it would be necessary to go to all-red prior to displaying the dwell phase. Variable Mode Operation FYA GUIDANCE April 17, P a g e

43 Variable mode operation, changing between protected only to protected / permissive mode, or between protected /permissive to permissive only operation by time of day is possible with the 4-section FYA signal face where a study shows this type of operation to be beneficial. However, it is important to ensure that the traffic signal controller is capable switching between modes in a manner such that the flashing yellow arrow indication and the opposing through movement indication terminate together. In other words, the controller should be capable of transitioning between modes without the flashing yellow arrow terminating while the opposing through movement stays green. Additionally, when switching between protected / permissive to permissive only, ensure that the controller is capable of reassigning the left turn detectors to call the associated through phases by time of day. Public Notification Installation of FYA left turn operation should be coordinated with the District Public Information Office. Consider press releases with specific details on when the public can expect to see the new indications. Press releases should be prepared and sent out (approximately 2 weeks or more in advance of conversion). Special attention should be given to the first installation in an area, if available, place portable changeable message signs in advance of the affected signals at least five (5) days before the FYA activation date. Equipment Issues The majority of current TxDOT traffic signal equipment is not compatible with FYA operation. TxDOT signal cabinets can be modified to perform FYA with fairly minor equipment changes. Prior to installing or converting an intersection to FYA left turn operations it will be necessary to ensure that there is adequate field wiring, the signal controller cabinet has adequate channels (load switches), and the controller and Malfunction Management Unit (MMU) are capable of FYA operation. Configuration of the traffic signal cabinet may be dependent on several conditions at the intersection. The controller requirements; the monitor requirements; the cabinet size and available load switches, whether pedestrian signals are being utilized are just a few of the issues. Careful planning is required to ensure a successful installation. Cabinet Modification Controller manufacturers have not standardized on FYA operation. Cabinet modification will depend on controller make and model. An MMU capable of FYA operation is required. Install a new MMU recommended by the controller manufacturer. A modification to the cabinet flash programming is required. Contact the manufacturer representative or TRF-TE Signal Operations Branch for assistance if needed. Signing While the 2011 TMUTCD does not require this signing, a Left Turn Signal Yield on Flashing Arrow (with no graphics) sign should be installed adjacent to the new head for clarification. If the FYA face is to be installed at an existing location with a 5 section face, verify the sign can be installed and ensure any conflicting signs such as the Left Turn Yield on Green sign (R10-12) is removed if in place. FYA GUIDANCE April 17, P a g e

44 Observations Signal observations should be performed periodically as discretely as possible, and particularly during the times where the phasing has changed from the previous installation. When converting left turn signal operations to FYA protected-permissive be sure to observe driver behavior, especially when the intersection was previously a protected only operation. Crash Data With the initial FYA installations in your area, monitor the crash data for at least one year after installation. Other Considerations The 2011 TMUTCD provides a new figure, Figure 4d-3, Recommended Vehicular Signal Faces for Approaches with Posted, Statutory, or 85 th Percentile Speed of 45 mph or Higher, and a new table, Table 4D-1. Recommended Minimum Number of Primary Signal Faces for Through Traffic on Approaches with Posted, Statutory, or 85 th -Percentile Speed of 45 mph or Higher. These are shown below for reference. Requirements from this table are a should condition, the table should be consulted for minimum number and location of primary signal faces for through traffic. FYA GUIDANCE April 17, P a g e

45 References: 1. David A. Noyce, Casey R. Bergh, Jeremy R. Chapman, NCHRP Web Only Document, 123, Evaluation of the Flashing Yellow Arrow Permissive-Only Left-Turn Indication Field Implementation 2. Yi Qi, Xiaoming Chen, Lei Yu, Yubian Wang, Min Zhang, Peina Yuan and Khali R. Persad, FHWA/TX-09/ , Use of Flashing Yellow Operations to Improve Safety at Signals with Protected-Permissive Left Turn (PPLT) Operations 3. Manual on Uniform Traffic Control Devices (MUTCD). Federal Highway Administration, 2009 FYA GUIDANCE April 17, P a g e