 Unlike the other two motorway plans approved by the Croatian government, Zagreb–Split and Zagreb–Rijeka, which were cancelled after the suppression of the Croatian Spring, the Zagreb–Belgrade motorway plans remained in place and an expansion of the existing motorway into a dual-carriageway, six-lane motorway with exclusively grade-separated intersections proceeded.The additional carriageway was to be built south of the existing road, which was in turn to be widened to accommodate two traffic lanes and an emergency lane.Construction of the A3 motorway in Croatia in its present form started in 1977, when the first six-lane (including emergency lanes) sections were constructed as a part of the Zagreb bypass.