ATSF
| Atchison Topeka & Santa Fe | 6 |
BN
| Burlington Northern | 19 |
BNSF
| BNSF Railway | 21 |
CBQ
| Chicago Burlington & Quincy | 2 |
CGW
| Chicago Great Western | 3 |
CNW
| Chicago & Northwestern | 15 |
CR
| Conrail | 3 |
CTIE
| Kansas City Southern Railway Company | 1 |
DME
| Dakota, Minnesota and Eastern | 2 |
DMVW
| Dakota Missouri Valley and Western Railr | 1 |
DRGW
| Denver & Rio Grande Western | 7 |
GREX
| Georgetown Rail Equipment Company | 1 |
HZGX
| Herzog Contracting Corporation | 4 |
KCS
| Kansas City Southern | 1 |
KMUX
| Kershaw Manufacturing Company | 2 |
LMIX
| Loram Maintenance of Way Inc. | 1 |
MILW
| Milwaukee Road | 1 |
MP
| Missouri Pacific | 26 |
MPM
| MPM | 1 |
MPX
| COLUMBIAN CARBON CO., MAGNETIC PIGMENT DIV. | 1 |
MRL
| Montana Rail Link | 8 |
MSRC
| Kansas City Southern | 2 |
NS
| Norfolk Southern | 1 |
NW
| Norfolk & Western | 1 |
RGAX
| RGAX | 4 |
RGDW
| RGDW | 1 |
RGH
| RGH | 1 |
RKCX
| Knox Kershaw Incorporated | 2 |
RMSX
| Pandrol Jackson Incorporated | 18 |
SOU
| Southern | 1 |
SPMW
| Southern Pacific Maintenance of Way | 2 |
TSSX
| U.S. Dept. of Energy Albuquerque Operations Office | 1 |
TTX
| TTX Company | 2 |
TVRR
| Tulare Valley Railroad Company | 3 |
UCP
| UCP | 1 |
UP
| Union Pacific Railroad Company | 30 |
WWEX
| Wood Waste Energy Incorporated | 2 |