> That's true for roads and mass transit. Ideally, as the population grows, you expand both Difference is that mass transit benefits substantially from scale,

> That's true for roads and mass transit. Ideally, as the population grows, you expand both Difference is that mass transit benefits substantially from scale, with cost per rider dropping with ridership increases. Road networks, not so much. Kickstarting the process is a little tricky. But just about every other developed country has managed it, I’m sure the US can figure it out too.