The ships themselves are giant cylinders. They barely have enough power to get moving. Fuel enough to get to speed, and fuel enough to Slow down.
The Exodus project undertaken by Starfleet is emptying the ships as quickly as possible using El Nanth Starships' Behemoth Class Heavy Container ships. The ten vessels equipped with steerage class accommodations (the trip is short) shuttle back and forth between the Exodus Fleet and Newhome, even with the size of the shuttles it will take a decade to empty the vessels.
Plans are being examined to preserve one of the giants, somehow. There is a lively debate as to whether to mine the empty ships for materials, the last gift of the old world.