調査担当者はどのルートが一番容易に、すなわち一番安上がりに作れるかも、鉄道の推進者にアドバイスしうるであろう。

tbd

The surveyor could also advise the promoters which route could be most easily—and therefore most cheaply—constructed.

あなたの菜園で作れる穀物や野菜を食べて生活する方がずっと安上がりだ。

tbd

It's much cheaper to live on grains and vegetables you can grow in your garden.