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**Fixed Time Signal Coordination**

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**Objectives Factors affecting coordination**

Basic theory of signal coordination Application to arterial progression

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**Factors Affecting Coordination**

Benefits Purpose of signal system Factors lessening benefits Exceptions to the coordinated scheme

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**Concept: Maximize Progression By Adjusting Offsets**

1st Signal 2nd Signal 3rd Signal t3 Distance (ft) t2 t1 Time (sec) Note: Definitions of offset vary, but text convention is offset is t2 – t1 and t3 – t2

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**Benefits of Signal Coordination**

Stops and Delay Performance index: combining measures Cost =A x (total stops) + B x (total delay) What are some other benefits?

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**Engineering Options Types of systems Movements to be coordinated**

Types of objectives Types of scenarios

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**Factors Lessening Benefits**

Inadequate roadway capacity Side friction Complicated intersection timing plans Wide variability in traffic speeds Short signal spacing Heavy turn volumes

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**Time Space Diagrams and Ideal Offsets**

What is an offset? What is an ideal offset?

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1st Signal 2nd Signal 3rd Signal t3 Distance (ft) t2 t1 Time (sec)

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**One-Way Progression Things to know for one-way progression offsets**

Desired platoon speed Length of queue at coordinated approaches Block length What does this list not consider, based on the list of factors lessening benefits?

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**One-Way Progression How do you construct a time-space diagram?**

Vertical scale Horizontal scale Start first intersection on main street green with t = 0 Next intersection main street green starts at offset relative to downstream start of______________ Repeat for each intersection Note: You can specify offsets relative to one (master) intersection and it is expressed in terms relative to the master intersection

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1st Signal 2nd Signal 3rd Signal t3 Distance (ft) t2 t1 Time (sec)

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**Effect of Queued Vehicles**

How do you determine the offset with queuing? Q number of vehicles queued per lane (veh/lane) h discharge headway of queued vehicle (sec/veh) Loss1 loss time associated with vehicles starting from rest at the first downstream signal (sec)

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**Different Types of Progression**

What are the different types of progression? Simple Forward Flexible Reverse Simultaneous

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**Two-Way Progression Progression in one direction suffers**

Segment offsets tSB+tNB = nC Maximizing bandwidth Popular Limited C

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**Two-Way Progression (Cont.)**

Simultaneous progression Closely spaced intersections Queue management Alternate progression Uniform block length 50:50 split N the number of blocks with simultaneous green How do you determine N?

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5th Signal 4th Signal 3rd Signal Distance (ft) 2nd Signal 1st Signal Working Line Time (sec) 1000 ft intersection spacing 2 lanes in each directions C = 60 sec w/ 50:50 split What is the progression speed? What is the nonstop volume?

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**Two-Way Progression (cont.)**

What about arterials with non-uniform intersection spacing?

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