Unless it was a charter, it must have been running way late, unless the story has an error. I can't find any Greyhound services that run from New York to St. Louis that would be 90 minutes to 2 hours out of Philadelphia at about 6:00 a.m. There is a a service from New York to St. Louis that leaves the Big Apple at about 9:15 p.m. and arriving in the City of Brotherly Love around midnight. It has a rest stop at "Sliding Rock" starting at 4:20 a.m., and arrives in the Steel City (or whatever Pittsburgh's nickname is) at 6:05, which might have caused the confusion in the story (i.e., the ETA for Pittsburgh might have been given as the time of the accident).