IF articles

In this article, a method to evaluate the effect

of the frequency of transport service on the overall travel

time is proposed for a given origin destination connection.

In particular, a formula for the calculation of the "time

displacement" is proposed between the traveller's desires

and timetable, which takes into account the traveller’s time

adaptability as well as the frequency of services. Time displacement

calculated with this formula is to be added to

the on board travel time of the chosen transport means, as

an alternative to the average waiting time, in case of services

with low enough frequencies to exclude random access

to service, as is the case for example of medium-long

distance railway services.

With the formula proposed, the values of average time

displacement are determined, in cases of uniform and

non-uniform interval services and in the case of services

involving the alternation of services at different speeds,

with varying frequency values and travellers’ time adaptability.

An application example clarifies the potential use of the

formula, which transforms the frequency in equivalent unit

of time, to sum to the travel time, in cases where we want

to assess the effects of changes in the frequency or more

generally evaluate the relative attractiveness of alternative

timetable structures.

The arguments are presented with reference to the

case of railway services, but are more generally extensible

to scheduled services in the field of medium-low frequencies,

such as in the case of road-based extra-urban services.