The purpose of this TechNote is to assist the user in correctly programming ring and concurrency structures using V80.x/V85.x/Scout software on Trafficware's Commander, ATC or 2070 Controller Platforms.

Version 80/85/Scout supports thirty-two phases assigned to eight rings on Linux platforms.  Phases may time concurrently with phases in other rings that are defined as concurrent phases.  Any phase not defined as a concurrent phase is considered to be a conflicting phase.  The controller uses ring sequence and concurrency definitions to determine the order that the phases are serviced and to insure that conflicting phases never time concurrently.  Phase concurrency establishes “barriers” between non-concurrent phases.

Ring and Concurrency overview using STD8 

Many intersections utilize Standard 8 phase operation as shown on the diagram below

There are basic rules that controller software adheres to under standard eight phase quad operation.

1. Phases are separated into 2 sequential rings.  Ring 1 runs phases 1-2-3-4 in sequential order and Ring 2 runs Phases 5-6-7-8 in sequential order.  A phase can be skipped if there is no demand but the software will always follow the sequential order looking for demand.
2. Phases can be run in both rings at the same time as long as they are concurrent.  Under standard 8 Phase operation Phases 1 and 2 are concurrent with phases 5 and 6 (main road) and phases 3 and 4 are concurrent with phases 7 and 8 (side road). A virtual barrier, defined by the concurrency table, separates the roads.
3. Phases in both rings must cross the barrier together before serving the next phase in sequence.

Programming the Sequence and Concurrency Tables

The screens below were programmed for STD8 operation as shown above.  

V80.x: To get STD8 Operation, program the Phase Mode setting under MM->1->2->1 to STD8 or Initialize the controller software to Full-STD8 under MM->8->4->1.

V85.x/Scout: To get STD8 Operation, program the Phase Mode setting under MM->8->4->4 to STD8 or Initialize the controller software to Full-STD8 under MM->8->4->1.

There are two sets of menus in the controller to program the sequence and the concurrency.  Both must be programmed to truly define the sequence and concurrency that is needed for a particular intersection.  To program the sequence table chose the sequence menu at to MM->1->2->4.

The sequence menu is designed to display 8 rings.  Each ring defines the sequential operation of phases. Once a phase is selected for a ring, it cannot be used in another ring. Menu selection 1 displays eight rings that can utilize first 16 phases in the sequence.

Menu selection 2 displays an additional 16 phases in the sequence

To program the concurrency tables go to MM->1->1->4

User defined Sequences and Concurrency Rules

The user has the ability to define sequences and concurrencies to accommodate various traffic geometries by selecting the unit parameter known as Phase Mode to User under MM-1-2-1 as shown on the screen below.  Phase mode must be set to user before programming the phase sequence and concurrency screens.

When modifying phase sequences and concurrency, V80/V85/Scout was updated to accommodate various iterations of sequencing and concurrency needs. Its programming has been modified and will act differently than prior versions of Trafficware controller software (V61.x, V65,x and V76.x) .  For V80.x/V85.x/Scout the following rules must be adhered when programming the sequence and concurrency structure to properly run the controller for the desired operation declared by the agency.

1. The goal of the V80.x/V85.x/Scout ring logic is to never skip a phase.  To achieve this operation, the precedent of a phase is first by it ring and second by its position in the sequence.  
2. There must always be a phase concurrent at the first barrier (add dummy phase “0” if necessary). 
3. There must always be a phase assigned in ring 1 for each concurrency barrier. 
4. Use dummy phase “0’s” to align the barriers.  Phases assigned to each column in the sequence table must be concurrent with each other.  Therefore with V80.x/V85.x/Scout the position of the phase in the sequence is needed to give the controller some information about how to prioritize.  In versions prior to these versions, this was not necessary.

These rules will address the prioritization aspects of V80.x/V85,x/Scout sequence concurrency algorithm, which implies you need to place dummy phase “0” in front of a phase, if you want the one in the other ring to service it first in sequence when the concurrent phases are part of two different barrier groups.  

NOTE: The concurrency table programming (MM-1->4->1) works the same as prior versions of software but the user must program the sequence tables differently in V80.x/V85.x/Scout

 To understand this new algorithm, consider the following structure that is required by the agency. Imagine the following ring & barrier structure:

In controller software versions prior to V80.x/V85.x/Scout , the sequence table would have been programmed as shown below

Now imagine that the controller is crossing the barrier at the end of phases 2 and 6. The controller software must decide if it is going to service phase 10 or phase 7, because they’re not compatible. If there is a call on both phase 10 and 7, it will serve phase 10 because it is in ring 1. If there are calls on phases 11 and 7 (no call on 10), the controller will service phase 7 because it is before 11 in the sequence. As you can see, this could lead to skipping phases 11, 20, and 21.  In version 80 we added the ability to eliminate this issue by adding place holders(“0”)  to mimic the concurrency in the sequence table.

The correct implementation for V80.x/V85.x/Scout of the example above is:

The requirement about having a phase in every barrier for ring 1 may not be immediately obvious from the example above, but if you do not follow this rule there may be problems with coordination. Specifically, there may be problems with determining force-off points correctly.

As another example consider the sequence and concurrency requirements shown below:

In controller software versions prior to V80.x, the sequence table would have been programmed as shown below

Software prior to V80.x/V85.x/Scout, when running phases 2 and 5 with demand on Phases 3 and 6,  phase 6 could be skipped. This was because phase 3 in the ring sequence has a higher “priority” than phase 6 because not only is in in a lower number ring, but it is also earlier in sequence.

 In V80.x/V85.x/Scout to get the desired operation, please program the Ring sequence table as shown below:

This way, in the event that phase 4 does not have a call, but phase 3 does and phase 6 has a call, the controller software will service 6 before 3.

NOTE: Dual Entry (MM->1->1->2) should NOT be set on any phases that are a part of a barrier which is not fully concurrent. The reason is because the Dual Entry programming checks to see if the phase that is next is compatible with the dual-entry phase using the assumption that the software is crossing a barrier.

 As a final example consider the CFI Intersection shown below:

The operational requirements are as shown below:

The proper programming in V80.x/V85.x/Scout for the ring sequence table will be:

Summary

In V80.x, the expanded ability of programming 32 phases, eight rings and up to 31 concurrent phases gives the agency flexibility of accommodating various geometries.  In particular, the programming of sequence tables are different than prior versions of Trafficware’s software. As always, the agency should fully test the specialized programming to insure the safety of the motoring public prior to installing in the field.