R21 (South Africa)

The R21 is a major north–south provincial route (with a freeway portion designated as a National Road) in eastern Gauteng Province, South Africa. Built in the early 1970s, it remains one of two freeways (the other being the N1) linking Pretoria with Johannesburg, via the R24. As the eastern of the two freeways, it links the Pretoria city centre with OR Tambo International Airport and Boksburg. Between the Solomon Mahlangu Drive on-ramp in Monument Park, Pretoria, and the N12 interchange in Boksburg, the R21 is an 8 lane highway and motorway (freeway), with 4 lanes in each direction. It has off-ramps leading to Irene, Olifantsfontein, Benoni, and Kempton Park. The route intersects the N1 highway (Eastern Pretoria Bypass; Danie Joubert Freeway) near Centurion, the R24 near the airport, the N12 and N17 in Boksburg, and the N3 near Vosloorus on the East Rand, where it ends. The section from the N12 to the N3 is not a freeway. The R21 is also designated as the P157.

The R21 is the lowest "R" designated route number in South Africa. The portion of the R21 where it exists as a freeway, from the M10 Solomon Mahlangu Drive off-ramp in Pretoria to the N12 Freeway in the East Rand was declared a National Road in 2008, as part of the Gauteng Freeway Improvement Project, when it was also transferred to the South African National Roads Agency. The improvement project increased the number of lanes (previously, the freeway portion had been a dual carriageway freeway, with 2 lanes in each direction, from the Rietfontein Interchange to Pretoria), and installed lighting along the length of the freeway section.

As a result of the Gauteng Freeway Improvement Project, the freeway section of the R21 was effectively declared as an e-toll highway (with open road tolling) from 3 December 2013 onwards. The South African government announced on 28 March 2024 that e-tolls in Gauteng would officially be shut down on 11 April 2024 at midnight, therefore returning the R21 to being a toll-free route.