Fig. 3

Relative risk increase (RRI) of crash probabilities in situations with precipitation and negative temperature (\({\text {Tmp}}=-3\) \(^\circ\)C and \({\text {Prc}}=1\) mm/h) compared to situations without precipitation and positive temperatures (\({\text {Tmp}}=+3\) \(^\circ\)C and \({\text {Prc}}=0\) mm/h). Significant changes (i. e. more than 95 of 100 models fitted with randomly drawn training data show the same direction of change) are indicated with an asterisk