T chief confident Orange Line will reopen Monday

New rails in between the tracks ready for use for the Orange Line.David L. Ryan/Globe Staff

MBTA General Manager Steve Poftak said that 82 percent of the planned work on the shuttered Orange Line is complete and said he is confident the line will reopen as scheduled on Monday.

“We are in a great position to finish strong and finish on time,” he told reporters in a construction zone along the Orange Line tracks under the I-93 overpass near Community College Station Tuesday afternoon.

The T is aiming to have most of the track work completed by this weekend so that workers can begin the complex task of reactivating the Orange Line, such as turning back on the electrified third rail, Poftak said.

“There’s no single on or off for the Orange Line,” he said.

The system expects to begin running test cars as early as Sunday morning.

The six slow zones that the T has been targeting during the monthlong shutdown will be eliminated, Poftak said, but that won’t happen instantly. Poftak expects those slow zones to be lifted five to seven days after service resumes, once safety inspectors have a chance to observe trains’ performance on those sections. However, a few other slow zones will remain on the line, and the T is not yet able to estimate how much faster trips on the Orange Line will be than before the shutdown, he said.

One of the major projects the T undertook during the shutdown was the replacement near Tufts Medical Center of rail fasteners called “Cologne Eggs,” which dampen vibrations and provide a smoother ride and had not been replaced since the 1980s. Three-hundred ninety-five of the 400 Cologne Eggs the T was seeking to replace have been, and workers now need to replace the rails that run over them, Poftak said.

Rail replacement is 65 percent complete, track replacement is 90 percent complete, and special track replacement is 99 percent complete, Poftak said. Signal testing at Oak Grove and Malden Center is 84 percent complete, he said.

Poftak said that when service restarts next Monday, the system will be able to deploy 64 new Orange Line cars, meaning the “vast majority” of cars on the line will be new.

With the increase in traffic that came after Labor Day, the replacement shuttle buses have seen “significantly” longer travel times of about 55 minutes on the north end of the line and 45 minutes on the south end, Poftak said.

Poftak continued to allude to the possibility of shutdowns on other lines to complete track work, referencing the track safety directives contained in the scathing report federal regulators released about the MBTA late last month.

“We’re absolutely talking about it,” he said. “We cannot get all this work done on a narrow window on the overnight, we’re going to have to do some more significant investment and that’s going to mean greater access to the track, [but it] doesn’t necessarily mean diversions of this size.”

Mayor Michelle Wu said Tuesday that T crews have done “great work” during the monthlong Orange Line shutdown and that she doesn’t expect a comparable shutdown of another line on the transit system.

“I don’t think that there will be anything of the same scale of an entire line being shut down,” Wu said during her regular appearance on “Boston Public Radio” on GBH Radio.

“The city of Boston does not have a seat on the [MBTA] board. We’re not privy to the deepest of conversations,” she added. “But from all that I understand about the actual state of the infrastructure, the Orange Line, by far, had been in need of the greatest scope of repairs.”

Wu echoed other state officials in expressing confidence that the Orange Line will reopen on Monday as scheduled. But she said hiring enough workers will take longer.

“We should just set expectations as well about what the experience will be when folks return,” she said. “One big key that has not been resolved and will take time to resolve is staffing levels — the T is so short on positions like signal dispatchers and others that control the trains, it will still take some time to build that workforce back to be able to run at full stretch.”