Bundesstraße
One distinguishing characteristic between German "Bundesstraßen" and "Autobahnen" is that there usually is a general 100 km/h (62 mph) speed limit on federal highways out of built-up areas, as opposed to the merely advisory speed limit ("Richtgeschwindigkeit") of 130 km/h (83 mph) in unmarked sections of the autobahns. However, a number of "Bundesstraßen" have been extended as expressways (dual carriageways) (colloquially called "Yellow Autobahns"). Many of these have speed limits of usually 100–120 km/h, others have only an advisory speed limit like autobahns. Most sections of the federal highways are only single carriageway with one lane for each direction and no hard shoulder pull-out area.
Bundesautobahn 24
On that road, there is a 150 km (93 mi) long section that has no speed limit at all (only a recommended speed of 130 km/h), which means that about 65% of that Autobahn can be driven at very high speed.
Planning for the autobahn began as far back as the 1930s; before World War II numerous bridges and sections of roadside shoulder were built between Hamburg and Berlin. The German divide, however, put a hold on further work and it was not until 1978 that construction was resumed, carried out by a GDR work force and paid for by West Germany. In 1982 the A 24 could finally be opened. Most pre-war bridges could not be used, however, and were replaced by new structures.