is an autobahn in Germany. It runs from Heiligenhafen to Saarbrücken, a distance of 730 km (456 miles), but is incomplete between Cologne and Trier. continues north from Heiligenhafen to Puttgarden, at the end of the island of Fehmarn, with a ferry to Rødby, Denmark.
thumb|left|200px|The BAB-1 at Wuppertal
The part north of Hamburg is part of the Vogelfluglinie (Flying bird line) and may be connected via a bridge to Denmark and Copenhagen (see below). The term Hansalinie (Hansa line) refers to the part from Lübeck (north of Hamburg, thus overlapping the Vogelfluglinie) south to the Ruhr Area (near Dortmund).
The Autobahn has either two or three lanes each way. Congestion is possible around Hamburg, during holiday periods between Hamburg and Münster, between Dortmund and Köln because of roadworks and especially around Köln. During the rush hour the section around Köln is very busy (AADT 100,000-120,000), especially the southbound carriageway suffers from severe congestion as it is only 2 lanes between exits 102 and 104. For the World Cup a temporary third lane has been added between exits 102 and 103. Due to the narrow 3 lanes the speed limit there is only 80 km/h (50 mph).

History

The A 1 and were first planned in the 1920s. The interchange between the two (Kamener Kreuz) was one of the first cloverleaf interchanges in Germany, opened in 1937. A 1 around the southern side of Hamburg was opened in 1962, including a bridge across the Elbe. This bypass connected the existing Autobahn segments on both sides of the city.

Plans

The A 1 is still being extended north, with an extension to Heiligenhafen-North planned for opening in 2011. A treaty has been entered between Germany and Denmark about the construction of the bridge across the Fehmarnbelt to Denmark, to be finished in 2018. In the treaty Germany also undertakes to build the A 1 to Puttgarden, with the exception of the Fehmarn Sound bridge, which will remain.

The Vulkaneifel interchange with the , just south of the gap south of Cologne, was built in the 1970s. Plans have been made to complete the missing link. Until then, through traffic between the two sections uses and and various regional roads.