ARR
| Alaska Railroad | 5 |
BN
| Burlington Northern | 1 |
BNSF
| BNSF Railway | 8 |
GREX
| Georgetown Rail Equipment Company | 1 |
HZGX
| Herzog Contracting Corporation | 2 |
MP
| Missouri Pacific | 1 |
MRL
| Montana Rail Link | 2 |
SP
| Southern Pacific | 2 |
UP
| Union Pacific Railroad Company | 13 |