Urban infrastructure typically lasts for long periods of time. Hence, while urban infrastructure investment has to be made ex-ante at the time of rapid urban growth over a period of 10-15 years, benefits may well flow for periods as long as fifty years or more.
Life would be easy if financing sources were such that civic authorities could raise resources in such a manner that the repayment schedule matched the benefit schedule. A scan of urban financing systems across the world does not reveal any uniformity in pattern.