Reliability of C-ADAS and the importance of the acceleration function for cycling safety

Driving characteristics of bicyclists and motorists differ significantly in critical, uncritical and unaffected situations in road traffic. When bicyclists cross the path of right-turning motorists, bicyclists seem to mitigate conflicts that can develop into crashes, while motorists seem to avoid non-critical but close interactions that can develop into conflicts. This is one of the key findings of the evaluation of a recently developed and successfully tested cooperative driver assistance system (C-ADAS) that warns right-turning motorists of potential collisions. The warning is given by a special traffic light, which we called ‘amber light’, lighting up only in dangerous situations. Whether a situation becomes dangerous or not is determined by a decision tree, fed by the measured kinematics and specific surrogate measures of safety of the interacting road users. Most notably, the results demonstrate that criticality can be rated by measuring anticipation (or surprise) by computing the cross-power spectrum and applying entropy metric on the acceleration functions of the road users. However, one of the outcomes is that the time for the road users to perceive the amber light state might be too low to react properly. These findings can be used to improve the performance of such a C-ADAS.