I have no idea, why, after assembling, is not possible to dissasemble AGMu, to transport it again.
Whole idea of "dissasembled" category is unnecessary and misleading for new users,
AGMu's and other small trackbuilders should be just capable to be always transported by truck -
just use dssasembled model.

About game balance: these draisines are so slow and with low capacity, that their only use is to make initial line or add/remove some small part of tracks. Player should be able to transport it for his convenience.