It always used to be the case that SEPTA ran the Silverliners with the doors and traps open (save for express service, etc.). About 5-6 years ago, I noticed an abrupt change in behaviour. Suddenly these were being opened and closed at each station, so I am certain that SEPTA set new rules at the time that these are to be closed. However, as time has worn on either the rule has been relaxed or the crews started to fall back into their old habits and disregarded them. Nowadays it really depends on the crew. Some trains I see with both doors and traps open, others with the doors closed but the traps open (perhaps slightly more common), and on rare occasion those with both closed. The big advantage to SEPTA of running the traps open is that they do not need to have crew member present at each door to open these traps at each station. Many a time I have detrained a Silverliner when there was no crew member in my car pairing, so it really requires more manpower than SEPTA is accustomed to using. Opening both traps (i.e., the rear on car one, the front on car two) also takes a non-trivial amount of time away from collecting tickets and fares (at least on the Paoli-Thorndale line where the distance between stations is so small). Perhaps that is why the practice has persisted.
