protected permitted left turn displays nchrp 3-54 (02)
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Protected Permitted Left Turn Displays NCHRP 3-54 (02) Presentation to City of Beaverton Transportation Commission February 7, 2002 Kent Kacir Siemens Gardner Transportation Systems Principal Investigator Project Manager. Presentation Outline. Background Information Model 2070 Features - PowerPoint PPT PresentationTRANSCRIPT
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Protected Permitted Left Turn DisplaysNCHRP 3-54 (02)
Presentation to City of Beaverton Transportation Commission
February 7, 2002
Kent Kacir
Siemens Gardner Transportation Systems
Principal Investigator
Project Manager
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Presentation Outline Background Information
Model 2070 Features
Anticipated Uses/Current Uses
Deployment
Agency’s that have standardized on the Model 2070
Specifications
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Project Objective Project objective: evaluate the safety and
effectiveness of different signal displays used with PPLT control
Determine PPLT usage in the U.S.
Evaluate safety and operational effects
Evaluate drivers’ understanding of various PPLT displays and indications
Evaluate field implementations of selected display(s)
Project deliverables: recommend display(s) for uniform application across the U.S.
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Study Tasks Agency Survey
Static Driver Survey
Operational and Conflict Study
Crash Analysis
Interim Report and Panel Meeting
Animated Driver Survey
Field Study
Panel Meeting and Final Report
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MUTCD and PPLT MUTCD says that a separate traffic signal display for PPLT
control is not required
PPLT Display:
5-section
green arrow protected indication
green ball permitted indication
through movement indication displayed simultaneously with protected indication
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What is the Problem? Some traffic engineers think the green ball permitted display is
problematic
Argue that left-turn drivers may interpret the green ball as a protected indication
At least 4 variations of the permitted indication has been developed
Signal display arrangement and supplemental sign use varies
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Yellow Trap
1
6
5
2
When 1 lags …… 5 gets the yellow trap
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RESEARCH RESULTS
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PPLT Use in the United States
107,219 signalized intersections represented in 168 surveys analyzed
29 % of those intersections use PPLT phasing on at least one approach
IntersectionsWithout PPLT71%
PPLTIntersections29 %
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Use of PPLT by State
5-SECTION CLUSTER5-SECTION VERTICAL4-SECTION VERTICAL3-SECTION VERTICAL5-SECTION HORIZONTAL
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Mounting Location
0%
20%
40%
60%
80%
100%
Per
cent
of
Tot
al
Center overLT Lane
Btwn LT andThru Lane
Other VaryLocation
3 V
4 C
4 V
4 H
5 C
5 V
5 H
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Location of Unique PPLT Indications
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Data Collection Locations
Dallas
College Station
Portland
Seattle Detroit
Dover
Cupertino
Orlando
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Static Survey
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Demographics 2,465 drivers
73,950 scenarios
58 % male - 41 % female
Driver’s age
27 % < 24
44% 24 to 44
21 % 45 to 65
7 % > 65
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Early Conclusions Drivers had better understanding of flashing permitted
indications (less fail critical errors)
No age difference with flashing indications
Drivers over the age of 65:
32 % correct response rate with green ball
Over 63 % correct response rate with flashing indications
2 - 3 seconds additional response time
Response time lower with flashing indications
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Further Study Permitted Indication
The use of flashing permitted indications should be considered in future evaluation
Driver understanding
Fail critical responses
Older driver comprehension
Additional study required
clearance interval - right turns
driving - shared lanes
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Proposed Vertical FYA Display
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UMASS Simulator
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Example of Virtual World
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FIELD IMPLEMENTATION
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FYA Implementation Sites
Implemented
Near Implementation
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Woodburn, Oregon
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Woodburn, Oregon
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ODOT News Release
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Local Press
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Citizen Response
“My opinion is that if the intersection had flashing yellow arrows at the turn-lane, this accident may have been avoided…When I see a green light, my first reaction is “go” so I sometimes find myself responding to that trained response rather than the one that says “don’t go when another car is coming.” Alternatively, when I see a flashing yellow arrow, there is no question that I need to watch what I’m doing, look for approaching vehicles, and turn when it’s safe…”
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What is Required ? Identify 3 intersections that are currently operating with PPLT, and
that have been doing so for 3 years.
Identify 3 intersections to serve as control sites.
Provide background information: Lane widths
Historical crash data
Traffic volumes
Track and report change over costs and implementation issues.
Provide the necessary change over (equipment and man-power).
Submit a Request for Experimentation to Federal Highway Administration
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What Does the NCHRP Contractor Do? Assist Agency in site identification
Provide technical assistance related to controller logic
Provide “form letter” to submit FHWA request
Collect Before and After Conflict data
Analyze field operational data
Analyze field conflict data
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Potential SitesWestern / 5th
Allen / Wilson
Allen / Menlo
125th / Longhorn
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Questions ?Kent Kacir
503-624-7635