The F train is the MTA's most delayed subway line, according to a new report from the Straphangers Campaign, a non-profit activist group that monitors NYC's public transportation and advocates for commuter rights. The group's third annual analysis of the MTA's electronic alert system has found that the number of "delay-generating incidents" has increased 35% since 2011. The F train is most-delayed (followed by the 4 train), the J/Z is the best, and the number of L train delays has increased 91% in two years.

According to an official MTA response to questions from the Straphangers campaign, an alert is issued for any reported incident that will impact service more than 8 to 10 minutes. Only incidents deemed "controllable" were accounted for, i.e. track problems, but not sick passengers or police activity. There were 3,998 such incidents in 2013.

The report compared 2013 to 2011, as the effects of Hurricane Sandy in 2012 were anomalous, and probably confirmed what you already know and experience on your daily commute. The F train ranked first for the most delays of all 20 subway lines reviewed, the number of L train delay incidents has jumped from 96 MTA in 2011 to 183 in 2013, mechanical and signal problems accounted for 66% of all incidents, and the number of track delay alerts jumped 101% in two years, from 254 to 510.

The report raises a number of additional questions: is there a connection between the number of incidents and the amount of service a line provides? Why are signal and mechanical problems the leading causes of delays? And are delays related to outstanding service problems and ongoing repairs?

Gene Russianoff, an attorney for the Straphangers Campaign, concluded from the report that "the increase in alerts is a troubling sign that subway service is deteriorating." The MTA does not release information on how long specific incidents take to be resolved. On Friday, an F train in Queens derailed injuring 19.

UPDATE: The MTA has released this statement in response to the report:

Since 2011, the amount of time customers have had to wait for a train throughout the system has remained flat. We agree that the service alerts are a powerful tool that deliver meaningful information to customers. We have increased staff and have become more efficient in providing service information in a more timely manner so customers are quickly aware of any incidents that may impact their commute. owever, the cause of such incidents can quickly change upon further investigation which is why the alerts were never meant to serve as a performance metric. Our wait assessment metric, which includes BOTH controllable and non-controllable incidents and measures the amount of time customers have had to wait for a train , provides a more comprehensive picture of service quality. Despite increased ridership and the challenges we face with these incidents, we continue to develop and deploy strategies to maintain even intervals of service for our customers, and our wait assessment metric reflects this focus. Again, since 2011, the amount of time customers have had to wait for a train throughout the system has remained flat.