I wanted to know will traps and landmines disappear after a duration of time if they are not tripped? I also wanted to know will there be a limited on how many landmines you place or can carry at one time?

That's a very good question. If they don't expire then you can have big mine fields around your settlements to help ward off raiders. Just make sure they aren't in the path of traders.

Does not seem like the best way to have traders keep coming...

Oops, I left out the n't

They didn't in FONV. I'd often leave some at Legion campsites in the southeastern areas after I killed the sporting goods savages. I would know that a respawn happened at a campsite because I'd hear the mines all pop in the distance. Just toss a single mine on each bedspread and leave.

I hope they do not disappear after a certain time. I'm looking forward to more explodey hijinx and boomtastic shenanigans!

Consider both 3 and NV could keep track of mines pretty much indefinitely, I have a hard time thinking it would change for 4.

The game actually keeps track of landmines? That really surprises me. It would have been great if I left some bottlecap mines in Project Purity so Autumn would immediately bite the dust!

Yep. Distant explosions in certain areas for me in FONV often meant some more Legion denarii and thus more fodder for the Blackjack table, as detailed above.

The previous games saved the location of every item you or someone else dropped (also applies to ash piles). Which why the weapons dropped by enemies cause such issues in Skyrim. Also any clutter that moves from it's original position is remembered by the game forever, or untill you pick it up.

Of course that may change in the new game, but seeing how it is the same engine, i wouldn't bet on it.

So if you go Shouting in a cluttered house you just increased your save file size by 1 MB

Perhaps if multiple mines were conformed to one one of a set several patterns (whichever is closest), the game could save markers for 5 (or 8/12/16?) at a time) where there are minefields?

I hope that mines do not disappear. It was once my hope that improved world-AI [not NPC combat AI], could allow for things like the player forgetting a live mine they set, and later a town resident might step on it, and spawn a quest in the sheriff's office about it. Or that the next time they return to he town, there would be a funeral in progress.

Creation Engine is pretty good at keeping track of those things, but I'd imagine if you put down thousands of mines in one area it would start to adversely affect performance.

But it would be essentially the same as dropping a bunch of junk in an area to save on carry weight. Except the junk explodes in this case.

They could pull a trick with mines though. One mine would detonate any nearby; so they could use sets of mines, and detonate the entire set.

Not too adversely with the vast increases in memory though, we hope!

*sets path to acquire 'light step' perk

Yeah, it should help that the baseline no longer has 512MB of RAM

It does sort of put into perspective just how remarkable a feat it was to get some of the more expansive games from later on in that generation to actually run fairly stable on those systems.