MTA text and email alerts warning subway riders about delays are on the rise, and the F line has the most, according to a report released Tuesday.
The report by the rider advocacy group, NYPIRG Straphangers Campaign, said the MTA sent 2,967 alerts about "controllable delays" in 2011 and 3,998 in 2013, an increase of 35 percent.
The group said it did not count alerts about sick passengers and police activity, and only analyzed alerts about delays it decided were under the agency's control, like signal or mechanical problems.
Mechanical problems accounted for 1,411 of the 3,998 alerts in 2013, followed by signal issues with 1,230. Track problems accounted for 510 alerts, and switch issues were blamed in 438. Power problems accounted for 30 alerts.
The F line had the most delay alerts in 2013, with 326 alerts, followed by the 4 line, with 298, and the 2, with 289. The J/Z had the fewest, with 1 percent.
The L line had the poorest performance from 2011 to 2013, going from 96 delay alerts to 183 alerts.
The MTA said the report does not paint an accurate picture of subway delays. The agency does its own "wait assessment" that includes both controllable and non-controllable problems, and asserts that rider wait time remains flat since 2011.
"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," the MTA said.
The MTA launched its alert service in 2008. More than 104,755 people have signed up, including 90,000 who are specifically subway riders.