If the MTA still plans to open the first phase of the Second Ave. Subway by the end of December, as the agency continues to insist it will, completion of the work will require an “aggressive and unprecedented” effort, an independent engineering consultant warned the MTA Board on Monday. For their part, MTA officials continue to say that December is not only feasible but realistic, and after years of delay, the agency has yet to push back the opening date for the project.

Word of delay isn’t exactly new. Setting aside the fact that this project was supposed to be completed three or four years ago, delays have been the theme in December, January, February, March, and April — essentially every month during which the Board has received regular updates. In May, the IEC raised a skeptical eyebrow but didn’t have additional words of warning. This month’s report lands with a bang.

As the MTA Board materials indicate, the same hot-button items are the culprits. Elevators and escalators won’t be ready for testing, and fire safety systems are lagging behind. If this sounds familiar, well, it’s why the 7 line extension opened nearly 20 months behind schedule, and it’s an issue on the Upper East Side as well. The IEC put it bluntly in its latest update:

“Initial testing activities have not kept pace with the schedule for test completion. 67% of scheduled tests were completed by the end of May. Another 1104 tests need to be completed by the end of October 2016. Should the Project experience delays in testing at the three new stations similar to that which occurred at the Lexington Ave/63rd St. Station, the December Revenue Service Date would be impacted. The time available for testing of station equipment and rail systems requires a very aggressive and unprecedented performance of the combined MTACC and NYCT test teams.”

That last sentence is key. The MTA’s agencies are not known for cooperating with each other. Due to political inter-agency turf battles and the issues with handing over the keys from one agency to the other, MTACC is very territorial, and joint testing between Transit — the folks ultimately responsible for operating the Second Ave. Subway — and MTACC — those tasked with building it — is complicated in part by design and in part by stubbornness.

Meanwhile, both the IEC and MTA officials have thrown up red flags. The MTA keeps implementing change orders, and the IEC notes that the contractor installing communications equipment is going to miss every single upcoming deadline, putting the project’s completion at risk. Meanwhile, MTA Capital Construction President Michael Horodniceanu found no one working at project sites over the weekend.

None of this sounds particularly promising as June ticks to a close, but MTA officials are hewing to the party line. “There is no reason at this time to believe the project won’t open by the end of the year,” newly installed MTA communications head Beth De Falco said to the Daily News — no reason, that is, except many of them, if you believe the IEC, and a history of failing to finish projects on time.