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Green waves through interchanges
Coordination for Diverging Diamond Interchanges (DDI)

Diverging diamond interchanges (DDI) are an elegant and ingenious way to ensure safe, non-stop left turns when exiting a highway onto an intersecting road. This is achieved by swapping left and right lanes between two signalized intersections.

Green Traffic Software allows to include DDI in the coordination scheme, with ease. Only through movements are permitted at each intersection, and they cannot overlap. So, the two intersections in the time-space diagram (TSD) will look as below.

  • Insert the fictitious left turn times equal to the correspondent through times in both directions in the input GTS table,
     

  • Set red times to zero
     

  • Forbid the Lead/Lead and Lag/Lag phase sequences
     

  • Click “Calculate”, get the Arterial Portrait, press one of the green asterisks in it, and get your green wave in the form of a time-space diagram with the sets of offsets and phase sequences.

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For intersections inside DDIs, treat phase sequence Lead/Lag as "outbound first" and Lag/Lead as "inbound first".

Coordination for Single Point Urban Interchanges (SPUI)

At Single Point Urban Interchange (SPUI), all traffic flow is controlled by one set of traffic lights at one intersection.
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Green Traffic Software coordinates it in the usual way with one difference to be considered when filling the input table. Vehicles moving along the coordinated (vertical) arterial have to stop only when those traveling on the crossing (horizontal) road turn left because the horizontal through traffic passes on a different level.

 

hat decreases the red light and thus increases the possibilities of coordinating this intersection.

  • Set the coordinated red time equal to the sum of the two left turn times, those are to and from the coordinated artery,
     

  • Click “Calculate,” get the Arterial Portrait, press one of the green asterisks in it, and get your green wave in the form of a time-space diagram with the sets of offsets and phase sequences.

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