I-235 Landscaping
Fiscal Year 2009 Landscaping Projects
The design
The landscape design concept for the I-235 corridor is "Linear
Parkway."
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The intent of I-235 reconstruction is to create
a roadway corridor that emulates the landscape character of
more traditional transportation corridor “parkways”.
Although I-235 will not have a wide landscaped median to effect
the central boulevard of traditional parkway design, the open
spaces of the roadway corridor will be dressed with an informal
arrangement of a variety of plantings. This variety of plants
will convey a “green” image for the roadway corridor
and will accomplish a “parkway” feel and appearance
for the roadway user. |
At primary interchanges, where traffic enters and exits Des Moines
metropolitan community neighborhoods, the landscape will be developed
with informal and formal arrangements of plantings. This arrangement
of plants will suggest the blend of Iowa’s natural landscape
with Iowa’s agrarian landscape features, such as fence rows,
row crops, contour farming,
terraces, etc.
Also, throughout the corridor, mass plantings of perennial wildflowers
and native grasses will be used to add seasonal interest and drama
to the landscape. Ultimately, fields of flowers and grasses, with
informal tree and shrub plantings, will create a pastoral foreground
for views of significant and attractive features of the metro area
skyline.
Other significant features of the landscape design
concept that are incorporated in the “parkway” design
are a “mow edge” and the use of low maintenance materials,
such as perennial wildflowers and native grasses. Both of these
design components are proposed to minimize annual landscape maintenance
expenditures and improve the landscape appearance
and character of the roadway corridor.
Click on the above image for an enlarged view of the landscape design plan for I-235 between the west mixmaster and the 22nd St. interchange in West Des Moines.
Schedule for landscaping the I-235 corridor
Planting began in early spring 2005 in the western portion of the I-235 corridor between the west mixmaster and the 22nd St. interchange. Roadway work is nearing completion in this area. Other areas of the corridor will be planted where large sections of the roadway construction have been completed.
Planting work, Spring 2005
For more information on the vegetation that will be planted in the I-235 corridor, click here for a list of the plants. For more detailed information and photos of these plants, visit the online Iowa's Living Roadway Plant Profiler.
Roadside revegetation process
The first phase of revegetation eliminates existing, competing plants. This
is normally done by mowing, then spraying the regrowth with glyphosate
herbicide. While this process leaves the roadside looking barren
for one season, it is necessary for the long-term establishment
of new plants. Once the competing plants have been eliminated, the
roadsides are seeded with native grasses and wildflowers.
On each revegetation project, the DOT is using anywhere from three
to 10 grass species, mixed with a variety of forb species. Each
project will have seed mixes designed specifically for the conditions
of that project. For the first two years these roadsides will be
mowed periodically to reduce weed competition, promote germination
and develop deeper root systems for healthier vegetation. After
the third year of planting, minimal maintenance should be required. Typical roadside revegetation project
First year of planting |
First/second year of planting |
Third/fifth
year of planting |
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