AASHTO Journal, 18 March 2016
Thousands of Norway, Colorado and blue spruce trees the Michigan Department of Transportation planted last year alongside windswept routes in northern Michigan are now emerging from their first winter cycle as a “living snow fence” that can cut labor and material costs of fighting snow buildup on roads.
“We want them to stop the wind and the snow,” said MDOT Gaylord Transportation Service Center maintenance coordinator Rob Hall, “and these are some of the best you can use in a roadside environment.”
Hall and MDOT crews planted 2,000 young spruce trees at 10 sites along Interstate 75 in Otsego and Cheboygan counties, placing them on the west side of the freeway in open areas frequently plagued by blowing and drifting snow where crews previously installed plastic snow fencing.
Snow fences help reduce blowing snow that can hamper drivers’ vision, plus the snow accumulation and ice conditions that can contribute to crashes. Working with MDOT maintenance worker Mark Phillips and the Otsego and Cheboygan County Road commissions, Hall also prioritized locations by crash history, MDOT said.
“When salt residue remains on the roads, blowing snow sticks to it, melts, then refreezes as ice,” Hall said. “We’d place snow plastic fence in those areas in the past to prevent that, but it requires ongoing labor and costs a lot of money, so having the trees will save us in the long run.”
Lyn Zuiderveen, Hall’s counterpart in MDOT’s Cadillac TSC, had earlier planted 500 3- to 5-foot-tall trees to act as living snow fence along M-115 in Wexford County, M-66 in Missaukee County and US-131 in Osceola County. That’s in addition to 15,000 pine seedlings he’s had planted on US-131 in Wexford and Osceola counties in the last three years.
MDOT said other states including Minnesota and Wyoming use living snow fence programs for their highways, using bushes and standing corn as well as trees.
It said studies in both states have shown these to be effective replacements for traditional snow fences, and more economical when properly located. In addition, it said data from the Minnesota Department of Transportation showed living snow fences decreased the number and severity of crashes and cut travel delays.
Michigan’s batch of trees came from the Dutchman Tree Farm in Manton, one of the largest suppliers of evergreens in the country.
MDOT paid $25,000 for 2,000 trees, noting that the $12.50 per tree “is far less than usually charged for nursery stock, and the supplier delivered trees of 3 to 6 feet tall to planting sites at no additional charge.
There, workers from the MDOT Youth Development and Mentoring Program planted the trees in two rows, staggered 10 feet apart. Crews watered them through the summer, with assistance from a Michigan Department of Natural Resources firefighting rig.
The trees are within the road right of way but outside of the “clear zone” that traffic needs – an area 30 feet from the white line. MDOT said that’s the amount of space in which 85 percent of vehicles leaving the roadway will come to a stop, so the department makes sure there are no obstacles in that zone.
“So far, about 90 percent of the trees survived the first season, which is better than the 70 percent usually expected,” MDOT said.
Hall said crews will return to clip the top-most shoots of the trees, which MDOT said will encourage them to grow “bushier and wider, rather than taller. Ideally, crews will keep their height at about 10 feet, and the trees’ energy focused on growing together into an effective windbreak.”
