Johannesburg in context: Street-network sprawl trends

Johannesburg in context

3.244.85.6<19751976–19901991–20052006–2020SNDi of street additions
3.244.85.6<19751976–19901991–20052006–2020SNDi of entire street network
JohannesburgGauteng (Region)South Africa (Country)

The chart above shows SNDi trends for new street additions (left panel) and the entire network (right panel), with Johannesburg plotted against Gauteng and South Africa. The SNDi of new construction in Johannesburg peaked in 1991-2005, compared to Gauteng which peaked in 1991-2005 and South Africa which rose steadily. Most recently, Johannesburg's incremental SNDi fell from 5.7 to 5.29 between 1991-2005 and 2006-2020. In terms of the aggregate network, Johannesburg ranked 12th out of 14 cities in Gauteng and 65th out of 81 in South Africa as of 2020.

New Street Additions (2006–2020)

SNDi value
5.29
Rank in South Africa
64th of 81
Rank in Gauteng
11th of 14

Entire Network (Aggregate)

SNDi value
4.24
Rank in South Africa
65th of 81
Rank in Gauteng
12th of 14

Rankings go from most connected to most disconnected — rank 1 is the most connected.

What about similarly populated cities?

3456<19751976–19901991–20052006–2020SNDi of street additions
3456<19751976–19901991–20052006–2020SNDi of entire street network
JohannesburgHangzhouSurabaya

While Hangzhou and Surabaya both fluctuated in its street-construction patterns, Johannesburg built increasingly disconnected streets from 1975 through 1991-2005, then improved in new street additions. For the full street network, though, all three cities follow the same trend. Johannesburg and Surabaya have been converging in their street-network character since 1975.