Can anyone direct me as to where I can possibly find the answers to the following questions about Valley Yard and the general area around it?

1. When was Valley Yard abandoned?
2. When was BRIDGE tower demoed?
3. When was the Roundhouse in Valley yard demoed? (Lots of brick from the roundhouse laying around still.)
4. When was the Branch to Warren PA abandoned?

I am trying to look for these answers, but my Google-Fu has had no luck. I am attempting a modeling project, and would like to know these things to try to make it as prototypical as possible for the multiple eras I am doing it in.

I would try contacting the Historical Society, maybe they can help you out.

Did you talk to anyone from the OC&T RR? They seemed to know where everything was on the ride I took last year.

I did not ask them, I probably should have. I didn't think to since it isn't on the OC&TRR, but on the Old PRR Allegheny Division/WNY&P.

Looks like most things were still standing untill at least 1963 judging by the cars in the parking lot. The whole area was included in an egineering book which these photos are from that was published in 1971.

http://www.prrerie.com/oilcity.shtml

You could also check the historic aerial photos from the http://www.pennpilot.psu.edu/ site.

I took a quick look, but didn't see anything newer than 1968-1972 there, which showed the roundhouse still standing.

Hello there, it isn't often that you find someone inquiring about railroads in Oil City Pa anymore. Once one of the major hubs for five different railroads, now absolutely nothing except for one spur left from Oil City to Titusville Pa running an excursion trip. The railroad known today as the Oil Creek/Titusville railroad.
The yard you are speaking of was done away with in the late 1960's early and mid 1970's. The roundhouse and turntable around the same time. There still remains a signal bridge although all the signals have been removed. Most of the trackage was removed around the same time also.
I can remember standing on the road bridges as a youngster watching and listening to the steam locomotives move about the area. The main passeger station was also torn down in the 70's. I believe there is still a very small freight building located close to where the passenger station was, and also the single rail line that services the Oil Creek/Titusville railroad.
Hope this helps you a bit and sure brought back memories when railroads were prime around here and fun to watch.
Good luck, Pete