The barges have towers at their fronts that convert to long, drop-down bridges, so the vessels can connect to each other. If the first barge in a line of them touches the land, they can form a pier standing on the seabed and extending 800 metres or more to deeper water. Chinese soldiers, equipment and supplies could be offloaded from big ships that need that water depth, and the invasion force would have less need for ports.
Or so the theory goes. But analysts in Taiwan say that, for the moment, the barges are not helping China much in achieving a capability to invade the island.
