This is a great video, camera facing steadily west, apparently taken c. 1946-48 from either a PRR or (pre-GM&O) Alton passenger train about to arrive at Chicago Union Station. The string of FOM-liveried PRR cars is on the south leg of the wye formed by the Burlington main line arriving from the west teeing against the north/south PRR/Alton lines that will entering the station together. This handy-dandy wye (using the Burlington main line) was AFIK used by all railroads at CUS (save the Milwaukee) to turn their trains and still is by Amtrak.
In a relatively recent year, I was on board and actually at the helm of a Lake Michigan-bound yacht, the height of which required the very bridge across the Chicago River depicted in the video to be raised for clearance to pass under. I cringed when I noted that we had stabbed the outbound Amtrak Lake Shore Limited in the process! (the train crew on the ground was on the ground watching us pass by).
The steel open platform Burlington cars (replete with hard turnover rattan seats) were THE standard commute cars on the Aurora commute lines. I spent a childhood lifetime on these cars, freezing in the winter, and roasting in the summer, ashes and the occasional spark from the antique CB&Q 4-6-2s ahead wafting in through the open windows leaving one commonly filthy when stepping off in CUS. The old tea kettles could really get up and move on this superb trackwork when allowed to do so.
These cars were then rebuilt soon after the war by the Burlington with closed vestibules and some sort of crude cooling, as a recall, (to be then be themselves then replaced the beautiful and iconic Budd double deckers about 1952 onwards.
One of the most odd, and most sad memories I have was an eastbound mid-day Chicago-bound commute local (with an RPO and baggage being worked) trailed by several open platform coaches stopping patiently at the Riverside, IL depot c. 1949, the motive power a recently demoted still handsome and shiny shovel-nosed EMD/Budd Zephyr locomotive nosed right up to the Riverside Road village grade crossing. How the mighty had fallen, and how fortuitous it was that the weather required no train heat (these locomotives had NO steam generators for train heat). In the background out of sight somewhere was a recently sadly-retired 4-6-2 itself now indirectly replaced by a brand new E-7.
This has brought up a lot of good memories.
Denny S. Anspach MD