When the world's oldest roller coaster breaks at the worst possible moment, skilled engineers and technicians race against the clock to investigate what went wrong and how to fix it before it's opened to the public.

Working thousands of feet above the California desert, engineers and crews perform perilous high-wire acts to keep a hi-tech tramway system operating safely for the hundreds of daily tourists it transports.

Lighting technicians battle extreme desert conditions to keep the lights bright in Las Vegas; at extreme heights, they perform risky neon bulb replacements.

When sea levels rise, storm surge barriers work overtime to fight floods; it takes a team of experts to maintain these engineering marvels to prevent catastrophe and keep millions of people safe.

Maintenance crews at a remote airstrip are exposed to the elements as they keep water-bombing aircraft flying to battle forest fires; mechanics race against the clock to get transport helicopters to safely shuttle oil rig workers.

Technicians battle staggering heights and fierce winds to upgrade a communications tower that keeps millions connected; special access to this dangerous job site reveals what it takes to get the job done.