Looking at the end of the car, the steam heat line is to the left of the coupler. To the right of the coupler is the brake pipe and train signal line. Train signal line is usually made of smaller pipe than the brake pipe.
But...... according the book of AFE's, 280 did not get any of this. The only open platformed cars to get signal and steam heat lines and electric power conduits were 284. 306 & 320. Picture of 280 by RWR at Moffat in 1949 shows no steam line or electrical conduit on the roof.
My guess is its a signal line installed "on the sly" by the Alamosa boys.