CEE 764 – Fall 2010CEE 764 – Fall 2010

Topic 3Topic 3

Basic Signal Timing and Basic Signal Timing and Coordination PrinciplesCoordination Principles

CEE 764 – Fall 2010CEE 764 – Fall 2010

Signal System ClassificationSignal System Classification

Traditional SystemsTraditional Systems Closed-Loop (Field Master)Closed-Loop (Field Master) Centralized Computer ControlCentralized Computer Control

AdaptiveAdaptive

CEE 764 – Fall 2010CEE 764 – Fall 2010

Signal Timing ProcessSignal Timing Process

Data Collection

Signal Timing Development

Field Implementation

CEE 764 – Fall 2010CEE 764 – Fall 2010

Basic TerminologyBasic Terminology

CycleCycle Phase Split Phase Split Phasing SequencePhasing Sequence OffsetOffset Force-offForce-off

CEE 764 – Fall 2010CEE 764 – Fall 2010

Cycle Length and SplitCycle Length and Split

Cycle LengthCycle Length

All signals must have a common cycle length to achieve coordination

SplitSplitSplit = Green + Yellow + All-red

CEE 764 – Fall 2010CEE 764 – Fall 2010

Signal CoordinationSignal Coordination

Intersection #1 Intersection #2

East Bound

CEE 764 – Fall 2010CEE 764 – Fall 2010

OffsetOffset

Offset is the time difference between two Offset is the time difference between two reference pointsreference points

Offset must be specified byOffset must be specified by PhasePhase Begin/end phaseBegin/end phase

Offset = Offset = 00 ~ ~ cycle lengthcycle length

CEE 764 – Fall 2010CEE 764 – Fall 2010

OffsetOffset

ф 2,6

ф 2,5

ф 1,5

ф 4,8

ф 2,6

ф 1,5

ф 4,8

ф 3,7

Local zero Local zero

When the local zero occurs at 40 sec of the master clockWe say the Offset = 40 sec

CEE 764 – Fall 2010CEE 764 – Fall 2010

Time-Space Diagram Time-Space Diagram One-way StreetOne-way Street

26

26

26

26

8 4 8 4

8 4 8 4

G=25 Y=5 R=30

G=35 Y=5 R=20

Time

#1

#2

EB Band

CEE 764 – Fall 2010CEE 764 – Fall 2010

Time-Space DiagramTime-Space DiagramTwo-way StreetTwo-way Street

26

26

26

26

8 4 8 4

8 4 8 4

G=25 Y=5 R=30

G=35 Y=5 R=20

Time

#1

#2

EB Band WB Band

CEE 764 – Fall 2010CEE 764 – Fall 2010

Question 1:Question 1:2 and 2 and 6 at intersection #1 turn to green at 60 sec, 6 at intersection #1 turn to green at 60 sec, 2 and 2 and 6 at 6 at intersection #2 turn to green at 20 sec, what are the offset s at the two intersection #2 turn to green at 20 sec, what are the offset s at the two intersections, assuming the offset is referenced to the start of green of intersections, assuming the offset is referenced to the start of green of 2 2 and and 6? 6?

Questions Questions

Question 2: Question 2: Given the offsets number in Q1, what will the offsets be if the offsets are Given the offsets number in Q1, what will the offsets be if the offsets are referenced to the end of green of referenced to the end of green of 2 and 2 and 6? 6?

Question 3: Question 3: If the travel speeds are different for the two directions, will it affect the If the travel speeds are different for the two directions, will it affect the above offset results? above offset results?

CEE 764 – Fall 2010CEE 764 – Fall 2010

Offset and TransitionOffset and Transition

Synch point/clock: the time all offsets are Synch point/clock: the time all offsets are referenced to. It is also called referenced to. It is also called Master Clock Zero. Master Clock Zero. It is usually set at 12:00 – 3:00 a.m. when traffic is It is usually set at 12:00 – 3:00 a.m. when traffic is light. light.

12:00 a.m. (Master Zero)

Local Zero Local Zero Local Zero

Master Zero Master Zero Master Zero

Offset

CEE 764 – Fall 2010CEE 764 – Fall 2010

ExampleExample

If the Synch point is set at 3:00 a.m., for a signal If the Synch point is set at 3:00 a.m., for a signal operating at an 90-sec cycle and an offset of 40, operating at an 90-sec cycle and an offset of 40, what would be the master clock timer and the what would be the master clock timer and the local clock timer at 11:20 a.m.?local clock timer at 11:20 a.m.?

CEE 764 – Fall 2010CEE 764 – Fall 2010

Transition MethodsTransition Methods

Transition occurrencesTransition occurrences Plan changePlan change PreemptionPreemption PedestrianPedestrian

Transition methods/algorithmsTransition methods/algorithms DwellDwell Max DwellMax Dwell AddAdd SubtractSubtract ShortwayShortway

CEE 764 – Fall 2010CEE 764 – Fall 2010

ExampleExample

CEE 764 – Fall 2010CEE 764 – Fall 2010

Offset and TransitionOffset and Transition

2

6

26

8 4

8 4 8 4

#1

#2

1

5

2

6

1

5

EB:20 sec

WB:8 sec

CEE 764 – Fall 2010CEE 764 – Fall 2010

BandwidthBandwidth(Dual LT Leading)(Dual LT Leading)

2

6

26

8 4

8 4 8 4

#1

#2

1

5

2

6

1

5

EB:20 sec

WB:8 sec

CEE 764 – Fall 2010CEE 764 – Fall 2010

Bandwidth - AdjustedBandwidth - Adjusted(Dual LT Leading)(Dual LT Leading)

2

6

26

8 4

8 4 8 4

#1

#2

1

5

2

6

1

5

EB:20 sec

WB:12 sec

CEE 764 – Fall 2010CEE 764 – Fall 2010

Bandwidth - InitialBandwidth - Initial(Lead/Lag)(Lead/Lag)

2

6

26

8 4

8 4 8 4

#1

#2

1

5

2

6

1

5

EB:20 sec

WB:12 sec

CEE 764 – Fall 2010CEE 764 – Fall 2010

Bandwidth - AdjustedBandwidth - Adjusted(Lead/Lag)(Lead/Lag)

2

6

26

8 4

8 4 8 4

#1

#2

1

5

2

6

1

5

EB:20 sec

WB:20 sec

CEE 764 – Fall 2010CEE 764 – Fall 2010

MOEsMOEs

Bandwidth Concept (PASSER II)Bandwidth Concept (PASSER II) BandwidthBandwidth, , secondsseconds Bandwidth Efficiency = Bandwidth/CycleBandwidth Efficiency = Bandwidth/Cycle Attainability = Bandwidth/gAttainability = Bandwidth/gminmin

System-Wide Delay (Synchro)System-Wide Delay (Synchro)

System-wide Stops and Delay (TRANSYT-7F)System-wide Stops and Delay (TRANSYT-7F)

CEE 764 – Fall 2010CEE 764 – Fall 2010

Yellow TrapYellow Trap

“Yellow trap” is a situation faced by a left-turn movement when the display of “yellow” occurs to both the left-turn phase and the adjacent through phase, but the opposing through is not terminating.

(1)

(2) (3)

(4) (5)

CEE 764 – Fall 2010CEE 764 – Fall 2010

Dallas phasing has louver that through vehicles cannot seeDallas phasing has louver that through vehicles cannot see

CEE 764 – Fall 2010CEE 764 – Fall 2010

Left-turn phase about to endLeft-turn phase about to end

CEE 764 – Fall 2010CEE 764 – Fall 2010

Through movements move both directions. Left-turn yield Through movements move both directions. Left-turn yield to opposing through.to opposing through.

CEE 764 – Fall 2010CEE 764 – Fall 2010

Yellow trap occurs when the leading left-turn sees yellow Yellow trap occurs when the leading left-turn sees yellow and thinks the opposing through phase will also endand thinks the opposing through phase will also end

CEE 764 – Fall 2010CEE 764 – Fall 2010

Dallas phasing does not display yellow, and left-turn sees Dallas phasing does not display yellow, and left-turn sees green ball and is supposed to still yield.green ball and is supposed to still yield.

CEE 764 – Fall 2010CEE 764 – Fall 2010

When left-turn sees yellow, the opposing phase also about When left-turn sees yellow, the opposing phase also about to endto end

CEE 764 – Fall 2010CEE 764 – Fall 2010

Main street phases end, side street phases beginMain street phases end, side street phases begin

CEE 764 – Fall 2010CEE 764 – Fall 2010

Yellow TrapYellow Trap

• Only the leading left-turn has the “yellow trap” with protected/permitted phasing

• Dallas Phasing solves the "yellow-trap" problem by holding a solid green indication.

• Louvers are used to shield the left-turn display so that the green display in the left-turn signal cannot be easily seen by thru drivers.

•When can a “yellow trap” occur with standard PPLT with left-turns leading or lagging?

http://projects.kittelson.com/pplt/LearnAbout/Learn3.htm

http://projects.kittelson.com/pplt/displays/dallas_doghouse_lag.htm

CEE 764 – Fall 2010CEE 764 – Fall 2010

SummarySummary

What is “Yellow Trap” and when it occurs?What is “Yellow Trap” and when it occurs? What is the main purpose of using “Lead-Lag” phasing? Can What is the main purpose of using “Lead-Lag” phasing? Can

“Lead-Lag” phasing increase an intersection capacity? “Lead-Lag” phasing increase an intersection capacity? What is the exception that a different cycle length can be used at What is the exception that a different cycle length can be used at

an intersection while still maintaining coordination? an intersection while still maintaining coordination?

OffsetOffset BandwidthBandwidth Time-Space DiagramTime-Space Diagram

CEE 764 – Fall 2010CEE 764 – Fall 2010

Lab ExerciseLab Exercise

1.1. Use the Synchro offset optimization (keep cycle length and splits unchanged) and answer the Use the Synchro offset optimization (keep cycle length and splits unchanged) and answer the following questions:following questions:

• What are the phasing sequences at each intersection?What are the phasing sequences at each intersection?• How are the offsets referenced and what are the offsets?How are the offsets referenced and what are the offsets?• Examine the timing solution and indicate where stops may occur if driving on the main street both Examine the timing solution and indicate where stops may occur if driving on the main street both

directions.directions.

2.2. Can you further improve the bandwidth by changing the phasing sequences from Synchro? Answer Can you further improve the bandwidth by changing the phasing sequences from Synchro? Answer the same questions above.the same questions above.

3.3. Which intersection is controlling the bandwidth?Which intersection is controlling the bandwidth?

Use the Kietzke system (3 signals) to perform Use the Kietzke system (3 signals) to perform the following exercise.the following exercise.

CEE 764 – Fall 2010CEE 764 – Fall 2010

Lab ExerciseLab Exercise

1.1. Understand the existing timing sheets and compare with Synchro coding.Understand the existing timing sheets and compare with Synchro coding.

2.2. Use the Synchro offset optimization (keep cycle length and splits unchanged) and compare Use the Synchro offset optimization (keep cycle length and splits unchanged) and compare Synchro timing solution with the existing (bandwidth)Synchro timing solution with the existing (bandwidth)

3.3. How was the phasing sequence changed at each signal? Can you further improve the How was the phasing sequence changed at each signal? Can you further improve the bandwidth by changing the phasing sequences from Synchro?bandwidth by changing the phasing sequences from Synchro?

4.4. Which intersection is controlling the bandwidth?Which intersection is controlling the bandwidth?

5.5. Try only with two intersections (Harmon and Tropicana) and see how the solution changes.Try only with two intersections (Harmon and Tropicana) and see how the solution changes.

Use the Boulder Highway system (3 signals) to Use the Boulder Highway system (3 signals) to perform the following exercise.perform the following exercise.

CEE 764 – Fall 2010CEE 764 – Fall 2010

Signal Timing Sheets (NextPhase)Signal Timing Sheets (NextPhase)

Boulder Hwy/Tropicana IntersectionBoulder Hwy/Tropicana Intersection

1.1. 1.1 – Schedule of timing plans1.1 – Schedule of timing plans

2.2. 2.3.x – Information of a timing plan: cycle, split, offset, sequence2.3.x – Information of a timing plan: cycle, split, offset, sequence

3.3. 2.4.x – Phasing sequence 2.4.x – Phasing sequence

4.4. 2.5.x – Phase data (min green, yellow, all-red etc.)2.5.x – Phase data (min green, yellow, all-red etc.)

5.5. 4.2.1- Phase designation (direction/movement) and ring structure4.2.1- Phase designation (direction/movement) and ring structure

CEE 764 – Fall 2010CEE 764 – Fall 2010W

B =

36

secE

B = 16 sec

Lead/Lag PhasingLead/Lag Phasing

CEE 764 – Fall 2010CEE 764 – Fall 2010W

B =

45

sec

EB

= 16 sec