the traffic signal as an edr; did it publishing record your crash? · 2020-03-11 · march 9-11,...
TRANSCRIPT
March 9-11, 2020 Slide 5
The Traffic Signal as an EDR; Did it Record Your Crash?
Alan Moore, P.E.A.B.Moore Forensic Engineering, Inc.
Orlando, FL
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March 9-11, 2020 Slide 7
Alan Moore, P.E.
• Mr. Moore is a mechanical engineer and principal of A.B.Moore Forensic Engineering. He specializes in vehicle accident reconstruction, vehicle design analysis, and mechanical engineering consulting.
• Mr. Moore holds a Bachelor of Science in Mechanical Engineering from Michigan State University and a Masters degree in Business Administration from the University of Florida. He is a licensed Professional Engineer, a Board Certified Forensic Engineer, and an ACTAR-certified accident reconstructionist. His past experience includes two decades of accident reconstruction and automotive engineering. He previously worked at Ford Motor Company as a design engineer on the Ford Expedition and Excursion. Mr. Moore also serves as a high-performance driving coach for aspiring race car drivers through the Porsche Club of America.
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March 9-11, 2020 Slide 55
Kids’ bike ride to Target
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March 9-11, 2020 Slide 56
Traffic Signal monitoring using ATSPM
ATSPMs (Automated Traffic Signal Performance Measures) consist of a
high-resolution data-logging capability added to existing traffic
signal infrastructure and data analysis techniques.
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March 9-11, 2020 Slide 57
Pedestrian Call Button #2
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March 9-11, 2020 Slide 58
ATSPM – Pedestrian Delay, Crossing Side Street
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March 9-11, 2020 Slide 59
ATSPM – Pedestrian Delay, Crossing Main Street
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March 9-11, 2020 Slide 60
Approach Delay on Main Street
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March 9-11, 2020 Slide 61
Crossing on the “Walk” signal, 10:10 a.m.
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March 9-11, 2020 Slide 62
Split history for main street ped crossing
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March 9-11, 2020 Slide 63
Split history for side street ped crossing
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March 9-11, 2020 Slide 65
Did the eastbound left-turn (Phase 1) driver have a green arrow? No, based on the split monitor.
(Dates redacted)
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March 9-11, 2020 Slide 66
Was the speeding vehicle “moving with traffic”? From a radar advance traffic sensor
Utah ATSPM Region 1, Main St. @ US-91, Signal # 5299https://udottraffic.utah.gov/ATSPM
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March 9-11, 2020 Slide 67
Signal timing sheet, with no data specific
to a date or time.
Red light reconstruction, the old way
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March 9-11, 2020 Slide 68
Brief Overview of Traffic Signal Design
Signal Phasing, Ring Barriers, Phase Diagrams, and Timing Sheets
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March 9-11, 2020 Slide 69
Traffic Signal NEMA Phase Numbers
• Even numbers are through movements• 2 & 6 are usually the main street through movements
• 4 & 8 are usually the side street through movements
• Odd numbers are left turns• 1 & 5 are usually the main street left turns
• 3 & 7 are usually the side street left turns
• Pedestrian phases are usually numbered the same as the parallel movement
• Right turn phase is numbered as the same-direction through movement, plus 10. So a main street right turn phase is usually 12.
Signal Timing Manual, 2nd Edition – NCHRP Report 812, 2015
https://transops.s3.amazonaws.com/uploaded_files/Signal%20Timing%20Manual%20812.pdf
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March 9-11, 2020 Slide 70
Traffic Signal NEMA Phase Numbers
Traffic Signal Systems Operation and Design - Kyte & Urbanik, U. Idaho.
https://www.webpages.uidaho.edu/TrafficSignalSystems/traffic/instructor/ch3a.pdf
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March 9-11, 2020 Slide 71
Phase Diagram
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March 9-11, 2020 Slide 72
Ring and Barrier Diagram
Signal Timing Manual, 2nd Edition – NCHRP Report 812, 2015
https://transops.s3.amazonaws.com/uploaded_files/Signal%20Timing%20Manual%20812.pdf
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March 9-11, 2020 Slide 73
Ring and Barrier Diagram
• Signal phases on the left of the “barrier” must finish before the signal can cross the barrier
• A phase on one ring can coincide with any phase on the other ring (on its own side of the barrier)
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March 9-11, 2020 Slide 74
Sample Timing Sheet
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March 9-11, 2020 Slide 75
Why Record the Signal Operation?
• Monitor and improve signal timing
• Identify traffic backups
• Emergency response
• Evaluate public complaints
• Automate traffic studies
• Research projects
• Accident reconstruction is a side benefit
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March 9-11, 2020 Slide 76
How To Use Networked Traffic Signal Data
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March 9-11, 2020 Slide 77
Forensic Approach to Networked Traffic Signal Accidents
Investigation: Was the signal able to log events?
Analysis: Is the logging valid?
Evidentiary Value: What does it say about accident causation?
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March 9-11, 2020 Slide 78
How To Determine if Signal Is Networked and Has Data
• Look for fiber-optic or network hardware
• Look for high-tech sensors (microwave, radar, camera)
• Request split history from municipality
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March 9-11, 2020 Slide 79
Public Records Request to Municipality
Request the following:
• Signal timing plans
• Phase diagram
• Timing sheet
• Intersection schematic
• Split history
• High resolution detector data
Municipality may not be familiar with some of the records, and may not be aware that they exist.
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March 9-11, 2020 Slide 80
Record a long (~30 minute) video of
signal operation with a clock reference
occasionally visible in the video
(www.time.gov)
Accident Site Inspection
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March 9-11, 2020 Slide 81
Evaluate Changes At Intersection
• Did the intersection or traffic signal change between the crash and the inspection date? Compare signal plans to evaluate.
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March 9-11, 2020 Slide 82
Validate Split History Data with Inspection Video
Use timers to compare signal operation in video to split history
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March 9-11, 2020 Slide 83
Compare Crash Date/Time to Split History
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March 9-11, 2020 Slide 85
How To Tell When The Crash Occurred?
• Crash Report Time Estimate
• GPS Data in Vehicles
• 911 dispatch records
• Security video
• Emergency vehicle pre-emption at signal
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March 9-11, 2020 Slide 86
Using Detailed Signal and Detector Data to Investigate Intersection Crash Causation - Final Report Gary A. Davis , Indrajit Chatterjee - Department of Civil Engineering, University of Minnesota CTS 13-05 , January 2013
Crash Time From Detector Data
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March 9-11, 2020 Slide 88
High Resolution Detector Data
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March 9-11, 2020 Slide 89
Sample Split History
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March 9-11, 2020 Slide 94
Split history, on inspection date
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March 9-11, 2020 Slide 95
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March 9-11, 2020 Slide 96
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March 9-11, 2020 Slide 97
Split history time discrepancy of 50-55s
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March 9-11, 2020 Slide 98
Network time vs GPS time
GPS time can vary from “network” time by 16~52 seconds, due in part to leap seconds.
Does the GPS correct for this error? Some do, and a correction signal is broadcast
https://timetoolsltd.com/gps/gps-ntp-server/
https://timetoolsltd.com/gps/what-is-the-gps-clock/
https://en.wikipedia.org/wiki/Leap_second
https://tycho.usno.navy.mil/leapsec.html
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March 9-11, 2020 Slide 99
Possible causes of time discrepancies
• GPS time vs network time
• Asynchronous data logging
• Reference point of timestamp may not be the start of Phase 1 green
• Error in parsing of data from individual events to split monitor reports
• ?
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March 9-11, 2020 Slide 100
Event Logging Raw Data
Performance Measures for Traffic Signal Systems, Day et al, Purdue University, 2014 https://t2center.uconn.edu/pdfs/PerformanceMeasuresTrafficSignalSystemsPurdue%202014.pdf
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March 9-11, 2020 Slide 101
V2I – Networked Signal Timing & Split History
Connected Signal’s Enlighten app, BMW and Audi for predictive signal timing
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March 9-11, 2020 Slide 102
BlueTOAD
• http://www.trafficcast.com/index.html
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March 9-11, 2020 Slide 103
Further Info
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March 9-11, 2020 Slide 104
Alan Moore, P.E.A.B.Moore Forensic Engineering, Inc.
Orlando, [email protected]
321-946-1283
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