where:

c = A commodity group

e = A direction: emis for productions or dest for attractions

j = A coarse internal zone

l[j] = The “country” containing zone j. This value is looked up in Model.ZonalSystem.Country.

X_cej = The external (that is, import or export) trip end (tons per year) for commodity group c, direction e, and coarse internal zone j.

T_cej = The initial estimate for the total trip end (tons per year) for commodity group c, direction e, and coarse internal zone j. This value was calculated in the previous step.

f_cej = The external fraction for commodity group c, direction e, and course internal zone j. This value is found in table Zone.ExpImpFraction.

h_cel[j] = The external fraction growth factor for commodity group c, direction e, and country l[j]. This value is found in table Para.ExpImpTrend.

y = The time, in years, from the base year to the year for which CUBE Cargo is being run. This is found by subtracting the two control data parameter values.