Why can short payback rules obstruct infrastructure?

Why do public bodies struggle to fund useful infrastructure?

Accounting rules can demand repayment over a much shorter period than the infrastructure's useful life.

A 50- to 100-year business case is proposed for long-lived public infrastructure. A five- or ten-year business case can miss much of its value. Dr. Clarke recalls a council accountant explaining that a project might repay its cost within about 20 years and remain useful for 50, yet struggle to meet a ten-year approval test. A viewer's example of a two-year payback requirement draws the further objection that such a short horizon leaves little room for research and development.