More A and F trains are leaving riders hanging on platforms than most other subway lines in the system, according to new MTA stats.

With an increase in repairs and inspections, about 70% of weekday trains on the A and F lines last year were on time, a 4% drop from 2013. And when it comes to major gaps -- meaning a train was late by double the time it had been scheduled for -- it got even worse for the 1.2 million riders who use those lines each day. Each had 12% of trains arriving after such a delay, about 6 percentage points higher than the year before.

"What's disappointing is that you'll see no trains for an extended period of time," said Alex Freij, 35, a contractor in Manhattan who commutes to Brooklyn on both the A and F. "There'll be none for 15 to 20 minutes, and then they'll be back to back to back."

Ricardo Valle, 25, of Harlem, said it's "hit or miss" waiting for the A train at his West 145th Street stop after leaving his house around 7 a.m., when trains are supposed arrive every six to nine minutes.

"If I do catch the train, it'll be really late, or it'll be too crowded and I'll have to take another one," he said.

By comparison, the 15 lettered lines, including the Brooklyn and Queens shuttles, together had an 80.6% on-time average for trains last year, holding steady from 2013; average weekday wait times in December improved 3.5% to 81.5%, compared to the same month the prior year.

The only trains that had similar performance issues were the Nos. 4, 5 and 6 on Manhattan's chronically congested Lexington Avenue line.

That line carries roughly 1.5 million riders a day, moving more people than some cities' entire mass transit systems are capable of carrying.

The MTA, which calculates platform wait times on a 12-month average, put the blame for increased delays on more track work in the past 18 months, particularly on Superstorm Sandy-related repairs and infrastructure improvements, said spokesman Kevin Ortiz.

Additionally, there are more inspections and tougher safety rules protecting track workers while trains are running, he said.

"We think we can do better at determining when and how we go out to do planned work on the system," Ortiz said in a statement. MTA officials will be working to "optimize the distribution of work throughout the system, and to target specific locations with increased preventive maintenance in a way that minimizes impact to service."

Systemwide, the top three reasons for trains getting held up -- overcrowding, "right-of-way" delays, and track gangs -- made up 63% of 47,430 delays in December.

Thomasin Bentley, a member of the Riders Alliance, a transit advocacy group that has called for A and C train improvements, said she has noticed the construction and delays.

"I definitely feel it most on the F train than any other line," said Bentley, who commutes on the F train from Windsor Terrace. "It's both in the morning and the evening."

"It's just not a reliable train," she added.