Putting your neck on the track is pretty much the surefire way but it's frowned upon because it's gruesome and the driver has to live with knowing in some ways that he was the one who ran you over. I guess a slightly more considerate version is to get it done somehow without anyone realising you were ever there and your body not being seen for sometime (during night or heavily obscured?), maybe even eaten by wild animals, which brings it more in line with something such as jumping from height or crashing your car.