Thanks all! I have made my decision on this bus. I don't need to be 100 percent sure as I feel relatively certain that with appearing to be a normal tourist, stepping on the railing and jumping quickly with careful pacing, ensuring no one is around and jumping to land flat so that my back hurts with maximum surface area and head snaps into the water shortly after with momentum built up will cause both the severe internal damage and secondary unconsciousness / instant concussion that I'll die very quickly. I have a PhD in chemistry (literally) and though I can calculate the mg/kg and even get any poison I want, I know my own psyche and I'm far more determined to jump and not be able to claw back to the bridge that to start taking a drug or poison and then try to somehow save myself. I just know me.
I bought my bus (plane) ticket! I can't tell you how empowered and totally strong this makes me feel. It's secret, I don't have to worry about being berated afterwards, I won't have to argue with anyone or get out down and beat up. I can take this action and every consequence is mine and I can't be torn to shreds of a human afterwards. In these moments of this trip I actually won't have to feel afraid of being screamed at or berated and that fills me with the most profound joy!