A railway's return should be assessed over the decades it is intended to serve. The suggested planning horizon is about a hundred years. Designing around a five-year payoff can leave the state building a replacement after those five years. It may then have to fund the same durable project it originally rejected, adding an avoidable round of construction.
Notable Point · 10:45-11:51
Short planning horizons can mean building twice
Judging a railway by a five-year return can favour short-lived construction and leave the state paying for a replacement soon afterwards.