Just wondering if any museum or historical organization out there has thought of preserving any pneumatic switch movements, such as the US&S A-1 or A-5. Their numbers are slowly dwindling, as each time Amtrak or Septa rebuilds a pneumatic installation these days, they're replaced with electric machines. It would be a shame to see such a remarkable and important piece of machinery disappear from the landscape without being preserved.

Does CTA still have pneumatic switch machines at the Howard St. interlocker? I haven't been there in a long time, but I still remember the "PFFFF-ka-chunk" as the tower operator set up a route for the Skokie Swift or the Evanston Express. For years they had a bank of old streetcar-type air compressors (Westinghouse D-2's?) that would cycle on with the nostalgic sound of old-time traction when action picked up. There were probably plenty of "retired" compressors at Skokie Shops; it may have been cheaper to run them off the 600-volt third-rail power supply than run 3-phase AC and install modern compressors.