DOWNTOWN — What did it take for the city to help stage Nik Wallenda's Downtown tightrope walks last month?

An extra 96 police officers and supervisors on the ground for crowd control, 20 aides to direct traffic, two police boats with four officers aboard each and even a Fire Department boat with four divers in case Wallenda fell into the Chicago River.

For the 24 hours before, during and after the Nov. 2 event — which Wallenda pulled off before millions of Discovery Channel TV viewers and tens of thousands of in-person gawkers — the city provided $76,546 in public safety support, according to documents obtained by DNAinfo Chicago.

Tanveer Ali breaks down the numbers:

The city then sent bills to NBC Universal, which owns Discovery Channel, and to another company associated with the event, Sconnie Productions.

The biggest chunk of the cost was for an extra 82 police officers on the street, costing $37.51 an hour apiece for a total of more than $24,000.

The city billed NBC Universal and Sconnie Productions $50,000 each to cover all city costs for the event. Those payments have been made, said Mary May, spokeswoman for the Department of Cultural Affairs and Special Events, which handles film permits.

Other costs included:

• A boat with a four-member Fire Department dive team ($3,000)

• Two boats from the police marine unit, each with four officers aboard ($18,000 over three days)

• Ten police sergeants ($49.31 an hour apiece for eight hours, or $3,944)

• Three police lieutenants ($53.95 an hour apiece for eight hours, or $1,294)

• One police commander ($74.49 an hour for eight hours, or $595)

• Four squad cars for the entire day ($150 apiece over three shifts, or $1,800)

• Additional supervisors on the CTA ($750 apiece, or $6,000)

• Barricades ($1,500)

• Twenty traffic aides from the Office of Emergency Management and Communications ($25 an hour, or $6,000)

The stunt drew 6.7 million Discovery Channel viewers. It required that the producers apply for film permits much like the television show "Chicago Fire" or the upcoming "Batman v Superman" movie would.

The production teams, who approached the city a year before the event, submitted a series of documents required of such events. Those documents, which cover cost estimates, insurance policies, maps and diagrams of the wire-rigging system, show just how meticulous the planning for this spectacle was.

To cover any potential legal issue that could've come out of the production, Wallenda's company was insured for $9 million, while NBC Universal took out a $10 million policy.

During the world record-breaking stunt, the daredevil from the famed "Flying Wallenda" clan walked a tightrope between a Marina City tower and the Leo Burnett Building, crossing the Chicago River more than 500 feet in the air with no harness, net or much hope of surviving a plunge.

He then was shuttled back to Marina City, where he walked a tightrope strung between the two towers ... blindfolded.

Mayor Rahm Emanuel declared the day after "Nik Wallenda Day."

"It was a unique event," May said.

Still, the death-defying walks didn't surpass the viewership of an earlier Wallenda stunt. The previous year, the number of television viewers watching Wallenda walk across the Grand Canyon peaked at 13 million.

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