Revelations of mismanagement surrounding Oahu’s rail transit project have, unfortunately, become routine: the ever-increasing price tag (now at $8.6 billion), the inability to properly address utility clearance issues along the route, delays in construction timetable, and so on.

Now, though, new reports that parts of the rail guideway are cracking and snapping before the first stretch of the guideway is finished further diminishes public confidence in the beleaguered project.

Construction costs are already skyrocketing — but to hear that what’s built is already falling apart should cause even the most ardent rail proponent to shudder.

Cracks are forming in the “shims,” the plastic padding used to give the tracks a level surface, and strands in three of the tendons that help keep the guideway structure in place have snapped apart.

Future riders can take no great comfort in hearing that if one tendon breaks, it would not cause “catastrophic failure,” as a Honolulu Authority for Rapid Transportation (HART) design manager stated.

Already, one dozen defective tendons have been replaced, including the three with snapped strands. But taxpayers footing the bill deserve a full explanation from Kiewit Infrastructure West, the firm building the first half of the guideway — and assurances that what’s being built won’t crumble under the stress of occupied rail cars.

Rail officials are banking on strong ridership, but that can only be achieved if future passengers are confident they will be safe on each daily commute.

The defects were highlighted in reports by HART and the project’s federal oversight agency and discussed Thursday at a HART board meeting.

HART officials told the board that water draining out of the rail guideway’s concrete spans apparently seeped into some of the anchors that lock the steel tendons to the structure, causing them to corrode.

It’s no wonder that Colleen Hanabusa, HART board chairwoman, said she had “serious concerns” about whether Kiewit has sufficiently tested tendons to make sure they don’t miss any more damage along the first 11 miles.

“We need to be able to assure the public that (Kiewit officials) have done everything they can,” she rightly said.

Rail officials and Kiewit originally opted to use the plastic, narrow shims instead of a “plinth” — essentially an elevated concrete platform — because they estimated it would save more than $7.5 million along the project’s first 11 or so miles. Now, though, questions emerge on repair costs, as well as about corner-cutting and substandard materials and techniques.

There’s too much at stake to be penny-wise but pound foolish. The structural issues cannot be brushed aside. The public deserves to know the true extent of the damage, a detailed action plan to fix what is wrong and the costs involved. To provide anything less is unacceptable.

News of the safety concerns follow months of turmoil at HART, including the recent resignation-under-pressure of its executive director, Dan Grabauskas.

And further tumult is ahead for the agency: Both Hanabusa, who is running for her former congressional seat, and acting Executive Director Mike Formby are expected to exit before the Nov. 8 general election.

What will be left is a gaping leadership void at HART at a time when critical issues need to be addressed — for starters, reining in costs and bringing the project back on track.

The current $8.6 billion price tag is $700 million more than the figure HART issued just four months ago, in early June, when the cost for the rail line and its 21 stations was estimated at $7.9 billion.

Firm figures will be needed before HART and city officials lobby state lawmakers to extend the 0.5 percent general excise tax surcharge — unlike the underestimated financials in 2015 when the surcharge was extended.

The HART board, including its incoming member to replace Hanabusa, must ask hard questions to be the taxpayers’ forceful gatekeeper.

As for hiring HART’s executive director, an effective administrator with a strong construction background is crucial. Grabauskas’ experience, unfortunately, had been in rail operations, and clearly, we are a long way from that.

It is unrealistic to expect a major public infrastructure project such as Honolulu’s rail transit system would be built without price hikes and stumbling blocks. However, to now add defective construction on a growing list of management problems further diminishes public hope that this project will somehow, ever, turn the corner.

Some assurance from those in charge is sorely needed.