Transportation agencies manage approximately 12
million acres of land surrounding state, interstate,
county, and municipal roads.[N]
DOT roadside vegetation management involves a wide
range of concerns including prevention of erosion and
sedimentation control and spread of noxious weeds,
in addition to transportation concerns and efficient
use of resources to accomplish management objectives
for the right-of-way.[N]
Today, ROW managers must be concerned with multiple
use aspects of ROW management; multiple use concerns
necessitate the development of plant communities that
resist the invasion of woody plants, are aesthetically
pleasing, provide food and/or cover for wildlife, and
can be economically established and maintained.[N]
In the name of safety, improved visibility and obstacle-free
roadsides, roadside vegetation managers favor grasslands,
which formerly covered more than half the U.S.[N]
Once established, the native grasses save maintenance
dollars over time, provide a self-reliant and hardy
plant community, improve wildlife habitat, and protect
the local character and natural heritage of a site.[N]
WSDOT's State Roadside Manual outlines some of the
many functions vegetation contributes that add significant
value to our environment, including: [N]
 Traffic
calming- Stress reduction
- Buffer or shade for pedestrian or park and ride
facilities
- Stream bank stabilization
- Wetland mitigation
- Water quality improvement
- Water retention and smoother flows
- Air pollution mitigation
- Noise abatement
- Wildlife habitat
- Enclose, screen, expose, or blend
- Visual quality, quality of life
- Corridor continuity
Several years back, NCHRP 20-5, 33-04 surveyed a
sample of state DOTs and identified erosion control
as a primary concern in management of vegetation. Indiana,
Minnesota, Texas, and Washington reported that their
vegetation management activities were affected by stormwater
management objectives. Florida, Illinois, Indiana,
Maryland, Ohio, Texas, and Washington reported control
of roadside fire starts as a concern addressed by their
vegetation management practices. The use of native
plants in construction or restoration of roadside vegetation
patterns was mandated by policy or state laws in slightly
more than 40 percent of the reporting states. The dollar
value assigned to benefits of "environmentally
sensitive" maintenance methods (i.e., mowing of
brush verses spraying of brush) have been established
by four of the responding states: Florida, Illinois,
South Carolina, and Texas. The same valuation in regard
to construction methods was identified by only Florida
and Illinois. Connecticut, Illinois, Maine, Minnesota,
Nebraska, Ohio, Pennsylvania, Texas, Utah, Washington,
and West Virginia said that environmental impacts from
long‑term sustainability were given consideration
in construction of new roadside projects.[N]
The author performed a survey of DOT roadside vegetation
managers in 2005 regarding their key considerations,
obstacles, and priorities in vegetation management,
particularly related to invasive species control. In
turn, this input from practitioner leaders helped identify
areas where best practice identification and sharing
were most needed. Chapter 9 of AASHTO's Environmental
Stewardship Practices Compendium has been totally revised
as a result, in the attempt to fill some of those gaps.
Detailed guidance on best practices is also provided
in Chapter 4 on Construction practices, as so many
of these can either promote or control invasives species.
Of particular relevance in the latter are topsoil stockpiling,
erosion and sedimentation control, and proper stabilization. |
