Environmental Engineering Reference
In-Depth Information
2
International trade and global shipping
James J. Corbett and James J. Winebrake
The freight transportation system is the network of specialized vessels, the ports they visit,
and transportation infrastructure from factories to terminals to distribution centers to
markets (MARAD, 1999). Within such a de
nition, it is nearly impossible to consider
ocean shipping separately from the goods movement context. On a worldwide basis,
nearly 50 000 oceangoing vessels move cargo more than 33 billion tonne-km annually. In
the European Union, marine transportation moves more than 70 percent (by volume) of
all cargo traded with the rest of the world; in the USA, more than 95 percent of imports
and exports are carried by ships (MARAD, 2000). This work is accomplished by ships
using 2 to 4 percent of the world's fossil fuels (Corbett, 2004).
These inbound and outbound freight
fi
ows through national ports are connected to
truck and train movement of goods through a transportation network. In fact, ocean
shipping can be considered to be a 'trip-generator' for intermodal cargoes in global trade,
blending with domestic freight movements on nations' roads and rails. This intermodal
context is important when considering impacts of ocean shipping, particularly where
modal tradeo
fl
er. This chapter discusses the role of
ocean shipping within the context of international goods transportation, with speci
ff
s in energy intensity and emissions di
ff
fi
c
attention paid to the energy and environmental impacts of such shipping.
Multimodal freight context
International maritime shipping is a critical element in the global freight transportation
system that includes ocean and coastal routes, inland waterways, railways and roads, and
air freight. The freight transportation network connects locations by multiple modal
routes, functioning as modal substitutes (see Figure 2.1a) A primary example is con-
tainerized shortsea shipping, where the shipper or logistics provider has some degree of
choice about how to move freight between locations. However, international maritime
transportation is more commonly a complement to other modes of transportation (see
Figure 2.1b). This is particularly true for intercontinental containerized cargoes
1
and for
liquid and dry bulk cargoes, such as oil and grain. International shipping connects roads,
railways, and inland waterways through ocean and coastal routes.
Mode choice (especially for containerized cargo movement) involves balancing
tradeo
s to facilitate trade among global corporations and nations. In the current global
economy, competing factors have been time, cost and reliability of delivery. Low-cost
modes may be less preferred than faster modes if the cargo is very time sensitive; however,
slower, lower-cost modes often carry much more cargo and, with proper planning, these
modes can reliably deliver larger quantities to meet just-in-time inventory needs.
Mode share in freight transportation can be measured in several ways, but a common
metric is work done in cargo tonne-km (tkm). The EU and the USA have similar mode
shares for trucking, about 45 percent of total freight transport work (EPA, 2005a;
Mantzos and Capros, 2006). However, it is important to note that European waterborne
ff
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