U.S. Open spectators must wait out rain delays at Arthur Ashe Stadium for one more year. In the meantime, they're getting a break from Mother Nature in a very different way: shade from the blazing sun.

A framework of more than 6,500 tons of steel now sits atop center court for the Grand Slam tournament. In 2016, it will support a retractable roof, the culmination of a project that requires two years to complete.

Two of the four sides were covered during the first phase of construction, creating newfound shade for many fans in the upper deck who used to bake on steamy days. With warm weather and mostly clear skies in the forecast for the first few days once the Open starts Monday, that could make a difference right away.

Spectators arriving at Flushing Meadows will see the crisscrossing white beams rising above the world's largest tennis stadium. It's still very much an outdoor venue: The opening in the middle is 62,500 square feet. The structure won't look much different once the two retractable panels are installed.

There are 24 steel columns that rise 150 feet above ground to support the stand-alone framework, which is made up of 1,700 structural beams and 115,000 bolts. A gap between the top of the stands and the framework allows for ventilation.

Four video screens have been added, replacing the previous two and located lower in the stadium. New sound and lighting systems have also been installed.

What happens when you add a massive structure to the top of a massive stadium? The sum of the parts may come as a surprise: Players and other visitors this week have noted that Ashe now seems less cavernous.

"They felt the world's largest tennis stadium now felt more intimate," said Danny Zausner, the chief operating officer of the USTA Billie Jean King National Tennis Center.

"It just helps bring the whole outside down a little bit," he added.

Last winter and spring, Ashe was dwarfed by the cranes towering above the stadium. Every corner of the tennis center was filled with equipment and materials.

The last crane left the facility after July 4 weekend, leaving about seven weeks to clean up the site before players arrived to start practicing last Saturday.

Once this year's Open closes with the men's final in mid-September, the process will begin to resume construction. Along with the installation of the retractable panels, the second phase will include a chilled water ventilation system to control humidity inside the stadium when the roof is closed.

During this year's tournament, the U.S. Tennis Association has set up meteorological equipment around the stadium and retained a Canadian wind-testing company to measure conditions, seeking to ensure they will remain similar when the roof is open or closed. Zausner said players practicing on Ashe have reported no significant changes in wind patterns from the construction at a venue where swirling gusts are not uncommon during matches.

The Open's men's final was delayed until Monday because of rain for five straight years from 2008-12. USTA officials long maintained adding a roof over Ashe wasn't feasible, but in 2013 architectural firm Rossetti finally came up with a workable plan. The last two years, the men's final was slated for Monday from the start, partly to reduce the chances of a postponement by spreading out matches.

The men's final returns to Sunday this year under the USTA's new TV contract with ESPN, which allows for an altered schedule.

Wimbledon and the Australian Open already have retractable roofs over their main stadiums, with plans under discussion for the French Open to add one.

The Ashe roof project is part of a broader, $500 million-plus renovation plan for the tennis center. Spectators this year will see the ongoing construction for a larger Grandstand, the Open's third-biggest court, on the opposite corner of the complex from its current location.