10
THE DAVEY BULLETIN
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July/August 2022
BEAUTIFYING A MICHIGAN HIGHWAY
Detroit-area motorists driving along I-75 will see 4,500 new
trees and shrubs along the northbound and southbound
lanes of an 8.1-mile stretch of highway this year. The plant-
ings are part of "Segment 2" of a massive greening project,
"Segment 1," started in 2018 (see sidebar) for the Michigan
Department of Transportation (MDOT).
Davey was awarded the contract for Segment 2 landscaping
in the summer of 2021. The planting of the trees and shrubs
began in Fall 2021 and was completed in Spring 2022.
"This corridor is narrower than the Segment 1 corridor,"
said Cheryl Daniels, principal consultant, DRG. "Keeping
safety in the forefront of everyone's minds is critical out here
along the side of the highway. Even with maintenance of
traffic set up, everyone always needs to watch and be aware
of what is going on around them due to the dangers working
along the highway."
DRG worked with MDOT and ROWE Professional Services'
landscape architects to choose the trees and planting
locations. The biggest considerations for the trees were
whether they were salt tolerant and could withstand the
very high pH soil.
"Roadway deicing is hard on vegetation because salt spray
will be in the air and will get in the soil on the roadsides
and remain there for six months each year," Daniels said.
"Roadside conditions are also difficult on vegetation
because as part of roadway construction, limestone is
added to harden roads, which raises the pH in the roadside
soil permanently."
MDOT tries to balance evergreens along the highway with
deciduous trees, but evergreens prefer a lower pH than is
typically found along the roadside. Davey has found native
eastern red cedar trees do the best, but the project also
added green giant arborvitae, blue spruce, black hills spruce,
Austrian pine and Serbian spruce to increase the diversity
of conifer plantings. Some of the deciduous tree species
planted include various species of oak, silver linden, red hor-
sechestnut, Japanese zelkova and liberty London planetrees.
"We add a polymer to the soil to help with water retention,
because the soil gets so dry along the highway," Daniels
said. "We also put deer repellant on the more susceptible
trees. Once the Davey Nursery's skid steers were off site,
DRG crews restored the turf."
PERSEVERANCE
DRG crews staking conifer trees as part of the MDOT Segment 2
highway greening project. Out of the native conifer species, eastern
red cedar performs the best along the roadway, but other ever-
greens were added to increase the diversity of coniferous species.
