Ben,

Take some earplugs with you on the train. You might not be able to eliminate a bump but you can eliminate the edginess to noise...the more symptom overload you can keep at a manageable level the better your system can tolerate that which you can't change, keep the glass half full sort of.

Pay attention to your thoughts that accompany whatever makes you think possible damage can occur. If your thoughts go directly to a worst case outcome, I'll never get over this bump, the need to bolt from the situation, racing thoughts etc you can chalk that up to anxiety. Anxiety is a very tricky foe but once identified can be slowed down with accurate assessments/identifiable facts from past similar incidents. Deal in fact.

Bud