During the widening works of phase 1 of expressway M0, south section between motorways M1 and M6, the expressway was reconstructed from two double-lanes into two triple-lanes + emergency lane motorway in a length of 6.56 km between chainages 2+840-9+400 km. This entailed 60 000 m3 of topsoil removal, 88 000 m3 of embankment construction and 310 000 m3 of cut. The 26 400 m3 material of the concrete pavement is two-layered, high load bearing concrete, which is (for the first time in Hungary) made of two concretes with different types. The surface is exposed aggregate type which also differs from the technology applied so far. The new carriageway was constructed on the left side (considering the order of chainage) by doubling the crown width. The section includes 3 interchanges, the branches of which are also reconstructed. Our task included the construction 7 bridges, the most important of which is 250 m long. We also construct 3 retaining walls with the use of Gabion baskets and 27 000 m3 crushed stone. Most of the works affected densely populated areas, where we put great emphasis on compliance with noise protection and air pollution tolerance levels by continuous environmental action plans, inspections and assessment.