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.
Reichsautobahn
A speed limit of had been imposed in May 1939 to save fuel; during the war this was lowered to , and private cars were allowed on the autobahns only in exceptional circumstances. (By 1943, traffic was so low that bicycles were permitted.) Other than official traffic, which picked up toward the end of the war, the autobahns were used for some deliveries of tank parts and finished U-boats and motor-boats, and as runways for fighter planes, including in one case for final assembly and test flights of Messerschmitt Me 262s after the factories in Augsburg and Regensburg were bombed. As the war progressed, vehicles were at risk of strafing by Allied aircraft. However, most damage to the autobahns was caused late in the war by the retreating Wehrmacht, which blew up numerous bridges in an effort to slow the Allied advance; on March 19, 1945, Hitler ordered the destruction in retreat of "all military, transportation, news, industrial, and provisions facilities".