There was a rear-ender in Wales some years ago involving two 2-car diesel mu trains, one of which was leaving while the one behind it was arriving -- fully according to the rules, restricted speed, and so forth. As the lead train departed, a passenger was seen running along the platform waving his arms, and since this was a rural part of Wales and the next train was several hours later, the driver of the lead train stopped for him. The writer of the report commented that "dmus don't have brake lights," and since both trains were moving slowly it was not apparent that the lead train was slowing down instead of accelerating until it was too late for the following train to stop in time. This seems like just the thing that could happen at Temple or any other Center City station. And putting in a special instruction that a train is not permitted to stop once in motion might seem rather draconian, since hourly headways are common on SEPTA outside peak hours.
(Put brake lights on the Silverliner VI's?)