A new mismatch problem has been discovered between train wheels and train track along the city’s troubled rail project.

The distance between rail tracks is too narrow by less than one-eighth of an inch leading into at least five spots where the trains cross onto different tracks.

The problem was just discovered on track that was laid in 2015, Lori Kahikina, CEO and executive director of the Honolulu Authority for Rapid Transportation, told the HART board today.

It’s a different problem than the current plan to fix the “double crossover” frogs themselves where the width of the frogs is too wide by half an inch by closing the gap through specialized welding work.

“It is a surprise that it is separate and different from what we’ve been talking about: The welding and the wheels and so forth and so on,” HART board Chairwoman Colleen Hanabusa said.

The new problem was discovered along 500 feet of rail track leading into at least five frogs, where the tracks are too narrow by one-eighth of an inch.

The entire 20.2-mile route from East Kapolei to Ala Moana Center is expected to have 12 frogs overall and seven already have been installed, with problems discovered at five of them between East Kapolei and Aloha Stadium, Kahikina said.

“This could potentially affect all of them,” she said. “… We don’t know the extent of the issue.”

There are two main ideas to fix the mismatch, including unbolting the track that leads into the frogs and then ”slide them over slightly” then rebolting the track — a process that could take weeks, Kahikina said.

Another idea would be to cut the problematic track, re-weld and retest in a process that could take months and potentially cost “a couple thousand per cut,” she said.

Kahikina told the board she had little other information.

“In the spirit of being open, honest and transparent I don’t have all of the answers,” she said. “We are still trying to determine the root cause of this issue. We are still trying to determine the appropriate solution to address this tight gauge issue. … It’s still very fresh. … This is as much as I know at this point.”

Asked by board member Anthony Aalto about the possibility of a derailment, Kahikina said the trains and tracks have been undergoing testing before the latest mismatch was discovered.

But, Kahikina said, “Worse case scenario there could be a derailment” but “… there hasn’t been an issue.”

Board member Jade Butay, director of the state Department of Transportation, asked Kahikina: “The track has been installed for years, so how is it possible that we didn’t know that this was not in tolerance?”

Kahikina responded:

“It could be all the way back from the design, to the manufacture to the installation … and our own inspection. … Right now the main focus is what is the extent of the issue and how can we fix it? … Why wasn’t this found sooner? Very good question and we’re asking the same thing.”