The third major Mbsetup task is to preprocess speed profiles, if they are provided. Speed profiles, which can be used instead of the average-speed values in the inventory, permit hourly speeds to be assigned and used in computing the emission factors. Mbsetup first checks if the USE_SPEED_PROFILES option is set to Y, and if it is, reads and uses a user-defined speed profiles cross-reference file (SPDREF). Speed profiles must be used if the on-road mobile inventory does not contain any speed information.

If speed profiles are being used, Mbsetup reads the speed profile cross-reference file and assigns a speed profile to each source. Each line of this cross-reference file requires a FIPS code, an SCC, and a speed profile code; Mbsetup verifies that the FIPS code is an integer, the SCC is 10 digits long, and the speed profile code is also an integer and is greater than zero. Note that Mbsetup does not read or process the actual speed profiles; that is handled later by Emisfac, so any inconsistencies in profile numbering will not be discovered until then. After reading the speed profile cross-reference file, SMOKE assigns the appropriate speed profile code to each source in the inventory by matching different combinations of FIPS codes and SCCs.