BROOKLYN — A Brooklyn railway buff is attempting to reopen a historic tunnel under Atlantic Avenue - despite the city deeming it unsafe.

Bob Diamond, president of the Brooklyn Historic Railway Association, has drafted a 355-page study in hopes of reopening a famed tunnel under Atlantic Avenue and conducting tours as he had for decades.

In 2010, the city told Diamond that he could no longer access the 169-year-old tunnel after the FDNY found that it was unsafe for the public. The tunnel has since been closed.

Diamond plans to restart their tours by “improving public access and restoring the tunnel as a museum and historic attraction,” according to a draft of the study shared with DNAinfo New York.

“It’s a win-win situation,” he said.

Diamond and the BHRA, whose website lists only two other members, once sought praise for their popular tunnel tours. But the group has also ruffled feathers in Brooklyn and Red Hook, where they have stubbornly pursued a rejected plan to bring a streetcar system to the neighborhood.

The BHRA has launched a Kickstarter campaign to raise $5,000 that would go toward the cost of printing 100 copies of the study. The final document would be handed to everyone from local officials and community groups to Mayor Bill de Blasio for the city's approval.

The proposal suggests fire and safety improvements for the tunnel, including creating a second egress in addition to an existing manhole at Atlantic Avenue and Court Street.

The proposed restoration and upgrades would cost a little more than $3 million and have the tunnel open by December, according to Diamond and the study.

Neither the Department of Transportation nor the FDNY commented on the study.

The tunnel was built in 1844 and is touted to be the world's oldest subway tunnel.

Diamond rediscovered the tunnel in 1981 after finding the sealed manhole on Atlantic Avenue. Soon after, he began hosting private and public tours, which continued until his operation was shut down in 2010.

The BHRA said it hosted thousands of visitors in the tunnel and planned to use it for guided tours, “cultural gatherings” and as a site location for media production, according to the study.

The same study also looks to revive a decades-old plan to construct a streetcar system from Red Hook to Downtown Brooklyn.

The city’s DOT rejected the plan in 2011 because of the project's expense, land use considerations and impacts on the street network, according to a DOT spokesman.

The DOT found that the 6.8-mile loop would cost $176 million with an additional $6.2 to $7.2 million in annual operating costs, while adding only 1,822 new riders to the city’s transit system.

But Diamond estimates that the project would cost only $50 million. He said the streetcar system would revitalize the neighborhood, bring more people to Red Hook and attract new riders to the system, according to the study.

“That’s something that the DOT study neglected to look at,” he said.

Diamond is relying on de Blasio to see value in his vision, which the previous administration pushed aside, he said.

“I’m very optimistic actually,” he said.

Brooklyn Historic Railway Association Draft Study 2014 by nikhitavenugopal