Trends
3.25
SNDi (2020)61,000 km
Total street network1975–2020
Analysis periodDisconnectedness burden of street construction in Pennsylvania
▸ Hover over bars to see values
The chart above shows, for each construction period in the Pennsylvania region, the SNDi of new street additions (bar height) and the volume added (bar width), so that bar area reflects the total disconnectedness burden of that period's construction. The 1975 period contributed the greatest disconnectedness burden, with 33,700 km of street added at an SNDi of 2.5. Overall, the SNDi of new street additions in the region rose steadily.
How have Pennsylvania's street networks changed over time?
Most recent snapshot
Taking into account the entire (i.e. aggregate) street network in Pennsylvania as of 2020, the overall level of street-network sprawl is 3.25, which is moderately connected.
Trends in street network construction
The SNDis of street construction for the respective time periods are 2.5, 4.32, 4.76 and 4.88. In each period, new street development in Pennsylvania steadily grows more disconnected than in the last. This increase has slowed: between 1975 and 1976-1990, SNDi rose by 1.82 points, but between 1991-2005 and 2006-2020, it rose by just 0.12.
Quantity of street network construction
The street network in Pennsylvania spans a total of 61,000 kilometers. It is dominated by roads constructed prior to 1975. These roads have an SNDi of 2.5, which is relatively well-connected.
Effect on the aggregate network
New construction in each period adds to the total stock of streets, but does not change streets that have already been built. Therefore, it has a limited effect on the street network as a whole. The SNDis of the aggregate street network in the respective time periods are 2.5, 2.85, 3.19 and 3.25. Overall, the SNDi of the aggregate street network has risen: the street network in Pennsylvania has become more disconnected. This increase has slowed: between 1975 and 1976-1990, SNDi rose by 0.36 points, but between 1991-2005 and 2006-2020, it rose by just 0.07.