Bundesanstalt für Straßenwesen

VIKING Monitoring-WorkshopHamburg 2007

Use of Data on Road and Weather Conditions for slippery warning

Ralf Meschede/Horst Badelt

15. März 2007Ralf Meschede/Horst Badelt Folie Nr. 2

Ice warning systems for the winter maintenance:

Objective: preventive winter service call-outs

Time: at least 90 minutes before the road becomes icy

Place: where icy roads occurred frequent and particularly earlier than in the neighbouring network

15. März 2007Ralf Meschede/Horst Badelt Folie Nr. 3

Ice-warning systems collect data from only one single tiny point of a road or a road network.

The warnings are actually limited to black ice or white frost without additional meteorological information.

The suppliers of such systems don’t disclose the algorithms for generating an ice-warning from the measured data.

Ice-warning systems suffer from the same old weaknesses:

15. März 2007Ralf Meschede/Horst Badelt Folie Nr. 4

The model generates four reports:

No risk of icy roadway

Icy roadway possible if the trend changes

Icy roadway soon possible owing to the trend

Icy roadway immediately possible

15. März 2007Ralf Meschede/Horst Badelt Folie Nr. 5

Roadway surface temperature

>5°C 5°C

Air temperature

2°C > 2°C

No risk of skid-hazard conditions

Slippery snow or freezing rain possible in the case of

precipitation

Roadway surface temperature

> 2°C 2°C

Roadway surface temperature in 90 minutes linear trend extrapolation from values of the last 10 minutes

2°C > 2°C No values available Trend calculation not possible

Roadway condition

dry moist or wet

Difference between roadway surface temperature and dew point temperature in 90 minutes linear trend extrapolation from values of

the last 10 minutes

> 0 K 0 K

Slippery snow or freezing rain possible in the case of precipitation and roadway

frost possible

Black ice possible

Roadway surface temperature

3°C > 3°C

Roadway condition

moist or wet

dry

Risk of skid hazard possible if weather

changes

Roadway condition

dry moist or wet Skid-hazard conditions present

Black ice possible immediately

Difference between roadway surface temperature and dew point

temperature

> 0 K 0 K

Slippery snow or freezing rain possible immediately in the case of precipitation and roadway frost possible immediatelyDifference between roadway

surface temperature and dew point temperature

> 2 K 2 K

Slippery snow or freezing rain possible immediately in the case of

precipitation

Difference between roadway surface temperature and dew point temperature in 90 minutes linear trend extrapolation from values of the last 10 minutes

> 0 K 0 K

Slippery snow or freezing rain possible immediately in the case of precipitation

and roadway frost possible

Bundesanstalt für Straßenwesen

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