“Major challenges” with station canopies could stall the planned December 2020 launch of interim service for Oahu’s rail line, project leaders revealed Thursday.

The nearly identical canopy designs for the nine westernmost stations, from East Kapolei to Aloha Stadium, have “constructability issues,” according to Honolulu Authority for Rapid Transportation Executive Director Andrew Robbins.

The designs by the engineering firm AECOM will need “tweaks” if those structures are to be built, Robbins said.

There was an ”engineering issue in terms of how suitable the design was for construction,” he said after a HART board meeting Thursday. Robbins didn’t elaborate.

Oahu’s station canopies were originally designed to represent the sails of the modern Hawaiian voyaging canoe Hokule‘a, and they’re supposed to provide shade and shelter to waiting passengers.

However, cables and conduits that help operate the rail line must also pass through the arms of the canopies, Robbins said. If the canopies are delayed, that would postpone installation of rail’s communications systems as well.

HART staff members recently started dealing with the station challenges on a daily basis because otherwise, “we won’t get there,” Robbins said of the quest to open rail for service as far as Aloha Stadium by the end of 2020.

“I don’t intend to give up,” Robbins told board members.

Toby Martyn, one of four nonvoting HART board members appointed last year by state legislators, brought up the interim opening during the meeting. He said that west Oahu residents have asked him when the interim service will start and he wants to be sure to give them accurate information.

Under HART’s most recent schedule estimates, the launch of the island’s full 20-mile, 21-station rail line won’t happen for another seven years — December 2025 at the earliest.

The interim launch to Aloha Stadium in 2020 has long been touted as a key step to help familiarize the public with the transit system years before the complete line starts running to Ala Moana Center.

Robbins said Thursday that a delay in interim service would not affect rail’s full opening. He did not specify how long the interim service to Aloha Stadium might be delayed. He also said he wasn’t sure of the ridership projections for the interim service, if there are any, and HART staff did not provide any follow-up details.

The nine western stations would need to be completed by September 2019 to leave HART enough time to test the rail system and hit its interim opening goal about a year later, Robbins said.

It’s not the first time the rail station canopies have caused headaches for rail officials. In 2016, the HART board approved a nearly $4 million change order to help cover design revisions to the elevated guideway after the canopies were added to the plan.

Officials realized that in heavy winds the canopies — like the sails they emulate — would create heavier loads. The concrete-and-steel guideway would need to be able to handle them.

Unlike the west-side station canopies, the 12 east-side canopies are being designed by the same company handling construction. So if there are any issues with those canopies they can’t be blamed on a separate designer, Robbins said.

HART has repeatedly considered simplifying the canopy designs as a way to save some costs in the face of budget problems.