The Autobahn (IPA: [ˈaʊtoˌbaːn] ; German pl. Autobahnen, pronounced [ˈaʊ̯toˌbaːnən] ) is the federal controlled-access highway system in Germany. The official term is Bundesautobahn (abbreviated BAB), which translates as 'federal motorway'. The literal meaning of the word Bundesautobahn is 'Federal Auto(mobile) Track'. Much of the system has no speed limit for some classes of vehicles. However, limits are posted and enforced in areas that are urbanised, substandard, accident-prone, or under construction.
https://en.wikipedia.org/wiki/Autobahn