Traffic Signal Timing Coordination
Pre-Timed Signals All phases have a MAX recall placed on them. How do they work All phases do not have detection so they are not allowed to GAP out All cycles are a consistent length Page 2 2
Semi-Actuated Signals Main-street phases have a MAX recall placed on them. How do they work The main street does not have actuation so it is not allowed to GAP out All other phases are actuated Page 3 3
Fully Actuated Signals Closely spaced actuated signals without coordination are actually designed to stop cars. How do they work Terminates when a gap is present on the main street First car leaving a Signal has a gap in front of it Therefore Page 4 4
Coordination Multiple (2 or more) signals working together along an arterial Requirement A common cycle length Repeatable Pattern Good Coordination minimizes stops on the main street Bad coordination Can increase stops along the main street Page 5 5
Coordination Goals Maximize Progression Keep speeds up by reducing stops Limit Calls from Public Minimize Cross-Street Delay Page 6 6
Signal System Efficiency Measures Intersection Delay Amount of Delay for vehicles on ALL approaches Your logo here Page 7 7
Signal System Efficiency Measures Arterial Bandwidth Band of progression green time for vehicles traveling on Main Arterial 20 40 60 80 100 120 140 160 180 28 sec 27 sec Page 8 8
Signal System Efficiency Measures Driver Perception Good if no stops on arterial Bad if waiting on cross street while no one on main street Page 9 9
Factors Affecting Progression Page 10 10
Factors Affecting Progression: Cycle Length Minimum Acceptable System Cycle Length Signal 3 Delay Signal 2 Signal 1 Cycle Length Page 11 11
Realistic Range of Cycle Length 1800 In this range, Limited increase in capacity 1600 1400 1200 1000 800 2 Phases 3 Phases 4 Phases 600 400 200 0 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 Page 12 12
Factors Affecting Progression: Intersection Spacing Every System has a Natural Cycle-length based on intersection spacing which will provide the best progression solution. Page 13 13
Factors Affecting Progression: Phasing Permissive Only Protected Only Protected + Permissive 3 lanes Can create yellow-trap with lead-lag phasing example: Lead- Lag Fewer number of phases = more time for progression band on main street 40 mph Your logo here Page 14 14
Effects of Lead / Lag Phasing Can significantly increase bandwidth Page 15 15
Optimization Models Synchro Based on least delay in system Passer 2 Based on green-band maximization Passer 3 Diamond Interchange Optimization Page 16 16
Data Requirements Turning Movement Counts Actual Speed along the arterial Intersection Geometry Number of Lanes (Capacity) Types of Signals faces (Phasing allowed) Street widths (for pedestrian timing) Intersection Spacing Page 17 17
Progression Optimization Process Page 18 18
PASSER2 Progression Efficiency Page 19 19
PASSER2 Time-Space Diagram Page 20 20
Synchro Data Input Page 21 21
Synchro Time-Space Diagram Page 22 22
Measures of Effectiveness Number of Stops Emissions Delay Travel Time Fuel Consumption Page 23 23
Measures of Effectiveness Process (PASSER3, PASSER2, and Synchro) Optimization Trimmier NB Trimmier SB Synchro Optimization Trimmier NB Trimmier SB Travel Time (min) 1:31 1:23 1:54 1:36 Total Delay (hr) 9 7 15 12 Stops (#) 1323 1293 1477 1351 Fuel Consumed (gal) 36 37 41 40 CO Emissions (kg) 2.5 2.6 2.9 2.8 VOC Emissions 13 11 19 16 Page 24 24
Synchro - Simulation Page 25 25
Field Programming and Fine-Tuning To be outstanding in the field, you have to be out standing in the field! Observe real world field conditions Adjust timing on actual conditions Not everything can be any simulated Page 26 26
Detection and Coordination Page 27 27
Detection and Coordination Detection on the Non-coordinated phases Allows unused time to be given to a different phase which reduces delay Typically given to the coordinated Phase Can be shared with other non-coordinated phases Detection on the coordinated phases Can extend the coordinated phases past the force-off to allow the end of a platoon to progress through the intersection. Page 28 28
Controller Features How does a controller achieve coordination? Coordination has two critical Aspects 1 When/How do you get into a phase (Permissive Period) 2 When/How do you get out of a phase (Force-Off Point) Page 29 29
Permissive Period Opening of the permissive (When/How do you get into a phase) Open all permissives at once This can reduce cross-street delay. This gives unused time to the beginning of the coordinated phase. Open one permissive at a time in order as defined by the ring structure. This can favor the end of the coordinated phase. Your logo here Page 30 30
Cross-Street Benefits from Unused Coord Time Random arrivals (platoon through intersection) - allows coord phase to leave at beginning of PYP Unused PYP time given to cross street Page 31 31
Force Off Points When a phase uses all the time allocated by the coordination plan, a Force-Off is applied. The Force-Off as a third way to terminate a phase and exists only in coordination. The three ways are: Gap Termination Max Termination Force Off Your logo here Page 32 32
Force Off Points Two types of Force-Offs exist FLOATING FORCE-OFF Determined by when the phase actually comes on and how much time is programmed. This point can move from cycle to cycle (it floats). Will allow maximum early return to the coordinated phase. FIXED FORCE-OFF Predetermined as soon as a coordination plan is entered. It does not ever change (it s fixed). Will allow none coordinated phases to share time. Your logo here Page 33 33
Floating vs. Fixed Force-Off Reference Point: beginning of coord green Programmed Splits 2 6 3 7 4 8 1 5 Page 34 34
Effect of Floating Force-Off Floating Force-Off 2 6 3 7 3 and 7 Gap Terminate 4 8 1 5 2 6 Early Return Programmed Splits 2 6 3 7 4 8 1 5 Page 35 35
Effect of Fixed Force-Off Programmed Splits 2 6 3 7 4 8 1 5 Fixed Force-Off 2 6 3 7 Time not used by 3+7 4 8 1 5 Increases time for the next phase Page 36 36
Floating vs Fixed Force-Off Which is better? Floating Force-Off 2 6 3 7 4 8 1 5 2 6 Programmed Splits 2 6 3 7 4 8 1 5 Fixed Force-Off 2 6 3 7 4 8 1 5 Page 37 37
Reference Point Reference Point: end of coord green Programmed Splits 3 7 4 8 1 5 2 6 Page 38 38
Offset Correction Dwell Electro-Mechanical way of getting into coordination. In step in 1 cycle Dwell Max - Dwells only for the programmed time. Shortway Automatically selects the shortest route (long or short) to get in step over the following 3 cycles. Your logo here Page 39 39
Shortway Correction Desired offset > 50% out of step < 50% out of step 50% out of step decision line Start of coordinated phases (actual offset) during recognition cycle (ex. 40% out of step) Your logo here Page 40 40
Shortway Correction Offset < 50% out of step If actual offset is less than 50% out of step the controller will decide to shorten each interval proportionally to achieve new offset in 3 cycles Desired offset Correction in 3rd cycle Correction in 2 nd cycle Correction in 1 st cycle Start of coordinated phases (actual offset) in old plan (ex. 40% out of step) Your logo here Page 41 41
Shortway Correction Offset > 50% out of step If actual offset is more than 50% out of step the controller will decide to lengthen each interval proportionally to achieve new offset in 3 cycles Correction in 3rd cycle Desired offset Correction in 2 nd cycle Correction in 1 st cycle Start of coordinated phases (actual offset) in old plan (ex. 60% out of step) Your logo here Page 42 42
Data Entry Requirements Cycle Length- The time required to services all the phases programmed times Split times The sum of the green + yellow + red times Offset the amount of time from the reference clock to the scheduled on time of the coordinated phase Coordinated Phases The reference phases on the arterial street (typically one in each ring) that is given a guaranteed green interval to provide progression Time of day plan The schedule of when each timing plan will run (day, timing plan, and special functions) Your logo here Page 43 43
Coordination Data Timing Rules Each Phase Split MUST Accommodate: OR Min Time + Yellow Time + Red Clearance Time Ped timing (which ever is longer) The sum of splits in each ring on each side of the barrier must be equal The sum of all splits in a ring CANNOT exceed the cycle length The offset CANNOT be longer than the cycle Length Your logo here Page 44 44
Coordination Troubleshooting How can you tell if a coordination plan is running? Check error logs Check to see if the coordination timer is running Your logo here Page 45 45
Coordination Example 1 Phase 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Min 5 15 5 5 5 15 5 5 -- -- -- -- -- -- -- -- PASS 1 1 1 1 1 1 1 1 Max 20 40 20 20 20 40 20 20 Walk 7 7 7 7 Clear 15 15 15 15 Yel 4.0 4.0 4.0 4.0 4.0 4.0 4.0 4.0 Red 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 Cycle Length 90 coord phases 2+6 Offset 10 Phase 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Split Mode 15 30 15 30 15 30 15 30 -- 0 1 0 0 0 1 0 0 -- -- -- -- -- -- -- Your logo here Page 46 46
Coordination Example 1 Phase 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Min 5 15 5 5 5 15 5 5 -- -- -- -- -- -- -- -- PASS 1 1 1 1 1 1 1 1 Max 20 40 20 20 20 40 20 20 Walk 7 7 7 7 Clear 15 15 15 15 Yel 4.0 4.0 4.0 4.0 4.0 4.0 4.0 4.0 Red 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 Cycle Length 90 coord phases 2+6 Offset 10 Phase 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Split 15 30 15 30 15 30 15 30 -- -- -- -- -- -- -- -- Your logo here Page 47 47
Coordination Example 2 Phase 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Min 5 15 5 5 5 15 5 5 -- -- -- -- -- -- -- -- Max 20 40 20 20 20 40 20 20 Walk 7 7 7 7 Clear 15 15 15 15 Yel 4.0 4.0 4.0 4.0 4.0 4.0 4.0 4.0 Red 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 Cycle Length 70 coord phases 2+6 Offset 10 Phase 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Split 15 20 15 20 15 20 15 20 -- -- -- -- -- -- -- -- Your logo here Page 48 48
Coordination Example 2 Phase 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Min 5 15 5 5 5 15 5 5 -- -- -- -- -- -- -- -- Max 20 40 20 20 20 40 20 20 Walk 7 7 7 7 Clear 15 15 15 15 Yel 4.0 4.0 4.0 4.0 4.0 4.0 4.0 4.0 Red 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 Cycle Length 70 coord phases 2+6 Offset 10 Phase 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Split 15 20 15 20 15 20 15 20 -- -- -- -- -- -- -- -- Your logo here Page 49 49
Coordination Example 3 Phase 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Min 5 15 5 5 5 15 5 5 -- -- -- -- -- -- -- -- Max 20 40 20 20 20 40 20 20 Walk 7 7 7 7 Clear 15 15 15 15 Yel 4.0 4.0 4.0 4.0 4.0 4.0 4.0 4.0 Red 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 Cycle Length 70 coord phases 2+6 Offset 10 Phase 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Split 20 20 15 15 15 20 15 20 -- -- -- -- -- -- -- -- Your logo here Page 50 50
Coordination Example 3 Phase 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Min 5 15 5 5 5 15 5 5 -- -- -- -- -- -- -- -- Max 20 40 20 20 20 40 20 20 Walk 7 7 7 7 Clear 15 15 15 15 Yel 4.0 4.0 4.0 4.0 4.0 4.0 4.0 4.0 Red 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 Cycle Length 85 coord phases 2+6 Offset 10 Phase 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Split 20 30 15 20 15 20 15 30 -- -- -- -- -- -- -- -- Your logo here Page 51 51
Coordination Example 4 Phase 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Min 5 15 5 5 5 15 5 5 -- -- -- -- -- -- -- -- Max 20 40 20 20 20 40 20 20 Walk 7 7 7 7 Clear 15 15 15 15 Yel 4.0 4.0 4.0 4.0 4.0 4.0 4.0 4.0 Red 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 Cycle Length 90 coord phases 2+6 Offset 100 Phase 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Split 15 30 15 30 15 30 15 30 -- -- -- -- -- -- -- -- Your logo here Page 52 52
Coordination Example 4 Phase 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Min 5 15 5 5 5 15 5 5 -- -- -- -- -- -- -- -- Max 20 40 20 20 20 40 20 20 Walk 7 7 7 7 Clear 15 15 15 15 Yel 4.0 4.0 4.0 4.0 4.0 4.0 4.0 4.0 Red 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 Cycle Length 90 coord phases 2+6 Offset 100 Phase 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Split 15 30 15 30 15 30 15 30 -- -- -- -- -- -- -- -- Your logo here Page 53 53
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