If you do it in a rural area they probably won't bother to clean up the mess as thoroughly as they would have to do in a city.
It's likely to be fatal if you put your neck on the track, and fatal almost instantaneously, so you probably wouldn't have time to feel anything.
With this method there is always the issue of the trauma you could cause for the driver. If you do it at night, so there is no way the driver could have seen you, that might lessen the effect on the driver, as they will know they couldn't have done anything. If it's at night with a fast, heavy train, the driver might not even know they had hit someone. You could leave a note with your body saying that you know the driver was not at fault in any way, You could even leave a note addressed to the driver, apologising for the inconvenience. They would probably help them.