Joe Sommer may not oversee the largest railroad empire around, but it’s arguably the most impressive in Manchester.

At last count, his Route of the Olympic Slug covers nearly 2,000 square feet and services dozens of inanimate patrons who inhabit the 40 or so buildings he’s erected along the 500 feet of G-scale track that circumnavigates his residential backyard.

“It keeps me out the bars,” Sommer jokes about the hobby in which he’s invested more than a decade and “many thousands” of dollars.

“That’s the problem with a hobby like this,” he said. “You’re never finished.”

Sommer, who began pursuing his passion for garden railroading earnest in 2000, when he and wife Miriam moved into their retirement home overlooking Puget Sound, said the elaborate layout just sort of evolved over the years.

“This is sort of a deal I made my wife when I retired,” Sommer said. “She told me, ‘Joe, you better find a hobby if you plan on hanging around the house all day.’ This is what I came up with.”

He said he originally planned on using only a corner of the back yard for his trains but, “My wife told me, ‘Go ahead and use it all. You know you’ll wind up taking it over anyway.’”

Sommer said most of the year he spends between 15 and 20 hours a week tinkering with his trains.

This month was an exception, however, since the Puget Sound Garden Railway Society, of which he’s a member, was picked to host the group’s national convention, which brought more than 1,000 garden railroading enthusiasts from all around the country to view his display.

“Leading up to that, I was working about 60 hours a week for about a month to get it ready,” Sommer said. “I ordinarily don’t have as much out here as I do now.”

The tableau includes everything from a mining camp, a working waterfall, a wedding chapel and a hobo jungle — each element either handcrafted or built from a kit by Sommer himself.

“Most model railroaders tend to be greyhairs like me,” he said. “And most indoor railroaders are fairly solitary individuals because they spend a lot of time by themselves working on their hobby.

“Garden railroaders are a different breed,” Sommer said. “Most of us are couples, and the main reason I do it is for the socializing we do at club meetings. Each month during what we laughingly call the good weather months, we have a potluck at the home of a different member and we get to admire their handiwork.”

Sommer said his wife takes care of the garden aspect of the garden railroad.

“She does all the pruning” he said, “and she picks out all the plants. She has a better eye than I do for that kind thing.”

Each of the three locomotives that circle the track are battery-powered and radio-controlled.

“With an indoor layout, you electrify the track,” Sommer said. “But you can’t do that outdoors. Every time the track got wet, the wires would short out.”

Likewise, all the cars are treated with an ultraviolet inhibitor to prevent their being damaged by the sun.

Sommer said the fascinating thing about his hobby is that it lends itself to so much individual expression.

“If you took five different garden railroaders,” he said, “gave them identical trains and identical buildings and told them to design a layout, you’d come up with five completely different ideas. It’s completely subjective.”

Also, different hobbyists specialize in different aspects. Some spend hours detailing the trains so they look as aged and careworn as the genuine article. Others are more into the landscaping, while others specialize in the mechanics and wiring.

Sommer doesn’t consider himself a specialist, though.

“I specialize in the potlucks,” he laughed.

For the most part, the train layout is for Sommers’ own enjoyment, since it can’t be seen from the road and invitations are rare.

“We do put on a show for the neighborhood kids once a summer — if they’re good,” he said. “A lot of them say they’re never seen an old-time locomotive in real life. I think that’s kind of sad.”

Sommer said the current spectacle may have to be scaled back at some point.

“My 73-year-old knees can’t take as much squatting as they used to,” he said. “Then again, what would I do with the back yard if I didn’t have it.”