There are some provisions in Chapter 4D that, in my opinion, are
conflicting or confusing, or that seem to have been overlooked when
revising the 2003 MUTCD, and need to be clarified to reflect the changes
made that allow flashing yellow arrow signal faces and flashing red
arrow signal faces that are now being implemented.

I am suggesting some revisions and minor editorial changes to the
following sections:

**Section 4D.07 [Positions of Signal Indications Within a Vertical
Signal Face]{.underline}**

**Section 4D.08 [Positions of Signal Indications Within a Horizontal
Signal Face]{.underline}**

**Section 4D.10 [Application of Steady Signal Indications]{.underline}**

**Section 4D.17 [Signal Indications for Left-Turn Movements --
General]{.underline}**

**Section 4D.18 [Signal Indications for Permissive Only Mode Left-Turn
Movements]{.underline}**

**Section 4D.19 [Signal Indications for Protected Only Mode Left-Turn
Movements ]{.underline}**

**Section 4D.20 [Signal Indications for Protected/Permissive Mode
Left-Turn Movements]{.underline}**

**Section 4D.21 [Signal Indications for Right-Turn Movements --
General]{.underline}**

**Section 4D.22 [Signal Indications for Permissive Only Mode Right-Turn
Movements]{.underline}**

**Section 4D.24 [Signal Indications for Protected/Permissive Mode
Right-Turn Movements ]{.underline}**

**Section 4D.26 [Yellow Change and Red Clearance
Intervals]{.underline}**

I have started with the "clean text" version of the proposed MUTCD Text
and made suggested revisions and comments as necessary. (Please pardon
the length; I have often it easier to suggest revisions and make
comments on a copy of the original document rather than on a separate
stand-alone page.)

My suggested additions are in **blue text**.

~~My suggested deletions are in **red strikethrough,**~~

  -----------------------------------------------------------------------
  My comments are in yellow highlight.

  -----------------------------------------------------------------------

My comments also make some references to some engineering reports; there
is a References section at the end for the references that I cited in
support of some of my commentary.

**Section 4D.07 [Positions of Signal Indications Within a Vertical
Signal Face]{.underline}**

**Standard:**

**In each vertically-arranged signal face, all signal sections that
display red signal indications shall be located above all signal
sections that display yellow and green signal indications.**

**In vertically-arranged signal faces, each signal section that displays
a YELLOW ARROW signal indication shall be located immediately above the
signal section that displays the GREEN ARROW signal indication to which
it applies.**

  -----------------------------------------------------------------------
  This needs to be revised for flashing yellow arrow signal faces, with
  the flashing YELLOW ARROW signal section between the steady GREEN ARROW
  and steady YELLOW ARROW signal sections (a steady YELLOW ARROW that is
  NOT immediately above the GREEN ARROW), and also for the fact that the
  steady YELLOW ARROW is also used to clear the flashing YELLOW ARROW and
  flashing RED ARROW permissive turn indications (in the case of the
  flashing RED ARROW where the steady YELLOW ARROW is BELOW the flashing
  RED ARROW). (Refer to Sections 4D.17-24)

  -----------------------------------------------------------------------

**If a dual-arrow signal section (capable of alternating between the
display of a GREEN ARROW and a YELLOW ARROW signal indication) is used
in a vertically-arranged signal face, the dual-arrow signal section
shall occupy the same position relative to the other sections as the
signal section that displays the GREEN ARROW signal indication in a
vertically-arranged signal face would occupy.**

**The relative positions of signal sections in a vertically-arranged
signal face, from top to bottom, shall be as follows:**

**CIRCULAR RED**

**Steady and/or flashing left-turn RED ARROW**

**Steady and/or flashing right-turn RED ARROW**

**CIRCULAR YELLOW**

**CIRCULAR GREEN**

**Straight-through GREEN ARROW**

**Steady left-turn YELLOW ARROW**

**Flashing left-turn YELLOW ARROW**

**Left-turn GREEN ARROW**

**Steady right-turn YELLOW ARROW**

**Flashing right-turn YELLOW ARROW**

**Right-turn GREEN ARROW**

  -----------------------------------------------------------------------
  This was revised to reflect the signal arrangements of flashing yellow
  arrow signal faces and flashing red arrow signal faces in Sections
  4D.17 through 4D.25. The NCUTCD has also proposed a similar change.

  -----------------------------------------------------------------------

Option:

In a vertically-arranged signal face, signal sections that display
signal indications of the same color, and signal sections that display
steady GREEN ARROW and flashing YELLOW ARROW signal indications, may be
arranged horizontally adjacent to each other at right angles to the
basic straight line arrangement.

**Standard:**

**Such clusters shall be limited to ~~two identical signal sections or
to two or three different signal sections that display signal
indications of the same color~~ the following:**

A.  **Two identical signal ~~lenses~~ sections, or**

B.  **Two or three different signal sections that display signal
    indications of the same color, or**

C.  **Two different signal sections that display steady GREEN ARROW and
    flashing YELLOW ARROW signal indications.**

**Signal sections that display flashing yellow and steady yellow signal
indications during steady mode operation shall not be placed in the same
vertical position in a vertically arranged signal face.**

+-----------------------------------------------------------------------+
| This was revised to accommodate the provisions of Section 4D.25,      |
| which states the following:                                           |
|                                                                       |
| **Standard:**                                                         |
|                                                                       |
| **...**                                                               |
|                                                                       |
| **When there are no pedestrian or vehicular movements that conflict   |
| with the left-turn or right-turn movements, the signal faces provided |
| for the approach shall be one of the following:**                     |
|                                                                       |
| **...**                                                               |
|                                                                       |
| **a shared left-turn/right-turn signal face capable of displaying     |
| CIRCULAR RED, left-turn YELLOW ARROW, left-turn GREEN ARROW,          |
| right-turn YELLOW ARROW, and right-turn GREEN ARROW signal            |
| indications...**                                                      |
|                                                                       |
| This allows for a signal face that is laid out as follows:            |
|                                                                       |
|   -------------------------------- ---------------------------------  |
|   **Steady CIRCULAR RED**                                             |
|                                                                       |
|   **Steady left-turn YELLOW        **Steady right-turn YELLOW         |
|   ARROW**                          ARROW**                            |
|                                                                       |
|   **Steady left-turn GREEN ARROW** **Steady right-turn GREEN ARROW**  |
|   -------------------------------- ---------------------------------  |
|                                                                       |
| The Standard referenced in Section 4D.25 also allows for, in the case |
| of a conflicting vehicular or pedestrian movement, the substitution   |
| of a flashing YELLOW ARROW for the steady GREEN ARROW for the turn    |
| movement(s) in conflict, as follows:                                  |
|                                                                       |
| **Standard:**                                                         |
|                                                                       |
| **...**                                                               |
|                                                                       |
| **If a vehicular movement and/or pedestrians crossing in conformance  |
| with a WALKING PERSON (symbolizing WALK) or flashing UPRAISED HAND    |
| (symbolizing DONT WALK) signal indication conflict with the left-turn |
| or right-turn movement or both turning movements, the signal faces    |
| provided for the approach shall be one of the following:**            |
|                                                                       |
| **...**                                                               |
|                                                                       |
| **the signal face or faces described \[above\], but with...a flashing |
| YELLOW ARROW signal indication in place of the GREEN ARROW signal     |
| indication for the turning movement(s) that conflicts with the        |
| signalized pedestrian or vehicular movement...**                      |
|                                                                       |
| The resulting substitution would result in a signal face that could   |
| be laid out as follows: (The example here is for a protected left     |
| turn, but with a right-turn movement that conflicts with a pedestrian |
| crossing.)                                                            |
|                                                                       |
|   -------------------------------- ---------------------------------  |
|   **Steady CIRCULAR RED**                                             |
|                                                                       |
|   **Steady left-turn YELLOW        **Steady right-turn YELLOW         |
|   ARROW**                          ARROW**                            |
|                                                                       |
|   **Steady left-turn GREEN ARROW** **Flashing right-turn YELLOW       |
|                                    ARROW**                            |
|   -------------------------------- ---------------------------------  |
|                                                                       |
| So this Standard should be modified to allow for this case. A         |
| suggested revision is shown above.                                    |
+-----------------------------------------------------------------------+

**Section 4D.08 [Positions of Signal Indications Within a Horizontal
Signal Face]{.underline}**

**Standard:**

**In each horizontally-arranged signal face, all signal sections that
display red signal indications shall be located to the left of all
signal sections that display yellow and green signal indications.**

**In horizontally-arranged signal faces, each signal section that
displays a YELLOW ARROW signal indication shall be located immediately
to the left of the signal section that displays the GREEN ARROW signal
indication to which it applies.**

  -----------------------------------------------------------------------
  This needs to be revised for flashing yellow arrow signal faces, with
  the flashing YELLOW ARROW signal section between the steady GREEN ARROW
  and steady YELLOW ARROW signal sections (steady YELLOW ARROW that is
  NOT immediately to the left of the GREEN ARROW), and also for the fact
  that the steady YELLOW ARROW is also used to clear the flashing YELLOW
  ARROW and flashing RED ARROW permissive turn indications (in the case
  of the flashing RED ARROW where the steady YELLOW ARROW is displayed to
  the RIGHT of the flashing RED ARROW). (Refer to Sections 4D.17-24)

  -----------------------------------------------------------------------

**If a dual-arrow signal section (capable of alternating between the
display of a GREEN ARROW and a YELLOW ARROW signal indication) is used
in a horizontally-arranged signal face, the signal section that displays
the dual left-turn arrow signal indication shall be located immediately
to the right of the signal section that displays the CIRCULAR YELLOW
signal indication, the signal section that displays the straight-through
GREEN ARROW signal indication shall be located immediately to the right
of the signal section that displays the CIRCULAR GREEN signal
indication, and the signal section that displays the dual right-turn
arrow signal indication shall be located to the right of all other
signal sections.**

**The relative positions of signal sections in a horizontally-arranged
signal face, from left to right, shall be as follows:**

**CIRCULAR RED**

**Steady and/or flashing left-turn RED ARROW**

**Steady and/or flashing right-turn RED ARROW**

**CIRCULAR YELLOW**

**Steady left-turn YELLOW ARROW**

**Flashing left-turn YELLOW ARROW**

**Left-turn GREEN ARROW**

**CIRCULAR GREEN**

**Straight-through GREEN ARROW**

**Steady right-turn YELLOW ARROW**

**Flashing right-turn YELLOW ARROW**

**Right-turn GREEN ARROW**

  -----------------------------------------------------------------------
  This was revised to reflect the signal arrangements of flashing yellow
  arrow signal faces and flashing red arrow signal faces in Sections
  4D.17 through 4D.25. The NCUTCD has also proposed a similar change.

  -----------------------------------------------------------------------

**Section 4D.10 [Application of Steady Signal Indications]{.underline}**

  -----------------------------------------------------------------------
  Should this Section also be revised to include flashing YELLOW ARROW
  and flashing RED ARROW indications that are displayed as part of a
  steady mode operation?

  -----------------------------------------------------------------------

**Standard:**

**When a traffic control signal is being operated in a steady
(stop-and-go) mode, at least one indication in each signal face shall be
displayed at any given time.**

**A signal face(s) that controls a particular vehicular movement during
any interval of a cycle shall control that same movement during all
intervals of the cycle.**

**Steady signal indications shall be applied as follows:**

> **A. A steady CIRCULAR RED signal indication:**
>
> **1. Shall be displayed when it is intended to prohibit traffic,
> except pedestrians directed by a pedestrian signal head, from entering
> the intersection or other controlled area. Turning after stopping is
> permitted as stated in Item C.1 of Section 4D.09.**
>
> **2. Shall be displayed with the appropriate GREEN ARROW signal
> indications when it is intended to permit traffic to make a specified
> turn or turns, and to prohibit traffic from proceeding straight ahead
> through the intersection or other controlled area, except in protected
> only mode operation (see Sections 4D.19 and 4D.23), or in
> protected/permissive mode operation with separate signal faces,
> flashing yellow arrow signal faces, or flashing red arrow signal faces
> (see Sections 4D.20 and 4D.24), or where it is physically impossible
> for traffic to go straight through the intersection such as on the
> stem of a T-intersection.**
>
> **B. A steady CIRCULAR YELLOW signal indication:**
>
> **1. Shall be displayed following a CIRCULAR GREEN or straight-through
> GREEN ARROW signal indication in the same signal face.**
>
> **2. Shall not be displayed in conjunction with the change from the
> CIRCULAR RED signal indication to the CIRCULAR GREEN signal
> indication.**
>
> **3. Shall be followed by a CIRCULAR RED signal indication except
> that, when entering preemption operation, the return to the previous
> CIRCULAR GREEN signal indication shall be permitted following a steady
> CIRCULAR YELLOW signal indication (see Section 4D.27).**
>
> **4. Shall not be displayed to an approach from which drivers are
> turning left permissively unless one of the following conditions
> exists:**
>
> **(a) A steady CIRCULAR YELLOW signal indication is also
> simultaneously being displayed to the opposing approach;**
>
> **(b) A separate left-turn signal face, a flashing yellow arrow signal
> face, or a flashing red arrow signal face is provided and operated as
> described in Sections ~~4D.18 and~~ 4D.17 through 4D.20;**

+-----------------------------------------------------------------------+
| This paragraph was revised to reflect the use of flashing yellow      |
| arrow signal faces and flashing red arrow signal faces used in        |
| Sections 4D.18 and 4D.20, that also eliminate the "yellow trap"       |
| condition, and that is consistent with similar language found in      |
| Section 2C.50.                                                        |
|                                                                       |
| Because the flashing red arrow signal faces and flashing yellow       |
| signal faces, when used for left turns, display the flashing          |
| permissive indication for left turns during intervals when oncoming   |
| traffic has a green light, and that the steady left-turn YELLOW ARROW |
| indication (as described below) is only permitted to be displayed     |
| when oncoming traffic also has either a CIRCULAR YELLOW signal        |
| indication or a CIRCULAR RED signal indication, the "yellow trap"     |
| condition is completely eliminated, and the use of a flashing yellow  |
| arrow signal face or a flashing red arrow signal face should also be  |
| grounds for permitting the CIRCULAR YELLOW signal indication to be    |
| displayed to the approach where drivers are turning left permissively |
| without the simultaneous display of the CIRCULAR YELLOW signal        |
| indication to the opposing approach.                                  |
|                                                                       |
| *See also Section 4D.26---the texts of the two Sections need to be    |
| consistent.*                                                          |
+-----------------------------------------------------------------------+

> **(c) An engineering study has determined that, because of unique
> intersection conditions, the conditions described in items (a) and (b)
> above cannot reasonably be implemented without causing significant
> operational or safety problems and that the volume of impacted
> left-turning traffic is relatively low, and those left-turning drivers
> are advised that a steady CIRCULAR YELLOW signal indication is not
> simultaneously being displayed to the opposing traffic if this
> operation occurs continuously by the installation near the left-most
> signal head of a W25-1 sign (see Section 2C.50) with the legend
> ONCOMING TRAFFIC HAS EXTENDED GREEN; or**
>
> **(d) Drivers are advised of the operation if it occurs only
> occasionally, such as during a preemption sequence, by the
> installation near the left-most signal head of a W25-2 sign (see
> Section 2C.50) with the legend ONCOMING TRAFFIC MAY HAVE EXTENDED
> GREEN.**
>
> **C. A steady CIRCULAR GREEN signal indication shall be displayed only
> when it is intended to permit traffic to proceed in any direction that
> is lawful and practical.**
>
> **D. A steady RED ARROW signal indication shall be displayed when it
> is intended to prohibit traffic, except pedestrians directed by a
> pedestrian signal head, from entering the intersection or other
> controlled area to make the indicated turn. Except as described in
> Item C.2 of Section 4D.09, turning on a steady RED ARROW signal
> indication shall not be permitted.**
>
> **E. A steady YELLOW ARROW signal indication:**
>
> **1. Shall be displayed in the same direction as a GREEN ARROW signal
> indication following a GREEN ARROW signal indication in the same
> signal face, unless:**
>
> **(a) The GREEN ARROW signal indication and a CIRCULAR GREEN (or
> straight-through GREEN ARROW) signal indication terminate
> simultaneously in the same signal face, or**
>
> **(b) The green arrow is a straight-through GREEN ARROW.**
>
> **2. Shall be displayed in the same direction as a flashing YELLOW
> ARROW signal indication or flashing RED ARROW signal indication
> following a flashing YELLOW ARROW signal indication or flashing RED
> ARROW signal indication in the same signal face, when the flashing
> arrow indication is displayed as part of a steady mode operation, if
> the signal face will subsequently display a steady red signal
> indication.**
>
> **3. Shall not be displayed in conjunction with the change from a
> steady RED ARROW signal indication, a flashing RED ARROW signal
> indication, or a flashing YELLOW ARROW signal indication to a GREEN
> ARROW signal indication (except when entering preemption operation as
> described later in this Section).**

  -----------------------------------------------------------------------
  Revised to reflect the use of flashing yellow arrow and flashing red
  arrow signal indications for permissive turns in Section 4D.17 through
  4D.24.

  -----------------------------------------------------------------------

> **4. Shall not be displayed when any conflicting vehicular movement
> has a green or yellow signal indication (except for the situation
> regarding U-turns described in the Option below) or any conflicting
> pedestrian movement has a WALKING PERSON (symbolizing WALK) or
> flashing UPRAISED HAND (symbolizing DONT WALK) signal indication,
> except that a steady left-turn YELLOW ARROW signal indication used to
> terminate a flashing left-turn YELLOW ARROW or a flashing left-turn
> RED ARROW signal indication in a signal face controlling a permissive
> left-turn movement as described in Sections 4D.18 and 4D.20 shall be
> permitted to be displayed when a CIRCULAR YELLOW signal indication is
> displayed for the opposing through movement. Vehicles departing in the
> same direction shall not be considered in conflict if, for each turn
> lane with moving traffic, there is a separate departing lane, and
> pavement markings or raised channelization clearly indicate which
> departure lane to use.**

+-----------------------------------------------------------------------+
| What about in the case where opposing left turns and right turns      |
| conflict and turn into the same lanes of traffic?                     |
|                                                                       |
| ![](media/image1.png){width="2.252083333333333in"                     |
| height="1.0708333333333333in"}                                        |
+-----------------------------------------------------------------------+

> **5. Shall be terminated by a RED ARROW signal indication for the same
> direction or a CIRCULAR RED signal indication except:**
>
> **(a) When entering preemption operation, the return to the previous
> GREEN ARROW or flashing arrow signal indication, or the transition to
> a GREEN ARROW signal indication from a flashing arrow indication,
> shall be permitted following a steady YELLOW ARROW signal
> indication.**

  -----------------------------------------------------------------------
  In a preemption situation (for instance, railroad preemption), there
  could be instances where, when opposing traffic has to go to a "clear
  track" green interval, the left turn signal (that is tied to the
  opposing CIRCULAR GREEN indication) opposite the railroad crossing
  could potentially go from flashing YELLOW ARROW to steady YELLOW ARROW
  back to flashing YELLOW ARROW. Additionally, the left-turn movement
  that crosses the railroad track in advance of the left turn could also
  make the transition from flashing YELLOW ARROW to steady YELLOW ARROW
  to steady GREEN ARROW depending on how the controller is programmed to
  operate during pre-emption. (Note that these sequences would ONLY be
  permitted when entering preemption.) As it is, transitions from steady
  GREEN ARROW to steady YELLOW ARROW back to steady GREEN ARROW are
  already permitted during the transition into preemption.

  -----------------------------------------------------------------------

> **(b) When the movement controlled by ~~the arrow~~ a GREEN ARROW
> signal indication is to continue on a permissive mode basis during an
> immediately following CIRCULAR GREEN, ~~or~~ flashing YELLOW ARROW, or
> flashing RED ARROW signal indication.**

  -----------------------------------------------------------------------
  Minor editorial change that reflects the use of flashing red arrow
  signal indications for some permissive turns that require all traffic
  to make a complete stop before turning during the permissive turn
  interval, as discussed in Sections 4D.17 through 4D.24.

  -----------------------------------------------------------------------

> **F. A steady GREEN ARROW signal indication:**
>
> **1. Shall be displayed only to allow vehicular movements, in the
> direction indicated, that are not in conflict with other vehicles
> moving on a green or yellow signal indication or with pedestrians
> crossing in conformance with a WALKING PERSON (symbolizing WALK) or
> flashing UPRAISED HAND (symbolizing DONT WALK) signal indication.
> Vehicles departing in the same direction shall not be considered in
> conflict if, for each turn lane with moving traffic, there is a
> separate departing lane, and pavement markings or raised
> channelization clearly indicate which departure lane to use.**
>
> **2. Shall be displayed on a signal face that controls a left-turn
> movement when said movement is not in conflict with other vehicles
> moving on a green or yellow signal indication (except for the
> situation regarding U-turns described in the Option below) or with
> pedestrians crossing in conformance with a WALKING PERSON (symbolizing
> WALK) or flashing UPRAISED HAND (symbolizing DONT WALK) signal
> indication. Vehicles departing in the same direction shall not be
> considered in conflict if, for each turn lane with moving traffic,
> there is a separate departing lane, and pavement markings or raised
> channelization clearly indicate which departure lane to use.**

3.  **Shall not be required on the stem of a T-intersection or for turns
    from a one-way street.**

Option:

If U-turns are permitted from the approach and a right-turn GREEN ARROW
signal indication is simultaneously being displayed to road users making
a right turn from the conflicting approach to the left, road users
making a U-turn may be advised of the operation by the installation near
the left-turn signal face of a U-TURN YIELD TO RIGHT TURN (R10-16) sign
(see Section 2B.59).

If not otherwise prohibited, a steady straight-through GREEN ARROW
signal indication may be used instead of a CIRCULAR GREEN signal
indication in a signal face on an approach intersecting a one-way street
to discourage wrong-way turns.

If not otherwise prohibited, steady red, yellow, and green turn arrow
signal indications may be used instead of steady circular red, yellow,
and green signal indications in a signal face on an approach where all
traffic is required to turn or where the straight-through movement is
not physically possible.

**Standard:**

**If supplemental signal faces are used, the following limitations shall
apply:**

> **A. Left-turn arrows shall not be used in near-right signal faces.**
>
> **B. Right-turn arrows shall not be used in far-left signal faces. A
> far-side median-mounted signal face shall be considered a far-left
> signal for this application.**

**A straight-through RED ARROW signal indication or a straight-through
YELLOW ARROW signal indication shall not be displayed on any signal
face, either alone or in combination with any other signal indication.**

**The following combinations of signal indications shall not be
simultaneously displayed on any one signal face:**

> **A. CIRCULAR GREEN with CIRCULAR YELLOW.**
>
> **B. CIRCULAR RED with CIRCULAR YELLOW.**
>
> **C. CIRCULAR GREEN with CIRCULAR RED.**
>
> **D. Straight-through GREEN ARROW with CIRCULAR RED.**

E.  **Straight-through GREEN ARROW with CIRCULAR YELLOW.**

**Additionally, the above combinations shall not be simultaneously
displayed on an approach as a result of the combination of displays from
multiple signal faces unless the display is created by a signal face(s)
devoted exclusively to the control of a turning movement and:**

> **A. The signal face(s) controlling the turning movement is
> visibility-limited from the adjacent through movement or positioned to
> minimize potential confusion to approaching road users, or**

B.  **A LEFT (RIGHT) (U) TURN SIGNAL (R10-10) sign (see Sections 4D.17
    through 4D.24) is mounted adjacent to the signal face(s) controlling
    the turning movement.**

**The following combinations of signal indications shall not be
simultaneously displayed on any one signal face or as a result of the
combination of displays from multiple signal faces on an approach:**

> **A. GREEN ARROW with YELLOW ARROW pointing in the same direction.**
>
> **B. RED ARROW with YELLOW ARROW pointing in the same direction.**

C.  **GREEN ARROW with RED ARROW pointing in the same direction.**

**Except as otherwise provided in Sections 4F.03 and 4G.04, the same
signal section shall not be used to display both a flashing yellow and a
steady yellow indication during steady mode operation.**

+-----------------------------------------------------------------------+
| An editorial change, as some types of signal faces (that are NOT      |
| considered hybrid signals) are, in some cases, allowed to display a   |
| flashing and a steady indication from the same signal section during  |
| steady mode operation:                                                |
|                                                                       |
| Flashing red arrow signal faces are permitted or required (in         |
| Sections 4D.18, 4D.20, 4D.22, and 4D.24) (the requirement needs to be |
| clarified) to display the flashing RED ARROW and steady RED ARROW     |
| signal indications from the same signal section during steady mode    |
| operations.                                                           |
|                                                                       |
| Flashing yellow arrow signal faces are permitted to use a dual-arrow  |
| signal section that can alternate between the display of steady GREEN |
| ARROW and flashing YELLOW ARROW signal indications. The same is true  |
| for the shared left-turn/right-turn signal face described in Section  |
| 4D.25.                                                                |
|                                                                       |
| However, flashing yellow arrow signal faces in Sections 4D.18, 4D.20, |
| 4D.22, and 4D.24, and the shared left-turn/right-turn signal face in  |
| Section 4D.25, are required to display the flashing YELLOW ARROW and  |
| steady YELLOW ARROW signal indications from *different* signal        |
| sections. Also, in Chapter 4G, emergency vehicle signals are          |
| permitted to display a flashing CIRCULAR YELLOW indication from the   |
| normal position of the steady CIRCULAR GREEN signal indication.       |
| Again, requiring that flashing yellow and steady yellow be from       |
| different signal sections.                                            |
|                                                                       |
| But the allowances of flashing red and steady red from the same       |
| signal section, and of flashing YELLOW ARROW and steady GREEN ARROW   |
| from the same signal section, during steady mode operation are the    |
| reasons for this editorial change.                                    |
+-----------------------------------------------------------------------+

Guidance:

No movement that creates an unexpected crossing of pathways of moving
vehicles or pedestrians should be allowed during any green or yellow
interval, except when all three of the following conditions are met:

> A. The movement involves only slight conflict, and
>
> B. Serious traffic delays are substantially reduced by permitting the
> conflicting movement, and
>
> C. Drivers and pedestrians subjected to the unexpected conflict are
> effectively warned thereof by a sign.

**Section 4D.17 [Signal Indications for Left-Turn Movements --
General]{.underline}**

  -----------------------------------------------------------------------
  As a general comment for Sections 4D.17 through 4D.25: Several
  protected/permissive signal faces are allowed to use a dual-arrow
  signal section. I believe that Figures 4D-11, 4D-12, 4D-18, and 4D-19
  should be revised to include illustrations of signal faces containing a
  dual-arrow signal section if we are to permit the use of dual-arrow
  signal sections in various types of signal faces. Also, I believe that
  a figure should be added to illustrate some of the signal arrangements
  that are permitted as specified in the requirements of Section 4D.25.

  -----------------------------------------------------------------------

Support:

Sections 4D.17 through 4D.20 describe the use of the following four
types of signal faces for controlling left-turn movements:

> A. Shared signal face -- This type of signal face controls both the
> left-turn movement and the adjacent through movement and can serve as
> one of the two required signal faces for the through movement. A
> shared signal face always displays the same color of circular
> indication that the adjacent through signal face or faces display. If
> a shared signal face that provides protected/permissive mode left
> turns is mounted overhead at the intersection, it is usually
> positioned over the lane line separating the left-turn lane from the
> adjacent through lane, or over the extension of this lane line.
>
> B. Separate left-turn signal face -- This type of signal face controls
> only the left-turn movement and cannot serve as one of the two
> required signal faces for the adjacent through movement because it
> sometimes displays a different color of circular signal indication
> than the adjacent through signal faces display or it is comprised only
> of steady left-turn arrow indications. If a separate left-turn signal
> face is mounted overhead at the intersection, it is usually positioned
> over the left-turn lane, or over the extension of this lane.
>
> C. Flashing yellow arrow signal face -- This type of signal face
> controls only the left-turn movement and cannot serve as one of the
> two required signal faces for the adjacent through movement because it
> consists entirely of left-turn arrows and cannot display any circular
> signal indications. If a flashing yellow arrow signal face is mounted
> overhead at the intersection, it is usually positioned over the
> left-turn lane, or over the extension of this lane. A flashing yellow
> arrow signal face displays a flashing left-turn YELLOW ARROW signal
> indication (instead of a steady CIRCULAR GREEN signal indication)
> during steady mode (stop-and-go) operation to control permissive
> left-turning movements from an intersection approach.
>
> D. Flashing red arrow signal face -- This type of signal face is used
> only for unusual geometric conditions, such as wide medians with
> offset left-turn lanes, and only when an engineering study determines
> that each and every vehicle must successively come to a full stop
> before making a permissive left turn. This type of signal face
> controls only the left-turn movement and cannot serve as one of the
> two required signal faces for the adjacent through movement because it
> consists entirely of left-turn arrows and cannot display any circular
> signal indications. If a flashing red arrow signal face is mounted
> overhead at the intersection, it is usually positioned over the
> left-turn lane, or over the extension of this lane. A flashing red
> arrow signal face displays a flashing left-turn RED ARROW signal
> indication (instead of a steady CIRCULAR GREEN signal indication)
> during steady mode (stop-and-go) operation to control permissive
> left-turning movements from an intersection approach.

It is not necessary that the same mode of left-turn operation or same
type of left-turn signal face be used on every approach to a signalized
location. Selecting different modes and types of left-turn signal faces
for the various approaches to the same signalized location is
acceptable.

> Section 4D.13 contains provisions regarding the lateral positioning of
> left-turn signal faces.

Although Sections 4D.17 through 4D.20 describe the use of flashing
yellow arrow signal faces and flashing red arrow signal faces for
certain modes of left-turn operation, there are no provisions in this
Section or any other Section that requires the use of these types of
signal faces. The use of these types of signal faces is optional and is
a matter of engineering judgment.

+-----------------------------------------------------------------------+
| I fully support the implementation of flashing YELLOW ARROW signal    |
| indication for protected/permissive left turns. I think it's easier   |
| to understand than the traditional CIRCULAR GREEN indication, and     |
| much less confusing. It's also safer if a conflict monitor is         |
| programmed to recognize the steady left-turn YELLOW ARROW and         |
| oncoming CIRCULAR GREEN signal indications as conflicting signal      |
| indications, thereby preventing the "yellow trap" condition from ever |
| happening.                                                            |
|                                                                       |
| I believe that the use of flashing yellow arrow signal faces and      |
| flashing red arrow signal faces should be required if their use is    |
| the only way to resolve a "yellow trap" condition at a given          |
| location.                                                             |
|                                                                       |
| I believe that the flashing arrow signal face should be recommended   |
| to be used for permissive-only or protected/permissive left turns if  |
| the opposing left turn movement operates in protected/permissive or   |
| protected only mode, because the flashing arrow indication provides   |
| more flexibility in intersection operations and eliminates the yellow |
| trap.                                                                 |
|                                                                       |
| I also believe that, eventually---maybe not with this edition of the  |
| MUTCD but in future revisions---at intersection approaches with an    |
| exclusive left-turn lane, the use of the shared signal face to        |
| regulate *protected/permissive* mode left turns should be PROHIBITED, |
| and the separate flashing yellow arrow signal face or the flashing    |
| red arrow signal face should be REQUIRED for the                      |
| *protected/permissive* mode left turn. (I believe that the shared     |
| signal face is still the best display for a protected/permissive left |
| turn from a shared through/left-turn lane.)                           |
|                                                                       |
| Under these conditions, a flashing yellow arrow signal face should    |
| NOT be required for *permissive-only* left turns from an exclusive    |
| left-turn lane UNLESS the opposing direction left turn operates in    |
| protected/permissive mode or protected only mode. (These conditions   |
| could create the "yellow trap" condition for the permissive only turn |
| movement under some conditions, requiring the flashing arrow          |
| indication for the permissive-only left turn movement.)               |
|                                                                       |
| The provisions of flashing yellow arrow signal faces as described in  |
| Sections 4D.18 through 4D.20 should be adopted as is, according to    |
| the recommendations of NCHRP Report 493 and the language contained in |
| Interim Approval IA-10.                                               |
|                                                                       |
| In Michigan, shared signal faces are no longer allowed to be used to  |
| regulate protected/permissive left turns (according to MDOT's         |
| "Flashing Yellow Arrow Left-Turn Signal Guidelines" \[2007\]).        |
+-----------------------------------------------------------------------+

Sections 4D.17 through 4D.20 set forth provisions for the display of
four types of messages to drivers intending to turn left from a
signalized approach (see specific paragraphs in this Section for the
appropriate display to use in each circumstance):

> A. A message to stop, which is accomplished by displaying either:
>
> 1\. A steady left-turn RED ARROW signal indication that requires a
> driver to stop and await authorization to proceed; or
>
> 2\. A steady CIRCULAR RED signal indication that requires a driver to
> stop and await authorization to proceed under the rules as set forth
> in the applicable Motor Vehicle Code.
>
> B. A message to turn left in a protected manner, which is accomplished
> by displaying a left-turn GREEN ARROW signal indication.
>
> C. A message to turn left in a permissive manner, which is
> accomplished by displaying either a CIRCULAR GREEN signal indication
> or a flashing left-turn YELLOW ARROW signal indication. (For unusual
> geometric conditions, such as wide medians with offset left-turn
> lanes, and only when an engineering study determines that each and
> every vehicle must successively come to a full stop before making a
> permissive left turn, the message to turn left in a permissive manner
> can be accomplished by displaying a flashing left-turn RED ARROW
> signal indication.)
>
> D. A message that the status of the left-turn operation is changing,
> which is accomplished by displaying a steady left-turn YELLOW ARROW
> signal indication when the left-turn status is changing from protected
> to permissive, or by displaying a steady left-turn YELLOW ARROW signal
> indication or a steady CIRCULAR YELLOW signal indication (as
> applicable) when the left-turn status is changing from permissive to
> stopped or from protected to stopped.

It is not necessary to display a change interval when the status of the
left-turn operation is changing from permissive to protected.

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 modes 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.

Option:

In areas having a high percentage of elderly drivers, special
consideration may be given to the use of protected only mode left-turn
phasing, when appropriate.

**Standard:**

**During a permissive left-turn movement, the signal faces for through
traffic on the opposing approach shall simultaneously display green or
steady yellow signal indications. If pedestrians crossing the lane or
lanes used by the permissive left-turn movement to depart the
intersection are controlled by pedestrian signal heads, the signal
indications displayed by those pedestrian signal heads shall not be
limited to any particular display during the permissive left-turn
movement.**

**During a protected left-turn movement, the signal faces for through
traffic on the opposing approach shall simultaneously display steady
CIRCULAR RED signal indications. If pedestrians crossing the lane or
lanes used by the protected left-turn movement to depart the
intersection are controlled by pedestrian signal heads, the pedestrian
signal heads shall display a steady UPRAISED HAND (symbolizing DONT
WALK) signal indication during the protected left-turn movement.**

**A protected only mode left-turn movement that does not begin and
terminate at the same time as the adjacent through movement shall not be
provided on an approach unless an exclusive left-turn lane exists.**

**If 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, the requirements in Sections 4D.18 through
4D.20 that are appropriate to that mode of operation shall be met,
subject to the following:**

~~A. The CIRCULAR GREEN and CIRCULAR YELLOW signal indications shall not
be displayed when operating in the protected only mode.~~

~~B. The left-turn GREEN ARROW and left-turn YELLOW ARROW signal
indications shall not be displayed when operating in the permissive only
mode.~~

  -----------------------------------------------------------------------
  This needs to be revised to more accurately reflect the different types
  of left-turn signal faces and their operational requirements.

  -----------------------------------------------------------------------

Option:

Additional static signs or changeable message signs may be used to meet
the requirements for the variable left-turn mode or to inform drivers
that left-turn green arrows will not be available during certain times
of the day.

A signal face that is shared by left-turning and right-turning traffic
may be provided for a shared left-turn/right-turn lane on an approach
that has no through traffic (see Section 4D. 25).

**Section 4D.18 [Signal Indications for Permissive Only Mode Left-Turn
Movements]{.underline}**

**Standard:**

  -----------------------------------------------------------------------
  I am suggesting the following addition to reinforce the Standards in
  Sections 2C.50, 4D.10, and 4D.26 prohibiting the "yellow trap"
  condition that can occur with a "shared" signal face in some situations
  unless an engineering study has determined that a different type of
  signal face cannot be used, the trap condition is absolutely necessary,
  and a W25-1 or W25-2 sign is installed.

  -----------------------------------------------------------------------

**A shared signal face shall not be used for permissive only mode left
turns unless either of the following conditions exists:**

> **A. The CIRCULAR YELLOW signal indication is never displayed
> simultaneously with the display of a CIRCULAR GREEN signal indication
> to the opposing approach; or**
>
> **B. An engineering study has determined that, because of unique
> intersection conditions, the condition described in item A above
> cannot reasonably be implemented without causing significant
> operational or safety problems and that the volume of affected
> left-turning traffic on the approach is relatively low, and a separate
> left-turn signal face, a flashing yellow arrow signal face, or a
> flashing red arrow signal face cannot be installed. In this case, a
> shared signal face shall be permitted provided that the left-turning
> drivers on the approach are advised that a steady CIRCULAR YELLOW
> signal indication is not simultaneously being displayed to the
> opposing traffic by the installation near the shared signal face of
> either a W25-1 sign with the legend ONCOMING TRAFFIC HAS EXTENDED
> GREEN (if this operation occurs continuously) or a W25-2 sign with the
> legend ONCOMING TRAFFIC MAY HAVE EXTENDED GREEN (if this operation
> occurs only occasionally, such as during a preemption sequence) (see
> Sections 2C.50, 4D.10, and 4D.26).**

**If a shared signal face is provided for permissive only mode left
turns, it shall meet the following requirements (see Figure 4D-6):**

> **A. It shall be capable of displaying, from top to bottom or from
> left to right, the following signal indications: steady CIRCULAR RED,
> steady CIRCULAR YELLOW, and CIRCULAR GREEN. Only one of the three
> indications shall be displayed at any given time.**
>
> **B. During the permissive left-turn movement, a CIRCULAR GREEN signal
> indication shall be displayed.**
>
> **C. A permissive only shared signal face, regardless of where it is
> positioned and regardless of how many adjacent through signal faces
> are provided, shall always simultaneously display the same color of
> circular indication that the adjacent through signal face or faces
> display.**
>
> **D. If the permissive only mode is not the only left-turn mode used
> for the approach, the signal face shall be the same shared signal face
> that is used for the protected/permissive mode (see Section 4D.20)
> except that the left-turn GREEN ARROW and left-turn YELLOW ARROW
> signal indications shall not be displayed when operating in the
> permissive only mode.**

**If a separate left-turn signal face with a CIRCULAR GREEN permissive
indication** [revised to increase clarity]{.mark} **is being operated in
a permissive only left-turn mode, it shall meet the following
requirements:**

> **A. It shall be capable of displaying, from top to bottom or from
> left to right, the following signal indications: steady CIRCULAR RED,
> steady CIRCULAR YELLOW, and CIRCULAR GREEN. Only one of the three
> indications shall be displayed at any given time.**
>
> **B. During the permissive left-turn movement, a CIRCULAR GREEN signal
> indication shall be displayed.**
>
> **C. If the CIRCULAR GREEN and CIRCULAR YELLOW signal indications in
> the separate left-turn signal face are visibility-limited from the
> adjacent through movement, the separate left-turn signal face shall
> not be required to simultaneously display the same color of circular
> signal indication as the signal faces for the adjacent through
> movement.**
>
> **D. If the CIRCULAR GREEN and CIRCULAR YELLOW signal indications in
> the separate left-turn signal face are visibility-limited from the
> adjacent through movement, the display of a CIRCULAR GREEN signal
> indication for a permissive left-turn movement while the signal faces
> for the adjacent through movement display steady CIRCULAR RED signal
> indications and the opposing left-turn signal faces display left-turn
> GREEN ARROW signal indications for a protected left-turn movement
> shall be permitted.**
>
> **E. If the separate left-turn signal face does not simultaneously
> display the same color of circular signal indication as the signal
> faces for the adjacent through movement, a LEFT TURN YIELD ON GREEN
> (symbolic circular green) (R10-12) sign or a LEFT TURN SIGNAL---YIELD
> ON GREEN (symbolic circular green) (R10-21) sign (see Figure 2B-30)
> shall be used.**

F.  **If the permissive only mode is not the only left-turn mode used
    for the approach, the signal face shall be the same separate
    left-turn signal face that is used for the protected/permissive mode
    (see Section 4D.20) except that the left-turn GREEN ARROW and
    left-turn YELLOW ARROW signal indications shall not be displayed
    when operating in the permissive only mode.**

Guidance:

Because signal faces containing a CIRCULAR GREEN signal indication
should not be post-mounted on the far side median or overhead above the
left-turn lane(s) or the extension of the lane(s) (see Section 4D.13), a
separate left-turn signal face with a CIRCULAR GREEN permissive
indication [revised to increase clarity]{.mark} should not be used for
permissive only mode left turns for new or reconstructed signal
installations.

**Standard:**

**If a flashing yellow arrow signal face is provided for permissive only
mode left turns, it shall meet the following requirements (see Figure
4D-7):**

> **A. It shall be capable of displaying, from top to bottom or from
> left to right, the following signal indications: steady left-turn RED
> ARROW, steady left-turn YELLOW ARROW, and flashing left-turn YELLOW
> ARROW. Only one of the three indications shall be displayed at any
> given time.**

B.  **During the permissive left-turn movement, a flashing left-turn
    YELLOW ARROW signal indication shall be displayed.**

> **C. A steady left-turn YELLOW ARROW signal indication shall be
> displayed following the flashing left-turn YELLOW ARROW signal
> indication.**
>
> **D. The display of a flashing left-turn YELLOW ARROW signal
> indication for a permissive left-turn movement while the signal faces
> for the adjacent through movement display steady CIRCULAR RED signal
> indications and the opposing left-turn signal faces display left-turn
> GREEN ARROW signal indications for a protected left-turn movement
> shall be permitted.**
>
> **E. During steady mode (stop-and-go) operation, the signal section
> that displays the steady left-turn YELLOW ARROW signal indication
> during change intervals shall not be used to display the flashing
> left-turn YELLOW ARROW signal indication for permissive left turns.**
>
> **F. During flashing mode operation (see Section 4D.30), the display
> of a flashing left-turn YELLOW ARROW signal indication shall be only
> from the signal section that displays a steady left-turn YELLOW ARROW
> signal indication during steady mode (stop-and-go) operation.**

G.  **If the permissive only mode is not the only left-turn mode used
    for the approach, the signal face shall be the same flashing yellow
    arrow signal face that is used for the protected/permissive mode
    (see Section 4D.20) except that the left-turn GREEN ARROW signal
    indication shall not be displayed when operating in the permissive
    only mode.**

  -----------------------------------------------------------------------
  Will a supplementary sign be permitted with a flashing yellow arrow
  signal face? NCHRP Report 493, page 81, specifies that a "**[left turn
  YIELD on flashing yellow]{.smallcaps}** (symbolic yellow arrow)" sign
  may be used with the flashing yellow arrow signal face if deemed
  necessary, but is not required to be used. Some jurisdictions use this
  sign; others do not. Should this sign be added to the MUTCD as well, in
  Figure 2B.30? The following addition is suggested if such a sign is to
  be added.

  -----------------------------------------------------------------------

> **H. A supplementary sign shall not be required. If used, it shall be
> a LEFT TURN YIELD ON FLASHING YELLOW (symbolic yellow arrow) (R10-XX)
> sign (see Figure 2B-30).**

Option:

For unusual geometric conditions, such as wide medians with offset
left-turn lanes, and only when an engineering study determines that each
and every vehicle must successively come to a full stop before making a
permissive left turn, a flashing red arrow signal face that flashes a
left-turn RED ARROW signal indication during the permissive left-turn
movement may be used.

  -----------------------------------------------------------------------
  I believe that it's a good thing that flashing red arrow signal faces
  are being permitted as well as flashing yellow arrow signal faces. For
  instance, in Michigan, where the experimental flashing CIRCULAR RED
  indication is being phased out, most signals are being replaced with
  the flashing yellow arrow display, which complies with the Interim
  Approval IA.10 and the provisions above in Sections 4D.18 and
  4D.20---but there are several existing flashing red left-turn signals
  in Michigan that, in my opinion, should remain flashing red (requiring
  a complete stop). The equivalent would be installing a STOP sign
  instead of a YIELD sign for the permissive turn movement. So this
  provides additional flexibility in those unusual situations.

  -----------------------------------------------------------------------

**Standard:**

**If a flashing red arrow signal face is provided for permissive only
mode left turns, it shall meet the following requirements (see Figure
4D-8):**

A.  **It shall be capable of displaying, from top to bottom or from left
    to right, the following signal indications: steady or flashing
    left-turn RED ARROW, steady left-turn YELLOW ARROW, and left-turn
    GREEN ARROW. Only one of the three indications shall be displayed at
    any given time. The GREEN ARROW indication is required in order to
    provide a three-section signal face, but shall not be displayed
    during permissive only mode.**

> **B. During the permissive left-turn movement, a flashing left-turn
> RED ARROW signal indication shall be displayed, thus indicating that
> each and every vehicle must successively come to a full stop before
> making a permissive left turn.**

C.  **A steady left-turn YELLOW ARROW signal indication shall be
    displayed following the flashing left-turn RED ARROW signal
    indication.**

  -----------------------------------------------------------------------
  I support the requirement that the flashing RED ARROW be followed by a
  steady YELLOW ARROW signal indication. In previous implementations,
  some flashing red left turns suddenly went to a steady red with no
  warning at all. This is not a good thing! (For this reason, many
  flashing red left turns in Michigan always followed the flashing red
  permissive left-turn indication with a GREEN ARROW indication---and the
  GREEN ARROW is not used in permissive only mode.) There needs to be
  some kind of change interval, a warning that the flashing red would
  soon end and the signal would turn to steady red. I support the use of
  the steady YELLOW ARROW indication for this purpose.

  -----------------------------------------------------------------------

D.  **The display of a flashing left-turn RED ARROW signal indication
    for a permissive left-turn movement while the signal faces for the
    adjacent through movement display steady CIRCULAR RED signal
    indications and the opposing left-turn signal faces display
    left-turn GREEN ARROW signal indications for a protected left-turn
    movement shall be permitted.**

E.  **During steady mode operation, the flashing left-turn RED ARROW and
    steady left-turn RED ARROW signal indications shall be displayed
    from the same signal section.**

+-----------------------------------------------------------------------+
| This was added to clarify that the flashing RED ARROW and steady RED  |
| ARROW signal indications need to be displayed from the same signal    |
| section. Paragraph A of this Standard, and Figure 4D-8, seems to      |
| require this operation, that the flashing red and steady red be       |
| displayed from the same signal section. (If a four-section signal     |
| face with steady red and flashing red signal sections from different  |
| signal sections is to be permitted, then the above addition would not |
| apply, and Paragraph A and Figure 4D-8 would have to be revised.      |
| According to NCHRP 3-54, flashing RED ARROW and steady red signal     |
| indications were displayed from different signal sections in Delaware |
| and in Cupertino, CA (Figure 1-1 on page 17)---these four-section     |
| signal faces would thus be non-compliant with the above text as I     |
| have suggested it to be).                                             |
|                                                                       |
| Personally, I vote for requiring that the flashing RED ARROW and      |
| steady RED ARROW only be displayed from the same signal section, and  |
| that the 3-section signal face be the only display allowed for the    |
| implementation of the flashing RED ARROW indication. It would avoid   |
| confusion for color-blind drivers, the positioning of the flashing    |
| arrow would make it obvious which color of flashing arrow it was      |
| (flashing arrow at the top or far-left = flashing RED ARROW; flashing |
| arrow towards the bottom or far-right = flashing YELLOW ARROW). Also, |
| it would be of additional benefit to color-blind drivers during the   |
| transition from a steady red to a flashing arrow---there would be a   |
| change in position for the change from the steady RED ARROW to a      |
| flashing YELLOW ARROW indication, but there would be NO change in     |
| position for the change from a steady RED ARROW to a flashing RED     |
| ARROW indication.                                                     |
|                                                                       |
| Note that this requirement will require an editorial change to        |
| Section 4D.10.                                                        |
|                                                                       |
| (This should also be the requirement for flashing red arrow signal    |
| faces used for right turn movements that don't contain a CIRCULAR RED |
| signal indication.)                                                   |
+-----------------------------------------------------------------------+

F.  **A supplementary sign shall not be required. If used, it shall be a
    LEFT TURN YIELD ON FLASHING RED ARROW AFTER STOP (R10-27) sign (see
    Figure 2B-30).**

**Section 4D.19 [Signal Indications for Protected Only Mode Left-Turn
Movements ]{.underline}**

**Standard:**

**A shared signal face shall not be used for protected only mode left
turns ~~only when~~ unless the CIRCULAR GREEN and left-turn GREEN ARROW
signal indications always begin and terminate together.** [(Revised so
as not to imply that a shared signal face is required in this
application)]{.mark} **If a shared signal face is provided for protected
only left turns, it shall meet the following requirements (see Figure
4D-9):**

> **A. It shall be capable of displaying the following signal
> indications: steady CIRCULAR RED, steady CIRCULAR YELLOW, CIRCULAR
> GREEN, and left-turn GREEN ARROW. Only one of the three colors shall
> be displayed at any given time.**

  -----------------------------------------------------------------------
  Will a straight-through GREEN ARROW be allowed in this situation?

  -----------------------------------------------------------------------

> **B. During the protected left-turn movement, the shared signal face
> shall simultaneously display both a CIRCULAR GREEN signal indication
> and a left-turn GREEN ARROW signal indication.**
>
> **C. The shared signal face shall always simultaneously display the
> same color of circular indication that the adjacent through signal
> face or faces display.**
>
> **D. If the protected only mode is not the only left-turn mode used
> for the approach, the signal face shall be the same shared signal face
> that is used for the protected/permissive mode (see Section 4D.20).**

**If a separate left-turn signal face is provided for protected only
mode left turns, it shall meet the following requirements (see Figure
4D-10):**

> **A. It shall be capable of displaying, from top to bottom or from
> left to right, the following signal indications: steady left-turn RED
> ARROW, steady left-turn YELLOW ARROW, and left-turn GREEN ARROW. Only
> one of the three indications shall be displayed at any given time.**

+-----------------------------------------------------------------------+
| As it stands, the CIRCULAR RED indication is proposed for deletion.   |
| The justification from the NPA in the Federal Register \[FHWA Docket  |
| No. FHWA-2007-28977\] states the following: "Red arrow signal         |
| indications have been in use for over 35 years, are extensively       |
| implemented for protected turn movements in the majority of States,   |
| are well understood by road users, present an unequivocal message     |
| regarding what movement is prohibited when the red indication is      |
| displayed, and eliminate the need for the use of a supplemental       |
| R10-10 LEFT TURN SIGNAL sign."                                        |
|                                                                       |
| I fully support the implementation of the RED ARROW replacing the     |
| CIRCULAR RED indication in most cases. However, there are a few       |
| limited situations where I believe the CIRCULAR RED indication may be |
| more appropriate:                                                     |
|                                                                       |
| 1\. At protected-only left turns from a one-way street onto another,  |
| if it is intended that the left turn on red movement be permitted.    |
| (The CIRCULAR RED would also be allowed for protected/permissive and  |
| permissive-only flashing arrow signal faces when they are used for    |
| left turns from a one-way street onto another and it is intended that |
| the left turn on red be permitted.)                                   |
|                                                                       |
| 2\. At some intersection approaches where the left turn movement is   |
| the only movement permitted, especially if it is a gentle left turn   |
| and a 45-degree arrow is used. (In this limited circumstance, with a  |
| 45-degree arrow, circular yellow should also be considered.) An       |
| example of this might be at a Single Point Urban Interchange (SPUI),  |
| for the left turn from the freeway ramp onto the crossroad (the left  |
| and right turns are separated WELL in advance of the crossroad, and   |
| in my opinion are two different intersection approaches). In this     |
| case, the left turn movement is so gentle, it is almost a through     |
| movement---and Section 4D.10 prohibits straight-through RED ARROW and |
| straight-through YELLOW ARROW indications. Note that the left turn    |
| ONTO the freeway ramp should be an all-arrows signal display, even    |
| with 45-degree arrows, to differentiate the left-turn movement from   |
| the through movement on the crossroad. An engineering reference that  |
| supports CIRCULAR RED at SPUIs is on Page 5-20 of MoDOT's             |
| publication, *Design of Single Point Urban Interchanges* (2004),      |
| found online at                                                       |
| <http://168.166.124.22/RDT/reports/RI02015/RDT04011.pdf>              |
|                                                                       |
| 3\. At approaches with shared left-turn/right-turn lanes and no       |
| through movement, as specified in Section 4D.25 that requires         |
| CIRCULAR RED for all signal faces at such an approach.                |
|                                                                       |
| But what about intersection approaches with exclusive left-turn       |
| lane(s), exclusive right-turn lane(s), no shared left-turn/right-turn |
| lane, and no through movement? In this case, I believe that a         |
| left-turn RED ARROW indication should be required for the left-turn   |
| movement---left turn signal faces would be an all-arrows display      |
| (with a RED ARROW), and right turn signal faces would use either a    |
| CIRCULAR RED or a RED ARROW depending on whether right on red is      |
| permitted---but the use of left-turn RED ARROW in such a situation    |
| would let stopped drivers know which signal faces controlled which    |
| turning movement without the use of supplementary signs.              |
+-----------------------------------------------------------------------+

> **B. During the protected left-turn movement, a left-turn GREEN ARROW
> signal indication shall be displayed.**
>
> **C. A steady left-turn YELLOW ARROW signal indication shall be
> displayed following the left-turn GREEN ARROW signal indication.**

D.  **A supplementary sign shall not be required. If used, it shall be a
    LEFT ON GREEN ARROW ONLY (R10-5) sign.**

  -----------------------------------------------------------------------
  This was relocated from above and revised to be more consistent with
  the Standards in Sections 4D.18 and 4D.20 with the use of supplementary
  signs.

  -----------------------------------------------------------------------

**If a flashing yellow arrow signal face is being operated in a
protected only left-turn mode, it shall meet the following
requirements:**

> **A. It shall be capable of displaying, from top to bottom or from
> left to right, the following signal indications: steady left-turn RED
> ARROW, steady left-turn YELLOW ARROW, and left-turn GREEN ARROW. Only
> one of the three indications shall be displayed at any given time.**
>
> **B. During the protected left-turn movement, a left-turn GREEN ARROW
> signal indication shall be displayed.**
>
> **C. A steady left-turn YELLOW ARROW signal indication shall be
> displayed following the left-turn GREEN ARROW signal indication.**
>
> **D. Because the protected only mode is not the only left-turn mode
> used for the approach, the signal face shall be the same flashing
> yellow arrow signal face that is used for the protected/permissive
> mode (see Section 4D.20 and Figure 4D-12) except that the flashing
> left-turn YELLOW ARROW signal indication shall not be displayed when
> operating in the protected only mode.**

**If a flashing red arrow signal face is being operated in a protected
only left-turn mode, it shall meet the following requirements:**

A.  **It shall be capable of displaying, from top to bottom or from left
    to right, the following signal indications: steady left-turn RED
    ARROW, steady left-turn YELLOW ARROW, and left-turn GREEN ARROW.
    Only one of the three indications shall be displayed at any given
    time. ~~A signal instruction sign shall not be required with this
    set of signal indications. If used, it shall be a LEFT ON GREEN
    ARROW ONLY (R10-5) sign.~~**

  -----------------------------------------------------------------------
  The LEFT ON GREEN ARROW ONLY (R10-5) sign would not be used with a
  flashing red arrow left-turn signal face if it is sometimes operated in
  permissive only mode or protected/permissive mode.

  -----------------------------------------------------------------------

> **B. During the protected left-turn movement, a left-turn GREEN ARROW
> signal indication shall be displayed.**
>
> **C. A steady left-turn YELLOW ARROW signal indication shall be
> displayed following the left-turn GREEN ARROW signal indication.**
>
> **D. Because the protected only mode is not the only left-turn mode
> used for the approach, the signal face shall be the same flashing red
> arrow signal face that is used for the protected/permissive mode (see
> Section 4D.20 and Figure 4D-8), except that the left-turn RED ARROW
> signal indication shall not be flashed when operating in the protected
> only mode.**

**Section 4D.20 [Signal Indications for Protected/Permissive Mode
Left-Turn Movements]{.underline}**

**Standard:**

  -----------------------------------------------------------------------
  I am suggesting the following addition to reinforce the Standards in
  Sections 2C.50, 4D.10, and 4D.26 prohibiting the "yellow trap"
  condition that can occur with a "shared" signal face in some situations
  unless an engineering study has determined that a different type of
  signal face cannot be used, the trap condition is absolutely necessary,
  and a W25-1 or W25-2 sign is installed.

  -----------------------------------------------------------------------

**A shared signal face shall not be used for protected/permissive left
turns unless either of the following conditions exists:**

> **A. The CIRCULAR YELLOW signal indication is never displayed
> simultaneously with the display of a CIRCULAR GREEN signal indication
> to the opposing approach; or**
>
> **B. An engineering study has determined that, because of unique
> intersection conditions, the condition described in item A above
> cannot reasonably be implemented without causing significant
> operational or safety problems and that the volume of affected
> left-turning traffic on the approach is relatively low, and a separate
> left-turn signal face, a flashing yellow arrow signal face, or a
> flashing red arrow signal face cannot be installed. In this case, a
> shared signal face shall be permitted provided that the left-turning
> drivers on the approach are advised that a steady CIRCULAR YELLOW
> signal indication is not simultaneously being displayed to the
> opposing traffic by the installation near the shared signal face of
> either a W25-1 sign with the legend ONCOMING TRAFFIC HAS EXTENDED
> GREEN (if this operation occurs continuously) or a W25-2 sign with the
> legend ONCOMING TRAFFIC MAY HAVE EXTENDED GREEN (if this operation
> occurs only occasionally, such as during a preemption sequence) (see
> Sections 2C.50, 4D.10, and 4D.26).**

**If a shared signal face is provided for protected/permissive mode left
turns, it shall meet the following requirements (see Figure 4D‑11):**

> **A. It shall be capable of displaying the following signal
> indications: steady CIRCULAR RED, steady CIRCULAR YELLOW, CIRCULAR
> GREEN, steady left-turn YELLOW ARROW, and left-turn GREEN ARROW. Only
> one of the three circular indications shall be displayed at any given
> time. Only one of the two arrow indications shall be displayed at any
> given time. If the left-turn GREEN ARROW signal indication and the
> CIRCULAR GREEN signal indication(s) for the adjacent through movement
> are always terminated together, the steady left-turn YELLOW ARROW
> signal indication shall not be required.**
>
> **B. During the protected left-turn movement, the shared signal face
> shall simultaneously display a left-turn GREEN ARROW signal indication
> and a circular signal indication that is the same color as the signal
> indication for the adjacent through lane on the same approach as the
> protected left turn.**
>
> **C. A steady left-turn YELLOW ARROW signal indication shall be
> displayed following the left-turn GREEN ARROW signal indication,
> unless the left-turn GREEN ARROW signal indication and the CIRCULAR
> GREEN signal indication(s) for the adjacent through movement are being
> terminated together, in which case a steady CIRCULAR YELLOW signal
> indication shall be displayed following the left-turn GREEN ARROW
> signal indication.**
>
> **D. During the permissive left-turn movement, the shared signal face
> shall display only a CIRCULAR GREEN signal indication.**
>
> **E. A protected/permissive shared signal face, regardless of where it
> is positioned and regardless of how many adjacent through signal faces
> are provided, shall always simultaneously display the same color of
> circular indication that the adjacent through signal face or faces
> display.**

+-----------------------------------------------------------------------+
| I am suggesting the following addition to clarify the use of a        |
| dual-arrow signal section in a shared signal face, and also to be     |
| consistent with language later in this Section for flashing yellow    |
| arrow (FYA) signal faces and flashing red arrow (FRA) signal faces.   |
| (Note that this is *different* from the requirements for the FYA      |
| display: Here, the dual arrow alternates between green and *steady*   |
| yellow; for the FYA display, the dual arrow alternates between green  |
| and *flashing* yellow.)                                               |
|                                                                       |
| (Note that this Standard also applies for the Dallas Display          |
| described below.)                                                     |
+-----------------------------------------------------------------------+

> **F. The display shall be a five-section signal face except in the
> following cases:**
>
> **1. A four-section signal face containing a dual-arrow signal section
> shall be permitted where physical conditions will not permit the use
> of a five-section signal face. The dual-arrow signal section, where
> used, shall display a steady GREEN ARROW for the protected left-turn
> movement and a steady YELLOW ARROW for the protected left turn yellow
> change interval.**
>
> **2. A four-section signal face omitting the steady left-turn YELLOW
> ARROW signal indication shall be permitted only if the left-turn GREEN
> ARROW signal indication and the CIRCULAR GREEN signal indication(s)
> for the adjacent through movement are always terminated together.**
>
> **G. A supplementary sign shall not be required. If used, it shall be
> a LEFT TURN YIELD ON GREEN (symbolic circular green) (R10-12) sign
> (see Figure 2B-30).**

**If a separate left-turn signal face with a CIRCULAR GREEN permissive
indication** [added to increase clarity]{.mark} **is being operated in a
protected/permissive left-turn mode, it shall meet the following
requirements:**

> **A. It shall be capable of displaying the following signal
> indications: steady CIRCULAR RED, steady CIRCULAR YELLOW, CIRCULAR
> GREEN, steady left-turn YELLOW ARROW, and left-turn GREEN ARROW. Only
> one of the three circular indications shall be displayed at any given
> time.**
>
> **B. During the protected left-turn movement, the separate left-turn
> signal face shall display a left-turn GREEN ARROW signal indication.**
>
> **C. A steady left-turn YELLOW ARROW signal indication shall be
> displayed following the left-turn GREEN ARROW signal indication,
> unless the left-turn GREEN ARROW signal indication and the CIRCULAR
> GREEN signal indication(s) for the adjacent through movement are being
> terminated together, in which case a steady CIRCULAR YELLOW signal
> indication shall be displayed following the left-turn GREEN ARROW
> signal indication.**
>
> **D. During the permissive left-turn movement, the separate left-turn
> signal face shall display only a CIRCULAR GREEN signal indication.**
>
> **E. If the CIRCULAR GREEN and CIRCULAR YELLOW signal indications in
> the separate left-turn signal face are visibility-limited from the
> adjacent through movement, the separate left-turn signal face shall
> not be required to simultaneously display the same color of circular
> signal indication as the signal faces for the adjacent through
> movement.**
>
> **F. If the CIRCULAR GREEN and CIRCULAR YELLOW signal indications in
> the separate left-turn signal face are visibility-limited from the
> adjacent through movement, the display of a CIRCULAR GREEN signal
> indication for a permissive left-turn movement while the signal faces
> for the adjacent through movement display steady CIRCULAR RED signal
> indications and the opposing left-turn signal face displays a
> left-turn GREEN ARROW for a protected left-turn movement shall be
> permitted.**
>
> **G. If the separate left-turn signal face does not simultaneously
> display the same color of circular signal indication as the signal
> faces for the adjacent through movement, a LEFT TURN SIGNAL---YIELD ON
> GREEN (symbolic circular green) (R10-21) sign (see Figure 2B-30) shall
> be used.**

Guidance:

Because signal faces containing a CIRCULAR GREEN signal indication
should not be post-mounted on the far side median or overhead above the
left-turn lane(s) or the extension of the lane(s) (see Section 4D.13), a
separate left-turn signal face with a CIRCULAR GREEN permissive
indication [revised to increase clarity]{.mark} should not be used for
protected/permissive only mode left turns for new or reconstructed
signal installations.

**Standard:**

**If a flashing yellow arrow signal face is provided for
protected/permissive mode left turns, it shall meet the following
requirements (see Figure 4D-12):**

A.  **It shall be capable of displaying, from top to bottom or from left
    to right, the following signal indications: steady left-turn RED
    ARROW, steady left-turn YELLOW ARROW, flashing left-turn YELLOW
    ARROW, and left-turn GREEN ARROW. Only one of the four indications
    shall be displayed at any given time.**

> **B. During the protected left-turn movement, a left-turn GREEN ARROW
> signal indication shall be displayed.**
>
> **C. A steady left-turn YELLOW ARROW signal indication shall be
> displayed following the left-turn GREEN ARROW signal indication.**
>
> **D. During the permissive left-turn movement, a flashing left-turn
> YELLOW ARROW signal indication shall be displayed.**
>
> **E. A steady left-turn YELLOW ARROW signal indication shall be
> displayed following the flashing left-turn YELLOW ARROW signal
> indication if the permissive left-turn movement is being terminated
> and the flashing yellow arrow signal face will subsequently display a
> steady left-turn RED ARROW indication.**
>
> **F. The display of a flashing left-turn YELLOW ARROW signal
> indication for a permissive left-turn movement while the signal faces
> for the adjacent through movement display steady CIRCULAR RED signal
> indications and the opposing left-turn signal faces display left-turn
> GREEN ARROW signal indications for a protected left-turn movement
> shall be permitted.**
>
> **G. When a permissive left-turn movement is changing to a protected
> left-turn movement, a left-turn GREEN ARROW signal indication shall be
> displayed immediately upon the termination of the flashing left-turn
> YELLOW ARROW signal indication. A steady left-turn YELLOW ARROW signal
> indication shall not 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.**
>
> **H. The display shall be a four-section signal face except a
> three-section signal face containing a dual-arrow signal section shall
> be permitted where ~~signal head height limitations~~ physical
> conditions will not permit the use of a four-section signal face. The
> dual-arrow signal section, where used, shall display a steady GREEN
> ARROW for the protected left-turn movement and a flashing YELLOW ARROW
> for the permissive left-turn movement.**

  -----------------------------------------------------------------------
  The "signal head height limitations" provision only applies for
  vertically-arranged signal faces. For horizontally-aligned signal
  faces, horizontal spacing limitations---NOT vertical height
  limitations---would control. If the minimum 8-foot (2.4-meter)
  center-to-center spacing specified in Section 4D.13 cannot be met with
  a 4-section horizontal signal face, then that is the situation where a
  horizontal 3-section signal face with a dual-arrow signal section would
  be used. Note that the wording in Interim Approval IA-10 refers to
  "physical conditions" and NOT "signal head height limitations".

  -----------------------------------------------------------------------

> **I. During steady mode (stop-and-go) operation, the signal section
> that displays the steady left-turn YELLOW ARROW signal indication
> during change intervals shall not be used to display the flashing
> left-turn YELLOW ARROW signal indication for permissive left turns.**

J.  **During flashing mode operation (see Section 4D.30), the display of
    a flashing left-turn YELLOW ARROW signal indication shall be only
    from the signal section that displays a steady left-turn YELLOW
    ARROW signal indication during steady mode (stop-and-go)
    operation.**

  -----------------------------------------------------------------------
  Will a supplementary sign be permitted with a flashing yellow arrow
  signal face? NCHRP Report 493, page 81, specifies that a "**[left turn
  YIELD on flashing yellow]{.smallcaps}** (symbolic yellow arrow)" sign
  may be used with the flashing yellow arrow signal face if deemed
  necessary, but is not required to be used. Some jurisdictions use this
  sign; others do not. Should this sign be added to the MUTCD as well, in
  Figure 2B.30? The following is suggested if such a sign is to be added.

  -----------------------------------------------------------------------

> **K. A supplementary sign shall not be required. If used, it shall be
> a LEFT TURN YIELD ON FLASHING YELLOW (symbolic yellow arrow) (R10-XX)
> sign (see Figure 2B-30).**

Option:

For unusual geometric conditions, such as wide medians with offset
left-turn lanes, and only when an engineering study determines that each
and every vehicle must successively come to a full stop before making a
permissive left turn, a flashing red arrow signal face that flashes a
left-turn RED ARROW signal indication during the permissive left-turn
movement may be used.

  -----------------------------------------------------------------------
  I believe that it's a good thing that flashing red arrow signal faces
  are being permitted as well as flashing yellow arrow signal faces. For
  instance, in Michigan, where the experimental flashing CIRCULAR RED
  indication is being phased out, most signals are being replaced with
  the flashing yellow arrow display, which complies with the Interim
  Approval IA.10 and the provisions above in Sections 4D.18 and
  4D.20---but there are several existing flashing red left-turn signals
  in Michigan that, in my opinion, should remain flashing red (requiring
  a complete stop). The equivalent would be installing a STOP sign
  instead of a YIELD sign for the permissive turn movement. So this
  provides additional flexibility in those unusual situations.

  -----------------------------------------------------------------------

**Standard:**

**If a flashing red arrow signal face is provided for
protected/permissive mode left turns, it shall meet the following
requirements (see Figure 4D-8):**

> **A. It shall be capable of displaying, from top to bottom or from
> left to right, the following signal indications: steady or flashing
> left-turn RED ARROW, steady left-turn YELLOW ARROW, and left-turn
> GREEN ARROW. Only one of the three indications shall be displayed at
> any given time.**
>
> **B. During the protected left-turn movement, a left-turn GREEN ARROW
> signal indication shall be displayed.**
>
> **C. A steady left-turn YELLOW ARROW signal indication shall be
> displayed following the left-turn GREEN ARROW signal indication.**
>
> **D. During the permissive left-turn movement, a flashing left-turn
> RED ARROW signal indication shall be displayed, thus indicating that
> each and every vehicle must successively come to a full stop before
> making a permissive left turn.**

  -----------------------------------------------------------------------
  This was revised to be more consistent with language found in Section
  4D.18.

  -----------------------------------------------------------------------

> **E. A steady left-turn YELLOW ARROW signal indication shall be
> displayed following the flashing left-turn RED ARROW signal indication
> if the permissive left-turn movement is being terminated and the
> flashing red arrow signal face will subsequently display a steady
> left-turn RED ARROW indication.**

  -----------------------------------------------------------------------
  I support the requirement that the flashing RED ARROW be followed by
  either a steady GREEN ARROW or a steady YELLOW ARROW signal indication.
  In previous implementations, some flashing red left turns suddenly went
  to a steady red with no warning at all. This is not a good thing! (For
  this reason, many flashing red left turns in Michigan always followed
  the flashing red permissive left-turn indication with a GREEN ARROW
  indication). There needs to be some kind of change interval, a warning
  that the flashing red would soon end and the signal would turn to
  steady red. I support the use of the steady YELLOW ARROW indication for
  this purpose.

  -----------------------------------------------------------------------

> **F. When a permissive left-turn movement is changing to a protected
> left-turn movement, a left-turn GREEN ARROW signal indication shall be
> displayed immediately upon the termination of the flashing left-turn
> RED ARROW signal indication. A steady left-turn YELLOW ARROW signal
> indication shall not be displayed between the display of the flashing
> left-turn RED ARROW signal indication and the display of the steady
> left-turn GREEN ARROW signal indication.**
>
> **G. The display of a flashing left-turn RED ARROW signal indication
> for a permissive left-turn movement while the signal faces for the
> adjacent through movement display steady CIRCULAR RED signal
> indications and the opposing left-turn signal faces display left-turn
> GREEN ARROW signal indications for a protected left-turn movement
> shall be permitted.**
>
> **H. The display shall be a three-section signal face. During steady
> mode operation, the flashing left-turn RED ARROW and steady left-turn
> RED ARROW signal indications shall be displayed from the same signal
> section.**

+-----------------------------------------------------------------------+
| This was added to clarify that the flashing RED ARROW and steady RED  |
| ARROW signal indications need to be displayed from the same signal    |
| section. Paragraph A of this Standard, and Figure 4D-8, seems to      |
| require this operation, that the flashing red and steady red be       |
| displayed from the same signal section. (If a four-section signal     |
| face with steady red and flashing red signal sections from different  |
| signal sections is to be permitted, then the above addition would not |
| apply, and Paragraph A and Figure 4D-8 would have to be revised.      |
| According to NCHRP 3-54, flashing RED ARROW and steady red signal     |
| indications were displayed from different signal sections in Delaware |
| and in Cupertino, CA (Figure 1-1 on page 17)---these four-section     |
| signal faces would thus be non-compliant with the above text as I     |
| have suggested it to be.)                                             |
|                                                                       |
| Personally, I vote for requiring that the flashing RED ARROW and      |
| steady RED ARROW only be displayed from the same signal section, and  |
| that the 3-section signal face be the only display allowed for the    |
| implementation of the flashing RED ARROW indication. It would avoid   |
| confusion for color-blind drivers, the positioning of the flashing    |
| arrow would make it obvious which color of flashing arrow it was      |
| (flashing arrow at the top or far-left = flashing RED ARROW; flashing |
| arrow towards the bottom or far-right = flashing YELLOW ARROW). Also, |
| it would be of additional benefit to color-blind drivers during the   |
| transition from a steady red to a flashing arrow---there would be a   |
| change in position for the change from the steady RED ARROW to a      |
| flashing YELLOW ARROW indication, but there would be NO change in     |
| position for the change from a steady RED ARROW to a flashing RED     |
| ARROW indication.                                                     |
|                                                                       |
| Note that this requirement will require an editorial change to        |
| Section 4D.10.                                                        |
|                                                                       |
| (This should also be the requirement for flashing red arrow signal    |
| faces used for right turn movements that don't contain a CIRCULAR RED |
| signal indication.)                                                   |
+-----------------------------------------------------------------------+

> **I. A supplementary sign shall not be required. If used, it shall be
> a LEFT TURN YIELD ON FLASHING RED ARROW AFTER STOP (R10-27) sign (see
> Figure 2B-30).**

**Section 4D.21 [Signal Indications for Right-Turn Movements --
General]{.underline}**

Support:

Sections 4D.21 through 4D.24 describe the use of the following four
types of signal faces for controlling right-turn movements:

> A. Shared signal face -- This type of signal face controls both the
> right-turn movement and the adjacent through movement and can serve as
> one of the two required signal faces for the through movement. A
> shared signal face always displays the same color of circular
> indication that the adjacent through signal face or faces display.
>
> B. Separate right-turn signal face -- This type of signal face
> controls only the right-turn movement and cannot serve as one of the
> two required signal faces for the adjacent through movement because it
> sometimes displays a different color of circular signal indication
> than the adjacent through signal faces display. If a separate
> right-turn signal face is mounted overhead at the intersection, it is
> usually positioned over the right-turn lane, or over the extension of
> this lane.
>
> C. Flashing yellow arrow signal face -- This type of signal face
> controls only the right-turn movement and cannot serve as one of the
> two required signal faces for the adjacent through movement because it
> consists entirely of right-turn arrows and cannot display any circular
> signal indications. If a flashing yellow arrow signal face is mounted
> overhead at the intersection, it is usually positioned over the
> right-turn lane, or over the extension of this lane. A flashing yellow
> arrow signal face displays a flashing right-turn YELLOW ARROW signal
> indication (instead of a steady CIRCULAR GREEN signal indication)
> during steady mode (stop-and-go) operation to control permissive
> right-turning movements from an intersection approach.

D.  Flashing red arrow signal face -- This type of signal face is used
    only when an engineering study determines that each and every
    vehicle must successively come to a full stop before making a
    permissive right turn. This type of signal face controls only the
    right-turn movement and cannot serve as one of the two required
    signal faces for the adjacent through movement. If a flashing red
    arrow signal face is mounted overhead at the intersection, it is
    usually positioned over the right-turn lane, or over the extension
    of this lane. A flashing red arrow signal face displays a flashing
    right-turn RED ARROW signal indication (instead of a steady CIRCULAR
    GREEN signal indication) during steady mode (stop-and-go) operation
    to control permissive right-turning movements from an intersection
    approach.

Section 4D.13 contains provisions regarding the lateral positioning of
right-turn signal faces.

Although Sections 4D.21 through 4D.24 describe the use of flashing
yellow arrow signal faces and flashing red arrow signal faces for
certain modes of right-turn operation, there are no provisions in this
Section or any other Section that requires the use of these types of
signal faces. The use of these types of signal faces is optional and is
a matter of engineering judgment.

It is not necessary that the same mode of right-turn operation or same
type of right-turn signal face be used on every approach to a signalized
location. Selecting different modes and different types of right-turn
signal faces for the various approaches to the same signalized location
is acceptable.

Sections 4D.21 through 4D.24 set forth provisions for the display of
four types of messages to drivers intending to turn right from a
signalized approach (see specific paragraphs in this Section for the
appropriate display to use in each circumstance):

> A. A message to stop, which is accomplished by displaying either:
>
> 1\. A steady right-turn RED ARROW signal indication that requires a
> driver to stop and await authorization to proceed (right turn on red
> is not permitted); or
>
> 2\. A steady CIRCULAR RED signal indication that requires a driver to
> stop and await authorization to proceed under the rules as set forth
> in the applicable Motor Vehicle Code (right turn on red is permitted).
>
> B. A message to turn right in a protected manner, which is
> accomplished by displaying a right-turn GREEN ARROW signal indication.
>
> C. A message to turn right in a permissive manner, which is
> accomplished by displaying either a CIRCULAR GREEN signal indication
> or a flashing right-turn YELLOW ARROW signal indication. (When an
> engineering study determines that each and every vehicle must
> successively come to a full stop before making a permissive right
> turn, the message to turn right in a permissive manner can be
> accomplished by displaying a flashing right-turn RED ARROW signal
> indication.)

D.  A message that the status of the right-turn operation is changing,
    which is accomplished by displaying a steady right-turn YELLOW ARROW
    signal indication when the right-turn status is changing from
    protected to permissive, or by displaying a steady right-turn YELLOW
    ARROW signal indication or a steady CIRCULAR YELLOW signal
    indication (as applicable) when the right-turn status is changing
    from permissive to stopped or from protected to stopped.

It is not necessary to display a change interval when the status of the
right-turn operation is changing from permissive to protected.

Right-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 right-turn YELLOW ARROW signal indication, or a
> flashing right-turn RED ARROW signal indication after yielding to
> pedestrians, if any.
>
> B. Protected Only Mode---turns made only when a right-turn GREEN ARROW
> signal indication is displayed.
>
> C. Protected/Permissive Mode---both modes occur on an approach during
> the same cycle.

D.  Variable Right-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.

**Standard:**

**During a permissive right-turn movement, if pedestrians crossing the
lane or lanes used by the permissive right-turn movement to depart the
intersection are controlled by pedestrian signal heads, the signal
indications displayed by those pedestrian signal heads shall not be
limited to any particular display.**

**During a protected right-turn movement, the signal faces for left-turn
traffic, if any, on the opposing approach shall simultaneously display
steady left-turn RED ARROW signal indications. If pedestrians crossing
the lane or lanes used by the protected right-turn movement to depart
the intersection are controlled by pedestrian signal heads, the
pedestrian signal heads shall display a steady UPRAISED HAND
(symbolizing DONT WALK) signal indication during the protected
right-turn movement.**

**A protected only mode right-turn movement that does not begin and
terminate at the same time as the adjacent through movement shall not be
provided on an approach unless an exclusive right-turn lane exists.**

**If 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, the requirements in Sections 4D.22 through
4D.24 that are appropriate to that mode of operation shall be met,
subject to the following:**

~~A. The CIRCULAR GREEN and CIRCULAR YELLOW signal indications shall not
be displayed when operating in the protected only mode.~~

~~B. The right-turn GREEN ARROW and right~~-turn YELLOW ARROW signal
indications shall not be displayed when operating in the permissive only
mode.

  -----------------------------------------------------------------------
  This needs to be revised to more accurately reflect the different types
  of right-turn signal faces and their operational requirements.

  -----------------------------------------------------------------------

Option:

Additional static signs or changeable message signs may be used to meet
the requirements for the variable right-turn mode or to inform drivers
that right-turn green arrows will not be available during certain times
of the day.

A signal face that is shared by left-turning and right-turning traffic
may be provided for a shared left-turn/right-turn lane on an approach
that has no through traffic (see Section 4D.25).

**Section 4D.22 [Signal Indications for Permissive Only Mode Right-Turn
Movements]{.underline}**

+-----------------------------------------------------------------------+
| The 2003 MUTCD contained the following language in Section 4D.07:     |
|                                                                       |
| **Standard:**                                                         |
|                                                                       |
| **...**                                                               |
|                                                                       |
| **Permissive Only Mode---A separate signal indication or signal face  |
| for right turns shall not be required. The signal indication for      |
| permissive only mode right turns shall be the same color as the       |
| signal indication for adjacent through traffic, except that if the    |
| right turn is held to provide an exclusive pedestrian movement, a     |
| separate right-turn RED ARROW signal indication shall be provided.**  |
|                                                                       |
| Therefore, the 2003 Standard would seem to allow a four-section       |
| shared right-turn signal face with steady CIRCULAR RED, steady        |
| right-turn RED ARROW, steady CIRCULAR YELLOW, and CIRCULAR GREEN      |
| signal indications (and perhaps also adding a fifth signal section    |
| displaying a steady right-turn YELLOW ARROW signal indication if      |
| necessary).                                                           |
|                                                                       |
| Will the separate right-turn RED ARROW signal indication continue to  |
| be permitted in a shared signal face? If so, then it needs to be      |
| listed in this Section as being allowed, and this Standard needs to   |
| be revised to clarify the requirements for its use. Also, under what  |
| circumstances will a steady right-turn YELLOW ARROW signal indication |
| be needed to be displayed before the steady right-turn RED ARROW      |
| indication?                                                           |
|                                                                       |
| If this type of signal display is allowed, it should be added to      |
| Figure 4D-13.                                                         |
+-----------------------------------------------------------------------+

**Standard:**

**If a shared signal face is provided for permissive only mode right
turns, it shall meet the following requirements (see Figure 4D-13):**

> **A. It shall be capable of displaying, from top to bottom or from
> right to right, the following signal indications: steady CIRCULAR RED,
> steady CIRCULAR YELLOW, and CIRCULAR GREEN. Only one of the three
> indications shall be displayed at any given time.**
>
> **B. During the permissive right-turn movement, a CIRCULAR GREEN
> signal indication shall be displayed.**
>
> **C. A permissive only shared signal face, regardless of where it is
> positioned and regardless of how many adjacent through signal faces
> are provided, shall always simultaneously display the same color of
> circular indication that the adjacent through signal face or faces
> display.**
>
> **D. If the permissive only mode is not the only right-turn mode used
> for the approach, the signal face shall be the same shared signal face
> that is used for the protected/permissive mode (see Section 4D.24)
> except that the right-turn GREEN ARROW and right-turn YELLOW ARROW
> signal indications shall not be displayed when operating in the
> permissive only mode.**

**A separate right-turn signal face with a CIRCULAR GREEN signal
indication, which does not always display the same color of circular
signal indication as the signal faces for the adjacent through movement,
shall not be used for permissive only mode right turns.**

+-----------------------------------------------------------------------+
| This was added to clarify which kind of separate signal face is       |
| prohibited for permissive only right turns, since flashing yellow     |
| arrow signal faces and flashing red arrow signal faces are also       |
| considered to be "separate" signal faces.                             |
|                                                                       |
| Some jurisdictions DO use a separate visibility-limited               |
| permissive-only right-turn signal face for the right-turn overlap     |
| movement that displays a CIRCULAR GREEN indication when traffic from  |
| the right has a left-turn GREEN ARROW indication and the adjacent     |
| through movement signals are displaying a CIRCULAR RED. This is used  |
| in some jurisdictions where there is a right-turn overlap that        |
| conflicts with a parallel crosswalk. Sort of like a "Dallas Display", |
| except it's for right turns and it's permissive only. Is it intended  |
| to prohibit this display starting with this edition of the MUTCD?     |
| Will these have to be phased out? And also, the possibility of the    |
| use of a steady RED ARROW in such a separate right-turn signal face   |
| needs to be clarified. The NPA in the Federal Register mentioned that |
| a "separate" signal face (that is, with a CIRCULAR GREEN permissive   |
| indication) would be prohibited for *protected/permissive* right      |
| turns, but did NOT mention that it would also be prohibited for       |
| *permissive-only mode* right turns. I think that this should be       |
| allowed in some situations.                                           |
+-----------------------------------------------------------------------+

**If a flashing yellow arrow signal face is provided for permissive only
mode right turns, it shall meet the following requirements (see Figure
4D-14):**

> **A. It shall be capable of displaying, from top to bottom or from
> left to right, one of the following sets of displays:**
>
> **1. Steady right-turn RED ARROW, steady right-turn YELLOW ARROW, and
> flashing right-turn YELLOW ARROW. Only one of the three indications
> shall be displayed at any given time.**
>
> **2. Steady CIRCULAR RED, steady right-turn YELLOW ARROW, and flashing
> right-turn YELLOW ARROW. Only one of the three indications shall be
> displayed at any given time. If the CIRCULAR RED signal indication is
> sometimes displayed when the signal faces for the adjacent through
> lane(s) are not displaying a CIRCULAR RED signal indication, a RIGHT
> TURN SIGNAL (R10-10R) sign shall be used unless the CIRCULAR RED
> signal indication in the flashing yellow arrow signal face is
> shielded, hooded, louvered, positioned, or designed such that it is
> not readily visible to drivers in the through lane(s).**
>
> **B. During the permissive right-turn movement, a flashing right-turn
> YELLOW ARROW signal indication shall be displayed.**
>
> **C. A steady right-turn YELLOW ARROW signal indication shall be
> displayed following the flashing right-turn YELLOW ARROW signal
> indication.**
>
> **D. When the flashing yellow arrow signal face is providing a message
> to stop, a steady right-turn RED ARROW signal indication shall be
> displayed if it is intended that right turns on red not be permitted
> (except when a traffic control device is in place permitting a turn on
> a steady RED ARROW signal indication) or a steady CIRCULAR RED signal
> indication shall be displayed if it is intended that right turns on
> red be permitted.**
>
> **E. The display of a flashing right-turn YELLOW ARROW signal
> indication for a permissive right-turn movement while the signal faces
> for the adjacent through movement display steady CIRCULAR RED signal
> indications shall be permitted.**
>
> **F. During steady mode (stop-and-go) operation, the signal section
> that displays the steady right-turn YELLOW ARROW signal indication
> during change intervals shall not be used to display the flashing
> right-turn YELLOW ARROW signal indication for permissive right
> turns.**
>
> **G. During flashing mode operation (see Section 4D.30), the display
> of a flashing right-turn YELLOW ARROW signal indication shall be only
> from the signal section that displays a steady right-turn YELLOW ARROW
> signal indication during steady mode (stop-and-go) operation.**

H.  **If the permissive only mode is not the only right-turn mode used
    for the approach, the signal face shall be the same flashing yellow
    arrow signal face that is used for the protected/permissive mode
    (see Section 4D.24) except that the right-turn GREEN ARROW signal
    indication shall not be displayed when operating in the permissive
    only mode.**

Option:

When an engineering study determines that each and every vehicle must
successively come to a full stop before making a permissive right turn,
a flashing red arrow signal face that flashes a right-turn RED ARROW
signal indication during the permissive right-turn movement may be used.

**Standard:**

**If a flashing red arrow signal face is provided for permissive only
mode right turns, it shall meet the following requirements (see Figure
4D-15):**

> **A. It shall be capable of displaying one of the following sets of
> displays:**
>
> **1. From top to bottom or from left to right, the following signal
> indications: steady or flashing right-turn RED ARROW, steady
> right-turn YELLOW ARROW, and right-turn GREEN ARROW. Only one of the
> three indications shall be displayed at any given time. The GREEN
> ARROW indication is required in order to provide a three-section
> signal face, but shall not be displayed during permissive only mode.**
>
> **2 Steady CIRCULAR RED on the left and steady right-turn RED ARROW on
> the right of the top position, steady right-turn YELLOW ARROW in the
> middle position, and right-turn GREEN ARROW in the bottom position.
> Only one of the four indications shall be displayed at any given time.
> The GREEN ARROW indication is required in order to provide three
> vertical positions, but shall not be displayed during permissive only
> mode. If the CIRCULAR RED signal indication is sometimes displayed
> when the signal faces for the adjacent through lane(s) are not
> displaying a CIRCULAR RED signal indication, a RIGHT TURN SIGNAL
> (R10-10R) sign shall be used unless the CIRCULAR RED signal indication
> in the flashing yellow arrow signal face is shielded, hooded,
> louvered, positioned, or designed such that it is not readily visible
> to drivers in the through lane(s).**
>
> **B. During the permissive right-turn movement, a flashing right-turn
> RED ARROW signal indication shall be displayed, thus indicating that
> each and every vehicle must successively come to a full stop before
> making a permissive right turn.**
>
> **C. A steady right-turn YELLOW ARROW signal indication shall be
> displayed following the flashing right-turn RED ARROW signal
> indication.**
>
> **D. When the flashing red arrow signal face is providing a message to
> stop, a steady right-turn RED ARROW signal indication shall be
> displayed if it is intended that right turns on red not be permitted
> (except when a traffic control device is in place permitting a turn on
> a steady RED ARROW signal indication) or a steady CIRCULAR RED signal
> indication shall be displayed if it is intended that right turns on
> red be permitted.**
>
> **E. The display of a flashing right-turn RED ARROW signal indication
> for a permissive right-turn movement while the signal faces for the
> adjacent through movement display steady CIRCULAR RED signal
> indications ~~and the opposing right-turn signal faces display
> right-turn GREEN ARROW signal indications for a protected right-turn
> movement~~ shall be permitted.**

  -----------------------------------------------------------------------
  This needs to be revised. Permissive right turns are different from
  permissive left turns---would a permissive right-turn indication that
  is displayed simultaneously with a CIRCULAR RED signal indication for
  the adjacent through movement necessarily require that the opposing
  right turn movement display a right-turn GREEN ARROW indication? I
  don't think so.

  -----------------------------------------------------------------------

> **F. A supplementary sign shall not be required. If used, it shall be
> a RIGHT TURN YIELD ON FLASHING RED ARROW AFTER STOP (R10-27) sign (see
> Figure 2B-30).**

**Section 4D.24 [Signal Indications for Protected/Permissive Mode
Right-Turn Movements ]{.underline}**

**Standard:**

**If a shared signal face is provided for protected/permissive mode
right turns, it shall meet the following requirements (see Figure
4D-18):**

> **A. It shall be capable of displaying the following signal
> indications: steady CIRCULAR RED, steady CIRCULAR YELLOW, CIRCULAR
> GREEN, steady right-turn YELLOW ARROW, and right-turn GREEN ARROW.
> Only one of the three circular indications shall be displayed at any
> given time. Only one of the two arrow indications shall be displayed
> at any given time. If the right-turn GREEN ARROW signal indication and
> the CIRCULAR GREEN signal indication(s) for the adjacent through
> movement are always terminated together, the steady right-turn YELLOW
> ARROW signal indication shall not be required.**
>
> **B. During the protected right-turn movement, the shared signal face
> shall simultaneously display a right-turn GREEN ARROW signal
> indication and a circular signal indication that is the same color as
> the signal indication for the adjacent through lane on the same
> approach as the protected right turn.**
>
> **C. A steady right-turn YELLOW ARROW signal indication shall be
> displayed following the right-turn GREEN ARROW signal indication,
> unless the right-turn GREEN ARROW signal indication and the CIRCULAR
> GREEN signal indication(s) for the adjacent through movement are being
> terminated together, in which case a steady CIRCULAR YELLOW signal
> indication shall be displayed following the right-turn GREEN ARROW
> signal indication.**
>
> **D. During the permissive right-turn movement, the shared signal face
> shall display only a CIRCULAR GREEN signal indication.**
>
> **E. A protected/permissive shared signal face, regardless of where it
> is positioned and regardless of how many adjacent through signal faces
> are provided, shall always simultaneously display the same color of
> circular indication that the adjacent through signal face or faces
> display.**

  -----------------------------------------------------------------------
  I am suggesting the following addition to clarify the use of a
  dual-arrow signal section in a shared signal face, and also to be
  consistent with language later in this Section for flashing yellow
  arrow (FYA) signal faces and flashing red arrow (FRA) signal faces.
  (Note that this is *different* from the requirements for the FYA
  display: Here, the dual arrow alternates between green and *steady*
  yellow; for the FYA display, the dual arrow alternates between green
  and *flashing* yellow.)

  -----------------------------------------------------------------------

> **F. The display shall be a five-section signal face except in the
> following cases:**
>
> **1. A four-section signal face containing a dual-arrow signal section
> shall be permitted where physical conditions will not permit the use
> of a five-section signal face. The dual-arrow signal section, where
> used, shall display a steady GREEN ARROW for the protected right-turn
> movement and a steady YELLOW ARROW for the protected right turn yellow
> change interval.**
>
> **2. A four-section signal face omitting the steady right-turn YELLOW
> ARROW signal indication shall be permitted only if the right-turn
> GREEN ARROW signal indication and the CIRCULAR GREEN signal
> indication(s) for the adjacent through movement are always terminated
> together.**

**A separate right-turn signal face with a CIRCULAR GREEN signal
indication, which does not always display the same color of circular
signal indication as the signal faces for the adjacent through movement,
shall not be used for protected/permissive mode right turns.**

  -----------------------------------------------------------------------
  This was added to clarify which kind of separate signal face is
  prohibited for protected/permissive right turns, since flashing yellow
  arrow signal faces and flashing red arrow signal faces are also
  considered to be "separate" signal faces.

  -----------------------------------------------------------------------

**If a flashing yellow arrow signal face is provided for
protected/permissive mode right turns, it shall meet the following
requirements (see Figure 4D-19):**

> **A. It shall be capable of displaying, from top to bottom or from
> left to right, one of the following sets of displays:**
>
> **1. Steady right-turn RED ARROW, steady right-turn YELLOW ARROW,
> flashing right-turn YELLOW ARROW, and right-turn GREEN ARROW. Only one
> of the four indications shall be displayed at any given time.**
>
> **2. Steady CIRCULAR RED, steady right-turn YELLOW ARROW, flashing
> right-turn YELLOW ARROW, and right-turn GREEN ARROW. Only one of the
> four indications shall be displayed at any given time. If the CIRCULAR
> RED signal indication is sometimes displayed when the signal faces for
> the adjacent through lane(s) are not displaying a CIRCULAR RED signal
> indication, a RIGHT TURN SIGNAL (R10-10R) sign shall be used unless
> the CIRCULAR RED signal indication in the flashing yellow arrow signal
> face is shielded, hooded, louvered, positioned, or designed such that
> it is not readily visible to drivers in the through lane(s).**
>
> **B. During the protected right-turn movement, a right-turn GREEN
> ARROW signal indication shall be displayed.**
>
> **C. A steady right-turn YELLOW ARROW signal indication shall be
> displayed following the right-turn GREEN ARROW signal indication.**
>
> **D. During the permissive right-turn movement, a flashing right-turn
> YELLOW ARROW signal indication shall be displayed.**
>
> **E. A steady right-turn YELLOW ARROW signal indication shall be
> displayed following the flashing right-turn YELLOW ARROW signal
> indication if the permissive right-turn movement is being terminated
> and the flashing yellow arrow signal face will subsequently display a
> steady red indication.**
>
> **F. When a permissive right-turn movement is changing to a protected
> right-turn movement, a right-turn GREEN ARROW signal indication shall
> be displayed immediately upon the termination of the flashing
> right-turn YELLOW ARROW signal indication. A steady right-turn YELLOW
> ARROW signal indication shall not be displayed between the display of
> the flashing right-turn YELLOW ARROW signal indication and the display
> of the steady right-turn GREEN ARROW signal indication.**
>
> **G. When the flashing yellow arrow signal face is providing a message
> to stop, a steady right-turn RED ARROW signal indication shall be
> displayed if it is intended that right turns on red not be permitted
> (except when a traffic control device is in place permitting a turn on
> a steady RED ARROW signal indication) or a steady CIRCULAR RED signal
> indication shall be displayed if it is intended that right turns on
> red be permitted.**
>
> **H. The display of a flashing right-turn YELLOW ARROW signal
> indication for a permissive right-turn movement while the signal faces
> for the adjacent through movement display steady CIRCULAR RED signal
> indications ~~and the opposing right-turn signal faces display
> right-turn GREEN ARROW signal indications for a protected right-turn
> movement~~ shall be permitted.**

  -----------------------------------------------------------------------
  This needs to be revised. Permissive right turns are different from
  permissive left turns---would a permissive right-turn indication that
  is displayed simultaneously with a CIRCULAR RED signal indication for
  the adjacent through movement necessarily require that the opposing
  right turn movement display a right-turn GREEN ARROW indication? I
  don't think so.

  -----------------------------------------------------------------------

> **I. A signal face containing a dual-arrow signal section in place of
> separate flashing right-turn YELLOW ARROW and right-turn GREEN ARROW
> signal sections shall be permitted where signal head height
> limitations are a concern. The dual-arrow signal section, where used,
> shall display a steady GREEN ARROW for the protected right-turn
> movement and a flashing YELLOW ARROW for the permissive right-turn
> movement.**

  -----------------------------------------------------------------------
  The "signal head height limitations" provision only applies for
  vertically-arranged signal faces. For horizontally-aligned signal
  faces, horizontal spacing limitations---NOT vertical height
  limitations---would control. If the minimum 8-foot (2.4-meter)
  center-to-center spacing specified in Section 4D.13 cannot be met with
  a 4-section horizontal signal face, then that is the situation where a
  horizontal 3-section signal face with a dual-arrow signal section would
  be used. Note that the wording in Interim Approval IA-10 for flashing
  yellow *left* turn signals refers to "physical conditions" and NOT
  "signal head height limitations".

  -----------------------------------------------------------------------

> **J. During steady mode (stop-and-go) operation, the signal section
> that displays the steady right-turn YELLOW ARROW signal indication
> during change intervals shall not be used to display the flashing
> right-turn YELLOW ARROW signal indication for permissive right
> turns.**

K.  **During flashing mode operation (see Section 4D.30), the display of
    a flashing right-turn YELLOW ARROW signal indication shall be only
    from the signal section that displays a steady right-turn YELLOW
    ARROW signal indication during steady mode (stop-and-go)
    operation.**

Option:

When an engineering study determines that each and every vehicle must
successively come to a full stop before making a permissive right turn,
a flashing red arrow signal face that flashes a right-turn RED ARROW
signal indication during the permissive right-turn movement may be used.

**Standard:**

**If a flashing red arrow signal face is provided for
protected/permissive mode right turns, it shall meet the following
requirements (see Figure 4D-15):**

> **A. It shall be capable of displaying one of the following sets of
> displays:**
>
> **1. From top to bottom or from left to right, the following signal
> indications: steady or flashing right-turn RED ARROW, steady
> right-turn YELLOW ARROW, and right-turn GREEN ARROW. Only one of the
> three indications shall be displayed at any given time.**
>
> **2. Steady CIRCULAR RED on the left and steady or flashing right-turn
> RED ARROW on the right of the top position, steady right-turn YELLOW
> ARROW in the middle position, and right-turn GREEN ARROW in the bottom
> position. Only one of the four indications shall be displayed at any
> given time. If the CIRCULAR RED signal indication is sometimes
> displayed when the signal faces for the adjacent through lane(s) are
> not displaying a CIRCULAR RED signal indication, a RIGHT TURN SIGNAL
> (R10-10R) sign shall be used unless the CIRCULAR RED signal indication
> in the flashing red arrow signal face is shielded, hooded, louvered,
> positioned, or designed such that it is not readily visible to drivers
> in the through lane(s).**
>
> **B. During the protected right-turn movement, a right-turn GREEN
> ARROW signal indication shall be displayed.**
>
> **C. A steady right-turn YELLOW ARROW signal indication shall be
> displayed following the right-turn GREEN ARROW signal indication.**
>
> **D. During the permissive right-turn movement, the flashing red arrow
> signal face shall display a flashing right-turn RED ARROW signal
> indication, thus indicating that each and every vehicle must
> successively come to a full stop before making a permissive right
> turn.**

  -----------------------------------------------------------------------
  This was revised to be more consistent with language found in Section
  4D.22 and also in Sections 4D.18 and 4D.20.

  -----------------------------------------------------------------------

> **E. A steady right-turn YELLOW ARROW signal indication shall be
> displayed following the flashing right-turn RED ARROW signal
> indication if the permissive right-turn movement is being terminated
> and the flashing red arrow signal face will subsequently display a
> steady red indication.**
>
> **F. When a permissive right-turn movement is changing to a protected
> right-turn movement, a right-turn GREEN ARROW signal indication shall
> be displayed immediately upon the termination of the flashing
> right-turn RED ARROW signal indication. A steady right-turn YELLOW
> ARROW signal indication shall not be displayed between the display of
> the flashing right-turn RED ARROW signal indication and the display of
> the steady right-turn GREEN ARROW signal indication.**
>
> **G. When the flashing red arrow signal face is providing a message to
> stop, a steady right-turn RED ARROW signal indication shall be
> displayed if it is intended that right turns on red not be permitted
> (except when a traffic control device is in place permitting a turn on
> a steady RED ARROW signal indication) or a steady CIRCULAR RED signal
> indication shall be displayed if it is intended that right turns on
> red be permitted.**
>
> **H. The display of a flashing right-turn RED ARROW signal indication
> for a permissive right-turn movement while the signal faces for the
> adjacent through movement display steady CIRCULAR RED signal
> indications ~~and the opposing right-turn signal faces display
> right-turn GREEN ARROW signal indications for a protected right-turn
> movement~~ shall be permitted.**

  -----------------------------------------------------------------------
  This needs to be revised. Permissive right turns are different from
  permissive left turns---would a permissive right-turn indication that
  is displayed simultaneously with a CIRCULAR RED signal indication for
  the adjacent through movement necessarily require that the opposing
  right turn movement display a right-turn GREEN ARROW indication? I
  don't think so.

  -----------------------------------------------------------------------

> **I. A supplementary sign shall not be required. If used, it shall be
> a RIGHT TURN YIELD ON FLASHING RED ARROW AFTER STOP (R10-27) sign (see
> Figure 2B-30).**

**Section 4D.26 [Yellow Change and Red Clearance Intervals
]{.underline}**

**Standard:**

**A steady yellow signal indication shall be displayed following every
CIRCULAR GREEN or GREEN ARROW signal indication and following every
flashing YELLOW ARROW or flashing RED ARROW signal indication displayed
as a part of a steady mode operation.**

**The exclusive function of the yellow change interval shall be to warn
traffic of an impending change in the right-of-way assignment.**

**A steady CIRCULAR YELLOW signal indication shall not be displayed to
an approach from which drivers are turning left permissively unless one
of the following conditions exists:**

> **A. A steady CIRCULAR YELLOW signal indication is also simultaneously
> being displayed to the opposing approach;**

B.  **A separate left-turn signal face, a flashing yellow arrow signal
    face, or a flashing red arrow signal face is provided and operated
    as described in Sections 4D.17 through 4D.20;**

+-----------------------------------------------------------------------+
| This paragraph was revised to reflect the use of flashing yellow      |
| arrow signal faces and flashing red arrow signal faces used in        |
| Sections 4D.18 and 4D.20, that also eliminate the "yellow trap"       |
| condition, and that is consistent with similar language found in      |
| Section 2C.50.                                                        |
|                                                                       |
| This paragraph requires a change similar to that which is commented   |
| on in Section 4D.10.                                                  |
+-----------------------------------------------------------------------+

> **C. An engineering study has determined that, because of unique
> intersection conditions, the conditions described in items (a) and (b)
> above cannot reasonably be implemented without causing significant
> operational or safety problems and that the volume of impacted
> left-turning traffic is relatively low, and those left-turning drivers
> are advised that a steady CIRCULAR YELLOW signal indication is not
> simultaneously being displayed to the opposing traffic if this
> operation occurs continuously by the installation near the left-most
> signal head of a W25-1 sign (see Section 2C.50) with the legend
> ONCOMING TRAFFIC HAS EXTENDED GREEN; or**
>
> **D. Drivers are advised of the operation if it occurs only
> occasionally, such as during a preemption sequence, by the
> installation near the left-most signal head of a W25-2 sign (see
> Section 2C.50) with the legend ONCOMING TRAFFIC MAY HAVE EXTENDED
> GREEN.**

Guidance:

When indicated by the application of engineering practices, the yellow
change interval should be followed by a red clearance interval to
provide additional time before conflicting traffic movements, including
pedestrians, are released.

**Standard:**

**The duration of the yellow change interval shall be determined using
engineering practices.**

**When used, the duration of the red clearance interval shall be
determined using engineering practices.**

Support:

Engineering practices for determining the duration of yellow change and
red clearance intervals can be found in ITE's "Traffic Control Devices
Handbook" and in ITE's "Manual of Traffic Signal Design" (see Section
1A.11).

**Standard:**

**The durations of yellow change intervals and red clearance intervals
shall be consistent with the determined values within the technical
capabilities of the controller unit.**

**The duration of a yellow change interval shall not vary on a
cycle-by-cycle basis within the same signal timing plan.**

**Except as described in the Option below for lagging left turns, the
duration of a red clearance interval shall not be decreased or omitted
on a cycle-by-cycle basis within the same signal timing plan.**

Option:

When an actuated signal sequence includes a signal phase for
permissive/protected (lagging) left-turn movements in both directions,
the red clearance interval may be shown during those cycles when the
lagging left-turn signal phase is skipped and may be omitted during
those cycles when the lagging left-turn signal phase is shown.

The duration of a yellow change interval may be different in different
signal timing plans for the same controller unit.

The duration of a red clearance interval may be different in different
signal timing plans for the same controller unit.

Guidance:

A yellow change interval should not have a duration of less than 3
seconds or more than 6 seconds. The longer intervals should be reserved
for use on approaches with higher speeds.

Except when clearing a one-lane, two-way facility (see Section 4H.02), a
red clearance interval should have a duration not exceeding 6 seconds.

**Standard:**

**Except for warning beacons mounted on advance warning signs on the
approach to a signalized location (see Section 2C.35), signal displays
that are intended to provide a "pre-yellow warning" interval, such as
flashing green signal indications, vehicular countdown displays, or
other similar displays, shall not be used at a signalized location.**

Support:

The use of signal displays (other than warning beacons mounted on
advance warning signs) that convey a "pre-yellow warning" have been
found by research to increase the frequency of crashes.

+-----------------------------------------------------------------------+
| **List of References cited in my commentary:**                        |
|                                                                       |
| 2003 Manual on Uniform Traffic Devices.                               |
|                                                                       |
| FHWA. Interim Approval IA-10. Mar. 20, 2006.                          |
| \<http://mut                                                          |
| cd.fhwa.dot.gov/resources/interim_approval/ia_10_flashyellarrow.htm\> |
| (Feb. 14, 2008)                                                       |
|                                                                       |
| Bremmer, C.; Kacir, K.; Noyce, D.; and Manser, M. (2003). "Evaluation |
| of Traffic Signal Displays for Protected/Permissive Left-Turn         |
| Control." *NCHRP Report 493.* Transportation Research Board,          |
| Washington, D.C.                                                      |
| \<http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_rpt_493.pdf\>      |
| (Jan. 24, 2008)                                                       |
|                                                                       |
| Michigan Department of Transportation (2007). "Flashing Yellow Arrow  |
| Left-Turn Signal Guidelines."                                         |
| \<http://mdotwas1.mdot.s                                              |
| tate.mi.us/public/tands/Details_Web/mdot_signals_flashing%20yellow%20 |
|                                                                       |
| arrow%20guidelines.pdf\> (Jan. 27, 2008)                              |
|                                                                       |
| Qurechi, M; et al. (2004) "Design of Single Point Urban               |
| Interchanges". *RDT 04-011*. University of Missouri-Rolla, Rolla, MO. |
| \<http://168.166.124.22/RDT/reports/RI02015/RDT04011.pdf\> (Jan. 19,  |
| 2008)                                                                 |
|                                                                       |
| Rodegerdts, L.; et al. (2004). "Signalized Intersections:             |
| Informational Guide". *FHWA Publication no. FHWA-HRT-04-09.* Federal  |
| Highway Administration, Washington, D.C.                              |
| \<http://www.tfhrc.gov/safety/pubs/04091/index.htm\> (Jan. 16, 2008)  |
+-----------------------------------------------------------------------+