A while ago I did a lot of research on several suicide methods and I concluded that jumping from height is not a good idea. But if you jump you need a minimum of 4 seconds of free fall and land on concrete/asphalt.
Another point I'd like to make is that 4 seconds of free fall is a very long time. It will give plenty of time to regret that you jumped and you will feel strong fear, and fear is also a form of pain.
Personally I have concluded to ctb by partial suspension hanging.