Twenty-one rail support columns have been injected with epoxy, and more material to fix the eight widest cracks is expected to be delivered within the month, according to the head of the Honolulu Authority for Rapid Transportation.

HART Executive Director and CEO Lori Kahikina told the authority board Thursday that repairs to all the so-called “hammerhead” columns and testing of the nearly $10 billion rail system are expected to be complete by the end of May, two months before paid passenger service is expected to begin.

When fully built out, the 18.75-mile rail system will serve 19 stations from East Kapolei to a proposed City Center station on Halekauwila Street in Kakaako.

HART board member Roger Morton, director of the city Department of Transportation Services, which will operate the rail system, told the Honolulu Star-Advertiser earlier this week that initial rail service is expected to begin in July from East Kapolei to Aloha Stadium, until additional segments are completed.

In 2018, cracks were discovered in 21 hammerheads that sit atop rail pillars and support stations. The widest gap was no more than 0.08 of an inch.

Ongoing testing of the rail system may be complete even before the end of May, Kahikina told the board.

She told the Star-Advertiser in December that contractor Hitachi Rail Honolulu, manufacturer of the system’s driverless trains, is being evaluated for 144 emergency scenarios and has to have a 98.5% average success rate in the trial runs over a 30-day period.

“And so far they are doing pretty good; they’re in the high 90s,” Kahikina told the board Thursday.

HART also announced this week that beginning Monday, HART and contractor Nan Inc. will extend work on Dillingham Boulevard from Alakawa to Kaaahi streets.

The current one-lane configuration will extend continuously from Middle to Kaaahi streets.

All left turns along Kameha­meha Highway and Dillingham Boulevard from Middle to Kaa­ahi streets will be restricted, except for the westbound left turn from Dillingham Boulevard onto Alakawa Street, which will remain open.

Intersecting streets along Dillingham Boulevard in the mauka and makai direction will continue to be closed as needed during nighttime hours from 7 p.m. to 5 a.m.