Life is too short to use any railroad ties for fencing, or any wood posts for that matter.  I built a lot of fence in 2000 with them and they are all being replaced.  Waste of time and money.  Cedar or hedge lasts longer.

Spend $21.00 on a 9ft piece of 2 7/8 used pipe for a post, and your grandchildren will thank you.

Buy a little Miller Bobcat portable welder to weld your braces together, and you also have a generator when the power goes out.  Amazing how quickly you can build a better fence.

Buy a Danuser post driver to drive the pipe in the ground - no more tamping, no more post hole digging.  Dont use concrete, dont weld a cap on the top.  Just keep driving posts.