The best think is not carried on person, but in somebody's brains. Most importent thing is to take cover when your too close and in the way. In the event of chemicals spills, check the direction of the wind. Do NOT stay in the downwind area. Equipment are just tools, they can be of great help, but knowing what to do is better.

Getting to know the risks will also help you in preparing for such an event. Is the track straight? is it a single or double track? What kind of chemicals are carried? Do you know how to read the UN and GEVI numbers on the hazardous materials signs? etc.