Guild Wars 2

An arrow cart and a catapult, each about an hour old, simply disappeared from a tower. There was no enemy engagement; they had never been fired in action.

The catapult disappeared at about 11:00 GMT today (7:00 EDT local time). In was on the wall of the Greenbriar tower, in the Everdon Terrace borderland.

While I was gathering info to write up this note, an arrow cart on the wall similarly disappeared.

I was unhappy to see this, because my charr had hauled supplies to build this equipment from nearby depots, so as not to slow the progress of structural improvements to the tower.

This seems like a bug; I can understand if siege is destroyed in combat, but there had been no combat.

Is this a feature rather than a bug — does siege equipment have a really short lifte-span when it is not used?

After XX time they disapear, not sure if this is one hour

So I guess this is not a bug. And, I have to say, it makes adding siege to an un-attacked tower a lot less fun.

EDIT
According to the GW2 wiki (http://wiki.guildwars2.com/wiki/Siege_weapon),

Siege weapons have a despawn timer of 30 minutes. If a player uses a siege weapon, the timer is reset. When the timer reaches 0, the siege weapon is removed from the game.

you just need to interact with them to reset the timer.