ON MAY 8, the MBTA sent out a press release saying the planned reopening of the Blue Line set for that day needed to be extended until May 13 “to complete additional work and finish scheduled work.”

The next day, on May 9, I contacted the MBTA asking for more information on the reason for the extension. A source at the T had passed along that a test train had derailed, which played a role in the need for an extension.

T spokeswoman Lisa Battiston responded that a test train had not derailed, but otherwise provided little information. I responded that the source’s terminology may have been inexact, but there was some problem with the track that caused a vehicle to come off of it.

I asked for more information. Battiston did not respond.

Over the next few days, I kept peppering Battiston with questions asking for more information. Very little was provided. On May 12, when another extension in the Blue Line shutdown was announced, the T did disclose that a vehicle had derailed “earlier in the week.”

Only on May 16 did MBTA General Manager Steve Poftak acknowledge that tool carts had actually derailed on three separate occasions. Asked why the derailments were not disclosed earlier, Poftak said: “I’m sharing that with you now. I don’t know the strategy of not doing it previously, but I wasn’t involved with that.”

Nearly two months later, the Boston Globe’s Taylor Dolven, citing emails, phone logs, and other information obtained through public records requests, reported Poftak and officials in Gov. Charlie Baker’s office had withheld information about the derailments from reporters and the public.

That wall of silence became a central focus on Monday of the first of several legislative oversight hearings examining safety issues at the MBTA. Lawmakers grilled Transportation Secretary Jamey Tessler and Poftak about a wide variety of safety concerns, but they kept coming back to the T’s lack of transparency about construction vehicle derailments on the Blue Line and what that said about the agency’s honesty with the public.

“They confirmed our worst fears,” said Sen. Brendan Crighton, the co-chair of the Legislature’s Transportation Committee, who initiated the questioning about the Blue Line construction derailments. “Transparency is not their priority, press strategy is.”

Poftak responded to the questions by saying he was mostly focused on getting the track repair work done quickly and safely. “The communication aspect, I concede, did not get my full attention,” he said.

Tesler said the governor’s office was brought into the discussion because the delay in reopening the Blue Line affected the state’s entire transportation system. He said he could not recall any direct conversations about the matter with the governor’s office, but said that if he did have a conversation on that subject it would have been with governor’s chief of staff, Tim Buckley.

Both Poftak and Tesler said they could have handled the situation better, but they insisted they would always incorporate the governor’s office into such discussions, even though lawmakers raised concerns about the governor’s aides micromanaging press dealings.

A good chunk of the hearing was focused on developing a strong safety culture at the MBTA. The  questions about the withholding of information on Blue Line derailments seemed intended to raise questions about whether transparency about safety issues is a high priority of the state’s top transportation officials.

“Why was this hidden?” Crighton asked. “It should have been an easy situation to deal with.”