The difficulty in the appraisal of public transport projects is well understood.
The main issue relates to accurately identifying and describing the costs and benefits.
Any initiative that improves public transport could be expected to increase public transport use.
Costs are short term (capital infrastructure and vehicles) and long term (operations and maintenance), and low or high cost.
Benefits can be short or longer term, quantifiable in monetary terms or described in qualitative terms and difficult to isolate from a whole range of other factors.