GLENWOOD SPRINGS, Colo. — It was during a Colorado Cave Rescue Network training exercise at the Glenwood Caverns park three years ago that avid caver and electrical engineer Dave Jackson got the spark for his new idea.

“They had this giant jumble of picnic tables set up with flagging tape hanging all over the place to represent the delicate formations in caves,” recalled Jackson, a Manitou Springs resident and member of the Southern Colorado Grotto chapter of the National Speleological Society.

As fellow cavers and search and rescue workers attempted to maneuver through the simulated cave, carrying a volunteer “patient” strapped to a rescue litter, they would often brush the tape aside to get through tight spots.

“That’s clearly something you want to avoid doing in a real cave,” Jackson said.

When the exercises did move inside the real Fairy Cave, the trainees did a little better, he said. Still, they weren’t quite as conscientious about their surroundings as they could have been.

So Jackson, who earned his master’s degree in electrical engineering from the Massachusetts Institute of Technology in 2005, put his thinking cap on.

“I decided to take my caving passion and my electrical passion and make a better solution,” he said.

Jackson, 29, is the inventor of the “Cave Sim,” a crawl-through electronic cave simulator. The device, which his wife, Tracy Jackson, helped him develop, was one of the hands-on attractions at a recent NSS convention, which was held at Glenwood Springs High School.

The 48-foot-long wooden passage twists and turns, with the ceiling height closing to just 18 inches in spots. There’s an actual dripping water feature inside, and scattered throughout are simulated stalactites hanging from the ceiling and stalagmites protruding up from the floor.

Each has an electronic sensor that, if touched as someone is crawling through, registers in a computer log. There’s even a fake bat. If a Cave Sim spelunker shines a head lamp on the bat for more than three seconds, it squawks out a warning, “Don’t shine your light on the bat!”

“Some formations are so fragile in real life, such as gypsum flowers, that even if you come too close it can be damaged,” Jackson said, adding that the simulator has a distance sensor for that particular formation.

Each section has a computer screen that tells the trainees how they’re doing as they crawl through. At the end, they’re given a final reading, as well as the time in which they completed the crawl-through.

“Of course, in a real cave you aren’t trying to go fast,” said Derek Bristol of Littleton. “The most important thing is to try not to damage anything.”

Cave Sim is not just a training device. It’s become a competition.

On his third attempt that week, Bristol made it through with no penalties to take the lead in the adult men’s category. His first try had yielded two penalties, and on his second try, although he was faster, resulted in four penalties.

Bristol has led several cave tours around the country, including some of the national parks caves.

“It’s very realistic to a lot of places I’ve been,” he said of the simulator. “To have something like this to simulate a real cave is a great educational tool.”

Jackson said about 600 people have used the simulator since he completed it. He has a patent on the design and intends to build more to sell to other caving organizations around the country.

The Cave Sim was included as part of this year’s NSS “Speleolympics,” a series of different contests that have taken place at the convention every year since 1970.

In addition to the cave simulator and rope climbing, an obstacle course was set up at the main campground at the Roaring Fork River park west of the high school.

The course had participants crawling through a tight-squeeze box, followed by the ever-popular mud crawl, a short trail run while carrying a fairly large rock, and a series of obstacles including climbing over a rubber raft and a trailer, a plastic tube crawl, ropes course, and back through the mud crawl.

“I was the sick doggy who started it,” said Rocky Brougham of Evergreen, who first organized the event at the 1970 NSS convention in Bloomington, Ind. “I just wanted to see people get muddy.”

The tradition continued, as new obstacles and different contests were added over the years.

This year’s event was organized by relative newcomer Rick Speaect of Aurora, who is attending his second NSS convention.

“We kind of make up the rules as we go,” Speaect said of the obstacle course. “And people can do it as many times as they want.”