Then why build roads at all? If N + 1 means more traffic than surely N - 1 means less? So 0 roads, no traffic! Seriously though isn't this a related rates probl

Then why build roads at all? If N + 1 means more traffic than surely N - 1 means less? So 0 roads, no traffic! Seriously though isn't this a related rates problem? Adding roads adds capacity and also induces demand. Are the two in lockstep? Can the capacity added be greater than the demand induced?