Building the Wildebeest - the world's longest water roller-coaster - is like assembling an enormous, jigsaw puzzle. The Wildebeest is fitted with special magnetic motors that enable the giant coaster carts to literally float on air. After assembling hundreds of meters of this water ride, moving the giant platforms and towers that support it, and securing enormous pieces of piping, it all comes down to a few critical centimeters as the team struggles to move the last massive pipes into place.

Three days, one 300,000-pound bridge, two buildings, and mere inches to spare - there is no room for error on this next-to-impossible fix, as Riley helps lift a bridge between two buildings. Working in downtown Salt Lake City - with a commuter train running through the worksite, power lines all around, and five stories of parking garages below - two massive cranes will work in tandem, and all work has to be done in the dead of night.

How do you safely drop a 25-ton metal structure 40 stories ... smack bang right in the middle of a city? Not only must San Antonio's rusty 90-foot-tall TV antenna be precisely cut apart and come down, but the crew must also lift and assemble a crane built from the old antenna itself. Riley teams up with a bunch of high-altitude riggers to get a bird's-eye view of one of the most dangerous fixes he's ever been on.

A fishing boat that ran aground in the treacherous Bering Sea is potentially a rusty death trap for the thousands of seals soon to arrive for mating. Sean Riley joins a crack crew of salvage operators who have only a few weeks to strip down and slice the boat into bite-sized bits. The rusty steel has to be removed by a jury-rigged cable stretched from a crane, because vehicles are forbidden on the ecologically sensitive beach.

In Utah, Riley joins a crew of more than 300 engineers, contractors and laborers as they gamble on an innovative installation technique: demolishing a crumbling concrete bridge and installing a new throughway bridge in just four days (WTF!). This fix involves huge remote-controlled trailers, enormous hydraulics, and a 4 million-pound, five-lane bridge that must be transported almost two miles before it is installed in one piece on Interstate 80 in Salt Lake City.

The Bay Bridge joining Oakland and San Francisco made headlines in 2009 when it was shut down for a major renovation. To make the fix, Riley joins the engineering team tasked with cutting a football field-sized section of roadway from the bridge and replacing it - in just 72 hours! With traffic halted and the world watching, the team encounters some unexpected challenges. A crack puts the operation on hold and requires custom-made colossal steel brackets. The clock is ticking.

WTF rides the rails in the City of Brotherly Love. While there, Riley teams up with crews of the nation's fifth largest public transportation system, Philadelphia's SEPTA, to find out what it takes to keep 2,200 miles of tracks safely running. The team must replace a three-mile section of 80-year-old high-voltage wire. It's a risky operation, with live wires just an arms reach away. Then, Riley heads to the garage to work on a train with a malfunctioning automatic control system.

An 856-foot-long luxury ship is taking on water, and no one knows exactly why. Riley heads to San Francisco Bay, where a team of specialists have just 15 days to pull this mega-ship out of the water, tear it apart, dive into its belly and find the leak. They'll need to work around the clock, because in just two weeks more than 2,000 paid guests arrive for the vacation of a lifetime! Reputations and a boatload of money are on the line.