1 of 10 Students walk past a Doris Duke Trail marker on their way back to the parking lot after working on the trial. ANDREW HINDERAKER FOR THE WALL STREET JOURNAL Field manager Erik Mickelson, of the New York-New Jersey Trail Conference, center, with a group of 7th-graders from the Waldorf School of Princeton as they work on the Doris Duke trail in the Sterling Forest State Park in Tuxedo Park ...Mr. Mickelson, right, shows student Isabel Mania how to use a clinometer, a device that measures incline. ANDREW HINDERAKER FOR THE WALL STREET JOURNAL Students, left to right, Camden Trent, Kathleen McCoy and Isabel Mania work on the Doris Duke trail in the Sterling Forest State Park in Tuxedo Park, N.Y. on June 8. ANDREW HINDERAKER FOR THE WALL STREET JOURNAL Mr. Mickelson clears a tree from the trail in the state park. He designs trails full-time for the New York-New Jersey Trail Conference, which maintains more than 2,000 miles of free trails in the region. ANDREW HINDERAKER FOR THE WALL STREET JOURNAL Students Owen Graham, Isaiah Ginsburg-Henry, John Nevers and Grace Roberts, left to right, move a rock on the Doris Duke trail. ANDREW HINDERAKER FOR THE WALL STREET JOURNAL Student John Nevers works on the trail as part of a group of seventh-graders from the Waldorf School of Princeton. ANDREW HINDERAKER FOR THE WALL STREET JOURNAL An amphibian next to the trail. ANDREW HINDERAKER FOR THE WALL STREET JOURNAL Mr. Mickelson demonstrates bench cutting, or leveling, the trail. ‘Laying a trail out is part art, part psychology, part science,’ he says. ANDREW HINDERAKER FOR THE WALL STREET JOURNAL Students Camden Trent, Kathleen McCoy, Isabel Mania and parent Bryce Roberts, left to right, take a lunch break from their work on the trail. ANDREW HINDERAKER FOR THE WALL STREET JOURNAL Students walk past a Doris Duke Trail marker on their way back to the parking lot after working on the trial. ANDREW HINDERAKER FOR THE WALL STREET JOURNAL Field manager Erik Mickelson, of the New York-New Jersey Trail Conference, center, with a group of 7th-graders from the Waldorf School of Princeton as they work on the Doris Duke trail in the Sterling Forest State Park in Tuxedo Park, N.Y., on June 8. ANDREW HINDERAKER FOR THE WALL STREET JOURNAL

A Trail Designer’s Job: Get Inside Hikers’ MindsFinding ways to discourage shortcuts and other rogue footfalls that adversely affect the landBy Tyler J. Kelley July 2, 2015 12:44 p.m. ET

Erik Mickelson barely glanced at the gorgeous views from Breakneck Ridge, views many New Yorkers give up a precious Saturday to see. As he scrambled past hikers on a recent spring afternoon, he had eyes only for the trail and the feet that may or may not stay on it.

Mr. Mickelson designs trails full-time for the New York-New Jersey Trail Conference, which maintains more than 2,000 miles of free trails in the region. His job: to get inside hikers’ minds and anticipate their movements.

“They vote with their feet,” said Mr. Mickelson.

An hour and a half north of Manhattan, Breakneck Ridge is one of North America’s most popular day hikes, in part because the Metro-North Railroad stops right at the trailhead just north of Cold Spring, N.Y. All a visitor has to do is follow the small squares of color, called blazes, into the woods.

At least that is the idea.

‘You’ll lay it out, you think you’ve done it well, and then they make a shortcut and you’re like, Damn, why didn’t I see that?’

—Erik Mickelson, trail designer, New York-New Jersey Trail Conference

“I never thought of trail design as something somebody does,” said Chris Bertinato, 33 years old, an engineer at the Lamont-Doherty Earth Observatory in Palisades, N.Y., who spent a recent Saturday volunteering for the nonprofit Trail Conference. “It’s almost like you take it for granted.”

“Laying a trail out is part art, part psychology, part science,” explained Mr. Mickelson, 44. Wearing insect-repelling pants and a backpack sprouting a drinking-water hose, he spends nine-hour days hauling his tall, angular frame through brambles and brush, scouting trails that independent-minded hikers will adhere to.

Problem is, if a path doesn’t take day trippers to an overlook or waterfall they want to see, they will create their own “social trail,” increasing the human impact on the land. To thwart this, Mr. Mickelson tries to anticipate renegade footfalls.

“You’ll lay it out, you think you’ve done it well, and then they make a shortcut and you’re like, ‘Damn, why didn’t I see that?’ ” he said.

THE WEEKEND PROFILE

Erik Mickelson

Designs trails for New York-New Jersey Trail Conference.

Holds a degree in plant science from the University of Arizona.

Spent 10 years working in the golf industry.

44 years old; likes to surf and is a vegan.

Social trails occur, for example, when a hiker sees the next leg of a switchback below, then cuts down the hill to shorten the distance. On a busy trail like Breakneck, people will also walk around one another, widening the path. To discourage these two-lane tendencies, Mr. Mickelson will cleverly guide a route through steep rocky terrain, along cliffs or between boulders.

Peter Jensen, president of the Professional Trail Builders Association, said sustainable trails are more enjoyable because they go unnoticed. A muddy or rutted one forces walkers to focus on their feet instead of what they came to see.

“A well-built trail,” said Mr. Jensen, “really blends into the background.”

Every year Mr. Jensen’s 90-member organization adds eight or 10 new trail-building companies. “Right now trails are hot,” he said.

Growing up in Virginia Beach, Va., Mr. Mickelson cared most about surfing. But when the waves were flat, he hiked in the woods behind his house.

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After receiving a degree in plant science from the University of Arizona, he spent 10 years in the golf industry. He tried teaching for a while, he said, but decided he needed to be outside.

“As a surfer I prefer a trail that kind of surfs the mountain,” he said. “It unfolds in front of you, it flows.”

Mr. Mickelson’s trails follow the rolling contours of a slope with a gentle sense of momentum. But to keep what he calls “that East Coast flavor,” he includes occasional steep “punchy” rock sections.

One of Mr. Mickelson’s worst enemies is water. He thinks about it constantly, looking for its source, predicting its movements and determining how a path can be laid out or adjusted to minimize erosion.

A poorly planned trail becomes a stream bed during heavy rain, carving the hillside as it descends. Hikers contribute, too. Last year Breakneck Ridge saw more than 100,000 hikers, 1,426 in a single day. Each foot takes a little of the mountain with it.

How people descend from the ridge is one of Mr. Mickelson’s current concerns. One descent is overused and eroded, and the other has hikers walking back through a dark, shoulderless highway tunnel.

He proposed a new descent that would shorten the current three-hour loop. State biologists denied the plan, saying it took people too close to protected habitats, like rattlesnake dens.

A cleared section of the Doris Duke trail, in the Sterling Forest State Park in Tuxedo Park, N.Y., worked on by a group of 7th-graders from the Waldorf School of Princeton. PHOTO: ANDREW HINDERAKER FOR THE WALL STREET JOURNAL

Mr. Mickelson can see their point. “I feel bad sometimes about putting a trail where there wasn’t one,” he said. “There are times when I kill some insect, or we overturn a rock and there’s a snake or a lizard that gets injured,” he said. “I am vegan, so that does make it harder for me.”

Daniel Yu, 40, a technology consultant from Brooklyn, spent a recent afternoon turning over half-ton rocks as a Trail Conference volunteer, seemingly oblivious to what lay beneath.

“At work my exercise is this,” Mr. Yu said, wiggling his fingers as if typing. The steps made from those rocks will probably last “at least my lifetime,” he said proudly, whereas after a day at the gym all you have to show are “sweaty clothes.”

Nearly 3,000 hours of volunteer labor by people like Mr. Yu went into building the Appalachian Way, a 1,777-foot-long trail segment 11 miles from Breakneck. Meticulously designed by Mr. Mickelson, it required jack-hammering bedrock and laying 27 stone steps.

“It takes me three minutes to walk by something it took two weeks to build,” mused Mr. Mickelson.

Volunteer Kevin Stamey, 60, a former systems analyst for Goldman Sachs, GS 0.45 % is also struck by the longevity of trail work. The infrastructure he built at Goldman is gone, he said, upgraded beyond recognition, but his trails could last 100 years.

“The permanence gives you an emotional stake,” he said.