The beleaguered project to rehabilitate and reopen the 1 train’s Cortlandt Street station that was destroyed on 9/11 is facing even more delays.

Complications with updating the original design threaten to further delay the planned August 2018 reopening, according to the MTA’s independent engineer on the project.

After the Cortlandt Street station was destroyed during the 9/11 terror attacks, the Port Authority aimed to reopen the station in 2014. But the agency disputed construction costs with the MTA, leading the MTA to take over the $158 million project in February 2016.

That takeover has proved to be difficult. The MTA and its contractor on the project, Judlau Contracting, have so far failed to negotiate needed changes to the original design, so that communications, electrical and architectural elements meet MTA standards.

“If the current rate of productivity continues, project completion will be delayed significantly,” said Dianne Rinaldi, an independent engineering consultant, at an MTA committee meeting on Monday.

Construction would need to increase by 300% to meet the current deadline, according to Rinaldi, who measured productivity by work completed and billed per month. Based on the past sixth months, the MTA averaged $800,000 billed per month. It would need to ramp up construction to $3.2 million per month to open on its current schedule.

“This is not a pretty sight,” said MTA board member Mitchell Pally. “I could come up with other words, but I want to be nice. … We’re being delayed and delayed and delayed. Every time we get delayed, it costs us more money.”

Anthony D’Amico, the executive vice president of MTA Capital Construction, said he was “a little more optimistic,” citing recent progress in negotiations and what he considered to be Judlau’s exceptional ability to speed up construction ahead of a deadline.