Low-cost retaining wall
However, 1.60 may seem cheap until you need several hundred of them.
Railway ties are very heavy, hard to drill through and full of creasote and/or arsenic which can be hazardous to your health ( if you chew on them I suppose ).
Usually when you install them, after prepping the earth, you angle them back as you raise the wall. It is best to use threaded rod or similar when locking them together. Also, there are usually "deadmen" pieces installed at 90 degrees to the wall ( not sure of the right term or postion ).
There are lots of books out there (especially landscaping books) which explain the various methods of building retaining walls.