Coordinated Operations, notes from the field

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Coordinated Operations, notes from the field

• Edward Fok
• Resource Center Operations Technical Service Team
• 2005 TRB Annual Meeting

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Whats all the hubbub?

• Improved driver experiences
• Reduced emission from fewer stops
• Improved safety from predictable operation
• Better transit operation from improved roadway
  reliability
• So Why cant we coordinate everything?

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Coordination

• Chicken or the Egg
• What came first? The driver or the engineer?
• More Cycle Length then you can shake a stick at!
• Network Coordination or snowflakes? Which is
  more delicate?
• Field checks are never an option
• Famous last words "Field check? What's that?"
• Measure Quantify and Testwe ARE the government!

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Chicken or the Egg (or who came first? The
driver or the engineer?)
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Driver? Demand based Coordination

• Observe existing platoon arrival patterns
• Adjust offset to Capture platoon to arrive on
  start of green
• Provide sufficient lead in to allow queue to
  clear before new platoon arrives

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Washington D.C.
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Engineered? Designed Coordination

• Coordination are considered at the planning stage
• Cycle length and Offset are predetermined.
• Drive at the rated speed or expect to have stops
• Deviation are not permitted"
• Yes, there ARE network progression!!!

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Los Angeles, CA
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The Story Does not end there

• Cycle length had to increase to meet new demands
• Designed Coordination eventually became Demand
  Based Coordination
• Network of signals became network of intersecting
  arterials.

Chicken or the Egg? It doesnt matter, its all
Omelets at the end of the meal.
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Before you start throwing Eggs at me

• Posted Speed Limit vs Designed Speed
• Posted Speed Limit
• Simplify customer calls
• Helps to protect against litigations if correctly
  set.

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Coordination and the Need for Speed
Be aware of wide green band when using
coordination for speed control!
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More Cycle Length then you can shake a stick at!

• How big of a difference?
• What are the causes?
• Temporary surges in Sources or Sinks?
• Freeway off-ramp or on-ramp?
• Fully actuated signal needs cycle length too!
• Data Data Data!!!
• Unless there are drastic changes supported by
  observation in the field, keep the cycle length
  the same!!!

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Coordination and Events

• Engineered coordination are critical
• Special events planning
• Coordination between temporary channelization and
  signal timing Focus on facilitating the
  temporary Origin-Destination pathways.
• Traffic Officers Critical link to inattentive
  drivers

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Your Traffic is in My Signals

• Match Cycle Length
• Share volume and timing information
• Pick up the PHONE!!!

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Free Operation inside a Coordinated Network?
Free Operations (Fully Actuated Control) in a
Coordinate Network -Use of both Max Green and
Volume Density Control Available storage capacity
are critical to success
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Network Coordination or snowflakesWhich is more
delicate?

• Death by School Zones (Especially when Law
  Enforcement are present)
• Death by Emergency Preemption
• Death by Railroad Crossings
• Death by Loading Zones

Interruption are generally temporary, Recovery
time needed is highly dependent on existing Level
of saturation.
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Death by Parking

• Extended violation causes massive disruption
• Changes in channelization
• Flow turbulence
• Reduction in safety

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Death by Pedestrians

• Problem from consistent flow of Pedestrian
  Traffic
• Seasonal variation
• Planned event driven
• Special Needs Operation
• Sabbatical Ped Recall!!
• Over 55 Intersection
• Forced recall operation.

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Death by Shopping-Reseda (It's really Los
Angeles, but don't tell them that)
114 Yds
125 Yds
176 Yds
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Field Checks Are Never An Option!

• Verify New Timing
• Did the technician put in the correct offset?
• Did someone check the controller clock?
• Validate New Timing
• Woa! Whats this a new sewer line going in?
• Are they driving where we though they were
  driving???

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Hollywood, CA (It's still Los Angeles, but they
could be in denial)

• What the original Coordination assumption Correct?

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So what did we actually do?

• Justify your existence before and after
  performance evaluation!
• Which Measure of Effectiveness does your customer
  care about?
• Volume?
• Delay?
• Travel Time?
• Number of Stop?
• Speed?
• Best Tool for Evaluation Floating Car Studies

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The Truth about Time-Space Diagram
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So Is it the Chicken or the Egg?

• Understand the nature of the coordination
  problem Is it due to urban layout or due to
  driver/capacity problems?
• Coordination cannot be guaranteed at all times.
• Computer optimization is only the beginning, not
  the end to coordination.
• Get ready to get your hands dirty!