About 25 years ago when I started working on the 4070 in the B&O roundhouse in Cleveland Ohio the roundhouse still had about 2/3 of its floor made up of blocks of wood, about 8 inchs long, 8 inchs on the sides that were installed standing up. There was concrete around the engine pits that had been put in when they filled in the pits. Only one stall had a pit and there was a pit outside we used for running inspections. If the blocks were displaced in some way they were torn up and concrete laid, the last to go was the machine shop floor, The blocks still are in the toolrooms I thought what a fire hazzard but the whole floor was sand and grease. you couldnt even see the blocks around the engine stalls. Oil and such would get spilled, they would throw sand on and get on with the job.
Charlie