I remember using 146.490 simplex, while chasing PM 1225 here in Michigan, and when it went down to West Virginia for the 1991 NRHS Convention. There were around a dozen of us chasing the 765 and 1225 as it went from Lima, south to Cincinnati and into Kentucky. Coordinating on 146.490 simplex gave us a lot of great information regarding the best directions, photo locations, restaurants, and speed traps were at.
The use of 146.490, 146.565, 223.620, 446.050, 1294.550 MHz was originated by Gary Sturm N9IJB, who wrote the now defunct "Compendium of American RR Radio Frequencies" book, listing all the radio frequencies railroads have licensed in North America, with their exact uses back in the day. I can think of several times in the 1990s when out chasing various steam excursions, 146.490 simplex was the most active. In fact, when I was in Toledo, Ohio 1993 chasing NKP765 dressed up as C&O 2765, one of the hams down in Toledo, who lived about two miles away from the railyard where the engine was serviced at, set up a cross-band repeater on 146.490 out / 446.050 in. This allowed us to communicate over a much greater distance with our portable radios.
73's
Ron