Section 4. National highways to vest in the Union

4. National highways to vest in the Union.— All national highways shall vest in the Union, and for the purposes of this Act "highways" include-- (i) all lands appurtenant thereto, whether demarcated or not; (ii) all bridges, culverts, tunnels, causeways, carriageways and other structures constructed on or across such highways; and (iii) all fences, trees, posts and boundary, furlong and milestones of such highways or any land appurtenant to such highways.