DENVER -- As the construction boom transforming Denver shows no sign of slowing down, for better or worse, cranes towering over Denver have come to symbolize the city's rapid growth.
But are these cranes safe, and what's to prevent them from collapsing like we've seen in Seattle and in Dallas?
"These are very rare, they tend to be big news," said Troy Clark, owner of the Colorado Crane Safety School and MSC Safety Solutions.
Clark runs one of the largest crane operator schools in Colorado and contractors hire his company to conduct third party inspections.
"Many of these cranes can hold up to 90MPH," he said.
Clark said while it's too early to speculate what went wrong in the deadly collapse in Dallas over the weekend, all cranes are required to be "weathervaned."
"In other words, if the winds blowing they turn like a weathervane. If they don't weathervane them there's a chance that these things can blow over," he explained.
Like how a weathervane works on your roof. When the wind blows, crane operators are supposed to release a swing brake so the giant boom can freely spin.
"There's a crane up there and it's going crazy -- yeah, it's supposed to do that," said Clark. "Tower crane operators are pretty good at letting them weathervane, but it could be a mistake."
The Occupational Safety and Health Administration (OSHA) oversees regulating cranes. Clark said they do require annual inspections and effective November 2018 all crane operators must be certified nationally, but it does not require third party inspectors.
However, Clark said most larger Denver contractors do choose to conduct third-party inspections before using a crane.
Where he sees areas for improvement are within the industry itself.
"We need to improve as companies — do I have the appropriate people in place to do the assembly, disassembly? Do I have the appropriate people to run the cranes, are they all certified?" said Clark.