City of Portland - Isolated Timing Operations January 9, 2005 Isolated Timing Operations - Workshop on Best Practices for Signal Timing Bill Kloos Signals & St. Lighting Division Manager City of Portland, Oregon

City of Portland - Isolated Timing Operations January 9, 2005 A typical day in Portland!

City of Portland - Isolated Timing Operations January 9, 2005 Mt. St. Helens is at it again!

City of Portland - Isolated Timing Operations January 9, 2005 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???

City of Portland - Isolated Timing Operations January 9, 2005 Talk outline for today Goals for isolated intersection operation Review of recent ITE report on the signal timing practices - “State of the Practice” When should we display the Yellow? Review of Portland left turn operation Closing issues and questions

City of Portland - Isolated Timing Operations January 9, 2005 Talk outline for today Goals for isolated intersection operation Review of recent ITE report on the signal timing practices - “State of the Practice” When should we display the Yellow? Review of Portland left turn operation Closing issues and questions

City of Portland - Isolated Timing Operations January 9, 2005 Goals for isolated intersection operation Safety –Not require panic stops –Not have veh/peds in unsafe situations –Display yellow at “best” time Efficiency –Minimum delay –Minimum stops

City of Portland - Isolated Timing Operations January 9, 2005 Goals for isolated intersection operation Bill’s basics: –Keep the cycle length as short as possible –Provide “snappy” operation, especially for minor movements –Provide for “safe” display of yellow –Don’t violate KISS principle

City of Portland - Isolated Timing Operations January 9, 2005 Talk outline for today Goals for isolated intersection operation Review of recent ITE report on the signal timing practices - “State of the Practice” When should we display the Yellow? Review of Portland left turn operation Closing issues and questions

City of Portland - Isolated Timing Operations January 9, 2005 Signal Timing Practices and Procedures - State of the Practice ITE - March 2005 Phil Tarnoff and Javier Ordonez

City of Portland - Isolated Timing Operations January 9, 2005 Report based in part on a survey 100 state, city, and county agencies responded Included questions in following categories - –Controller types –General considerations for timing (phasing, etc) –Timing for actuated controllers –Timing plan selection and calculation processes –Traffic responsive and adaptive systems –Retiming of individual intersections and systems

City of Portland - Isolated Timing Operations January 9, 2005 State of the Practice findings Phasing - –phasing selection practices - little agreement –Left-turn phasing - more permissive than anticipated Signal timing at isolated intersections –wide variance on calculating max, min, and ext

City of Portland - Isolated Timing Operations January 9, 2005 State of the Practice findings

City of Portland - Isolated Timing Operations January 9, 2005 State of the Practice findings

City of Portland - Isolated Timing Operations January 9, 2005 State of the Practice conclusions –“After 50 years there is still disagreement and lack of understanding on many of the fundamental aspects of traffic signal timing.” –There is “inconsistency in the engineering processes being used, as well as a surprising degree of reliance on the judgement of the engineer or technician responsible for the timing process.” –“A definitive document defining best practices is needed.”

City of Portland - Isolated Timing Operations January 9, 2005 Talk outline for today Goals for isolated intersection operation Review of recent ITE report on the signal timing practices - “State of the Practice” When should we display the Yellow? Review of Portland left turn operation Closing issues and questions

City of Portland - Isolated Timing Operations January 9, 2005 Recent ITE Listserv discussion “Using yellow as green” What is the probability of someone stopping at certain time distance from stop bar? More opinion than fact. Main question - at what point will someone continue through the intersection at the onset of yellow?

City of Portland - Isolated Timing Operations January 9, 2005 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

City of Portland - Isolated Timing Operations January 9, 2005 Talk outline for today Goals for isolated intersection operation Review of recent ITE report on the signal timing practices - “State of the Practice” When should we display the Yellow? Review of Portland left turn operation Closing issues and questions

City of Portland - Isolated Timing Operations January 9, 2005 City of Portland basics 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)

City of Portland - Isolated Timing Operations January 9, 2005 Typical data sheet

City of Portland - Isolated Timing Operations January 9, 2005 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

City of Portland - Isolated Timing Operations January 9, 2005 Advance detection vs stop bar Use method discussed by Peter K 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

City of Portland - Isolated Timing Operations January 9, 2005 Left Turn Example - SW Barbur & Hamilton Left Turn Example - SW Barbur & Hamilton Major Street

City of Portland - Isolated Timing Operations January 9, 2005

City of Portland - Isolated Timing Operations January 9, ’ 36’ Left Turn Example - SW Barbur & Hamilton Left Turn Example - SW Barbur & Hamilton Timing Min = 3 sec Ext = 0.5 sec Yellow = 3.0 sec Carryover back loop = 2.1 sec Timing Min = 3 sec Ext = 0.5 sec Yellow = 3.0 sec Carryover back loop = 2.1 sec

City of Portland - Isolated Timing Operations January 9, 2005 LT lane Opposing traffic indication

City of Portland - Isolated Timing Operations January 9, 2005 How should it work?

City of Portland - Isolated Timing Operations January 9, 2005 Desired operation - the video pause

City of Portland - Isolated Timing Operations January 9, 2005 Single vehicle operation Min time overrides gap

City of Portland - Isolated Timing Operations January 9, 2005 Max time out issues Left turn signal now yellow Left turn signal now red

City of Portland - Isolated Timing Operations January 9, 2005 Talk outline for today Goals for isolated intersection operation Review of recent ITE report on the signal timing practices - “State of the Practice” When should we display the Yellow? Review of Portland left turn operation Closing issues and questions

City of Portland - Isolated Timing Operations January 9, 2005 Issues and questions We already have a reasonable body of knowledge on how to make isolated intersections work better. Why aren’t we using it? Current fully actuated theory does not work any better (usually worse) under congested than pretimed. How do we handle the boundary between free flow operation and congestion? How do we truly get to a “best” practice?

City of Portland - Isolated Timing Operations January 9, 2005 Finally - Is there a silver bullet for improving local intersection operations? No, but maybe by using old techniques and new technology we can come up with some silver buckshot that will make things better!

The End