It’s tempting to celebrate any significant move for constructing Honolulu’s beleaguered rail project, which has been set back in so many ways. And Friday’s approval of the new recovery plan by the Honolulu Authority for Rapid Transportation (HART) board of directors is a significant move, bringing the city a step closer to securing the remaining half of a subsidy from the Federal Transit Administration.

But there’s more HART must do to make this enterprise an actual success. So much more.

For now, officials for the agency and for the city have found a blueprint that seems likely to convince the FTA that a functioning system can be finished with existing funds. That would free up $744 million in federal dollars pledged to the project.

One major catch, of course, is that the terminus now would be at Halekauwila and South streets, at what’s called the Civic Center stop. It would be 1.25 miles short of the long-approved terminus at Ala Moana Center, but it at least would enable commuters heading to downtown workplaces and government offices to use the rail routinely.

Unless the city moves aggressively to find funding sources to complete the project as envisioned, however, this could mean its death by a thousand cuts. Taxpayers want the Ala Moana Center end point, and they need to be shown expressly how the city plans to get it there, ultimately.

Another major drawback would be the proposed deferral of the multilevel 1,600-stall park-and-ride at the Pearl Highlands Transit Center.

On the Honolulu Star-Advertiser’s “Spotlight Hawaii” Monday webcast, HART CEO Lori Kahikina said the eye-popping cost estimate of $330 million breaks down to $206,000 per stall. That figure became more plainly ludicrous when a local developer told HART that a parking garage had been built in Honolulu for $35,000-$45,000 per stall.

Even if HART is proposing only a temporary delay, officials really should lay the groundwork now for the park-and-ride’s construction and present it to the Honolulu City Council, the next stop on the plan’s approval process.

One alternative Kahikina noted was a suggestion to save money by moving the facility somewhere with a foundation enabling construction at a more reasonable cost, such as Leeward Community College, or connected more directly to the shopping center.

This idea should be fleshed out for the City Council, and time is tight. The FTA has set a June 30 deadline for the city to produce an acceptable recovery plan.

The FTA believes HART will need more contingency funds than it’s penciled in, Kahikina said; some of that could come from reduced financing costs if the city could negotiate an accelerated release of the remaining federal subsidy.

Losing a park-and-ride facility will surely cost ridership from the Central Oahu to North Shore communities. HART hopes to blunt that decline with better bus-rail connections.

But with a terminus at Civic Center, the system will depend largely on work commuters for its ridership. The loss of a reliable park-ride option at Pearl City would discourage riders — likely more than the recovery plan projects.

So it’s an all-hands-on deck moment to preserve the system’s most critical elements. Hawaii’s congressional delegation needs to step up and identify more available dollars that could be used for park-and-ride from federal infrastructure funding.

Public-private deals could be struck with retailers and commercial interests — say, at Ala Moana and Pearl Highlands — that stand to benefit.

Kahikina still eyes a year-end partial opening of the rail, and that is hopeful. But the real goal now is find the financing for the practical transit solution that’s been promised, and to set it up for ridership success, long-term.