Precursor technology utilised by the Flood, since the Flood are distorted forms of the Precursors. Star Roads, along with all other Precursor technology, are immortal constructs which can ONLY be destroyed by Halos because they cancel out neural physics - the means through which Precursors build their shit. Star Roads could move entire stars across galaxies, connect entire solar systems together, and wipe out anything with ease - the Greater Ark and Omega Halo are both shredded to pieces in a matter of seconds by Star Roads in the penultimate battle of the Forerunner-Flood war. Also, Star Roads distort time, space and matter around them. They are able to shut off access to slipspace, and can send whole fleets into alternate dimensions.