If you’re going to hand spike your ties, (a) pre-drill the holes, and (b) if possible, use spikes that are longer than the ties are thick.
Pre-drilling’s a ruddy pain in the butt in the beginning, but it greatly reduces the spikes being pushed out by the ties as they swell with moisture. (It also makes pushing the spikes in a whole lot easier.) Making the spikes longer than the ties almost guarantees they’ll stay in place. Spikes are pushed out by the wood swelling against the pointed end of the spike. If that’s below the tie, the wood will swell around the shaft of the spike, but there’s no sloped surface for it to push against, so they stay in place.
If you’re really adventurous and want a 100% foolproof way to keep spikes from popping out, use staples. (Not commercial ones, but ones you bend from wire.) Dad and I used 1/16" aluminum welding rod when we first did our track in 1980. (He paid my sister and I a penny a staple to bend ‘em. You can bend a lot of staples during Saturday morning cartoons.) You’re going to need a good guide to make sure the holes are drilled such that the rail is kept in gauge, but that’s easy to build. I’ve got a 4’ long bridge deck I need to build this winter, and will probably be resurrecting that method.
As for the wood, I can get “redwood” out here in Colorado, though it’s nothing like the old-growth redwood dad got for his ties 35 years ago. Look through the pieces for a really tight grain. (And keep your ears open for neighbors tearing down old decks or throwing away old picnic tables and lawn chairs.)
Later,
K