Road Weather Sensors Road Weather Vaisala Solutions Taisto

Concept of Ice Warning and Prediction on Highways C Thermal mapping km One-time measurement

Road Weather Station • Monitors: – road surface conditions – e. g. icy, wet,

Typical Sensors in a Road Weather Station Atmospheric sensors: • • air temperature, humidity,

Road Surface Sensors in Testbed Road Surface Condition Sensor DRS 511 • • surface

Vaisala’s Road Surface Condition Sensor DRS 511 Black Ice Detection Measurement of Conductance and

DRS 511 Coverage Detection • Optical coverage detection is based on three fibre optics;

Salt Amount, Concentration and DFP Most common deicer is still rock salt (mostly Na.

Depression of Freezing Point 1. DFP 2. Surface becomes slippery here 3. All liquid

New Approach to Road Weather: Remote Sensing Surface Condition Surface Temperature ©Vaisala | 28.

Vaisala Remote Road Surface Temperature Sensor DST 111 Properties • • remote sensor, no

Vaisala Remote Road Surface Condition Sensor DSC 111 Properties • surface condition – dry,

DSC 111 Performance in Freezing Drizzle 09. 01. 2006 ©Vaisala | 28. 12. 2006

DSC 111 installed in a car ©Vaisala | 28. 12. 2006 | Ref. code

Highway 3, Helsinki 06. 03. 2006 ©Vaisala | 28. 12. 2006 | Ref. code

Ring Road 3, Helsinki 06. 03. 2006 ©Vaisala | 28. 12. 2006 | Ref.

Side Road in Helsinki 06. 03. 2006 ©Vaisala | 28. 12. 2006 | Ref.

DSC 111 Friction compared to Actual Measured Values ©Vaisala | 28. 12. 2006 |

Summary • Effective winter maintenance will result increased safety with reduced costs • Road

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Road Weather Sensors Road Weather, Vaisala Solutions Taisto Haavasoja

Concept of Ice Warning and Prediction on Highways C Thermal mapping km One-time measurement USER INFORMATION COMPUTER C SYSTEM + ROSA / Road surface analysis ICECAST t On-line real-time data SOFTWARE Actual road state on color map or data table Salting Route Optimization Road status warnings/alarms Road icing forecast map Salting conditions 3 h 6 h 12 h 2 5 3 CLOUDS 0 2 3 TEMP. Road weather forecast ©Vaisala | 28. 12. 2006 | Ref. code | Page 2 24 h forecast RAIN - LR - WIND 4 2 0 Statistics Training, Service, Help. Desk

Road Weather Station • Monitors: – road surface conditions – e. g. icy, wet, dry – road temperature – road weather conditions – precipitation – air temperature, humidity, dewpoint – wind, pressure, etc. • Warns of: – icy road surface – frost or precipitation ©Vaisala | 28. 12. 2006 | Ref. code | Page 3

Typical Sensors in a Road Weather Station Atmospheric sensors: • • air temperature, humidity, dew point precipitation, present weather wind speed and direction pressure, radiation, . . . Road sensors: • surface temperature • surface condition – ice, water, snow and how much – salt amount, concentration, depression of freezing point (DFP) ©Vaisala | 28. 12. 2006 | Ref. code | Page 4

Road Surface Sensors in Testbed Road Surface Condition Sensor DRS 511 • • surface temperature surface condition salt amount, salt concentration and depression of freezing point Road Surface Temperature Sensor DST 111 • infrared remote thermomometer Road Surface Condition Sensor DSC 111 • optical detection of ice and snow or frost ©Vaisala | 28. 12. 2006 | Ref. code | Page 5

Vaisala’s Road Surface Condition Sensor DRS 511 Black Ice Detection Measurement of Conductance and Polarization Optical Measurement of Layer Thickness Surface Temperature DRS 511 Multi-Sensor Block Ground Temperature ©Vaisala | 28. 12. 2006 | Ref. code | Page 6

DRS 511 Coverage Detection • Optical coverage detection is based on three fibre optics; one is transmitting and two are receiving. • The two reflected signals determine the water layer thickness (in mm) or the presence of snow on the sensor. ©Vaisala | 28. 12. 2006 | Ref. code | Page 7

Salt Amount, Concentration and DFP Most common deicer is still rock salt (mostly Na. Cl) • occasionally also Ca. Cl 2 is used Salt amount (s) is measured in grams per square meter (g/m²) Water or ice layer thickness (t) is measured in millimeters (mm) • 1 mm of water equals to: 1 kg/m² = 1 liter/m² = 1 mm m²/m² = 1 mm We get salt concentration as: c = s/t [(g/m²)/mm] = s/t [g/l] Depression of freezing point: DFP = f(c) ©Vaisala | 28. 12. 2006 | Ref. code | Page 8

Depression of Freezing Point 1. DFP 2. Surface becomes slippery here 3. All liquid frozen ©Vaisala | 28. 12. 2006 | Ref. code | Page 9

New Approach to Road Weather: Remote Sensing Surface Condition Surface Temperature ©Vaisala | 28. 12. 2006 | Ref. code | Page 10

Vaisala Remote Road Surface Temperature Sensor DST 111 Properties • • remote sensor, no installation in the road measures also under heavy traffic measures also air temperature and humidity accurate remote road surface temperature measurement – unique compensation of reflection errors – estimated accuracy of surface temperature – 1 °C within -20. . . +10 °C and with solar radiation < 200 W/m² – about 0. 3 °C in typical icing conditions ©Vaisala | 28. 12. 2006 | Ref. code | Page 11

Vaisala Remote Road Surface Condition Sensor DSC 111 Properties • surface condition – dry, moist, wet – snowy/frosty, icy, or slushy (wet snow) – independent measurement of – water, ice and snow/frost layer thicknesses • friction – slipperiness is output as a friction coefficient • easy installation and service – no asphalt cutting, easy traffic control • measures reliably even under heavy traffic conditions ©Vaisala | 28. 12. 2006 | Ref. code | Page 12

Summary • Effective winter maintenance will result increased safety with reduced costs • Road weather information system is the key component in achieving that target • Vaisala is the world leader in road weather systems • Vaisala’s unequaled Remote Road Surface Condition Sensor DSC 111 measures friction coefficient reliably • look at further details in – Proceedings of the SIRWEC 2006, page 13. – http: //www. vaisala. com/weather/dsc 111 ©Vaisala | 28. 12. 2006 | Ref. code | Page 19