evidence: Acts 2017, 85th Leg., R.S., Ch. 19 (H.B. 1791), Sec. 1, eff. May 18, 2017. [...] (2) a crossing gate is lowered, or a flagger warns of the approach or passage of a train or other on-track equipment; [...] (2) shall listen and look in both directions along the track for an approaching train or other on-track equipment and for signals indicating the approach of a train or other on-track equipment; and (3) may not proceed until the operator determines that the course is clear.