A federal judge’s acceptance of the city’s overall environmental assessment of Oahu’s rail project is a welcome stamp of approval. More-detailed review of cultural properties ordered by his ruling must now proceed with due diligence to enable construction to resume, but it brings huge relief that the judge rejected principal legal objections to the project.

From the outset, opponents of the rail project contended that alternatives — such as an express highway similar to the three-lane expressway in Tampa, Fla.; alternative rail technologies; or an improved bus system, embraced by lawsuit plaintiff and former Gov. Ben Cayetano — had been inadequately assessed in the project’s final environmental impact statement.

That was not the case, ruled Judge A. Wallace Tashima, a 9th U.S. Circuit Court of Appeals judge presiding over the District Court case. In preliminary assessments, experts had found that the Tampa project "was not a good cost comparator," bus rapid transit would not alleviate traffic congestion and the steel-on-steel system would be superior to other rail alternatives, judgments that were "neither arbitrary nor capricious," the judge explained in his 45-page ruling Thursday.

Tashima’s decision means the city will need to assess the rail’s effect on Mother Waldron Park, a Kakaako park listed on the National Register of Historic Places. The judge ruled that "there is a great deal of evidence" that the rail line’s effect on the park "will be quite serious," so the city will need to provide alternatives or "mitigate any adverse impact" to the park.

Tashima’s ruling also calls for the city to "fully consider the prudence and feasibility" of a tunnel underneath Beretania Street to avoid above-ground presence involving historic sites, including Chinatown and the Dillingham Transportation Building. The cost could be enormous, and the city will need to put forth a reason not to dig.

Let’s hope that Daniel Grabauskas, CEO of the Honolulu Authority for Rapid Transportation, is right in saying that city deliberations ruling out the feasiblity of this tunnel is actually "quite complete," that the issue is a simple matter of placing the tunnel assessment "within the EIS record."

While Tashima’s rulings on the tunnel, Mother Waldron Park and cultural properties potentially delay construction further, they should not put an end to rail. In fact, construction is already on hold for archeological survey work along the entire 20-mile route, ordered by the Hawaii Supreme Court in August. Tashima’s requirements could well occur concurrently, to keep as close to the project timetable as possible.

Delays due to the archeological work are estimated to cost $64 million to $95 million. There is considerable concern over how many more millions the work ordered by Thursday’s ruling will cost taxpayers, and we need to hear details on those costs to gauge the depletion from the project’s contingency fund. There also are questions of how this latest ruling will affect the pending $1.55 billion federal grant request.

However, we share the optimism of outgoing Mayor Peter Carlisle, who is "confident that a reasonable remedy can address the remaining issues in a timely manner." And Grabauskas rightly notes that Tashima’s ruling "underscores that the majority of alternatives were given proper consideration," including bus transit, a system proposed by Cayetano in his mayoral bid against Kirk Caldwell. That key race will be decided on Tuesday’s general election.

It’s important to realize that with these two recent court rulings, the rail project appears to have cleared its highest legal hurdles. Indeed, some obstacles seem to have been self-made by lack of past thoroughness, and yes, there remains a Dec. 12 hearing before Judge Tashima for a permanent injunction to stop rail. But remedies are well under way to correct the missteps, and these legal lessons should make for a tighter, more accountable project going forward.