A road can connect two places by dividing the place between them.

A major road links the places at either end and severs the place it passes through. What was one neighbourhood becomes two, separated by something difficult and unpleasant to cross, and the people who lose the connection are rarely the ones the road was built to serve.

Every infrastructure decision does this kind of arithmetic, connecting at one scale and dividing at another. When you hear about a project, ask who is being joined and who is being cut, since the second half is usually absent from the description of the benefits.