NEW YORK - Broadway might need a superhero to save the new Spider-Man musical.

"Spider-Man: Turn Off the Dark," the most expensive production in Broadway history, suffered its fourth accident in a month when a stuntman playing the web-slinger fell about 30 feet into a stage pit during a preview Monday night. The safety tether that clips to his back failed to prevent the spill.

The performer, Christopher W. Tierney, was wheeled out of the Foxwoods Theatre on a stretcher, still in his costume, and taken by ambulance to Bellevue Hospital with minor injuries. He suffered broken ribs and internal bleeding, said a castmate, who spoke on condition of anonymity because the person was not authorized to speak publicly about the musical.

An uncle in Florida, Michael Tierney, said when reached by phone Tuesday night that he had spoken with his nephew a few hours ago. "He sounded pretty good," Tierney said, adding that his nephew was still at the hospital when he spoke with him.

In a statement, Actors' Equity said investigators determined that the accident was caused by human error. It gave no details but said additional safety measures are being undertaken.

A state Department of Labor spokesman said the cause was under investigation.

The fall was the latest setback for the troubled, $65 million show.

Conceived by Tony-winning director Julie Taymor and U2's Bono and The Edge, who wrote the music, "Spider-Man" has been more than eight years in the making. It has been plagued by delays, money woes and several other accidents, including one in which an actress suffered a concussion and another in which a performer broke his wrists in an aerial stunt. Its official opening has been postponed twice, to early February.

The huge costs - a 41-member cast, 18 orchestra members, complicated sets and 27 daring aerial stunts, including a battle between two characters over the audience - mean the 1,928-seat theater will have to virtually sell out every show for several years just to break even. The weekly running bill has been put as high as $1 million. (Tickets are $67.50 to $135 for weekday performances, $67.50 to $140 on weekends.)

A spokesman for "Spider-Man," Rick Miramontez, said in a statement that new safety measures ordered by the government after the latest accident have been adopted. Wednesday's matinee was canceled, but Wednesday night's show will go on, Miramontez said. (No performance had been scheduled for Tuesday.)

Leo Rosales, spokesman for the New York Department of Labor, said the show's producers had not yet presented new safety protocols and would do so on Wednesday. If the measures were inadequate, he said, the state won't let the show perform the complicated aerial maneuvers.

"If it takes longer, it will need to take longer," he said of the show's timing. "We need to be satisfied."

Taymor, the director, said in a statement: "An accident like this is obviously heartbreaking for our entire team and, of course, to me personally. I am so thankful that Chris is going to be alright and is in great spirits. Nothing is more important than the safety of our Spider-Man family and we'll continue to do everything in our power to protect the cast and crew."

One audience member who attended Monday's performance, Brian Lynch, said he knew of the previous mishaps and still wanted to come.

"I was making jokes about it earlier in the day," said Lynch, visiting from Hollywood, Calif. "I said if anyone got hurt I was ready to jump in and help out. I never thought it would happen, I thought they probably worked it all out. I really didn't think it would happen like it did. It was pretty horrific."

The accident happened during the show's big finale, when the Green Goblin drops Mary Jane and Spider-Man leaps to her rescue.

"But then he just kept falling, it seemed, and then everything went dark and then people, crew ran up to the stage and we heard the girl playing Mary Jane screaming from the pit," Lynch said.

"Spider-Man" might yet prevail. Other Broadway shows have struggled with getting their sets and stunts to work during previews, including "Mary Poppins," whose house set went off track in 2006, and "Titanic," which was plagued by numerous technical problems during a month of previews in 1997. Both were hits.

Mary Martin, who starred many times in productions of "Peter Pan," had numerous accidents, "beauts," as she flew about the stage. A year before she died, in a 1989 interview with the Chicago Tribune, she recalled smashing into a concrete wall during a rehearsal as she was trying to show the children in the cast that they shouldn't fear being in the air.

"It was like a cannon shot," Martin said. "I thought, 'My God, these kids will never fly now,' never thinking that my arm might be broken. So we went right back and I said, 'Now we're going to fly it like it should be,' and we did, and it went perfectly."

But "Spider-Man" - whose costs beat the previous most expensive Broadway show, the $25 million "Shrek The Musical" - has reached a dangerous level of attention: fodder for comics. Online, where parodies by "Saturday Night Live" and "Conan" poking fun of the musical's early technical problems had recently been eagerly passed around, the tone shifted Tuesday from jokey schadenfreude to mild outrage.

An actor from TV's "Modern Family," Jesse Tyler Ferguson, wisecracked: "I'm torn between wanting to see 'Spider-Man' on Broadway and not wanting to see someone literally die doing musical theater."

The production - supervised by Juniper Street Productions, a management firm that has overseen such Broadway and Las Vegas productions as "The Producers" and "Promises, Promises" - has been under investigation by the federal Occupational Safety and Health Administration since Nov. 2 at the request of the state Labor Department, according to OSHA.

"It's certainly going to be continuing as a result of the latest incident," OSHA spokesman John Chavez said.

The state Department of Labor inspected 37 separate aerial maneuvers planned for the show at rehearsals in November and approved the use of all equipment in the show, Rosales said. "From what we saw back then," he said, the maneuvers appeared to be safe.

Miramontez said OSHA, Actors' Equity and New York State labor officials met with the "Spider-Man" company on Tuesday to discuss additional safety measures, and "it was agreed that these measures would be enacted immediately."

Tierney, who appeared in the national tour of "Moving Out" and in "Dirty Dancing" in Toronto, is the show's main aerialist and performs stunts for the roles of Spider-Man and the villains Meeks and Kraven the Hunter. The castmate who spoke on condition of anonymity said the cable to Tierney's harness snapped. But one special-effects expert raised the possibility that the rope was not hooked up securely.

Scott Fisher, president of Fisher Technical Services Inc. of in Las Vegas, which builds equipment for aerial stunts for the show, said the rope was supposed to be clipped to the stage at one end and the performer's back at the other.

"The stage crew would have been responsible for making the connection for hooking him up," Fisher said. "The actor is responsible for making the final check that he's good to go. It's sort of like packing your own parachute."

He said the script called for the stuntman to lurch forward at the end of a ramp as if leaping to Mary Jane's rescue. "He runs and stops and freezes in a position that you wouldn't normally be able to hold unless you had a little support from behind him," Fisher said. "If that's not hooked up and he leans forward, he's going to fall forward."

Fisher said the rope was not part of his company's onstage flight systems. But he said it was unlikely to have snapped: It is a 10,000-pound line.

After the actor fell, screaming could be heard coming from the pit.

"A voice yelled, 'Someone call 911!' Then there was a silence," an audience member, fashion blogger Mariana Leung, wrote on the website NearSay.com. "A minute later, the stage was still dark. Then there was an announcement that the show would be delayed. A few minutes later, a second announcement that the performance would not continue. The lights came up."

Just last week, the show's lead producer, Michael Cohl, delayed the official opening for the second time, pushing it back from Jan. 11 to Feb. 7. He cited "some unforeseeable setbacks, most notably the injury of a principal cast member."

The first preview on Nov. 28 did not go well. The musical had to be halted five times because of technical glitches, and actress Natalie Mendoza, who plays Spider-Man's evil love interest Arachne, was hit in the head by a rope and suffered a concussion. She was sidelined for two weeks.

Associated Press writers John Carucci, Tom McElroy, Karen Matthews, Ula Ilnytzky and Sara Kugler Frazier, Entertainment Writer Jake Coyle, Broadcast correspondent Warren Levinson and AP news researcher Jennifer Farrar contributed to this report.