Railway connectivity only upto Rishikesh. After that you have to avail of either private taxis or buses plying on the route. You will also find shared jeeps or similar vehicles from Haridwar or Rishikesh. Get sensible and hire a personal taxi. Do never go for small cars. It is a rough terrain. Settle for either a SUV or MUV like Innova, Tavera, Qualis, Scorpio etc. See if you can get hold of a Hummer.