Anyone have instructions of how to replace rotted railroad ties with poured concrete or retaining blocks.
TIA

This is far more complicated than you might have thought. A block wall or even a concrete wall will slowly lean over unless you can make deep attachments into the earth pushing on it. This is especially true if it freezes where you are living. Chances are good that you will run into some deep attachments with the ties when you try to remove them.

I agree with ballengerb1.

The following sites may be of use to you. I hope that they are:

Building a Block Retaining Wall

Home Improvement Article- Building a Retaining Wall - AOL Real Estate