A suicide prevention net on San Francisco’s Golden Gate Bridge that is already years behind schedule will cost about $400 million, more than double its original price, because of problems sparked by the government agency that manages the span, the lead contractors allege.

The allegations filed Monday in state court by Shimmick Construction Co. and Danny’s Construction Co. say that changes to and flaws in the government’s net design and the lack of transparency about the deterioration of the bridge’s maintenance platforms have raised the construction price from $142 million to at least $398 million.

“We were alarmed to discover the District concealed significant information during the proposal phase of the Project, including extensive deterioration in certain areas of the bridge,” Shimmick said in a statement.

The project aims to add 20-foot-wide (6-meter-wide) stainless steel mesh nets on both sides of the 1.7-mile (2.7-kilometer) bridge and replace maintenance platforms used by bridge workers that were built in the 1950s. Work on the net began in 2018 and was set to be completed by January 2021 but has been repeatedly delayed.

Bridge officials in 2008 voted to move forward with the net, meant to deter those looking to jump to their deaths and catch those who do. Paul Muller, president of the Bridge Rail Foundation, a nonprofit created to end suicides on the bridge, said the span with sweeping views of the Pacific Ocean and San Francisco bay has been the site of nearly 2,000 suicides since it opened in 1937, including 25 last year alone.

Shimmick Construction Co. and Danny’s Construction Co., which formed a joint venture to handle the project, were sued last year by subcontractor Vigor Works, LLC, which claims it’s owed millions of dollars. The joint venture countersued earlier this year. In the motion filed this week, they asked a judge to allow them to also sue the Golden Gate Bridge, Highway and Transportation District, which manages the span.

The contractors contend in the latest court documents that the district delayed the completion of the project and damaged their reputations by concealing “significant information … including extensive deterioration in certain areas of the bridge.”

According to the joint venture, the deterioration is mainly in the maintenance platforms — U-shaped structures known as travelers that are powered by diesel engines and hug the bridge on both sides and bottom to give workers access to the bridge’s underside and hard-to-reach areas.

The alleged problem with the platforms remains unclear because the information was redacted from the court documents. A spokesperson for Shimmick said that was done for security reasons and that it will be up to the judge to make the information public.

The contractors allege that they toured the bridge before submitting a bid but that they were not allowed to take photographs or record video and had access only to areas chosen by district officials.

District spokesman Paolo Cosulich-Schwartz said the delays and cost overruns are due in part to Shimmick having had three different owners since beginning work on the suicide barrier.

“We are deeply frustrated by Shimmick’s slow pace of construction and multiple delays building the suicide barrier,” Cosulich-Schwartz said in a written statement. “The District has been transparent about the condition of the Bridge with Shimmick throughout the project.”

The joint venture has completed about 47% of the net and expects to finish it by December 2023, nearly four years behind schedule. Adding the net requires the maintenance platforms to be reconfigured. The upgraded platforms are not expected to be completed until January 2026.

The contractors claim bridge officials also changed the design of the net when the project was already underway and imposed unnecessary requirements on the contractors that drove costs higher and caused delays. They cited a scaffolding standard not required by the California Occupational Safety and Health Standards Board, and said the district failed to obtain a waiver until this February for the federal requirement to buy the steel needed in the U.S.

“Rather than acknowledge its own mistakes, the District seeks to hold SDJV hostage and have it complete the work with no adjustment in price,” the contractors said in court documents. “In other words, the District wants to pay only $142 million for a Project that will cost well over $398 million because of the District’s mistakes.”

Suicide prevention advocates say they are frustrated by the delays because they are costing lives.

Muller said that even though part of the net has been built, suicides are happening at the usual rate of about two or three per month.

“This has been a life-and-death matter for 85 years,” Muller said. “We want this thing completed and they need to stop the bickering and arguing and get it done.”