At its southern end, the A1 freeway transitions from the B1 in Windhoek's Hochland Park district, at an interchange with the B6 to the city centre, Hosea Kutako International Airport and Gobabis, and the C28 road to Swakopmund.

In the early 2010s, a project commenced to upgrade the B1 between the northern end of the Western Bypass and Okahandja, to be constructed in four sections.

Construction commenced in January 2014 and was officially opened by the Roads Authority Namibia in April 2017.

Phase 4A continued upgrading 37 kilometres (23 mi) of the B1 to the A1 from the Dobra River to Osona, and was completed in September 2019.

Phase 4B entails the construction of a new route from Osona, bypassing Okahandja, and terminating at the existing junction of the B1 with the B2 to Swakopmund; it was expected to open in 2022.