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.
Speed limits in the United States by jurisdiction
Interstate Highways in Illinois are usually posted with both minimum and maximum speed limits, except in some urban areas, particularly Chicago. The standard speed limit is 70 mph for rural freeways, a 45 mph minimum speed limit, 65 mph for other 4 lane divided highways, and 55 mph for all other highways. Urban freeway/interstate speed limits can range from as low as 45 mph in downtown Chicago, where all the major interstates merge, to as high as 65 mph in the outer portions of the Chicago metro and East St. Louis metro areas, and in some smaller cities. Some interstates in small cities (e.g. I-55/74 through Bloomington-Normal, I-39/90 through the Rockford area, I-57 through Champaign-Urbana) do not have reduced speed limits, and a stretch of I-355 between I-55 and I-80 in the southwest suburbs of Chicago is signed at 70 mph. Most freeways and interstates in Cook, DuPage, and Lake Counties, and some interstates and freeways in Will County maintain a 55-60 mph speed limit. Due to the high population density, the only freeways in Cook County that exceed a speed limit of 60 mph are I-57 at the southern edge of the county, part of I-80 between Central Ave and Harlem Ave, I-90 west of Mt. Prospect Rd., and the southern segment of I-355, which passes through Cook County briefly before crossing into Will County to both the north and south. As of January 2010, a reduced speed limit posted in a construction zone must be obeyed 24 hours a day, regardless of whether workers are present.