When, after a long day of riding rides at Magic Mountain, 10-year-old roller coaster aficionado Lyle Pemble asked his dad why they don't have their own personal thrill ride, the 50-year-old father of two couldn't think of a good reason to say no. So he built one in his back yard.

Will Pemble, an e-commerce consultant who lives in the fringe of the Bay Area in Orinda, California, says none of the usual reasons (like cost, time investment or insurance) kept him from starting the project, which he likes to think of as an education opportunity for his Lyle and his 12-year-old sister, Ellie. “I try to say yes," Pemble explained, "rather than, ‘No, you’ll poke your eye out.’”

Pemble started the project last fall, spending around 300 hours and $3,500 to build a 180-foot, two-hill roller coaster that now takes up the majority of his family's quarter-acre yard. He even set up a video blog at CoasterDad.com to document the project.

While Will may be the engineer, Lyle is apparently the brains behind the whole operation. Will says the family has been spending their off days traveling around California and riding everything they can strap themselves into from Magic Mountain to Santa Cruz. As the elder Pemble explained, Lyle has "a data centric brain" and enjoys memorizing all the data on the rides he's taken: everything from track length to top speeds and manufacturer names. It's all part of his childhood dream of one day becoming a roller coaster designer himself.

And that dream may be coming true sooner than he thinks. Now that word has gotten out to friends, neighbors and the Internet, Will and Lyle have started work on their second coaster, even while the first still needs a few finishing touches like a mechanical lift to keep it running in a loop. Their second coaster looks to be even more ambitious than the first with full steel rails, a bike pedal lift system and even a treehouse boarding station. Lyle, the roller coaster design prodigy, is serving as a consultant on the project for his friend Abraham, but the team is still working out a few kinks:

[CoasterDad]
[H/T: Chron]
[CBS5]