Landscape planning techniques and designing highways

LANDSCAPE PLANNING TECHNIQUES
&
DESIGN AND DEVELOPMENT OF HIGHWAYS
LA/481 Master of Landscape Architecture School of Planning and Architecture-New Delhi
Date : 10th April, 2013
AR. TRUPTI BARKALE

AR. TRUPTI BARKALE LA/481 MLA SPA, NEW DELHI
AIM –
To understand landscape techniques while planning infrastructures development and learn its impact
on the environment
OBJECTIVES –
A. To study various aspect of highway design
i. Alignment – vertical and horizontal alignments ; combination of straight, curve and serpentine
ii. Visual quality impact
iii. Land cover or land-use of the surroundings
B. To evaluate the effect of highway on the local dwellers & its value on their lives, values of
properties, value of infrastructure, public places and landscape values enhanced
C. To understand the cut-fill, side slopes, embankments of highways

Alignment –
• Vertical and Horizontal alignments
• Combination of straight, curve and
serpentine
VERTICAL AND HORIZONTAL ALIGNMENTS
A.ASPECTOFHIGHWAYDESIGN

This graphic depicts how changes in the vertical alignment can affect sight distance at junctions. Even
small changes in grade can have a significant impact.
 Continuity in Vertical Alignment
From an esthetic point of view, one of the goal in alignment design is to achieve a continuous alignment.
Continuity is desirable so that the road fit the terrain, does not have a jarring aspect and present a path
which is easy to follow
To achieve continuity two different elements are considered
• Continuity of Form
• Continuity of Scale
Continuity of Form
For vertical curves continuity of form is not a problem. There is no sudden break in grade at the PC or PT
since the parabolic curve provides a gradual transition in grade
Continuity of Scale
Continuity of scale relates to the relative lengths of the tangent and curves
Source: Geometric Design of Transportation Facilities – lectures By Professor Norman W. Garrick

Common flaws from very short curves –
• Board Effect,
• Hump,
• Break

Alignment –
• Combination of straight, curve and
serpentine

Coordination of Vertical and Horizontal Alignment
Continuity in plan and profile does not guarantee overall continuity of alignment in 3-D.
Vertical and horizontal alignment must be designed to be in sync with each other.
Two main issues for coordination -
• Relative scale of vertical and horizontal elements
• Relative location of horizontal and vertical curves
General Rules for Proper Coordination –
i. Curves in vertical and horizontal alignment should be about the same length.
ii. Horizontal and vertical curves should not start and end at the same point. Horizontal curve
should lead and generally remain longer.
iii. Horizontal and vertical curves should generally coincide in location (location of vertices).
Alignment –
• Combination of straight, curve
and serpentine

• While visual obstructions are not the direct target of this objective, this problem must be considered when
applying these strategies.
• Trees may create various types of visual obstructions such as limiting sight distance at intersections,
driveways, and curves. Trees may also block a sign, or other roadside hardware, and also obstruct the
driver's view of pedestrians and other road users.
• At intersections, trees planted or allowed to grow in the sight triangle (FIG. 1) can obstruct drivers' view of
oncoming vehicles. The distances designated as "a" and "b" in FIG. 1are often set by local ordinances,
based upon the speed limit.
• The ordinances typically place height restrictions on objects in the sight triangle, such as "no objects
permitted between 30 and 96 inches above the ground."
Visual Obstructions –
FIG. 1 Intersection Sight Triangles

• FIG. 2 shows another example of an area where trees can block the sight distance of a driver.
• The area between the paths followed by the driver's eye, and the chord across the curve, should be free
of any obstructions.
• The middle ordinate distance depends on the radius of curvature and lane width.
• Other elements that affect sight distance in this situation include cross sectional elements and vertical
elements that affect the stopping sight distance.
• While the illustration shows the problem on the roadside, the same problem can exist in a wide median
where trees have been planted too closely to the road on the inside of a curve.
FIG. 2 Sight Distance around a Horizontal Curve

Land cover or land-use of the surroundings –
The Impact of Land Use Changes on Road Functions
• Land use is an important determinant of the function of an area's roads.
• As land use changes because of development, especially at the urban fringe, road functions
also change.
• Design standards or guidelines must change to meet actual or impending change in traffic
character and road function.
• Actions taken by a local jurisdiction to control or direct the form and location of growth or to
preserve the current physical and scenic characteristics of a highway corridor should also
reflect the need for a reexamination of existing functional classification and, perhaps, even a
change in jurisdictional responsibility
• For example, the construction of a new controlled access bypass route might allow for a
downward reclassification of what had been the existing arterial route through a community
to a collector level facility.

These views show changing
land use along a rural
highway. The first view -
a) shows a new road
through the country.
b) shows the first
residences along the
road.
c) shows suburbanization
and the need for
mitigation
Source: http://www.fhwa.dot.gov/environment/publications/flexibility/ch03.cfm

CONCLUSION –
One solution to the issue of changing land use is to directly relate the functional classification
of the highway system to the "level of development" or, in other words, the design criteria
that should be applied.
This process allows for improvements to even minor arterial type routes to be designed
using 3R standards, as opposed to applying traditional design criteria for new location
highway facilities that fall within this functional classification.
Functional Class Design Criteria
Interstate New Construction/Reconstruction Standards
Principal Arterial New Construction/Reconstruction Standards
Minor Arterial 3R Standards
Collector Maintenance of Structural Integrity and Operational Safety.
Relationship of Functional Classification and Design Criteria

TRUPTI BARKALE LA/481 MLA SPA, NEW DELHI
B.IMPACTSOFPLANNINGHIGHWAYS
IMPACTS ON AESTHETICS AND LANDSCAPE
IMPACTS AND SETTING
Principles of regional landscape design can be summarized as follows:
1. Respect natural and human processes of change. Analyze what nature and people have done to
the site. Try to maintain links with the past, allow today’ s lifestyles to continue, and do not attempt to
control the landscape.
2. Employ an economy of means. The road design that results in a minimum use of resources and effort
should contribute to enhanced environmental, economic and social benefit.
3. Respect and make the most of the diversity of the landscape. The biophysical determinants of a
site have traditionally constituted constraints on human activity. In this setting the local vernacular
landscape arose. Today’ s technologies free societies of many of those constraints. It is thus easier for
developments, such as roads, to be out of keeping with their settings. Today’ s designers have to make
responsible choices.
4. Respect the connectedness of natural elements and human uses of nature. The movement of water,
of wildlife, and of local people in their community all contribute to the coherence of a region’ s
landscape.
5. Recognize the potential for human development activities to contribute to environmental
enhancement. The principles, of energy and nutrient flows should be applied to the design of such
features of the human environment as roads.
6. Make visible the processes that sustain life. Opening the view from the road to life along the road,
rather than hiding it, maintains interest in the surroundings and extends understanding of that
environment and the communities it supports.
Source: ROADS AND THE ENVIRONMENT: A HANDBOOK

NEGATIVE AESTHETIC IMPACTS
Negative aesthetic impacts can be expressed as a product of –
the poor consideration of the mentioned design principles and
a resulting lack of harmony between the road and various features of the landscape, such as those
listed below:
a. The natural relief and morphology of the landscape- In this case, such disharmony can occur if
the route does not follow the relief as closely as possible and causes the formation of major cut and
fill zones, out of character with the terrain in height, length, and incline of slopes; or if the route cuts
transversely or diagonally across a system of parallel valleys; or does not avoid landscape with an
uneven relief.
b. The hydrology - e.g. if road construction results in rerouting and channeling of a waterway.
c. Vegetation - e.g. if the road project results in deforestation, destroys or does not bypass isolated
trees, avenue trees, or hedges; or if it interrupts the continuity of vegetation in a valley or other
setting.
d. The structure and pattern of the landscape - e.g. if the road distorts the existing field system by,
say, cutting obliquely through a rectangular farm system and creating numerous isolated plots which
may be difficult to cultivate, out of place, and thus aesthetically disturbing.
e. Urban or village areas - e.g. if the road separates two urban centers or if a strong existing urban
pattern has not been taken into consideration in its design. Roads can also modify the way a city or
village evolves and expands and can encourage new urban expansion. This may be an objective of
road development or an unexpected outcome with undesired visual and community impacts.
f. Recreational areas - e.g. if these areas, which will require good access, are not traversed with
sensitivity; and finally.
g. Architectural or cultural heritage-e.g. if the road crosses through a park of historical interest or
blocks or cuts off a view of archaeological or cultural interest.

Landscaping proposed for the route should
• Fit in with local vegetation (trees, shrubs, avenue
trees, hedges);
• Make use of vegetation to harmonize with or improve
the existing landscape;
• Respect views and not be planted systematically just
to fill in space;
• Take advantage of natural openings in the existing
vegetation;
• Frame and underscore the various landscape units
crossed;
• Suit and underscore the various engineering
structures;
• Ensure user safety by using the landscape to signal
changes in the route, e.g. by decreasing the space
between avenue trees before entering a curve or
village;
• Pay attention to the aesthetics of engineering
structures by selecting materials that adopt local colors
and textures and which give the structure a simple
shape.
Design of bridges
Design of special influence areas

IMPACTS ON COMMUNITIES AND THEIR ECONOMIC ACTIVITY
a. The split community -
Both new roads and significant widening can split a community. The introduction of faster
traffic, access controls, and median barriers generally cuts traditional lines of travel or
communication (see Figure a).
The alternative routes for local movements are sometimes substantially longer, directly
affecting businesses, pedestrians, and users of non-motorized transport. The burden of
accommodating the changes is generally greater for the poor.

b. In rural areas,
The normal links between villagers and their farmlands (i.e., their economic space) may be cut
by a new road or increased traffic.
On the scale of the individual farm, the same phenomenon may disrupt existing farming
patterns and connections between fields (see Figure b). The ensuing impact on economic
activity could be a loss of agricultural productivity or increased travel costs.

c. The loss of roadside community business and social activity
Permanent occupancy of the open space of a publicly owned right-of-way quite commonly
invites encroachment of local community activities onto the roadside, the footpaths, the
bus stops, and even the road surface itself. These activities take many forms, including -
• The selling of goods, whether from individual kiosks or more expansive markets;
• Small businesses such as cafes and vehicle repair shops;
• Uncontrolled stops by buses, taxis, and informal public transport;
d. The by-passed community
While by-pass roads can overcome some problems of conflict between road use and
community welfare, they may create other problems. On the positive side, by-pass roads
reduce the immediate impacts of traffic on the community, and local commercial activities
sometimes flourish as a result.
On the negative side, communities may fear a loss of business from the diversion of traffic,
and some community activities may “migrate” to the new route, potentially changing
existing land use patterns and possibly undermining the objective of greater control of
access on the new route.
Conclusion –
All of these factors give rise to justifiable concerns on the part of local communities about the
effects of proposed road projects on their lifestyles and welfare. It is always preferable to
identify and discuss these concerns at an early stage in the road planning process, so that
the magnitude of likely effects can be understood more fully and designs can be modified
accordingly.

The direct, indirect, and cumulative impacts of highway development can be
grouped into three general categories:
1. Destruction of habitat (resulting in the elimination of certain habitat types and
their replacement with non-natural uses or with specialized semi-natural
habitats).
2. Fragmentation of habitat (resulting in the loss of habitat integrity through the
creation of barriers to speciesand ecological processes).
3. Degradation of habitat (resulting in the loss gf habitat integrity through
disturbance of resident species, contamination with pollutants, alteration of
natural processes, and
IMPACTS ON ECOLOGY

Approaches to Meeting Ecosystem Protection Goals – For Categories of Highway Development
Source:EVALUATIONOFECOLOGICALIMPACTSFROMHIGHWAYDEVELOPMENT

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