Tuesday marked the deadline for groups interested in building the next stretch of rail guideway and stations to put their names in the running. But project officials say they can’t yet disclose who — or  how many parties — responded.

Such details about the level of interest in the so-called “airport guideway and stations” contract could prove significant, given project officials’ concerns over whether “viable” teams were forming to compete and eventually build such a massive chunk of the system.

The contract represents roughly a quarter of the 20-mile rail line, in a stretch that includes Honolulu Airport, plus four of the system’s 21 stations. Its cost will almost certainly climb into the hundreds of millions of dollars. The two contracts to build rail’s first 10 miles of guideway — which did not include any of the stations there — totaled $855 million combined, according to city records. Kiewit Infrastructure West Co. is handling that work.

In a May report, Jacobs Engineering Group, the transit project’s independent monitor, briefly mentioned the rail officials’ concerns over viable teams forming to do the airport guideway and station work.

However, Honolulu Authority for Rapid Transportation officials have blocked subsequent attempts by the media to gain insight into the issue, citing a need for the contract to be issued first.

HART did issue a statement Tuesday that touted the responses it received for the airport-area contract but didn’t specify what that number was.

“HART has invested much time and effort in listening to the contracting industry and we are working hard to ensure our contract solicitations generate a high level of interest and competition,” HART spokeswoman Jeanne Mariani-Belding wrote in an email. “We can confirm that we have received a competitive number of proposals and we are encouraged by the level of interest in this contract.”

Tuesday’s deadline originally was slated for June 9, but it wound up being extended about two months in order to allow joint-venture teams to form, according to the Jacobs report.

It was the first step in a two-step process. Any teams that responded by Tuesday had to list their qualifications, rail officials said. They can now advance to the next step, where they draft their proposals on costs and the technical aspects of the guideway and four stations.

HART officials said that they couldn’t release details on who or how many parties responded because state administrative rules on evaluating proposals force them to keep those details confidential until after the contract is awarded. (The rules section that they cited, 3-122-53(f), states that the “contents” of a proposal cannot be disclosed during the discussions for a contract.)

Last week HART also denied a Honolulu Star-Advertiser request for the emails and other correspondence that might shed light on the rail agency’s concerns about viable candidates. HART cited a need to protect the “quality of agency decisions by ensuring uninhibited discussion” in justifying its decision.

The denial came after HART had given itself a 10-day extension to process the paper’s request. Belding said that’s because HART’s legal counsel is always the last to review before the agency releases those records.

Those who responded by Tuesday’s deadline will now have to submit their price proposals by January, according to the Jacobs report.