Electronic monitoring of the location of vehicles
during transport can be achieved by two methods: auto-
144 L. Ruiz-Garcia et al. / Span J Agric Res (2007) 5(2), 142-156
matic vehicle identification and the global positioning
systems (GPS). The former involves the detection of
the conveyance at various critical waypoints along its
normal route. This is rather inexpensive and involves
a relatively small number of active systems reporting
to a central data processing site. The time elapsed
between waypoints can be monitored for compliance
with regard to expected travel times, though problems
can arise if a vehicle has to change its normal route