902.5 Traffic Control Signal Indications (MUTCD Chapter 4E)
902.5.1 Signal Indications – Design, Illumination, Color, and Shape (MUTCD Section 4E.01)
Standard. The illuminated part of each signal indication shall be circular or arrow, except those used for bicycle symbol signal indications, pedestrian signal heads and light rail transit signal indications.
Letters or numbers (including those associated with countdown displays) shall not be displayed as part of a vehicular signal indication.
Strobes shall not be used within or adjacent to any signal indication.
Except for the flashing vehicular and pedestrian signal indications and the distinctive indications for emergency-vehicle preemption (see EPG 902.6.19) that are expressly allowed by the provisions of this EPG 902, flashing displays shall not be used within or adjacent to any signal indications.
Each circular signal indication shall emit a single color: red, yellow, or green.
Each arrow signal indication shall emit a single color: red, yellow, or green.
The arrow, which shall show only one direction, shall be the only illuminated part of an arrow signal indication.
Arrows shall be pointed:
- A. Vertically upward to indicate a straight-through movement,
- B. Horizontally in the direction of the turn to indicate a turn at approximately or greater than a right angle, or
- C. Upward with a slope at an angle approximately equal to that of the turn if the angle of the turn is substantially less than a right angle, or
- D. In a manner that directs the driver through the turn if a U-turn arrow is used (see Figure 902.5.1)
All signal indications shall be Light Emitting Diode (LED).
The requirements of the Institute of Transportation Engineers’ publications entitled “Vehicle Traffic Control Signal Heads: Light Emitting Diode (LED) Circular Signal Supplement,” 2005, ITE, and “Vehicle Traffic Control Signal Heads: Light Emitting Diode (LED) Vehicle Arrow Traffic Signal Supplement,” 2008, ITE, that pertain to the aspects of the signal head design that affect the display of the signal indications shall be met for light-emitting diode (LED) traffic signal modules.
Guidance. The intensity and distribution of light from each LED signal module should comply with the publications specified in the preceding paragraph, as appropriate.
If a signal indication is so bright that it causes excessive glare during nighttime conditions, some form of automatic dimming should be used to reduce the brilliance of the signal indication.
902.5.2 Size of Vehicular Signal Indications (MUTCD Section 4E.02)
Standard. All vehicular signal indications shall be 12 inches.
902.5.3 Positions of Signal Indications Within a Signal Face – General (MUTCD Section 4E.03)
Support. Standardization of the number and arrangements of signal sections in vehicular traffic control signal faces enables road users who are color vision deficient to identify the illuminated color by its position relative to other signal sections.
Standard. Unless otherwise provided in the EPG for a particular application, each signal face at a signalized location shall have three, four, or five signal sections. Unless otherwise provided in the EPG for a particular application, if a vertical signal face includes a cluster (see EPG 902.5.4), the signal face shall have at least three vertical positions.
A single-section signal face shall be permitted at a traffic control signal if it consists of a continuously-displayed GREEN ARROW signal indication that is being used to indicate a continuous movement and positioned vertically upward to indicate a straight-through movement.
The signal sections in a signal face shall be arranged in a vertical or horizontal straight line, except as otherwise provided in EPG 902.5.4.
The arrangement of adjacent signal sections in a signal face shall follow the relative positions listed in EPG 902.5.4 or EPG 902.5.5, as applicable.
If a signal section that displays a CIRCULAR YELLOW signal indication is used, it shall be located between the signal section that displays the red signal indication and all other signal sections.
If a U-turn arrow signal section is used in a signal face for a U-turn to the left, its position in the signal face shall be the same as stated in EPG 902.5.4 and 902.5.5 for a left-turn arrow signal section of the same color.
A U-turn arrow signal indication pointing to the left shall not be used in a signal face that also contains a left-turn arrow signal indication.
Support. Figure 902.5.4 illustrates some of the typical arrangements of signal sections in signal faces that do not control separate turning movements. Figures 902.6.4 through 902.6.8 illustrate the typical arrangements of signal sections in left-turn signal faces. Figures 902.6.10 through 902.6.12 illustrate the typical arrangements of signal sections in right-turn signal faces.
902.5.4 Positions of Signal Indications Within a Vertical Signal Face (MUTCD Section 4E.04)
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 above the signal section that displays the GREEN ARROW signal indication to which it applies.
The relative positions of signal sections in a vertically-arranged signal face, from top to bottom, shall be as follows:
- CIRCULAR RED
- Steady left-turn RED ARROW
- Steady 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
Option. In a vertically-arranged signal face, signal sections that display signal indications of the same color may be arranged horizontally adjacent to each other at right angles to the basic straight line arrangement to form a clustered signal face (see Figure 902.6.7, Figure 902.6.14, and Figure 902.6.15).
Standard. Such clusters shall be limited to the following:
- A. Two or three different signal sections that display signal indications of the same color, or
- B. For only the specific case described in EPG 902.6.16 (see Drawing B in Figure 902.6.16.1, Figure 902.6.16.2, Figure 902.6.16.3) two signal sections, one of which displays a GREEN ARROW signal indication and the other of which displays a flashing YELLOW ARROW signal indication.
The signal section that displays a flashing yellow signal indication during steady mode operation:
- A. Shall not be placed in the same vertical position as the signal section that displays a steady yellow signal indication, and
- B. Shall be placed below the signal section that displays a steady yellow signal indication.
Support. Sections EPG 902.10.2 and EPG 902.14.2 contain exceptions to the provisions of this Article that are applicable to hybrid beacons.
902.5.5 Positions of Signal Indications Within a Horizontal Signal Face (MUTCD Section 4E.05)
Support. Other than in emergency vehicle signals, MoDOT does not typically utilize horizontal signal faces unless engineering judgment deems necessary because of poor visibility or low clearance.
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 to the left of the signal section that displays the GREEN ARROW signal indication to which it applies.
The relative positions of signal sections in a horizontally-arranged signal face, from left to right, shall be as follows:
- CIRCULAR RED
- Steady left-turn RED ARROW
- Steady 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
Except as otherwise provided in EPG 902.6.4, 902.6.8, 902.6.11, and 902.6.15 for a three-section separate turn signal face with a flashing YELLOW ARROW signal indication, the signal section that displays a flashing yellow signal indication during steady mode operation:
- A. Shall not be placed in the same horizontal position as the signal section that displays a steady yellow signal indication, and
- B. Shall be placed to the right of the signal section that displays a steady yellow signal indication.