Boulogne-sur-Mer in context: Street-network sprawl trends

Boulogne-sur-Mer in context

2.433.64.2<19751976–19901991–20052006–2020SNDi of street additions
2.433.64.2<19751976–19901991–20052006–2020SNDi of entire street network
Boulogne-sur-MerHauts-de-France (Region)France (Country)

The chart above shows SNDi trends for new street additions (left panel) and the entire network (right panel), with Boulogne-sur-Mer plotted against Hauts-de-France and France. All three follow the same trend in new construction, suggesting a shared regional pattern of development. Most recently, Boulogne-sur-Mer's incremental SNDi fell from 4.05 to 3.69 between 1991-2005 and 2006-2020. In terms of the aggregate network, Boulogne-sur-Mer ranked 4th out of 10 cities in Hauts-de-France and 22nd out of 73 in France as of 2020.

New Street Additions (2006–2020)

SNDi value
3.69
Rank in France
49th of 73
Rank in Hauts-de-France
7th of 10

Entire Network (Aggregate)

SNDi value
2.31
Rank in France
22nd of 73
Rank in Hauts-de-France
4th of 10

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

What about similarly populated cities?

36912<19751976–19901991–20052006–2020SNDi of street additions
36912<19751976–19901991–20052006–2020SNDi of entire street network
Boulogne-sur-MerZenicaShiheng

In new street additions, Boulogne-sur-Mer built increasingly disconnected streets from 1975 through 1991-2005, then improved, while Zenica built increasingly disconnected streets over time and Shiheng fluctuated in its street-construction patterns. For the full network, Boulogne-sur-Mer and Zenica both became progressively more disconnected, while Shiheng grew more disconnected from 1975 through 1976-1990, then improved.