Those giant construction cranes looming overhead are a sign of progress in the Tampa Bay area although they pose an unnerving sight as Hurricane Irma approaches.
But you can probably rest easy — tower cranes are designed to withstand the highest winds Tampa Bay is apt to see.
"One of the design features of tower cranes that makes them so sturdy is that they will spin just like a weather vane when the wind speeds get higher," said Scott Gerard, a vice president of Moss Construction, one of Florida's largest construction companies. "It looks a little disconcerting when you see it because you think something is wrong, but that is normal and a safety feature of cranes."
As a tropical storm nears, Gerard said, the general contractor on a project is also supposed to make certain that the vertical portion of the crane is securely fastened to the building with tiebacks. The precautions are necessary because it generally is not feasible to take down a large crane on relatively short notice.
"It could be a three or four day (process)," Scott said, "and there are only so many crews available to do that. That's why these are designed the way they are."
Huge tower cranes are currently at several sites around the bay area, including the 41-story ONE St. Petersburg condo project, the American Museum of Arts and Crafts and the 930 Central Flats apartments, all in or near downtown St. Petersburg.
In Tampa, cranes rise from the future sites of apartment complexes in the Channelside area and along the Hillsborough River where the Tampa Tribune building once stood.
Although cranes must meet state standards for wind loads, municipalities can adopt their own, tougher standards. Building officials in Tampa and St. Petersburg did not return calls today; an employee of St. Petersburg's Construction Services Department said building official Rick Dunn was busy contacting general contractors in regard to their hurricane safety plans.
"I'm sure that all those contractors out there that have the tower cranes and whatnot are buckling them down as best they can,'' Tampa Mayor Bob Buckhorn said. "Many of those contractors are South Florida-based. So this is not something that's new to them. But we're dealing with a storm of unprecedented capacity."
In Miami, where 22 to 25 big cranes dot the downtown skyline, city officials warned that cranes could not survive the most severe hurricane.
"These tower cranes are designed to withstand winds up to 145 miles per hour, not a Category 5 hurricane," Maurice Pons, deputy director of Miami's building department, said in a statement.
Pons said he would advise residents not to stay in a building next to a construction crane during Irma. While the horizontal arm swings around, the arm's counterbalance is heavy and poses a potential danger to adjacent buildings if the crane collapses.
Based on forecasts as of late Wednesday, Irma is projected to have maximum winds of about 130 miles an hour by the time it passes Miami and heads north.
During Super Storm Sandy in 2012, a crane atop a $1.5 billion luxury high-rise in midtown Manhattan collapsed in high winds and dangled precariously. Some buildings, including the Parker Meridien hotel with 900 guests, were evacuated as a precaution and the streets below were cleared, but there were no injuries.
Times staff writer Rick Danielson contributed to this report Contact Susan Taylor Martin at email@example.com or (727) 893-8642. Follow @susanskate