I posted this in the thread on MTL November releases:
The Dept of Interior had several cars that were assigned to the Bureau of Mines- some are lettered as "mine rescue", Our late friend Jerry Laboda had links to several photos on his Passenger Car Photo Index-
http://passcarphotos.rypn.org/Indices/U3a.htm The cars appear to have remained in use well into the 1950s or later.
scroll down to US Dept of the Interior
The "mine rescue" says a lot. Some of the photos of these cars found on various sites show them in use with rescue crews. I have a fuzzy recollection from my childhood of seeing some of these cars when we had a local mine accident. They would be used to transport rescue crews from the Bureau of Mines, the state, or other area mines to assist in the work of rescuing miners after an accident.
https://www.cdc.gov/niosh/mining/UserFiles/aboutus/history/USBMSafetyRailCar.jpgThe photo (in addition to the link on Jerry's site) is shown in an article on the CDC site on the history of mine safety and the Bureau of Mines. There it included the caption:
A Bureau of Mines mine safety railroad car equipped as a movable safety and rescue station.
The following is also from the article:
In addition to work on safer blasting materials and prevention of underground gas and dust explosions, mine post-disaster survival and rescue was another concern of the young USBM. Director Holmes initiated the scheme of equipping railroad cars, one of which was headquartered at Pittsburgh, as movable safety and rescue stations. These cars - purchased second-hand, and refitted and equipped at a total cost of $5,000 each - toured the Nation's coalfields, training miners in first aid, rescue work, and mine safety. In a mining emergency, the cars could be immediately dispatched to the accident scene.
The entire article is here:
https://www.cdc.gov/niosh/mining/content/history.html