Here is a recent research paper by Christopher Barrington-Leigh and Adam Millard-Ball that looks at the connectivity of local street networks across the world. They refer to this as "street-network sprawl" and they measure it using a Street-Network Disconnectedness index (SNDi).
This is important for many reasons. Compact street networks with shorter blocks and fewer dead ends are far more conducive to different forms of mobility, including transit. Street networks are also incredibly sticky. Once laid, they rarely change. And if they do, it's over very long periods of time.
