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Detector Operation and Timing . Bill Kloos Signals & St Lighting Mgr. City of Portland July 28, 2003. Best Practices for Signal Operations. A typical day in Portland!. Really!!!. Traditional Approach. Why have the presence detection and still have the sign?

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detector operation and timing

Detector Operation and Timing

Bill Kloos

Signals & St Lighting Mgr.

City of Portland

July 28, 2003

Best Practices for Signal Operations

traditional approach
Traditional Approach
  • Why have the presence detection and still have the sign?
  • How does this relate to detection in the street?
  • Or, the real question is:
  • What’s Peter’s thing about the toilet???
talk outline for today
Talk outline for today
  • What type of controllers & software do we use? What are the basic parameters?
  • Differences in through movement operation vs. left turns and side streets
  • Example of how our left turn design works
  • Various issues and questions
detection timing city of portland
Detection Timing - City of Portland
  • Use Type 170 controllers
  • Wapiti IKS actuated controller software
  • Primarily use ILD (round loops)
  • Basic detection timing functions used:
    • Min green
    • Passage
    • Volume density (TBR, TTR, Min gap,added/actuation)
  • Try not to violate KISS principle
detection timing city of portland cont
Detection Timing - City of Portland (cont)
  • Multiple input channels per phase
    • Allows carryover/delay programming within CPU
  • Can have 3 sets of timing parameters (time transfer)
  • Have separate table for entering carryover and delay by channel
  • Can do various “tricks” with Command Box
advance detection vs stop bar
Advance detection vs stop bar
  • Use method demonstrated by Dave Hatch for advance detection
  • For side streets and left turns, use two-double loops from stop bar and one single detector at 100’ from stop bar.
  • Most side streets set in “non-locking” operation

Left Turn Example -

SW Barbur & Hamilton

Major Street



  • Min = 6 sec - (typically 3 sec)
  • Ext = 0.5 sec
  • Yellow = 3.0 sec
  • Carryover back loop = 2.1 sec



Left Turn Example -

SW Barbur & Hamilton


Single vehicle issue

min overrides gap time


Max out problems

LT signal now yellow

LT signal now red

issues and questions
Issues and questions
  • Advance detection based on dilemma zone protection -
    • What happens when the phase maxes out?
    • How do we handle the boundary between free flow operation and congestion?
issues and questions18
Issues and questions
  • When should we display the yellow to the approaching motorist?
    • Portland method displays the yellow when motorist is at stop bar
    • Some research suggests that most motorists will not stop when yellow is displayed less than 2 seconds in advance of stop bar
    • For efficiency, shouldn’t we display the yellow that much sooner?
    • Note on this question - somebody else try first
issues and questions19
Issues and questions
  • Is detection technology really that much better now?
    • Concerns about video during various weather and lighting conditions
    • How reliable is reliable enough?
    • Are we straying away from the KISS principle?
Finally -

Is there a silver bullet detection solution for our transportation problems?

No, but maybe by using old techniques and new technology we can come up with some silver buckshot that will make things better!