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Operational OpenRoad verificationPresented by Robert Coulson

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Operational OpenRoad verification

• Introduction

• Verification Methodology

• Temporal Verification

• Economic skill in forecasts

• Questions and Answers

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Operational OpenRoad Verification

• Site specific verification.

• > 300 sites are verified.

• Observations from roadside sensors are used as TRUTH against which the forecasts are verified.

• A large sample size of matching forecast/observation pairs are collected over individual months and for the whole winter season for each site to ensure validation is reliable

Road travel on a timely basis is essential for economies globally in the modern world.

Cold winter climates impact on safety with dangerous travelling conditions causing delays if not acted upon.

Therefore, the prediction and prevention of ice formation is imperative to mitigate against these.

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Verification Methodology• Categorical verification of road surface frosts

The critical event is when the road surface temperature is less or equal to zero degrees Celsius due to formation of ice.

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Communication to end users

2x2 table Observed Frost No Observed Frost

No Forecast Frost

Miss (c) Correct Rejection (d)

Forecast Frost Hit (a) False Alarm (b)

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Temporal Verification

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N by M contingency tableThe road surface sensors enable the actual state of the road surface to be deduced, and this enables a time-series profile to be verified against the forecast road state.

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Economic skill values for forecasts

•Relative economic valueRelative value(V) ~ Cost-loss ratio Road Surface Temperature Oct-April 2011/12 (UK)

0

0.2

0.4

0.6

0.8

1

0.0 0.1 0.3 0.4 0.5 0.6 0.8 0.9

Cost-loss ratio

V

Value Added Forecast

Forecast

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Economic skill values for forecasts

Marginal Night analysis

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Questions and answers