That's not an express train but a freight train, and right behind the diesel locomotives (looks like two A - or cab - units and two B - all engine - units) are a Railway Express box car and one with the Pennsylvania Railroad logo (PRR in a keystone, because Pennsylvania is the Keystone State).

I grew up in Altoona and the world famous (and it was) Horseshoe Curve was maybe 20 minutes from town. My dad, who retired from the Pennsylvania Railroad after 38 years, used to take us kids in the 1940s and 1950s there to climb the steps up to the track level, where you could stand (with no fence, I think) and experience America's railroad traffic closeup in its glory years.

The road to the Curve continued on through a culvert under the track right-of-way, and beyond that culvert the shallow mountain stream that bordered it had a low bank where lots of people would drive their cars into the water to wash them. I can still see all those soap suds (and various engine drippings, I'm sure) going through the culvert and on their way to the Altoona Reservoir. No one gave it an environmental thought. Nor did anyone seemed to be bothered by the deer and other wildlife that drowned in our city's water supply. But I'm sure it all was treated. Well, I hope it was.

When I worked for Conrail in the early 80s, I had the opportunity to ride from Pittsburgh to Altoona on the head end of a freight train. Went by this spot and took pictures of people taking pictures of my train!