In addition to being the main road between Reykjavík and Keflavík Airport, it serves as a major traffic artery in the eastern and southern suburbs of the Capital Region.

It runs from the intersection of Miklabraut-Sæbraut-Vesturlandsvegur south towards Hafnarfjörður, where it bends, and continues from there to Keflavík.

[3] 2003 saw the start of construction to upgrade the non-urban part to a dual carriageway, being completed by October 2008.

[4] In 2021, the urban section of the road through Hafnafjörður was upgraded to a dual carriageway, with grade separated crossings.

[6] As a national highway the route includes a large part of Sæbraut [ˈsaiːˌprœyːt], a local road in Reykjavík that begins at the northern end of Reykjanesbraut.