The importance of timetable assumptions becomes particularly evident when appraising capacity improvements, since an increase in capacity can be used in any combination of increased frequencies, decreased travel times, and reduced delays. Depending on how the new capacity is used, an appraisal will give different results. The appraisal outcome will also depend on what is assumed about the use of the existing capacity in the do nothing case. It is not only the social benefits that depend on timetable assumptions; forecasts of revenues and passenger volumes obviously also do so.