Fig. 5

Relative risk increase (RRI) of crash probabilities in situations with low sun elevation angle and cloud free conditions (\({\text {Elv}}=20^\circ\) and \({\text {Cld}}=0\)%) compared to situations with low sun elevation angle and clouded conditions (\({\text {Elv}}=20^\circ\) and \({\text {Cld}}=100\)%). 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