A6 highway (Lithuania)
The speed limit for most of the length of A6 is default 90 km/h (outside city limits). The section from Kaunas to Jonava has been upgraded to a dual carriageway with at-grade junctions and traffic-lights. The remaining sections are roads with one lane in each direction, leading through towns like Ukmergė, Utena and Zarasai.
A6 (Croatia)
As the A6 motorway route runs through mountainous terrain of Gorski Kotar, it comprises a substantial number of major structures—bridges, viaducts, tunnels, underpasses, flyovers, and culverts. Out of the total length of the Rijeka–Zagreb motorway of , are situated within such structures. The northern part of the Rijeka–Zagreb motorway, designated as the A1 motorway, comprising between Zagreb and Karlovac, contains only of such structures as the section is situated in a plain. The between Karlovac and Bosiljevo 2 interchanges, contains as much as of the structures. Thus the A6 motorway has , or 21% of the route, located within such structures. The Rijeka–Zagreb motorway has a total of 24 viaducts, 13 tunnels, 5 bridges, 45 underpasses, and 26 flyovers. All of the bridges, viaducts, and tunnels on the A6 motorway have at least two driving lanes in each direction.
The longest tunnel on the A6 motorway route is the Tuhobić Tunnel, located on the Oštrovica–Vrata section. The tunnel was initially opened as a single-tube tunnel in 1996. The second tunnel tube was excavated in August 2007 and opened to traffic in 2008. The European Tunnel Assessment Programme (EuroTAP), a tunnel safety assessment programme supported by the European Commission, coordinated by FIA and led by the German motoring club ADAC, tested Tuhobić Tunnel twice—once in 2004, when it achieved poor results, and again in 2009 after implementation of EuroTAP safety recommendations. The 2009 test ranked the tunnel as the second safest in Europe. An unusual feature associated with the A6 tunnels is the close proximity of the Javorova Kosa and the Podvugleš tunnels—they are separated by less than of road. In order to prevent abrupt changes in road conditions caused by the weather, the distance between the tunnels is covered by translucent roofing. The tunnels are located on the Vrbovsko–Ravna Gora section. Other significant tunnels on the A6 motorway are the Veliki Gložac and Vrata tunnels. While the former, as with all the other tunnels mentioned, is significant due to its length, the latter is notable for the large cavern encountered during its excavation.