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Kevin J. Haas, P.E.Traffic Investigations EngineerOregon Department of Transportation
Intersections: Managing Performance—Operations and Safety
November 15, 2012 PPLT Operations & Safety presentation by Kevin J. Haas, P.E. 1
Protected Only vs. Protected/Permissive Left-Turn (PPLT) Phasing
Randall Laninga, P.E.Traffic EngineerIllinois Department of Transportation
Flashing Yellow Arrow (FYA)
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Protected Only Left-Turn Phasing Policy
• Required– Intersection sight distance
less than AASHTO minimums for left turn
• Recommended– Speed limit > 45 mph– Left-turn movement crosses
3 or more lanes– Dual left-turn lanes– High percentage of left-
turning trucks
November 15, 2012 PPLT Operations & Safety presentation by Kevin J. Haas, P.E. 2
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PPLT Left-Turn Phasing Policy
• PPLT provided when left-turns > 200 vph (existing volumes or within 5 years)
• 4-section head with flashing yellow arrow– No more “doghouse” heads!
• PPLT with FYA is preferred phasing unless Protected-Only criteria are met
November 15, 2012 PPLT Operations & Safety presentation by Kevin J. Haas, P.E. 3
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Traditional 5-Section “Doghouse”
November 15, 2012 PPLT Operations & Safety presentation by Kevin J. Haas, P.E. 4
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Intersection with a FYA Head
November 15, 2012 PPLT Operations & Safety presentation by Kevin J. Haas, P.E. 5
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Flashing Yellow Arrow (FYA) Head
November 15, 2012 PPLT Operations & Safety presentation by Kevin J. Haas, P.E. 6
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NCHRP 3-54 & Report 493• First Oregon FYA
installed in 2001– Oregon was one of the
lead States participating in NCHRP 3-54
• Oregon DOT (Woodburn)• City of Beaverton• Jackson County
• Interim Approval for FYA granted by FHWA in 2006
November 15, 2012 PPLT Operations & Safety presentation by Kevin J. Haas, P.E. 7
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State highways in Oregon• 8,000 centerline
miles– 10% of Oregon
total mileage– 60% of Oregon VMT– 1,500 signalized
intersections• Approximately 50%
with at least 1 PPLT leg
November 15, 2012 PPLT Operations & Safety presentation by Kevin J. Haas, P.E. 8
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Aggressive FYA outreach & education campaign since 2001
November 15, 2012 PPLT Operations & Safety presentation by Kevin J. Haas, P.E. 9
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NCHRP Web-Only Document 123
• Follow-up study to NCHRP Report 493– Published in 2007– 13 intersections
converted from PPLT “doghouse” heads to FYA signal heads
– 12 of 13 intersections saw reductions in left-turn crashes after FYA installed
November 15, 2012 PPLT Operations & Safety presentation by Kevin J. Haas, P.E. 10
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Oregon FYA crash reductions• Aggressive
campaign initiated in 2007 to replace all “doghouse” signal heads with FYA
• Typical conversion cost = $10,000 per intersection
• Typical left-turn crash reduction = 25%
November 15, 2012 PPLT Operations & Safety presentation by Kevin J. Haas, P.E. 11
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Conflicts with pedestrians & bicyclists for permissive left-turns
• Drivers focused on looking for gaps rather than pedestrians & bicyclists
• Portland is #1 bicycle commuting city in U.S.– 5.4% commute by bicycle
• Advanced traffic signal controllers provide options:– Protected only operation during
pedestrian call to controller– Set FYA parameters based on
gaps (requires good detection)
November 15, 2012 PPLT Operations & Safety presentation by Kevin J. Haas, P.E. 12
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Oregon Protected-Only vs. PPLT Summary
• Protected-Only– High speeds– Dual left-turn lanes– Crossing 3 or more
lanes• PPLT with FYA
– 25% left-turn crash reductions vs. 5-section “doghouse”
– Outreach & education a must!
– Addressing conflicts with bikes/peds is an ongoing challenge
November 15, 2012 PPLT Operations & Safety presentation by Kevin J. Haas, P.E. 13
