Transcript preliminary location survey

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Life in communities has changed over the
years.
One of those changes is in transportation.
Transportation is a way of moving people or
things from one place to another.
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Land
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Water
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Air
There are three main elements of automobile
transportation:
 The road users (Drivers and pedestrians)
 The vehicle
 The road way and geometric design
LOCATION SURVEY AND CONTROLS
Art of observing and making
measurements of relative
portions of natural and manmade
features on the surface of earth
and plotting these measurements
to some suitable scale to
form a map.
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Highway surveys involve measurement and
calculation of distances, angles (horizontal and
vertical) and elevations.
 The data is then used to form a base map
with contour lines and longitudinal crosssections.
Three major categories
1. Ground Surveys
Basic equipment is used for location survey
 Measuring Tape.
 Levels.
 Theodolite.
 Electronic distance measuring devices
(EDM’s).
2. Remote Sensing
 Measurement of distances and elevations by
using devices located above the surface of
earth.
 Data is collected through airplanes and
satellites using global positioning systems
(GPS).
 Photogrammetry (data is obtained with the
help of aerial photographs) is the most
commonly used technique.
3. Computer Graphics
 Available/collected data is compiled and
stored in the electronic form.
 Photogrammetric and general survey data is
combined digitally with the help of softwares.
 The files can then be plotted in the form of
maps.
Location controls are basically the factors that
effects the selection of location of a highway
Major factors are:
 Topography.
 Soil Characteristics.
 Environmental factors (noise and air
pollution).
 Economic factors.
Highway location process have four phases
 Desk study of available data/information
 Reconnaissance survey
 Preliminary location survey
 Final location survey
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Available data in the form of reports,
maps,aerial photographs and charts is
studied.
Data is obtained form government
authorities e.g. transport department (NHA),
geological survey of Pakistan etc.
Similarly, information is required to be
obtained on hydrology, mining, agriculture
and weather.
Data is obtained on the following
characteristics:
 Engineering (topography, geology, traffic
volume and climate)
 Social (land use trends and zoning)
 Environmental (air, noise and water
pollution, wildlife, historic and archaeological
sites)
 Economic (construction cost, agricultural,
commercial and industrial trends)
“Reconnaissance is the process of identifying
several possible routes & evaluating the
feasibility of these routes for a highway
between specific points”
 Aerial photographs are often used for the
purpose, especially for rural areas.
Feasible routes are identifies by keeping in
mind the following factors
 Terrain and soil conditions.
 Serviceability of route to industrial and
residential areas.
 Crossing of other transportation facilities like
rivers, rail and highways.
 Route directness.
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Identification of control points for each
feasible/selected route.
Routes are then plotted on a map.
The position of the feasible routes are set as
closely as possible by Establishing all control
points.
 Determining preliminary vertical and
horizontal alignments of each control point
 Economic and environmental feasibility of
the routes
 The best route is then selected as the
preliminary alignment for the highway.
Initial cost of the project and future
economic effects
 Road user cost
 Construction cost
 Road user benefits
 Economic drawbacks from the project
Information also helps in deciding the type of
highway for a particular route.
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Environment Includes
 plant
 animals
 Human community
 Effects on quality of life for all (animals and
human being)
An environmental impact statement should be
submitted which should include
 Available alternatives
 Assessment of all positive and negative
impacts
 Short and long term effects
 Unavoidable adverse environmental effects
 Use of natural resources
 Each route should be studied
e.g. Positive and negative effects of at grade or
grade seperated intersection.
Detailed layout of the selected route is carried
out at this stage
 Centreline of the road.
 Horizontal and vertical alignment.
 Property lines.
 Intersecting roads.
 Position of structures and drainage channels.
Factors that effect location of highway in urban
areas
 Connection to local streets (which street to
connect,traffic flow)
 Right-of-way acquisition (land cost, road on
elevated structures, noise and aesthetics)
 Coordination with other transportation systems
(integrated system, public transport)
 Provisions for bicycles and pedestrians
(sidewalks,crosswalks, traffic control devices,
ramps, bicycle path)