TRAFFIC SIGNAL CLASSIFICATION SYMBOLS

See phasing on your signal location map.

The usual method of location traffic signals on jurisdiction maps is to place a dot on the map with a signal number next to it. The map user must look at the number and then find the plan for the signal. But if the map user just wants to find out the phasing of the signal, these symbols could be helpful. They are intuitive symbols that show the phasing at a glance.

Always rotate the symbol to match the actual alignment of the intersection and directions of the protected left turns.

For information on the left turn phasings themselves, look here.

NAME SYMBOL DESCRIPTION COMMENTS
Circle Two-phase signal Two phase signal, or one phase for each street Any place where the signal alters right of way between two different streets, with no other phases.
Ped-xing signal Two phase signal for nonintersection pedestrian crossing Not used where a cross street exists.
Half signal Half signal: Two phase signal that stops only one direction of traffic: Used for a U-turn turnback, a directional median crossover, or a signal controlling traffic entering a freeway from a cross street, but not the exit ramps. half signal The diagram shows the straight movement not stopped, and the left turn provided for the symbol at left. The black half of the circle is on the side of the street that is stopped. Rotate the symbol to match the streets used.
Two-half signals Two half signals back to back: Used for directional median crossovers and superstreet median crossovers. double half signal The diagram shows the only median crossings allowed.
Bow-tie Alternating right-of-way Signal lets one direction on the road go, then the other. Used for alternating traffic flow on single lane roads, lane closures, and diverging diamond interchanges. diverging diamond
Alternating right-of-way The same symbol is used for both DDI crossovers, and both ends of a single-lane road. The right-of-way alternates, first moving traffic one direction, and then the other direction.


Alternating right-of-way
NAME SYMBOL DESCRIPTION COMMENTS
Teardrop Single leading left turn Single lead: White teardrop indicates a leading left turn phase from the leg the point indicates. single lead turn The diagram shows the indicated left turn phase.
Single lagging left turn Single lag: Black teardrop indicates a lagging left turn phase from the leg the point indicates.
Single leading left turn Teardrop also indicates a left turn phase into T intersection. Use white if leading, black if lagging. signal The diagram shows the left turn phase.
Single lagging left turn Teardrop also indicates a left turn phase into one-way street. Use white if leading, black if lagging. signal The diagram shows the left turn phase. The street is one-way from left to right in the diagram.
NAME SYMBOL DESCRIPTION COMMENTS
Diamond Dual leading left turn Dual lead: The points on a white diamond indicate a leading left turn phase from the intersection legs indicated by the points. dual left turn The diagram shows the indicated left turn phase. The diamond effectively combines two teardrops facing in opposite directions.
Dual lagging left turn Dual lag: The points on a black diamond indicate a lagging left turn phase from the intersection legs indicated by the points.
Dual split lead left turn Dual split lead: Black points on a white diamond indicate split lead left turn phases from the intersection legs indicated by the points. The left turns can end at different times. dual split left turn The diagram shows the indicated left turn phases. Also used for the signal in a Single Point Urban Interchange (SPUI).
Dual split lag left turn Dual split lag: White points on a black diamond indicate split lag left turn phases from the intersection legs indicated by the points. The left turns can begin at different times.
Dual unsplit lead-lag Dual unsplit lead-lag: The white end of the diamond indicates the leading leg. The black end indicates the lagging leg. Each leg has a separate phase. This is often called split-phasing the street.
leading side This diagram shows the leading left turn and concurrent straight phase.
lagging side This diagram shows the lagging left turn and concurrent straight phase.
Dual one-split lead-lag Dual one-split lead-lag: The black point on the white side indicates the leading left turn leg, and that the leading turn can end before the lagging left turn begins. The entirely black side of the diamond shows the lagging leg.
Dual two-split lead-lag Dual two-split lead-lag: The black point on the white side indicates the leading left turn leg, and that the leading turn can end before the lagging left turn begins. The white point on the black side indicates the lagging left turn, and that it can begin before the leading turn ends.
NAME SYMBOL DESCRIPTION COMMENTS
Square Quad leading left turn Quad lead: The points on a white diamond indicate leading left turn phases from the intersection legs indicated by the points.
dual split left turn dual split left turn The diagrams show the indicated left turn phases. This effectively combines a vertical diamond and a horizontal diamond into one symbol
Quad lagging left turn Quad lag: The points on a black diamond indicate lagging left turn phases from the intersection legs indicated by the points.
Quad split lead left turn Quad split lead: Black points on white corners indicate split lead left turn phases from the intersection legs indicated by the points. The left turns can end at different times.
dual split left turn dual split left turn The diagrams show the indicated left turn phases.
Quad split lag left turn Quad split lag: White points on black corners indicate split lag left turn phases from the intersection legs indicated by the points. The left turns can begin at different times.
Quad unsplit lead-lag Quad unsplit lead-lag: The white corner indicates the leading leg. The black corner indicates the lagging leg. Each leg has a separate phase, often called split-phasing the street.
leading side leading side These diagrams show the leading left turns and concurrent straight phases for each street
lagging side lagging side These diagrams show the lagging left turns and concurrent straight phases for each street.
Quad one-split lead-lag Quad one-split lead-lag: The black point on the white corner indicates the leading left turn leg, and that the leading turn can end before the lagging left turn begins. The entirely black corner of the square shows the lagging leg.
Quad two-split lead-lag Quad two-split lead-lag: The black point on the white corner indicates the leading left turn leg, and that the leading turn can end before the lagging left turn begins. The white point on the black corner indicates the lagging left turn leg, and that it can begin before the leading turn ends.
NAME SYMBOL DESCRIPTION COMMENTS
Center dot Quad clockwise left turn Quad clockwise: A black dot in the center of a white square indicates that each leg has a separate phase, and the legs are served in a clockwise order around the intersection (as viewed from above).
The order of quad clockwise (read diagrams left to right)
dual split left turn dual split left turn dual split left turn dual split left turn
The order of quad anticlockwise (read diagrams right to left)
Quad anticlockwise Quad anticlockwise: A white dot in the center of a black square indicates that each leg has a separate phase, and the legs are served in an anticlockwise (counterclockwise) order around the intersection (as viewed from above).
NAME SYMBOL DESCRIPTION COMMENTS
Combining forms Quad: dual split lead dual lead lag The north-south street (vertical) is dual split lead. The east-west street (horizontal) is dual unsplit lead lag, with the leading side on the east leg.
This combines the phasings shown by these two symbols: Dual split lead left turn Dual unsplit lead-lag left turn
Triple: dual split lead and single lead The north-south street (vertical) is dual split lead. The east-west street (horizontal) has a single lead on the east leg.
This combines the phasings shown by these two symbols. Dual split lead left turn Single lead
Double single lead The north-south street (vertical) is single lead. The east-west street (horizontal) has a single lead on the east leg.
This combines the phasings shown by these two symbols. Dual split lead left turn Single lead

How a teardrop is combined into a square.

The corner of the square farthest away from the point of the teardrop is rounded off or flattened.

The color of the end without a point matches the corner on the opposite leg.
NAME SYMBOL DESCRIPTION COMMENTS
External Dots Quad lead permissive Dots at ends of the left turn points indicate permissive turns are used. Absence of dots indicate exclusively protected turns. These dots indicate that permissive turns are allowed using the circular green, flashing yellow arrow, or flashing red arrow indications. The example main symbol shown is quad split lead.
Letter beside the symbol - Yellow Trap Prevention (none) Status not determined. (not shown)
A Anti-backup logic prevents yellow trap. (controller)
D Dallas Phasing (display)
E Yellow trap every cycle (NONE)
F Flashing Yellow Arrows (display)
P Inherently safe (phasing)
R Flashing Red Arrows (display)
S Phase skip prevention (controller)
T Safe pretimed signal (phasing)
X Experimental method (display - e.g. Flashing Yellow or Red Ball)
Y None - yellow trap exists (NONE)
NAME SYMBOL DESCRIPTION COMMENTS
Circled number numbered diagram The phasing can not be shown by a symbol, due to unusual phasing or more than 4 legs. Look at the diagram beside the map labeled with the same number. Here is a side diagram example:
numbered diagram dual split left turn dual split left turn dual split left turn dual split left turn

Links:

  1. All Yellow Trap Links are here:
    YELLOW TRAP INDEX PAGE
  2. How Left Turn Signals Work
  3. Left Turn Signals - Then and Now
  4. Unusual Traffic Problems, Hazards, and Solutions
  5. Home