The application of the ABC system to TT underscores the fact that the costs are
connected not only to the volume of the services provided but also to the characteristics
of the transport lines available and to the complexity of the company’s provision
process. For example, with the cost accounting system previously adopted by TT
(cost centres), the cost of “planning the shifts” would have been attributed to the
journeys, according to the driving time required by the journey, as though there were
proportionality between the cost and the production volume. We know, however, that
some lines require more work than others do in terms of planning shifts for reasons
that have nothing to do with the amount of driving time, such as the number of times it
was necessary to go back to the shift and timetable plan or the number of statistical
observations made.