The agency overseeing the island’s financially troubled rail transit project is losing another key leader.

Brennon Morioka, who’s worked nearly 4-1/2 years as the Honolulu Authority for Rapid Transportation’s deputy executive director, submitted his resignation earlier this month, according to rail officials. He’ll leave the agency this week.

In an email Friday, Morioka said he’s accepted a job at Hawaiian Electric Co. to help the local utility’s push for more electric-vehicle use. He previously led the state Department of Transportation under former Gov. Linda Lingle, and he’s been at HART since February 2013.

“It’s really been like a sprinter’s pace for the entire time. Having gone through this kind of pace once before when at HDOT, I knew that it was just time for me to take a different path in both my career and my life,” Morioka wrote Friday.

He’s the latest in a line of at least 16 directors, managers and other prominent personnel to leave HART since 2015, as the 6-year-old agency has struggled with vacancies and retaining institutional knowledge while overseeing the largest public works project in the state’s history.

“We really do have to fix the staffing problem,” Morioka said at a Nov. 10 rail board of directors meeting.

Additionally, the rail project has seen a near-total overhaul of its 10-member volunteer board in that same period. Only one original member from 2011 remains: board Chairman Damien Kim.

A peer review penned by transit industry experts from across North America flagged the issue in March.

“The frequency of staff turnover is high and impacts project delivery,” the report by the American Public Transportation Association stated. It blamed much of HART’s turnover on requirements for a one-year personal services contract, which it said deprives agency staff of long-term employment guarantees.

Morioka wasn’t subject to those one-year contracts, according to a rail spokesman. He has helped steer HART through several difficult years of tumult. In recent months Morioka’s been one of three key leaders at the agency, alongside Interim Executive Director Krishniah Murthy and Project Director Sam Carnaggio.

He played a big role in HART’s years-long wrangling with HECO to find a cheaper fix to rail’s utility-clearance woes. In February, he presented the agency’s agreed-upon plan to save some $140 million budgeted for utility relocation along the west side by using specialized trucks and cranes. HART still anticipates it will spend about $70 million to put power lines underground along Dillingham Boulevard, however.

Morioka was also a fixture at the state Capitol during hearings on rail’s massive budget shortfall, and officials say he’s spent much of 2017 meeting with lawmakers on the problem.

Earlier, in June 2016, as rail’s latest budget woes deepened, he presented to the board six rough options on how to address the problem. Later that summer, as the board and former Executive Director Dan Grabauskas hashed out an agreement in private for Grabauskas’ resignation, Morioka took on a greater role updating the board and the public on rail issues.

Murthy, the interim director, has a one-year contract that expires in December while the board seeks Grabauskas’ permanent replacement.