Construction of the approaches started in September 1958. Work on the lower level itself started on June 2, 1959, but work was briefly halted later that year because of a lack of steel. By February 1960, construction was underway on the lower level; the supporting steelwork for the future deck had been completed, and the sections for the lower deck were being installed. The George Washington Bridge's lower deck would comprise 75 steel slabs; each slab weighed 220 tons and measured wide by feet long, with a thickness of . The construction of the slabs proceeded from either side of the bridge. The right-of-way for the George Washington Bridge Expressway had been almost entirely cleared except for the ventilation buildings for the 178th-179th Street Tunnels. The segments of the lower deck had been laid completely by September 1960, at which point workers started pouring the concrete for the deck's roadway, a process that took five weeks. The layer of concrete measured thick. Finally, the deck was paved over with a layer of asphalt.