The R21 / P157 is a major north-south provincial route in eastern Gauteng Province, South Africa. Built in the early 1970s, it remains one of two freeways 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, the N12freeway, and Boksburg. Between the Solomon Mahlangu Drive on-ramp in Monument Park, Pretoria, and the N12 in Boksburg, the R21 / P157 is an 8 lane highway and motorway, with 4 lanes in each direction. It has off-ramps leading to Irene, Olifantsfontein, Benoni, and Kempton Park, including a partial offramp to Atlas Road. The route intersects the N1 Highway 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. As early as the 1970s there were proposals to extend the R21 / P157 freeway further south and the freeway may be linked with the current eastern terminus of the M2 in Germiston in future. The R21 / P157 is the lowest "R" designated route number in South Africa, since numbers 1-18 have been reserved for national route numbers. However a portion of the R21 / P157 where is exists as a freeway, from Hans Strijdom Drive in Pretoria, to the N12 Freeway in the East Rand is both a National Road and a toll road, having been declared such 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, and installed lighting along the length of the freeway section.
Route
The R21 begins just north-east of Fountains Valley in Pretoria as Nelson Mandela Drive, at a roundabout intersection with the M18 Christina De Wit Avenue, M7, M5 and M3 Metropolitan roads of Pretoria, heading south-east. After Fountains Valley, the R21 passes by Monument Park. After Monument Park, the R21 becomes a National Road, with the first off-ramp being the M10 Solomon Mahlangu Drive near the Waterkloof Airforce Base. It has Pretoria East to its east and Centurion to its west. Just after Solomon Mahlangu Drive, near the suburb of Pierre van Ryneveld Park, the R21 intersects with the N1 Highway, which is the freeway between Johannesburg and Polokwane. The Interchange is named the Flying Saucer Interchange. After The N1 Interchange, the R21 Freeway has 10 off-ramps and interchanges for the remaining length of its freeway section. It passes through various suburbs in various cities. The R21 intersects with the M31, R562, R25, R23, M32, M43, M96, R24, M41 and N12. After the M31 Irene off-ramp, the R21 leaves the City of Tshwane Metropolitan Municipality and enters the City of Ekurhuleni Metropolitan Municipality. From the M31 Irene off-ramp up to just after the O.R. Tambo International Airport, the R21 is followed by the M57 Metropolitan Route of Johannesburg from north to south. From the R562 off-ramp to the R25 off-ramp, the R21 bypasses the township of Tembisa. At the O.R. Tambo International Airport, south-east of Kempton Park Central, the R21 meets the R24 which connects the airport with Johannesburg Central in the west. Via the R24, the R21 is the only freeway apart from the Ben Schoeman Freeway that links Pretoria with Johannesburg. North of Boksburg, the R21 intersects with the N12 Highway to Johannesburg in the west and Witbank in the east at the Rietfontein Interchange, which marks the end of the R21 being both a freeway and a toll road. The R21 becomes Rietfontein Road when it junctions with the M44 Road at the East Rand Mall. At the suburb of Boksburg North, the R21 continues by way of a right turn at Rondebult Road. The R21 then meets the R29 and continues south, bypassing Boksburg Central. After Boksburg, the R21 crosses the N17 Highway at Elspark and continues south through Sunward Park. After Sunward Park, the R21 heads south-south-east, meeting the R554 and intersects the M43 Road for the second time at a t-junction in Dawn Park. The R21 and the M43 are co-signed south-west. As Bierman Road, the R21/M43 pass over the M35 Road, intersect with the R103, and end at Vosloorus at an intersection with the N3 Freeway.
As the R24 Freeway is known as the Albertina Sisulu Freeway in Ekurhuleni between Eastgate Shopping Centre and Johannesburg International Airport, the use of the name doesn't end there. The R21 is often also called the Albertina Sisulu Freeway, Particularly the section from the Johannesburg International Airport interchange north to the N1 Pretoria Eastern Bypass Flying Saucer interchange near Centurion and Pretoria in the City of Tshwane Metropolitan Municipality. It indicates that the R21 from Pretoria to the airport and the R24 from there to Bedfordview are together known as the Albertina Sisulu Freeway. The naming of the R24 Highway from Bedfordview eastwards, together with the R21 freeway from OR Tambo International Airport northwards to Pretoria as the Albertina Sisulu Freeway was already done by the time of the 2010 FIFA World Cup. Also, the R21 extension from OR Tambo International Airport to the N12 Interchange north of Boksburg may be counted as being part of the Albertina Sisulu Freeway.
