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.
Autobahn
The current autobahn numbering system in use in Germany was introduced in 1974. All autobahns are named by using the capital letter A, which simply stands for "Autobahn" followed by a blank and a number (for example A 8). The main autobahns going all across Germany have a single digit number. Shorter autobahns that are of regional importance (e.g. connecting two major cities or regions within Germany) have a double digit number (e.g. A 24, connecting Berlin and Hamburg). The system is as follows:There are also some very short autobahns built just for local traffic (e.g. ring roads or the A 555 from Cologne to Bonn) that usually have three digits for numbering. The first digit used is similar to the system above, depending on the region.