highly aggregated. Moreover, when dealing with questions re-
lated to grain/soybean transport via the unregulated barge and
truck modes, researchers have typically assumed rates to equal
the estimated accounting costs of an "average" load (e.g. Sor-
enson, Martin, Michaels et al., and Fuller and Shanmaugham).
Only one study in grain transport (Johnson) explored the role
of service quality differentials.

 Empirical research on the transportation of perishables
has emanated primarily from three sources: the USDA, Washing-
ton State University/University of Hawaii, and the University
of Florida. The USDA has conducted several studies. However,
they have primarily employed a costing approach which ignores
individual shipment and load characteristics (e.g. Klindworth
and Brooks and Boles).

 Of more direct bearing is the work done by a group of
researchers at Washington State University and the University
of Hawaii. In a series of articles spanning almost 20 years,
they have explored the intensity of intermodal competition for
perishables (Miklius), carrier and trip characteristics which
determine whether exempt loads are acquired (Pederson, Mittle-
hammer, and Casavant), and service characteristics which influ-
ence the demand for transportation of perishables (Miklius;
Miklius, Casavant and Garrod; Miklius and Casavant; and Garrod
and Miklius). It is clear from their work that the demand for
perishables transport is highly sensitive to service character-
istics. Further, the degree and even the direction of this
sensitivity vary from commodity to commodity. For example,
Miklius, Casavant, and Garrod found that for shippers longer
transit times for apples are often desirable, whereas speed is
always sought when transporting cherries. The reasons cited by
the authors are as follows. Apples are a long-lived fruit with
relatively low per unit value. A lengthy transit time may be
advantageous as it provides more storage-in-transit. Cherries,
on the other hand, are valuable and highly perishable. Slow
transit is costly, therefore, both because of high carrying