freezing of salty solutions vs mobile surface condition ...€¦ · connector or cigarette lighter...

TECONER OY Technical Consulting & Research

Freezing of Salty Solutions vs Mobile Surface Condition and

Friction Measurements

PIARC TC 2.4 Workshop, 11.03.2015 Helsinki

Taisto Haavasoja

name.surname@teconer.fi

Contents • Freezing process

– Composite mixture of clean ice and anti-icer solution

– Consequences to winter maintenance

• Mobile measurement of winter surface conditions – RCM411 Road Condition Monitor – Mapping of winter road conditions

• Future applications – Global service of slippery surface

conditions – Real time control of gritting based

on measured conditions

11.03.2015 PIARC TC 2.4 Mobile Road Surface Condition Measurements 2

Phase Diagram of NaCl

Ice Fraction = b / (a+b) Brine Fraction = a / (a+b)

Research on Freezing Solutions

T. Haavasoja, J. Nylander and P. Nylander, “Relation of Road Surface Friction and Salt Concentration”, SIRWEC 2012, Helsinki

• Low salt concentrations are adequate

• Pressure dependence

A. Klein-Paste, J. Wåhlin, “Wet pavement anti-icing — A physical mechanism”, Cold Regions Science and Technology 96 (2013), pages 1–7

• Minimum Brine Fraction is independent of anti-icer chemical

Salt Concentration and Slipperiness

Minimum Brine Fraction vs Pressure

Consequences to Winter Maintenance

• Fairly low salt concentrations keep friction at tolerable levels, even at low temperatures

0.1 mm * 1 % = 1 g/m² NaCl

• Let surface partially freeze -> reduce liquid spray

• Liquid anti-icers work well

• Potential for saving salt and anti-icers

– measure friction and water layer -> adjust required salt amount

– Mobile Winter Road Condition Monitoring

Road Condition Monitor RCM411

• measurements

– road surface condition • dry, • moist, • wet, • icy, • snowy, • slushy

– water layer thickness

– modeled friction

– surface temperature

Road Condition Monitor RCM411

• user interface

– cell phones • BlueTooth link to cell phone

• power from the trailer connector or cigarette lighter

– data communicated to selected servers

– results on a map interface as color coded lines

– Mobile Road Condition Map

µTEC Friction Meter

• µTEC

– cell phone application

– accelerometer based absolute friction meter

• used for friction reference

– development of RCM411 friction model

Map Interface for Friction …

Surface state…

… Water Layer

… Surface Temperature

Water layer, Hki-Vantaa Airport 29.12.2011

Research Publications, tests …

RCM411: • FTA 2011, test report of the Finnish Transport Agency

• FTA 2013, test report of the Finnish Transport Agengy

• SIRWEC 2012 Extended Abstract ”Experiences of Mobile Road Condition Monitoring”

• SIRWEC 2012 Presentation ”Experiencies of Mobile Road Condition Monitoring”

• PIARC 2014 Article ”Continuous Skid Resistance Test”

• PIARC 2014 Presentation ”Continuous Skid Resistance Test” – standard deviation in friction is on the order of 0.10

Freezing of Salty Solution and Friction: • SIRWEC 2012 Extended Abstract ”Relation of Road Surface Friction and Salt Concentration”

• SIRWEC 2012 Presentation ”Relation of Road Surface Friction and Salt Concentration”

• Look also at A. Klein-Paste, J. Wåhlin (NTNU Trondheim), “Wet pavement anti-icing — A physical mechanism”, Cold Regions Science and Technology 96 (2013), pages 1–7

• AASHTO/TRB SCOM 2015 ”Freezing of Anti-Icing Solutions on Road Surfaces”

Friction Test Run 11.3.2012 Road Laboratory of Aalto University

11.03.2015 PIARC TC 2.4 Mobile Road Surface Condition

Measurements 18

Aalto University Friction Test

11.03.2015 PIARC TC 2.4 Mobile Road Surface Condition

Measurements 19

FIRWE Project (2011-2014)

• TEKES project

• RCM411 testing started with Itella logistics vehicle in Helsinki – driving on working days in

the morning and in the afternoon

– moved to a taxi in Helsinki region

• Ravensburg, Germany – Buses!

• Finnish Transport Agency

New fixing parts for RCM411

Summary …

• Mobile Road Condition Monitor RCM411

– surface state, water layer, friction and surface temperature (RTS411)

• standard deviation is on the order of 0.10

– various user interfaces available

• cell phone, tablet or PC

• real time map interface

• Mobile Road Condition Map

Summary … • RCM applications

– a tool for winter maintenance

– a tool for quality control

– a tool for learning and training

– friction mapping

– thermal mapping

– information to drivers

– warning for aquaplaning, …

Future Vision • Global service of slippery surface conditions

• Real time view of slippery conditions on a world map

• Control of gritting based on measured conditions • From rules of thump to calculated amounts based on measurements

and weather forecasts to keep brine fraction on safe side

freezing of salty solutions vs mobile surface condition ...€¦ · connector or cigarette lighter...

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