In the later months of 2016, staffing problems have become the single most frequent cause of train annulments on the Regional Rail's 13 lines. From May to October this year, 596 out of 951 train annulments were caused by staffing problems, according to SEPTA records. That includes 236 trains canceled in July and August, when SEPTA was struggling with scheduling problems after taking a third of its rail fleet off the tracks due to systemic flaws in the railcars' construction. By comparison, from January 2015 to April of this year, a lack of personnel accounted for 138 train annulments.