It is striking to see the common aspects in all definitions: the
use of more than one transportation mode. Of course, the devil is
in the details and some definitions put more emphasis on certain
aspects of the transportation process. Synchromodal emphasizes
the (real-time) flexibility aspect, intermodal focuses on the same
loading unit, and co-modal adds resource utilization. Note, however,
that the basic definition of multimodal transportation does
not exclude any of the other definitions. In our view, the definition
of multimodal transportation is still valid and should be used
rather than developing new definitions and/or new words. Multimodal
is the broadest definition and includes the other notions.
Additionally, the relevant Operations Research (OR) literature does
not provide any additional explanations on the characteristics and
(conceptual) formulations. Our review reveals that in the literature,
multimodal and intermodal are used interchangeable. No
OR literature is found where co-modal or synchromodal is used.
In what follows, we use multimodal consistently.