How can you reduce snoring in your sleep on public transportation?

Keep head forward: Tilting the head back causes the airway to become narrow, and the palate then relaxes during sleep and begins vibrating in the throat, making the sound of snoring. Keeping the head upright or bent forward may help. The most appropriate help for snoring is to be evaluated thoroughly by a sleep specialist, to determine if there is a sleep disorder, and to identify the source of the snoring.

Oral Appliance: If this is a major concern, i would consider seeing a dentist who makes custom sleep appliances and possibly construct one that is not as noticeable or cumbersome so you can wear it on the public transportation. Interesting question.