The motorway passes the Mačkovec valley nearby Novo mesto city with two parallel 165m long semi-integral spanning structures. The viaducts are continuous over six spans with a prestressed RC slab of superstructure. The Mačkovec viaducts, characterised by sleek superstructures and uniform elegant funnel shaped middle supports, subtly span the valley under Trška gora hills.
Unified steel false-works were fixed underneath 2 spans of the viaducts superstructures and then moved to the following spans in the next building stages.