A watchman, Ernest Smith, at the Central Avenue railroad crossing in Canonsburg, PA, reported that 115 trains (passenger, coal, and general-freight), had crossed on a Thursday in April, 1902 on the Chartiers branch. That is a lot of traffic for a "simple" branch line! The pages linked to below provide all the prototype information about the equipment that ran on the Chartiers branch at around 1924. These pages will be updated over time.
As an aside, according to the Pennsy Power book, the PRR, in total in 1924, had a staggering 7,556 locomotives, 3,335 of which were the 2-8-0 engines. There were 579 2-8-2 engines, 700 4-6-2 engines, and 598 2-10-0 engines in their total fleet.