Impacts of Modal Competition and Intermodal Capacity on Transport
Transport supply is often assessed in terms of the capacity
of infrastructures. Although this dimension is suitable in a
number of circumstances, particularly when a single mode is
considered, the concept of transport supply must consider
circumstances where several modes are sharing the same
infrastructure or where intermodalism is the core factor of
- Modal competition. In this
modal competition two modes
(A and B) are sharing the same transport infrastructures. Assuming
that infrastructures are used to their full capacity,
the total capacity (C) is a function of their common demand, T(A) and T(B).
This common demand is the outcome of the respective modal
assignment; the shares of mode A and mode B. In this zero
sum environment, any change in the share of one mode will be done at the expense of the other.
This issue is particularly prevalent at transport bottlenecks
such as bridges where different modes, namely cars and trucks,
are competing for the same fixed capacity, which often results
in high congestion levels.
- Intermodal capacity. The capacity of two connected
intermodal terminals is derived from the terminal with the
lowest capacity. Two terminals
(A and B) have a respective capacity of C(A) and C(B). The maximum
transport demand possible between them, T(AB), is equal to the capacity
of the smallest terminal, C(B). This assumes that no other
activity is taking place between other terminals. In reality, an
intermodal terminal is connected with several other intermodal
terminals, implying that the capacity is even lower. This issue
is particularly prevalent for large port and airport facilities
that are running close to capacity. Any additional service must
be carefully considered in relation to the existing services.