Now then, let’s talk about the expedition. Although this is only the second expedition out of the forest using the skeleton carriages, some routes had already been established. This included the shortest route to get out of the forest from the base.
When the skeleton carriages advanced on difficult to traverse terrain such as the underbrush and overgrown forest/ mountain paths, they are able to change their shape according to the route, allowing them to more easily traverse the terrain.
Given the fact they're technically undead, they’ve also had a special coating applied that grants them a resistance to sunlight.