Counterfactual safety benefits quantification method for en-route driving behavior interventions

•Contributed to safety benefits quantification for driving behavior interventions.•Proposed a counterfactual driving behavior structural causality model based on the Theory of Planned Behavior (TPB)•Utilized Extreme Value Theory (EVT) to connect speed maintenance behavior with crash occurrence.•Established a closed-loop evaluation and optimization framework for various behavior interventions.•Observed a speed reduction of 6.30 km/h and a safety benefit of 40%, due to deceleration safety broadcasting.