Two highly anticipated reports on the extent of hairline cracks in the city rail system’s overhead “hammerhead” supports — and what should be done about them — were due Sept. 30 but still are not complete after a series of extensions.

Preliminary drafts of both engineering reports were turned in Friday and Monday but still need additional information to be complete, Lori Kahikina, CEO and executive director of the Honolulu Authority for Rapid Transportation, told the Honolulu Star-Advertiser from a rail industry conference in Seattle.

First discovered in the T-shaped hammerhead structures that sit atop the rail line’s support pillars in 2018, the cracks were found to have grown in length and width in June and July.

The cracks are present on a dozen or so hammerheads around five rail stations on the west side of the $9.8 billion project, which includes 19 stations along an 18.75-mile rail route.

The widest gap remains no more than 0.08 of an inch, Kahikina said, adding, “It hasn’t grown since” summertime.

The pillars and hammerheads were built separately, with the hammerheads later installed atop the pillars, Kahikina said.

HART is currently undergoing a series of tests to correct any shortcomings in all rail operations before turning the system over to the city for paid service, currently scheduled for early next year. A large-scale emergency drill of the rail system is slated for Oct. 22 at the East Kapolei station to evaluate first responders’ reactions.

With cracks on the hammerheads, the trains can be tested at speeds up to 55 mph because the weight of the trains is supported by the pillars — not by the hammerheads, which instead support the rail stations, Kahikina said. Each station is supported by two or three hammerheads, depending on the length of each station.

Engineering firm HNTB — the “engineer of record” for the rail project — concluded “that it is still safe to continue trial running,” Kahikina said. “The tracks run through the center, so the weight is on the columns themselves.”

But even if the rail system is cleared for service, the extent of the damage to the hammerheads could delay the turnover of the rail system to the city, Kahikina said.

“If those hammerheads are not deemed safe and structurally sound, we will not transfer to the city,” she said. “We will not transfer to DTS (the city’s Department of Transportation Services).”

In June and July crews from three mainland-based engineering firms — Consor, which represents DTS; Wiss Janney Elstner Associates, a “third-party engineer” hired by HART; and HNTB — joined HART’s structural engineers in taking independent measurements of the cracks.

HNTB and Wiss Janney Elstner Associates consulted with each other to reach agreement on baseline assumptions, but otherwise conducted their studies independently, Kahikina said.

“They needed to work together initially to make sure they were in alignment and one was not going off on a tangent,” Kahikina said.

While Wiss Janney Elstner Associates turned in its preliminary report Friday and HNTB turned in its report Monday, both need more data, she said. Consor is not doing its own report but will review the other studies once they’re final.

Kahikina plans to update the HART board on the status of the reports at its Oct. 21 meeting. But she likely still will not have an answer by then to the question of who will pay for any repairs to the hammerheads — HART or builder Kiewit Hawaii. “I’ve told board: I just want to fix it, and then we’ll talk” about “who’s going to pay for it,” Kahikina said.