More than 2,000 cracked plastic pads have been found along the first 10 miles of the rail line, rail officials said.
While the defects don't pose a safety issue and will be paid for by the contractor, Honolulu Authority for Rapid Transportation board members worry that the issue will further erode the public's confidence in the beleaguered $8.2 billion project.
"I think it's not acceptable for us as a board or even HART to just expect us to say OK," said HART Chairwoman Colleen Hanabusa.
"Imagine the stress of a train going over that. You don't think that if there's a problem there's going to be potential crack?"
The pads, or shims, are made of high-density plastic and are used to elevate the rail track. There are about 110,000 of these shims in use now.
According to the rail authority, the cracked pads may not conform to their specifications and don't contain enough protective material for UV damage.
Contractor Kiewit has agreed to replace them at its expense, but some worry about potential delay costs.
These and other construction defects were discussed at a HART board meeting Thursday.
Rail staffers also said that several of the metal cables within the rail system's concrete guideway were frayed. The also found some corrosion on the protective grout around some of the tendons.
The cables or tendons join each of the segments of the concrete guideway together. They help bear the weight on the guideway.
Kiewit recently checked to see what would happen if these tendons were ruptured.
"There was no discernible stress, no sign of cracking, the tendon didn't snap, things didn't fall apart," said HART staffer Taka Kimura.