infrastructure decrease with the traffic load. In Section 4.3,
this value will be used to calculate marginal costs.
One key to understanding why elasticities at the two
classes of lines differ is most probably that main lines
include track sections that are entirely or partly double
tracked, while secondary lines are typically single-tracked
with fewer meeting stations. Since maintenance activities
on main tracks can more often be undertaken with one of the
tracks closed off from traffic for a relatively convenient
period of time, the physically identical measures may
require workers to get off the line more frequently on
secondary lines; each job thus takes more time. As we have
noted, our data indicates that the technologies are similar
per se, both since bI is not significant and since we could not
reject the hypothesis of identical coefficients in the F-test
above.
While traffic and track length seem to be the most
important determinants of track maintenance costs, Table 3
shows that the number of switches and the quality index also