The benefits captured in an appraisal of a railway investment are determined by what timetables the
analyst assumes in the scenarios with and without the investment. Without an explicit, objective and
verifiable principle for which timetables to assume, the appraisal outcome is virtually arbitrary. This
means that appraisals of railway investments cannot be compared to each other, and opens the door for
strategic behaviour by stakeholders conducting seemingly objective cost-benefit analysis. We explain
and illustrate the nature and extent of the problem, discuss possible timetable construction principles,
and show that current practice is likely to exaggerate appraisal benefits.