Multimodal transport (also known as combined transport) is the transportation of goods under a single contract, but performed with at least two different means of transport; the carrier is liable (in a legal sense) for the entire carriage, even though it is performed by several different modes of transport (by rail, sea and road, for example). The carrier does not have to possess all the means of transport, and in practice usually does not; the carriage is often performed by sub-carriers (referred to in legal language as "actual carriers"). The carrier responsible for the entire carriage is referred to as a multimodal transport operator, or MTO.
Article 1.1. of the United Nations Multimodal Convention (which has not yet,[when?] and may never enter into force) defines multimodal transport as follows: "'International multimodal transport' means the carriage of goods by at least two different modes of transport on the basis of a multimodal transport contract from a place in one country at which the goods are taken in charge by the multimodal transport operator to a place designated for delivery situated in a different country"
Research
Multimodal transport research is being conducted across a wide range of government, commercial and academic centers. The Research and Innovative Technology Administration (RITA) within the U.S. Department of Transportation (USDOT) chairs an inter-agency Research, Development and Technology (RD&T) Planning Team. The University Transportation Center (UTC) program, which consists of more than 100 universities nationwide conducts multi-modal research and education programs.
Legal aspects
From a legal standpoint, multimodal transport creates several problems. Unimodal transports are currently governed by different, often-mandatory international conventions. These conventions stipulate different bases for liability, and different limitations of liability for the carrier. As of 2011, the solution to this problem has been the so-called network principle. According to the network principle, the different conventions coexist unchanged; the carrier’s liability is defined according to where the breach of contract has occurred (where the goods have been damaged during transport, for example). However, problems arise if the breach of contract is systemic (not localized).