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)

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

Ice Related CrashesIce Related Crashes

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 UnitRadar Unit

Wavetronix dual Wavetronix dual radarradar

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

Driver SurveysDriver Surveys

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

Traffic EngineeringLaboratory

Research TeamResearch Team

Traffic EngineeringLaboratory

Acknowledgements

Oregon Department of Transportation

Garry Binning, Adam Bradford, Kevin Haas, Joel McCarroll, Daniel Serpico, Michael Stinson, James Wittenberg

Advanced Traffic Products Wavetronix

Tim Janes Daniel Beck