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The Effects of Residual Chemical on The Effects of Residual Chemical on the Road During Blowing/Drifting the Road During Blowing/Drifting

Snow EventsSnow Events

Benjamin W. HersheyBenjamin W. HersheyGraduate Research AssistantGraduate Research Assistant

Surface Transportation Weather Research CenterSurface Transportation Weather Research CenterUniversity of North DakotaUniversity of North DakotaGrand Forks, North DakotaGrand Forks, North Dakota

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OutlineOutline

•• Problem Statement & Problem Statement & ObjectiveObjective

•• Blowing Snow & Blowing Snow & Residual ChemicalResidual Chemical

•• InstrumentationInstrumentation•• MethodologyMethodology•• Preliminary FindingsPreliminary Findings•• Ongoing & Future WorkOngoing & Future Work

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Problem Statement & ObjectiveProblem Statement & Objective

•• The interaction between residual The interaction between residual chemicals and blowing snow can present chemicals and blowing snow can present a serious safety hazard for motorists and a serious safety hazard for motorists and decision making difficulties for decision making difficulties for maintenance personal.maintenance personal.

•• Current field project investigate this Current field project investigate this interaction in a controlled setting.interaction in a controlled setting.–– Test segment selected Test segment selected –– Instrumentation used to validate effectsInstrumentation used to validate effects

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Residual ChemicalResidual Chemical

•• Blowing snow conditions can last for extended Blowing snow conditions can last for extended periods of time following snowfall event leading periods of time following snowfall event leading to the conclusion that blowing snow is the to the conclusion that blowing snow is the number one cause of road ice formation (number one cause of road ice formation (TablerTabler, , 2004)2004)

•• Chemicals are spread for deicing and antiChemicals are spread for deicing and anti--icing icing purposespurposes

•• Any residual chemical can lead to icing situationsAny residual chemical can lead to icing situations•• Chemicals can also produce an Chemicals can also produce an ‘‘ice cream ice cream

freezerfreezer’’ type affecttype affect

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Blowing SnowBlowing Snow

Image Courtesy of Leon Osborne

Qsusp Qsusp

Qsalt Qsalt

saltation layer

suspension layer

precipitation

verticaltransport

Fetch

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Blowing SnowBlowing Snow

Occurs in 3 different phases (vertical height)Occurs in 3 different phases (vertical height)•• Rolling < 0.01 mRolling < 0.01 m•• Saltation 0.01 m to 0.1 mSaltation 0.01 m to 0.1 m•• Suspension 0.1 m to 100 mSuspension 0.1 m to 100 m

•• Note that rolling particles can also be classified as saltation Note that rolling particles can also be classified as saltation particlesparticles

Blowing snow affects the pavement heat balance Blowing snow affects the pavement heat balance The mass flux of blowing snow on the roadway The mass flux of blowing snow on the roadway can exceed the highest mass flux amounts of can exceed the highest mass flux amounts of falling snow (falling snow (TablerTabler, 2004), 2004)Roadway visibility is typically calculated at 1.2 m Roadway visibility is typically calculated at 1.2 m because the average nonbecause the average non--commercial vehicles commercial vehicles viewpoint is this high (Matsuzawa and Takeuchi viewpoint is this high (Matsuzawa and Takeuchi 2004).2004).

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InstrumentationInstrumentation

•• 3 disdrometers located at:3 disdrometers located at:–– Cam #1: 0.4 m; lowest level Cam #1: 0.4 m; lowest level

possiblepossible–– Cam #2: 1.2 m; typical Cam #2: 1.2 m; typical

driver heightdriver height–– Cam #3: 2.1 m; close to Cam #3: 2.1 m; close to

commercial vehicle heightcommercial vehicle height

•• Other instruments used:Other instruments used:–– Sonic Wind AnemometerSonic Wind Anemometer

•• Met One Instruments, Met One Instruments, Inc. 50.5HInc. 50.5H

–– Temperature/RH SensorTemperature/RH Sensor•• VaisalaVaisala HMP45CHMP45C

–– LuftLuft Pavement sensorPavement sensor–– UND pavement sensorUND pavement sensor–– Salt Quantity Meter Salt Quantity Meter

SOBO 20SOBO 20

All data are collected from the UND Road Weather Field Research Facility just north of Buxton, ND along I-29.

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Instrumentation (contInstrumentation (cont’’d)d)•• The three disdrometers used for this research are The three disdrometers used for this research are

known as the Video Snowflake Imager (VSI)known as the Video Snowflake Imager (VSI)-- Donated by NASADonated by NASA

-- Hardware consists of flood lamp, camera & Hardware consists of flood lamp, camera & housing, and PC housing, and PC Camera Specifications

- ~ 60 frames per second - 640 x 240 pixels per image- Calibrated to yield 0.05 mm x 0.1 mm resolution- Viewing window is 32 mm x 24 mm

•• Custom software was developed to process the Custom software was developed to process the image filesimage files

Images courtesy of Dr. Larry Bliven

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Instrumentation (contInstrumentation (cont’’d)d)

•• SOBO 20 roadway salt quantity InstrumentSOBO 20 roadway salt quantity Instrument–– Loaned to STWRC by Iowa DOTLoaned to STWRC by Iowa DOT–– Ability to measure quantity of both Ability to measure quantity of both NaClNaCl and CaCland CaCl22

•• Conductivity of each chemical is virtually the sameConductivity of each chemical is virtually the same

–– Uses water and Acetone to measure conductivityUses water and Acetone to measure conductivity–– Measurements are in g/mMeasurements are in g/m22

–– Contains a setting of Contains a setting of ½½ and 1 to provide more and 1 to provide more accurate measurements in situations with low accurate measurements in situations with low chemical concentrationschemical concentrations

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MethodologyMethodology

•• Establish a test roadway Establish a test roadway segment (10segment (10’’ x 28x 28’’))

•• Apply Apply NaClNaCl/Sand mixture /Sand mixture to segment at an to segment at an application rate of application rate of 1000lbs/lane mile (1 lb)1000lbs/lane mile (1 lb)

•• Chemical composition was 50/50 by volumeChemical composition was 50/50 by volume•• Take initial readings with SOBOTake initial readings with SOBO•• All other instrumentation is continuously All other instrumentation is continuously

collecting data.collecting data.•• After the passage of blowing snow event more After the passage of blowing snow event more

SOBO measurements performedSOBO measurements performed

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Case StudyCase Study

•• 21 UTC on Feb. 821 UTC on Feb. 8thth to 21 UTC on Feb. 10to 21 UTC on Feb. 10thth

20062006•• Weather conditions the morning of the Weather conditions the morning of the

1010thth presented the Red River Valley with a presented the Red River Valley with a blowing snow eventblowing snow event

•• Analysis of both atmospheric and Analysis of both atmospheric and pavement conditions are performedpavement conditions are performed

•• SOBO measurements were taken in the SOBO measurements were taken in the aftermath of the blowing snow event on aftermath of the blowing snow event on the 10the 10thth

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Case StudyCase Study

PPAES output from the morning of Feb. 10th

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10 ft

28 f

tN

1d 2d

2a

1a2b 1b

2c1c

Roadway Segment LayoutRoadway Segment Layout

1 a-d Feb. 8th 21 UTC

2 a-d Feb. 10th 21 UTC

Actual test segment image

Feb 8th Feb 10th

a 0 a 1

b 0 b 0.5

c 4-5 c 1.5

d 2 d 0.5

SOBO setting of 1/2

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Atmospheric DataAtmospheric Data

2m Temperature

-30

-25

-20

-15

-10

-5

0

5

2/8/

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0

2/8/

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00

2/9/

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0:0

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2/9/

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00

2/10

/200

6 0:

00

2/10

/200

6 12

:00

2/11

/200

6 0:

00

Time

Tem

p. (

o C)

2 Meter

Wind Speed at 2 m

0

5

10

15

20

25

30

35

2/8/2006 0:002/8/2006 12:002/9/2006 0:002/9/2006 12:002/10/2006 0:002/10/2006 12:002/11/2006 0:00

TimeW

ind

Spd

m/s

2 Meter W ind

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Pavement ConditionsPavement Conditions

Lufft Pavement Temperature

-18

-16

-14

-12

-10

-8

-6

-4

-2

0

2/8/2006 0:002/8/2006 12:002/9/2006 0:002/9/2006 12:002/10/2006 0:002/10/2006 12:002/11/2006 0:00

Time

Tem

p. (

o C)

Temperature

UND Pavement Sensor

-12

-10

-8

-6

-4

-2

0

2/7/2006 12:002/8/2006 0:002/8/2006 12:002/9/2006 0:002/9/2006 12:002/10/2006 0:002/10/2006 12:00

2/11/2006 0:002/11/2006 12:00

TimeTe

mp.

(o C

)

Temperature

Temperature

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ConclusionsConclusions

•• Even with small amounts chemical left, Even with small amounts chemical left, blowing snow can build on the road blowing snow can build on the road causing slippery conditionscausing slippery conditions

•• Adjacent untreated road stayed snow/ice Adjacent untreated road stayed snow/ice freefree

•• Data collection during a winter storm Data collection during a winter storm event can be difficultevent can be difficult–– Data dropoutsData dropouts–– Overall weather conditionsOverall weather conditions–– Timing of eventTiming of event

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Continuing ResearchContinuing Research

•• Provide time lapse video of test segmentsProvide time lapse video of test segments•• Conduct more case studies during the winter of Conduct more case studies during the winter of

20062006--0707•• Use different chemicals that are used on the Use different chemicals that are used on the

roadwayroadway•• Create a more realistic test segment with known Create a more realistic test segment with known

vehicle trafficvehicle traffic•• Use addition data from the newly acquired friction Use addition data from the newly acquired friction

wheel from the Ohio DOT wheel from the Ohio DOT •• Improved data analysis for blowing snow Improved data analysis for blowing snow

deposited on the roadwaydeposited on the roadway

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AcknowledgementsAcknowledgements

•• Special thanks to Dr. Larry Special thanks to Dr. Larry BlivenBliven and NASA for and NASA for the donation of the VSI equipmentthe donation of the VSI equipment

•• Iowa DOT Winter Operations Division for loaning Iowa DOT Winter Operations Division for loaning the SOBO 20 for usethe SOBO 20 for use

•• North Dakota DOT for construction and ongoing North Dakota DOT for construction and ongoing support with Field Research Facilitysupport with Field Research Facility

•• Research support is provided by NDDOT and Research support is provided by NDDOT and Federal Highway Administration Contract #ITSFederal Highway Administration Contract #ITS--9999 (206) 9999 (206)

•• Advisor Prof. Leon F. Osborne Jr.Advisor Prof. Leon F. Osborne Jr.

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3980 Campus Road3980 Campus RoadUniversity of North DakotaUniversity of North DakotaGrand Forks, North Dakota 58202Grand Forks, North Dakota 58202http://http://stwrc.rwic.und.edustwrc.rwic.und.edu701701--777777--24792479

Thank You!