Marlins' hopes through roof

MIAMI — After years of playing baseball between rain delays and on sticky summer nights, the Marlins started with two non-negotiable features for the design of their new ballpark: a retractable roof and air conditioning.

Keeping fans comfortable will keep them coming back, the Marlins believe.


So when fans take in a baseball game at Marlins Park this season, which opens on Wednesday, they will be sitting under an 8,000-ton marvel of architecture and engineering that will keep it a cool and dry 75 degrees inside, no matter the weather outside.

"It is so humid and hot, we're going to close it at 4 p.m. every day and keep it closed for the majority of the summer," Marlins President David Samson said. "It really is a 60 percent heat roof and a 40 percent rain roof. We don't want people to be hot. That's the first priority."


Marlins Park is the sixth stadium in MLB with a retractable roof, joining the Blue Jays, the Diamondbacks, the Mariners, the Brewers and the Astros. It's the only retractable roof sports venue in Florida and one of fewer than 50 on the world.

The park's retractable roof is also one of the fastest, chugging along at 39 feet per minute by 44 transporters with 96 total wheels. It is driven by 76 high-efficiency electric motors, which use less than $10 worth of electricity to open or close.

The roof showed its worth when a squall moved in a half-hour before the Marlins' first exhibition earlier this month. It took fewer than 15 minutes for the roof to close. The game started on time. Nobody got soaked.

That would not have been the case during the Marlins' 19 seasons at Sun Life Stadium, where there were 200 delays (10.5 a season) totaling nearly 199 hours.

A click of a button on a computer screen in a nondescript control room beneath the scoreboard overlooking right field gets the three panels rolling along what amounts to giant overhead railroad tracks.

It is a simple procedure, according to Andrew Agosto of roof mastermind Uni-Systems, who was training Marlins personnel to operate it. In addition to the person at the controls, a couple of spotters keep watch on the panels as they move along the 750-foot beams.

Depending on the wind, it takes about 14 minutes to close, 171/2 minutes total to get it locked down and sealed. The Marlins plan to close the roof for about 70 of 81 games a season, even when rain is not an imminent threat.

"We have a lot of sensors that tell the operator what's going on and if there are any problems, or where it is exactly," Agosto said.

In hurricane mode, it is secured with 96 tie-downs, 70 of them deployed automatically.

Minneapolis-based Uni-Systems has become the go-to team for retractable roofs, which fall in the realm of kinetic architecture.

In addition to the roof for the Astros' Minute Maid Park, Uni-Systems engineered convertible tops for the NFL's Cowboys, Texans, Cardinals and Colts.

The opening atop Marlins Park is wider than any of the NFL retractable roofs. The two lower panels span about 530 feet, the upper panel 566 feet.


To open, the roof slides west and rests above the West Plaza, which is the size of 31/2 football fields and will be an entertainment area with music and other activities before and after games. The four large columns that support it will be illuminated at night by LED lights pulsing up and down suggesting four people breathing at slightly different rates.

The Marlins and their fans can breathe easier knowing the roof ensures the show will go on without delay each night.

The six 60-foot high operable windows facing downtown can be opened with the roof closed. Samson said the Marlins they will be checking to see how that affects fan comfort in sections closed to the windows.

Everything will be open for opening night of the regular season April 4 against the Cardinals.

Unless nature throws a curve. Then it's a simple click to Plan B, like before the Marlins' first exhibition.

"That's why we were building this, so the fans would have air-conditioning and wouldn't have rain delays, and that played perfect for the first event that we had," said Pat Delano, senior project manager for Hunt/Moss contractors. "I think everybody from the Marlins' staff and architects and us as the construction manager were very happy that we were able to implement that right away so the fans who were here could see that."

Getting to know the roof

Temperature: With the roof closed and the AC on, it will be 75 degrees inside Marlins Park.

Moving it: Rides on rails 750 feet long, on 96 wheels conveyed by 44 transporters powered by 76 10-horsepower electric motors; uses less than $10 worth of electricity to open or close.

Rain delays: In 19 seasons at Sun Life Stadium, the Marlins had 200 delays — 10.5 a season — totaling nearly 199 hours.

Elsewhere: Five other MLB stadiums have retractable roofs: in Toronto, Arizona, Seattle, Milwaukee and Houston. There are fewer than 50 retractable roof sports venues in the world and no others in Florida.

Opening/closing time: About 14 minutes; 17½ minutes fully sealed.

Cost: Retractable roofs add an estimated $100 million to a domed stadium.

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