Environmental Engineering Reference
In-Depth Information
All transportation modes require four basic essentials: vehicles, a network of routes, termi-
nals for loading and unloading, and a traffic control system (Chapman, 1989). The construc-
tion of a transportation system is capital-, material-, and energy-intensive and requires constant
maintenance, money, and energy to operate. Energy spent in transportation has three compo-
nents: energy to build vehicles and routes, energy spent in maintenance, and most important,
“propulsion energy” during the life of vehicles.
Transportation of goods, including food products, can be performed by only one transporta-
tion mode, but more frequently it involves the combination of more than one, which depends
generally on the distance, cost, and availability of infrastructure. Based on the distance, food
transport systems can be international, intercity, and intra-urban. As a general rule, the longer
the haul is, the more massive and less versatile the transportation mode becomes. From largest
to smallest mass of cargo transported, vehicles can be sorted in ocean ships, inland barges,
trains, large planes (e.g., Boeing 747-400), large trucks, midsize planes (e.g., Airbus 320), and
small trucks. Table 13.2 presents some typical cargo capacity for different transportation modes.
As a corollary to the general rule, the more massive and slower a transportation vehicle is,
the less energy it uses per unit of product transported. The opposite is generally true as well.
Lighter vehicles capable of higher speeds can deliver products faster but they are penalized
with higher energy consumption.
Ocean ships are used for international transport of food products and basically include two
types of vessels: dry bulk carriers, especially grains, and container ships. Refrigerated con-
tainers are used for fresh fruits and vegetables, meat, fish, and dairy, whereas nonrefrigerated
ones are used for shelf stable food products. Inland barges are common modes of transport for
grains and break bulk cargo by using rivers, inland lakes, canals, sounds, and bays. Trains and
large trucks are responsible for moving cargo between cities, from processing plants to distri-
bution centers, and to and from ports served by ocean ships and inland barges. Planes are used
for fast national and international transport of perishable foods. For the last leg of the trip from
distribution centers to retailers, food products are moved exclusively by large and small trucks.
Freight containers are a reusable metallic box of standard dimensions and are used for
“intermodal freight transport,” in which the container can be shipped by different modes with-
out handling the freight. So once the container is filled and sealed at origin, it is loaded on a
Picture 13.1
A turnpike double.
Photographer Ralf Peter Reimann; reproduced under the Creative Commons License.
