Butte Creek Ice Detection and Warning System Evaluation Roger Lindgren Associate Professor –...
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Transcript of Butte Creek Ice Detection and Warning System Evaluation Roger Lindgren Associate Professor –...
Butte Creek Ice Detection and Warning System Evaluation
Roger Lindgren Roger Lindgren Associate Professor – Oregon Institute of TechnologyAssociate Professor – Oregon Institute of Technology
June 4June 4thth , 2009 , 2009ODOT Traffic Operations Leadership Team Meeting ODOT Traffic Operations Leadership Team Meeting
Salem, OregonSalem, Oregon
Research Team: Research Team: Adam Bradford, Robert Bertini, Adam Bradford, Robert Bertini,
Quency Fahlgren, Roger Lindgren, Quency Fahlgren, Roger Lindgren, Jared Lowther, Sean St.ClairJared Lowther, Sean St.Clair
Traffic EngineeringLaboratory
Traffic EngineeringLaboratory Highway 140 Highway 140
(Lake of the Woods)(Lake of the Woods)
Study Site
Traffic EngineeringLaboratory Highway 140 Highway 140
(Lake of the Woods)(Lake of the Woods)
To Klamath Falls
To Medford
Traffic EngineeringLaboratory Roadway Prone Roadway Prone
to Icing Conditionsto Icing Conditions
Substantial change Substantial change in elevation from in elevation from valleysvalleys
Particularly from the Particularly from the west side (Medford) west side (Medford)
Traffic EngineeringLaboratory ODOT Ice Warning ODOT Ice Warning
SystemSystem
Butte Creek RWIS
To East Beacon
To West Beacon
Traffic EngineeringLaboratory
Beacons/SignsBeacons/Signs
Located at MP 21 and 41Located at MP 21 and 41 Installed in late 2005Installed in late 2005
Traffic EngineeringLaboratory
Butte Creek RWISButte Creek RWIS
Digital radar unit Digital radar unit ((installed for this studyinstalled for this study))
Wind direction/speedWind direction/speed
Moisture sensorMoisture sensor
TemperatureTemperature
Humidity / dew pointHumidity / dew point
Pavement condition Pavement condition sensorsensor
Traffic EngineeringLaboratory
Radar Speed TrapRadar Speed Trap
Vehicle speed/direction determined by Vehicle speed/direction determined by measuring the delay from one radar beam measuring the delay from one radar beam to the next to the next
Traffic EngineeringLaboratory
System HistorySystem History
Operational late 2005Operational late 2005
Beacons activated by certain RWIS station Beacons activated by certain RWIS station conditionsconditions Temperature / humidity / dewpoint etc.Temperature / humidity / dewpoint etc. Pavement sensor (Pavement sensor (not in operation during study seasonnot in operation during study season))
Traffic EngineeringLaboratory Evaluation Evaluation
Project GoalsProject Goals
Evaluate crash data BEFORE and AFTER Evaluate crash data BEFORE and AFTER warning system deploymentwarning system deployment
Relate road conditions to vehicle speedRelate road conditions to vehicle speed
Assess motorist experience with the Assess motorist experience with the warning systemwarning system
Is system making roads safer??Is system making roads safer??
Traffic EngineeringLaboratory
Crashes MP 21.7-41.7
0
10
20
30
40
50
60
70
80
90
03_04 04_05 05_06 06_07 07_08
Season
Cra
shes
Dry conditions
Icy conditions
Crash DataCrash Data
Without warning system With warning system
Traffic EngineeringLaboratory
Speed AnalysisSpeed Analysis
Beacon Status
OnOff
Me
an
Sp
ee
ds
(bo
th d
ire
ctio
ns)
62
60
58
56
54
52
50
48
46
Capture Site
ATR
RWIS
Traffic EngineeringLaboratory
Speed AnalysisSpeed Analysis
Speeds at RWIS are significantly reduced Speeds at RWIS are significantly reduced (9.5 mph overall) when the beacons ON (9.5 mph overall) when the beacons ON
Less decrease seen in WB traffic (8.4 mph)Less decrease seen in WB traffic (8.4 mph)
Since speed reduction is the primary goal of Since speed reduction is the primary goal of the system, data suggest that the beacons the system, data suggest that the beacons are fulfilling their intended purposeare fulfilling their intended purpose
Impossible to conclusively prove that the Impossible to conclusively prove that the system caused the decrease system caused the decrease
Traffic EngineeringLaboratory
Driver SurveysDriver Surveys
PHASE ONEPHASE ONEDirect survey of Direct survey of motorists at the five motorists at the five ODOT Sno-Parks on ODOT Sno-Parks on Lake of Woods PassLake of Woods Pass
PHASE TWOPHASE TWOSurvey of southern Survey of southern Oregon residents, Oregon residents, (internet and mailout)(internet and mailout)
Traffic EngineeringLaboratory
System ConfidenceSystem Confidence
Freqeuncy Percent
Extremely Confident 19 10.5Very Confident 68 37.6Somewhat Confident 77 42.5Not at all Confident 17 9.4
Yes 50 28.2No 61 34.5Do Not Recall 66 37.3
Yes 36 20.7No 68 39.1Do Not Recall 70 40.2
Driver Confidence in
Beacons
False Positives
False Negatives
91.6% of drivers expressed confidence 91.6% of drivers expressed confidence
False +/- cannot be verified False +/- cannot be verified
Traffic EngineeringLaboratory
Effect on Driver BehaviorEffect on Driver Behavior
Freqeuncy Percent
Much Slower 56 31.3Somewhat Slower 101 56.4Same 20 11.2
Much More Attentive 71 40.3Somewhat More Attentive 80 45.5No Change 24 13.6
Much More Cautious 67 39.0Somewhat More Cautious 85 49.4No Change 19 11.0
Effect on Speed
Effect on Attention
Effect on Caution
Very encouraging resultsVery encouraging results
Self-reporting survey bias may exaggerate Self-reporting survey bias may exaggerate the effect the effect
Traffic EngineeringLaboratory
Alert Distance Alert Distance
Freqeuncy Percent
Less Than 1 Mile 58 32.01 to 2 Miles 66 36.53 to 5 Miles 40 22.16 to 10 Miles 18 9.910 to 20 Miles 7 3.9
Distance from Beacons to Ice
68.5% expect ice within 2 miles of signs68.5% expect ice within 2 miles of signs
Actual distance is highly variable (0-Actual distance is highly variable (0-10miles)10miles)
““reinforcement” beacons may be beneficial reinforcement” beacons may be beneficial
Traffic EngineeringLaboratory
Driver CommentsDriver Comments
ODOT does a terrific job keeping the road open ODOT does a terrific job keeping the road open people are stupid no amount of signaling is people are stupid no amount of signaling is going to make them drive any better going to make them drive any better The beacons to serve a good purpose as a The beacons to serve a good purpose as a reminder to stay alert reminder to stay alert Maybe beacons that photo speeders! Maybe beacons that photo speeders! bigger and higherbigger and higherMore beacons, each describing no more than 5 More beacons, each describing no more than 5 miles of the road. To say it may be icy over the miles of the road. To say it may be icy over the next 20 miles doesn't alert you as to exactly next 20 miles doesn't alert you as to exactly when that icy patch is likely when that icy patch is likely