Excited shrieks of children have long faded from Kennywood amusement park. The calliope of the carousel has fallen silent. The ski lift chairs used to transport visitors from distant parking lots dangle in the wind.

It's winter at the West Mifflin park. From along Route 837, the park seems vacant. But tucked inside various buildings -- and throughout the park grounds -- work is in full swing for Kennywood Park's May reopening.

On a recent workday, crews erected tents on portions of the Thunderbolt track to protect them from the elements while they replaced wooden supports on the historic coaster. A burn barrel nearby gives workers a brief but welcome respite from the frigid temperatures. The coaster's cars were in another building, their chassis undergoing reconstruction.

"Winter is when we get all our work done," said Matt Hyatt, Kennywood project manager.

Hyatt said it's important for the maintenance work to be done on the off-season, because once Kennywood opens, the park doesn't want to have rides closed down because of mechanical issues.

"People are under the impression that we just go home and hang out until it's time to dust off the rides and start up again," Kennywood spokesman Jeff Filicko said.

Shortly after the park's Phantom Fright Night weekends end in October, workers begin pulling apart rides. Long-term storage facilities are at a premium, so permanent buildings such as the biggest picnic shelter, the bumper car ride and other structures are called into duty. Parts of the Paratrooper ride were stacked up alongside the historic carousel, which sits under a large steel-domed pavilion.

The story is the same at other amusement destinations: when the fun stops, the work starts.

At Idlewild and SoakZone in Ligonier, construction is continuing on the new "Wowabunga" wave pool, which will include the installation of underwater cameras so that lifeguards can keep an eye on swimmers.

At Sandcastle, adjacent to Kennywood, Filicko said, water has been drained from the attractions there, but will be refilled in the spring. No major upgrades were performed in the offseason, Filicko added, though office work is being done there.

Kennywood, Sandcastle and Idlewild are all owned by Spanish theme-park operator Parques Reunidos.

Filicko said nearly 150 people work at Kennywood during the winter. Along with those maintaining the rides and exterior of the park, office workers are selling season tickets and performing other administrative work.

In one machine shop, workers were pulling apart pieces of rides, cleaning, lubricating, making sure they're in top condition for the upcoming season.

"I'll be doing the same thing over and over and over for two weeks," said maintenance worker Jim Falosk of Rostraver, looking at the 32 seats from Swing Shot sitting in a heated maintenance building. "But I like working with my hands."

In the summer, Falosk said, the work actually slows a bit, at least for him. Each morning, from 7 to 11 a.m., he and others inspect rides. The rest of the day, Falosk said, workers will inventory supplies and order parts, getting ready for the next off-season and all the duties that come with it.

November, December and January are when the rides are taken apart and worked on. By February, Falosk said, workers already are starting to reassemble the rides.

Sometimes, the weather doesn't cooperate. In 2010, workers poured the foundations for the new Sky Rocket on Feb. 4, just two days before a monster storm dumped nearly 2 feet of snow on the area. Despite the setback, the ride opened in June.

"Every day, you're fighting the weather," Hyatt said.