Analyst Drive allows the user to estimate multiple OD matrices from a single count set as modeled by Equation Set 5.

Aggregate estimation allows the user to employ any combination of matrices, ICP files and screenline count files in the estimation by using the ICPARRAY and SLARRAY parameters. The number of values in each of the arrays is determined solely by the number of OD matrices to be estimated in the matrix input file, and the position of each value in the arrays corresponds to the OD matrix number. File numbering is the key here; every input file into Analyst Drive has a number associated with its type. OD matrices receive numbers based on their tab number in the input matrix file, while screenline and ICP files recieve a number based on their order as arranged in the Analyst Drive module in Cube Application Manager.

Each position in the respective parameter arrays corresponds to the OD matrix number; e.g. the 3rd spot to the 3rd OD matrix, the 6th spot to the 6th OD matrix, etc. The value in each position of the arrays corresponds to the appropriate file number; e.g. if SLARRAY position 3 has a value of 1, then the 3rd OD matrix uses screenline file 1; if ICPARRAY position 5 has a value of 2, then the 5th OD matrix uses ICP file 2. Note that corresponding ICP and screenline files must be consistent when perfroming aggregate static estimation (e.g. the number of screenline values in each associated file must match). To illustrate how to assign these arrays, some examples are given here in a similar manner to the examples given for the SLCODE parameter described above.

• SLARRAY and ICPARRAY Example 1 — If we had four matrices (so each array must contain four entries) to estimate with four individual ICP files and one screenline file, then all four OD matrices would use screenline file 1 and would have SLARRAY = 1,1,1,1. Since each OD matrix would have its own ICP file, they should be numbered accordingly and ICPARRAY = 1,2,3,4.

• SLARRAY and ICPARRAY Example 2 — If we had five matrices (so each array must contain five entries) to estimate and two screenline files with the first screenline file corresponding to OD matrices 1, 4 and 5 and the second screenline file corresponding to OD matrices 2 and 3, then we would have SLARRAY = 1,2,2,1,1. If in addition we only had four individual ICP files because OD matrices 1 and 4 shared the first ICP file (i.e. they have identical route choice assignments) then we would have ICPARRAY =1,2,3,1,4 with a 1 in the 4th spot to indicate that OD matrix 4 uses ICP file 1, and a 4 in the 5th spot to indicate that OD matrix 5 uses the 4th ICP file given.

• SLARRAY and ICPARRAY Example 3 — If we had eight matrices (so each array must contain eight entries) and four screenline files such that the first screenline file corresponded to the 1st matrix, the second to the 2nd, 4th and 5th matrices, the third to the 3rd, 6th and 7th matrices, and the fourth to the 8th matrix, then SLARRAY = 1,2,3,2,2,3,3,4. If in addition we had only six ICP files because OD matrices 4 and 5 share the 4th ICP file and also OD matrices 6 and 7 share the 5th ICP file, then we would have ICPARRAY = 1,2,3,4,4,5,5,6.

ICPARRAY and SLARRAY can be used for any combination of aggregated matrices, but note that using this method is memory-intensive as the program must load data for all matrices to be estimated into memory simultaneously. ICPARRAY and SLARRAY cannot be used with the SLCODE parameter.