You could do a masonry wall
Depending on your budget and size of the wall you could use 6x6 treated timbers, or retaining wall block or have a poured concrete wall. If you are attempting removal yourself please be careful with those railroad ties and use some heavy duty gloves. Beware of spikes, rebar and splinters jabbing into you with the creosote coating.
I built a wall project last year using the 6" landscape timbers.
many landscape companies in GA survived the recession by replacing failed railroad tie walls. They typically fail at 20 years.
We've recently been adding in retaining wall blocks directly in front of failing railroad ties at our house. We remove the top level and backfill with pea-gravel. It's prevents us from having to remove all of the railroad ties.
wow Nicole you have beautifully transformed the landscape. Well done!
What a difference!!! Beautiful!
I think if I was going to put work into this project, I would pour a footer and place concrete wall building landscape blocks there. This is good if you are going to be there a while and excellent for resale. People can look at RR Ties and tell they need replacing and a patch job takes value from your home. If it is not a large wall and you have the cash, call someone to do it...but make sure they lay a proper foundation!