Alcatraz Island closed to visitors on Monday, Oct. 26, while crews replace the pilings that hold its ferry dock in place. The National Park Service expects the work to be done by Nov. 18, and Alcatraz City Cruises plans to resume tours Nov. 19.

Why it matters: Alcatraz is one of the Bay Area's biggest attractions. More than 3,200 ferry trips carry about 1.5 million people to the island each year, according to the Park Service.

What crews are doing

Workers will drive new piles and fully replace the two remaining pilings that were flagged earlier this year, the Park Service said.

The timing is set by the San Francisco Bay Conservation and Development Commission, which restricts pile driving in the bay after Nov. 30.

Weather or other problems could change the schedule, officials said.

Third closure this year

The dock closed for nine days in January after one piling failed. An inspection found two of the five pilings needed repair, the Park Service said.

A second, six-day closure in April strengthened the other three pilings. Once this work is done, the whole dock system should last 20 to 30 years, the agency said.

Who pays

No tax dollars are being used. Alcatraz City Cruises, the park's ferry concessioner, is paying for and doing the work under its contract, the Park Service said.

If you had tickets

  • All island tours from Oct. 26 through Nov. 18 are canceled, Alcatraz City Cruises says.
  • Reservations will be refunded to the original form of payment, CBS News Bay Area reported.
  • A San Francisco Bay Discovery Cruise with views of the island is offered through Nov. 1.