If you will, picture a road along which there is some public transit: bus, train, street car, whatever. Perpendicular to that road are roads along which people live. The way to economize on travel from homes to wherever the transit is going is to have the frontage of homes along the perpendicular roads be very small. This is how cities in the US looked quite some time ago. Consider the following article which treats the configuration of lots as important elements in lowering costs in all sorts of public services: