Karatsu in context: Street-network sprawl trends

Karatsu in context

2.12.42.73<19751976–19901991–20052006–2020SNDi of street additions
2.12.42.73<19751976–19901991–20052006–2020SNDi of entire street network
KaratsuSaga (Region)Japan (Country)

The chart above shows SNDi trends for new street additions (left panel) and the entire network (right panel), with Karatsu plotted against Saga and Japan. The SNDi of new construction in Karatsu peaked in 1976-1990, compared to Saga which peaked in 1976-1990 and Japan which followed a zig-zag trend with an overall increase. Most recently, Karatsu's incremental SNDi fell from 2.45 to 2.34 between 1991-2005 and 2006-2020. In terms of the aggregate network, Karatsu ranked 2nd out of 3 cities in Saga and 62nd out of 135 in Japan as of 2020.

New Street Additions (2006–2020)

SNDi value
2.34
Rank in Japan
51st of 135
Rank in Saga
3rd of 3

Entire Network (Aggregate)

SNDi value
2.24
Rank in Japan
62nd of 135
Rank in Saga
2nd of 3

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

What about similarly populated cities?

1234<19751976–19901991–20052006–2020SNDi of street additions
1234<19751976–19901991–20052006–2020SNDi of entire street network
KaratsuGenetRybnik

In new street additions, Karatsu built increasingly disconnected streets from 1975 through 1976-1990, then improved, while Genet fluctuated in its street-construction patterns and Rybnik built increasingly disconnected streets over time. For the full street network, though, all three cities follow the same trend. Karatsu and Genet have been converging in their street-network character since 1975.