While trying to validate your 12k number (its more likely 65k and thats not long-haul, http://www.afdc.energy.gov/data/10309) I found an interesting data sheet:
http://www.trucking.org/ata%20docs/what%20we%20do/image%20an...
http://www.trucking.org/ata%20docs/what%20we%20do/image%20an...