is an autobahn in southern Germany that runs 497 km (309 mi) from the Luxembourg A13 motorway at Schengen via Neunkirchen, Pirmasens, Karlsruhe, Pforzheim, Stuttgart, Ulm, Augsburg and Munich to the Austrian West Autobahn near Salzburg.
The A8 is a significant east–west transit route. Its construction began in March 1934 during Nazi rule as a Reichsautobahn, the section between Karlsruhe and Salzburg having been completed by the time road works were discontinued in World War II. Although most parts have been modernized and extended since, significant sections remain in their original configuration from the 1930s - 2+2 lanes, no emergency lanes, steep hills and tight curves. In combination with today's traffic this makes the A8 one of the most crowded and dangerous autobahns in Germany. Especially in winter the slopes of the Black Forest, the Swabian Alb near Aichelberg, as well as the Irschenberg become bottlenecks when heavy trucks traverse the A8 uphill.
As of 2016, the following sections have three lanes in each direction of travel: Karlsruhe - Pforzheim-North, Pforzheim-South - Stuttgart - Mühlhausen, AK Ulm/Elchingen - Augsburg - Munich-Eschenried, and AK Munich-South - AD Inntal. Other sections in Saarland, Rhineland-Palatinate and Munich have two lanes in each direction of travel and follow current Autobahn standards.
As of 2016, the following sections have sections which are either incomplete or do not comply with modern Autobahn standards: near Merzig (under construction), AK Neunkirchen - Zweibrücken (no emergency lanes yet), Enz crossing near Pforzheim (modernizing planned), Alb crossing Mühlhausen - Hohenstadt (planned), Hohenstadt - Ulm-West (under construction), Ulm-West - AK Ulm/Elchingen (planned) and AD Inntal - Salzburg (planned). At least, complete section Karlsruhe - Salzburg will be extended to 3 + 3 lanes.
Plans for the section between Pirmasens and Karlsruhe were abandoned in the 1980s. Instead of this the B10 from Pirmasens to Landau is being widened. This is not completed as of early 2021.