SYVARI Bus Priority Strategy

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SYVARI Bus Priority Strategy

• Easy
• Effective
• Independent

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• Developed for implementing bus priorities in
  fixed cycle (coordinated) signal control
• Can also be implemented in isolated intersections
  or without bus priorities

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SYVARI synchronized phase ring control
SYVARI is based on phase ring control
which is synchronized to fixed cycle by pulses
and orders given by cycle counter (action table)
However a bus priority call can always disconnect
the phase ring and the synchronization
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Cornerstone 1Every real vehicle signal group
has fictional groups equipped with same
intergreen times as the real signal group
1) 2) 3)
Functions of groups 1) Real signal group
minimum green and guaranteed green 2) Fictional
extension group normal extensions and
synchronization 3) Fictional priority group
green extension, early green and extra green for
buses
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How does the synchronization work?
Proceeding the green
Ending the green
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Cornerstone 2Extra phases are included in the
phase ring like normal phases
Normal phases
1
3
4
5
6
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Extra phases
An extra phase will be skipped if a bus priority
calling this phase isnt requested
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Cornerstone 3Synchronization never prevents
extensions for buses
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Cornerstone 4A bus priority call ends the
conflicting greens according to minimum and
guaranteed green times
Minimum guarandeed green
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Priorities and synchronization after priorities -
example 1 Priorities have slowed down the
cycle, synchronization speeds it up again gt
Number of cycles is unchanged
Extensions for buses
Extra green
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Priorities and synchronization after priorities -
example 2 Priorities have speeded up the cycle,
synchronization slows it down again gt Number of
cycles is unchanged
Early greens for buses
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Priorities and synchronization after priorities -
example 3 Priorities have slowed down the
cycle, synchronization slows it down more gt
Number of cycles is decreased by one cycle
Green extensions for buses
Extra green
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Priorities and synchronization after priorities -
example 4 Priorities have speeded up the cycle,
synchronization speeds it up more gt Number of
cycles is increased by one cycle
Early greens for buses
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The history and the near future of SYVARI
HISTORY Developed and the first implementation in
Turku 2007 NEAR FUTURE SYVARI will be evaluated
and disseminated in co-operation project of eight
largest Finnish cities and Finnish Ministry of
Transport and Communication (JENKA project). The
first implementation in Helsinki, Tampere and
Oulu during 2008
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Appendix Keys of colours in the examples