Received the following text and photos via email from Nathan S. Clark, Jr.
To fully appreciate these pictures, click on them and you will get a larger version.
I took the attached photos on April 27, 1979. This incredible scene was between railroad overpasses on the former Pennsylvania RR main line in downtown Wilkinsburg, PA (just 6 1/2 miles east, by rail, from the passenger station in downtown Pittsburgh).
As I recall the details, Conrail SD40-2 #6480 and GP40 3184 were running light (helpers returning from assisting a road train over the grade) when they were sideswiped by derailing or overhanging equipment from an adjacent track. The GP40 derailed and crashed through the concrete abutment/retaining wall and plunged down onto South Avenue. Fortunately, this happened when there were no vehicles waiting at the traffic light visible just beyond the underpass. In fact, I don't recall hearing reports of any injuries, although I have to believe it was a 'rough ride' for the crew (look at the engineer's seat in the down-on view). At the very least, it had to be LOUD when that 250,000-pound GP40 landed on that street. Steve Timko had advised on the 25th Anniversary, a half-decade ago, that the engineer who had been sitting in that seat was still working for NS in 2004. Mike Repka also got photos of this mishap.