Honolulu Mayor Kirk Caldwell would like some answers, please.

After receiving a letter 10 days ago from the board chair and executive director of the Honolulu Authority for Rapid Transportation detailing more than $200 million in potential additional rail cost overruns and a likely one-year delay in the project’s completion, he replied to both leaders with a letter pointedly asking for details in six areas.

Principal among his concerns seems to be that the Sept. 14 letter sent by Board Chair Don Horner and Executive Director Dan Grabauskas differs from information the project provided last spring to legislators. HART and Caldwell sought and the Legislature passed a five-year extension of the .5 percent general excise tax surcharge funding the rail project.

Caldwell asked Horner and Graubaskas what information they obtained after the legislative session that led to the $200 million upward budget revision and the pushback of the “final Milestone date from January 2020 to the ‘more likely’ 2021 date?”

The Sept. 14 letter pointed to a total of nine of 21 rail stations that have come in “at or under budget” — three of them “well under.” “While this is encouraging news, the project’s construction over-budget number … remains at $594 million above original cost estimates included in our last budget update,” the HART leaders wrote, adding that they project an additional $100 million in GET shortfalls, as well as a $210 million loss in Federal Transit Administration funding.

That total of nearly $910 million in cost overruns plus the potential $200 million in potential escalating costs from construction in the city’s core would push the project $1.1 billion into the red.

Caldwell asks Board Chair Horner and Executive Director Grabauskas what steps they could take to stick to the 2020 completion date — and what those steps might cost.

In his response, the mayor requests deeper detail regarding project costs or elements that are no longer part of HART’s budget assumptions. He also asks Horner and Grabauskas what steps they could take to stick to the 2020 completion date — and what those steps might cost.

He asks about the potential opening date for an interim, 15-mile phase featuring 13 stations between East Kapolei and Middle Street — a section that would include Honolulu International Airport and Pearl Harbor. Opening that shorter segment early would allow the project to begin generating revenue and get people used to riding on the rail system.

Horner and Grabauskas said 73 percent of the land required to complete the entire project is now in hand, but Caldwell wants to know how much more land is needed to support the project’s “minimum operable segment” and how revenue from that would compare to revenue from the 15-mile interim phase.

It’s a cordial letter, with Caldwell’s questions bracketed by praise for new project communications that are “transparent and forward thinking,” for surpassing the four-mile mark in rail guideway construction and reaching 80 percent completion of the Rail Operations Center. The latter is particularly significant, given that rail cars are expected to be delivered to Honolulu in the first quarter of 2016.

But Caldwell also slips in a sentence seemingly to absolve himself of responsibility for incorrect or problematic information that may have been supplied during the legislative session, writing, “All substantive project information provided to the Legislature was provided by HART.”

Despite the fact that the Horner and Grabauskas letter was addressed to both Caldwell and Honolulu City Council Chair Ernie Martin, Caldwell’s reply went to Horner and Grabauskas only without even a “cc” for the council leader. A persistent Caldwell critic, Martin is thought to be preparing to challenge Caldwell when he stands for re-election next year.

Read Caldwell’s letter here:

Read the Sept. 14 letter from Horner and Grabauskas here: