March 15th 2007

Road segment forecasting A tool for salt spreader

control using GPSVIKING workshop

Hamburg, March 15th 2007by

Alexander Mahura, Claus Petersen and Bent SassPresented by

Torben Strunge PedersenThe Danish Meteorological Institute

March 15th 2007

Outline of the talk

• What is Road Segment Forecasting (RSF) ?

• A RSF method

• The Potential in RSF

• Quality and examples

• The future

March 15th 2007

Road station

March 15th 2007

Point forecasts (PF) from Road Condition Model (RCM) – Showing status

March 15th 2007

RSF - Showing status

March 15th 2007

Ice car – Used for thermal mapping

March 15th 2007

Thermal mapping, Halskov - Ringsted

Left and right lane

March 15th 2007

Mean thermal mapping profile

March 15th 2007

GPS equipped spreaders

• GPS has opened the opportunity for automatic control of width and asymmetry of the spreading pattern

• With reliable weather forecasts for segments of the route the automation can be taken a step further – to automatically vary the amount of salt applied along the route

March 15th 2007

New equipment for spreaders

• The price of infrared sensors determining the temperature of the road surface has come down

• Together with GPS this makes it economically possible to get thermal mapping data from spreaders in operation

• Provide data for validation

March 15th 2007

Infra red sensor mounted on spreader

March 15th 2007

Infra red sensor mounted on spreader

March 15th 2007

Test route – 2005 / 2006 season

Route VA 4 - Ribe County

March 15th 2007

Road segment forecast

• Based on PF ”near” the route forecasts for 2 km segments are obtained by interpolation

• Note this method does not use information from the infra red sensors!

March 15th 2007

End user presentation

March 15th 2007

Forecast quality

• Making a forecast is easy– But what is the quality ?

• Here we will look at quality through two measures– Mean Deviation (MD)– Mean Absolute Deviation (MAD)

March 15th 2007

Forecast quality NWP

• NWP MAD – PF for road stations

MAD: Road temperature February 2006 (about 27.000 forecasts)

1.22 1.17 1.19 1.19 1.19

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1 2 3 4 5

NWP

March 15th 2007

Forecast quality – Present system

• NWP versus RCM MAD – PF for road stations

MAD: Road temperature February 2006 (about 27.000 forecasts)

1,221,17 1,19 1,19 1,19

0,28

0,440,54

0,650,74

0,0

0,2

0,4

0,6

0,8

1,0

1,2

1,4

1 2 3 4 5

NWP RCM

March 15th 2007

Forecast quality – Present system

• The importance of road stations

MAD: Road temperature February 2006 (about 160.000 forecasts)

1.16 1.14 1.12 1.1 1.08

0.29

0.470.59

0.670.73

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1 2 3 4 5

RCM: no Obs RCM

March 15th 2007

RSF-Potential - Hypothetical route

March 15th 2007

“RSF” potential

MAD: Road temperature February 2006 (about 160.000 forecasts)

0,690,78 0,82

0,910,97

0,38

0,58

0,710,81

0,89

0,0

0,2

0,4

0,6

0,8

1,0

1,2

1,4

1 2 3 4 5

RSF RCM

March 15th 2007

Route VA 4 – thirty 2 km segments

March 15th 2007

Measurements from spreaders

• 2005 – 2006 season• 102 operations available (duration

from minutes to about 4 hours)• 90.459 measurements in all• Time averaging (1 min.) and allocation

to the corresponding 2 km road segment reduces the amount available for the evaluation to 5.844 measurements

March 15th 2007

Amount of observations by segment

March 15th 2007

Comparison of observations

Infra red sensor versus road station

Starup

MD -0.11 degree

MAD 0.51 degree

March 15th 2007

RSF (3 hour) versus observation I

March 15th 2007

RSF (3 hour) versus observation II

March 15th 2007

RSF (3 hour) versus observations MD

March 15th 2007

RSF (3 hour) versus observation MAD

March 15th 2007

The future

• The near future (now)– Integration of infra red sensor data in the RCM /

RSF forecasting– Increased horizontal resolution in the RCM– Include more test routes

• The not so distant future– Use of RSF for applying variable amounts of

salt along routes

• And then – eventually– Integration of RSF in spreaders for automatic

controlling of the salt amount used

March 15th 2007

Conclusion

• The technology for developing and evaluate RSF is available

• This pilot study shows that the quality of RSF is nearly comparable to the one known from state of the art PF– Road stations are essential for a good

quality of forecasts (both PF and RSF)

March 15th 2007

The future is very near (you)!

Thank you for your attention!!!