SAN FRANCISCO — A potential major stumbling block has developed for the Golden Gate Bridge suicide barrier project now that a low bid for the work has come in almost double the construction cost estimate.

The bridge district opened two bids for the work at its board meeting Tuesday. The low bid came in at $142 million from the Oakland-based Shimmick/Danny’s Joint Venture. The Pennsylvania-based American Bridge Co. submitted its bid at $174 million.

The bridge has a $76 million financing plan in place approved by the board that was based on consultant estimates.

“When you open bids you have to take a deep breath and go back and evaluate everything,” said Denis Mulligan, bridge district general manager. “Certainly, we were hoping for a different array of numbers.”

Each bid was hundreds of pages, and in the coming weeks bridge officials will look more closely at the submissions to determine if any cost savings might be found.

“Until we look at their numbers, we don’t know,” Mulligan said. “We want to get a sense for how they see it different from us. Clearly the contractors saw something that made them nervous.”

That such a project is unique may have been the reason for the cost discrepancy.

“Nobody has done this before,” said Ewa Bauer, chief engineer for the bridge. “The main thing right now is to look inside those submitted bids to see how the contractors see the job.”

After board review, the district must go to Caltrans and the Federal Highway Administration for approval of the bids, even if the they are ultimately rejected. That is expected to occur in the fall.

The high bids will almost certainly delay the start of the project, which has seen its share of fits and starts.

In a historic vote in June 2014, the Golden Gate Bridge board voted unanimously to build a suicide barrier to the applause and tears of supporters, including family members of those who jumped from the span.

By December 2014, the same panel approved a final design for the barrier, with a goal of going out to bid in March 2015 to commence work. The district was able to get permits from Caltrans and federal highway officials for the work, but delays in working with the National Park Service delayed the bid process from starting until last October.

In February, bridge officials reported there would be a two-month delay in opening the bids, in part because the original steel selected for the project could not be manufactured in large enough quantities in the United States. Because of the steel and other revisions, the bid opening date was moved from March 8 to May 3. But a second delay pushed the opening until Tuesday. That came about because potential bidders had multiple questions on the project that couldn’t be easily answered.

The barrier work was to have been completed by 2020, officials have said.

The bridge district’s barrier plan calls for a net extending 20 feet below and 20 feet from the side of the span, although it will have to be modified in certain areas because of surrounding terrain. The net will be made of stainless steel, marine-grade cable to stand up to the elements, bridge officials said. The net will be gray instead of red to better blend with the water.

Caltrans will contribute $22 million to the overall project, the state $7 million from Mental Health Services Act funds and the Golden Gate Bridge district $20 million in addition to $27 million from the Metropolitan Transportation Commission.

Despite the apparent setback, the barrier project will move forward, Mulligan said.

“Our board is committed to building it,” he said. “We will have to step back, evaluate the bids and go back to our funding partners and see what the next steps are.”