Transportation Secretary Monica Tibbits-Nutt, center, speaks at a NAIOP-MA event at Foaley Hoag's Seaport District offices in March 2024 as NAIOP-MA CEO Tamara Small (left) and MBTA General Manager Phil Eng (right) listen. Photo by James Sanna | Banker & Tradesman Staff

Gov. Maura Healey said she’s appointing the head of the MBTA to fill in after state Transportation Secretary Monica Tibbits-Nutt decided to step down this morning.

MBTA General Manager Phil Eng won’t be leaving his post as head of Greater Boston’s transit agency while also serving as interim head of the Massachusetts Department of Transportation, Healey’s office said.

Eng will be joined in the MassDOT C-suite by Jonathan Gulliver, who’s being promoted from highway administrator to undersecretary of transportation. Tibbits-Nutt’s last day is today, but she’ll stay on as an advisor until Dec. 31, Healey’s office said.

Healey heaped praise on Tibbits-Nutt in a statement included in the departure announcement Thursday morning.

“Under her leadership, we made significant progress on some of the most complex and consequential infrastructure investments in state history, including the Cape Cod Bridges, West/East Rail, and the Sumner Tunnel Restoration. During her tenure, MassDOT secured more than $1.8 billion in federal transportation funding – the highest in state history – and she was instrumental in advancing equitable fare policy across the state,” Healey said. “Even before she joined MassDOT, she was advocating for fare free regional transit and, as Secretary, she delivered the state’s first fully funded statewide fare-free transit program for our 13 Regional Transit Authorities. At the same time, she supported the establishment of a groundbreaking low-income fare program for the MBTA. These programs have already made transportation more affordable for millions of Massachusetts residents. We are grateful for Secretary Tibbits-Nutt’s hard work and dedication to MassDOT and for her willingness to continue to serve as a resource for our administration.”

Tibbits-Nutt, like Eng, also made significant efforts to network in the Massachusetts business community, to help rebuild trust in the MBTA after a series of bruising failures, starting with a system collapse during the winter of 2015, and which leadership installed by former Gov. Charlie Baker proved incapable of fixing.

Prior to leading MassDOT under Healey, first as an undersecretary and then as secretary, Tibbits-Nutt was head of the 128 Business Council, which provides transit service to office parks in Waltham and Lexington, and a senior member of the former MBTA Fiscal and Management Control Board.

Healey’s office said Tibbits-Nutt “plans to return to private industry,” but the secretary’s departure comes as controversy swirls around a failed effort to select a new operator for state-owned highway rest stops and alleged misconduct by the senior MassDOT real estate official in charge of evaluating bids for that contract.

MassDOT announced Wednesday it plans to rebid the service plaza contract.

During a press conference Thursday morning, Healey threw cold water on speculation Tibbits-Nutt’s departure was linked to the service plazas case or an earlier incident where Tibbits-Nutt drew flack from right-wing groups and business leaders for unguarded comments about considering new highway tolls to help pay for transit upgrades.

“I think it’s normal, if you look back at other administrations. These are hard jobs. These are really hard jobs, and I’m just really grateful to the strength and the quality of all who have served. Some have moved on, and others have moved in,” Healey said. She added that she did not ask Tibbit-Nutts to step down.

Asked how long Eng might serve in the secretary’s job, Healey said she is taking it “day by day.”

Eng said that he and Tibbits-Nutt have communicated with each other, but that it has “not been discussed” whether he’s a candidate for the permanent position. Asked if he’s open to holding it beyond the interim role, he said he’s “open to holding it as long as it’s needed.”

Material from State House News Service was used in this report.