ROAD NETWORKING AND SURVEYING

Introduction to Highway Planning:
Planning is a prerequisite for any engineering activity or project;
this is particularly true for the development of a highway
network or system in a country.
• The objectives of highway planning are:
• (i) Planning a highway network for safe, efficient and fast
movement of people and goods.
• (ii) Keeping the overall cost of construction and maintenance of
the roads in the network to a minimum.
• (iii) Planning for future development and anticipated traffic
needs for a specific design period.
• (iv) Phasing road development programmes from
considerations of utility and importance as also of financial
resources.
• (v) Evolving a financing system compatible with the cost and
benefits.

To fulfil these objectives, the following principles have
to be borne in mind:
• (i) The proposed road links should be a part of the
planned road network for the state/nation.
• (ii) The importance of the road shall be based on the
traffic demand, and hence its type should fall under
the standard classification.
• (iii) The maintenance needs of the roads should
receive prompt attention by setting aside funds for this
purpose.
• (iv) Statutory provisions for traffic regulation should
be in place.

Classification of Roads:
• The classification of roads
depends on the criterion
considered.
• They may be all-weather roads if they can be
used during all seasons of a year; fair-weather
roads, if traffic is interrupted during monsoon
at course ways where water overflows for a
few hours. Based on the type of carriage-way
or the road pavement, it may be a paved road
with at least a water-bound macadam layer;
or it may be an unpaved road. Earth roads
and gravel roads fall in this category.

Classification of Roads based on
their function:
• (i) Expressways— for movement
of heavy volume of traffic.
• (ii) Arterial streets—for
connecting the central area to
expressways.
• (iii) Sub-arterial streets—similar
to arterial roads but with less
spacing.
• (iv) Collector streets—for collection and distribution
of traffic through local streets in residential areas.
• (v) Local streets—to access private property like
residences, shops and industries. Traffic originates
here or ends here.

• (vi) Bypass road – A road constructed skirting a
village or a small town, taking off through a highway
and joining it after bypassing the inhabited area; this
helps through traffic to move fast without having to
enter the village or town.
• (vii) Freeway – An arterial highway with controlled
access crossing other roads at different levels.
• (viii) Service road – Used for servicing and as a means
of access to adjacent property; constructed parallel to
the main road adjacent to roadside buildings.

Highway Planning Studies:
• Highway planning involves the
assessment of the length of road required for a given
area, which may be a city, district, state or a country;
further, it includes the preparation of a master plan
for the area taking into consideration future needs,
and phasing the programme in annual or five-year
plans, based on the priorities and utility.
• For assessing the required road length for the area,
field studies are to be carried out to collect the
necessary data.

(i) Economic Studies:
• Details of the existing facilities, their utility, distribution of
the existing population in the area, population growth
trends, existing products in the agricultural and industrial
sectors, future trends of development in these sectors,
existing communication and education facilities, and the
per capita income are to be collected.
(ii) Road Use Studies:
-Details of the existing road facilities, traffic volume in vehicles
per day, traffic flow patterns, classes of traffic such as
passenger cars, busses and trucks, loads carried, average speeds,
anticipated future trends of traffic growth, and other traffic-
related studies are to be conducted.

(iii) Engineering Studies:
• These include study of the topography, soil, road life
and special problems, if any, relating to construction,
drainage and maintenance.
(iv) Financial Studies:
-Various financial aspects such as the sources of funding, estimated revenue
from taxes on vehicles, toll tax, and indirect benefits of raising the living
standards of the people due to the proposed road network are considered.
A systematic study of all these data will help the planner in the preparation of a
Master Plan to serve the needs of the area for a specified design period of say,
20 to 25 years.
For calculating the optimum road length a system called saturation system or
maximum utility system is used.
This system is based on the principle of qualifying the utility of a proposed road
network based on the villages and towns of different populations it serves, as
also the weight of agricultural or industrial products it carries.

Road Alignment:
• The laying out of the centre
line of a proposed highway
on the ground is called its ‘alignment’. A new road
should be aligned carefully since any change in
alignment may not be possible or may be expensive at
a later stage, owing to increased land acquisition costs
and roadside structures constructed after the road has
taken shape.

Horizontal Alignment:
• This is the alignment of the roadway in the
horizontal plane; although it is ideal to have a
straight route between end points, it is
practically impossible owing to several
constraints. A change in direction necessitates
the use of horizontal curves for smooth flow of
traffic.

Vertical Alignment:
• Although it is ideal to have a roadway at the same
elevation throughout, this is almost impractical and
gradients or slopes along the length become
mandatory. A change in gradient calls for curves in the
vertical plane; vertical curves should be designed and
constructed for smooth flow of traffic based on several
criteria.

Factors Controlling Alignment:
The selection of alignment of a proposed new
highway route will be based on a careful
consideration of the following factors:
1. Topographical Features:
• Topographical features like a lake or a hillock may
require the alignment to be taken around them. In the
case of a big hill the option of constructing a tunnel
through it for maintaining a straight alignment can be
considered. The relative costs of these options have to
be studied to finalise the alignment.

2. Geometric Design Aspects:
• Factors such as radius of curve, longitudinal gradients,
sight distances, road intersections, design speed,
lateral friction, and super-elevation govern the
alignment to a considerable degree; radii of horizontal
curves and longitudinal gradients should facilitate
easy maneuvering of vehicles.
3. Cross-Drainage Needs:
• The alignment should be such that bridges are located
at right angles to the direction of flow of the stream or
river .

4. Deviations Dictated by Circumstances:
• Although a straight horizontal road is the best option, it is
highly monotonous for a driver; so, to divert attention on a
straight road and break the monotony, a slight bend or curve
may be created at least once in a kilometre or two to make the
driver alert. Obstructions such as places of worship (such as
established temples and churches), monuments of historical
interest, public buildings such as hospitals and educational
institutions and utility services like water supply and sewerage
lines and overhead transmission lines may necessarily have to
be bypassed.
• This may dictate deviation in the alignment of the roadway,
leaving sufficient margin for these hindrances. Sometimes, the
alignment may have to be changed to bypass expensive private
property or agricultural or industrial area.
5. Proximity to Materials and Labour:
• Proximity to the sources of materials for road-making and the
availability of cheap labour may be a criterion for fixing the
alignment.

6. Economic Considerations:
• Before an alignment is chosen, two or three alternative
routes may have to be investigated and their overall
cost – initial outlay and maintenance cost over a
design period – compared. The route with the best
economy is then selected.
7. Political Considerations:
• Sometimes, political considerations may dictate the
choice of alignment, setting aside even economic
considerations. Of course, the other important criteria
have to be necessarily borne in mind.

Highway Project Preparation:
• A highway project may be an entirely new route or it
may involve re-alignment and re-design of an existing
road such as for upgrading its geometric design
standards.
• The work of a new highway project involves:
• (a) Selection of the alignment.
• (b) Geometric design.
• (c) Testing and selection of the materials for the sub
grade and the pavement.
• (e) Pavement construction including surfacing.
• (f) Rolling and compaction and curing, if necessary.
• (g) Quality control during construction.
• (h) Performance of review and appraisal under traffic.

Realignment of an Existing Road:
• An existing road may have to be realigned under a
variety of circumstances:
• (i) Redesign and improvement of geometric design aspects
owing to increased traffic needs.
• (ii) Raising the level of a
• road subjected to flooding.
• (iii) Reconstruction of
• weak culverts and bridges
• to take care of increased
• traffic needs.
• (iv) Construction of over-
• bridges and under-bridges
• at road intersections and
• level crossing.
• (v) Construction of a bypass
• near a busy town.

Engineering Surveys:
• Highway alignment and location are
• facilitated by a systematic step-by-step
• procedure of conducting ‘engineering
• surveys’.
• These surveys include: 1. Study of
• Topographic Maps 2. Reconnaissance
• Survey 3. Preliminary Survey 4. Location Survey
• 5. Soil Survey 6. Construction Survey.
• 1. Study of Topographic Maps:
• Topographic maps are available from the Survey of India; these are
contour maps with 15 to 30 m contour intervals and show important
topographic features like rivers, valleys, ridges, and hills. By a careful
study of these maps, it is possible to align highways bearing in mind
the obligatory points. Depending upon the elevations of the terminal
points, and considering the ruling gradients and other factors, two or
three alternative routes may be chosen.

• 2. Reconnaissance Survey:
• The objective of reconnaissance survey is to physically
examine the possible alignments observed during the
study of topographical maps. This is generally carried
out using simple surveying instruments such as
prismatic compass, Abney level, hand level or tangent
clinometer.
• Details of certain features not available from the map
study are collected during the reconnaissance survey.

Some of the details that
may be gathered are:
• (i) Approximate gradients, radii of horizontal curves necessary.
• (ii) Obstructions such as permanent structures not shown in the
maps.
• (iii) Ponds, lakes, valleys, bridges, hillocks, and similar topographical
features with relevant details.
• (iv) Information relating to cross-drainage structures such as
culverts, causeways and bridges required along each of the possible
routes.
• (v) Geological features and information on soil types along the route.
• (vi) Stability of slopes in the case of hilly terrain.
• (vii) Sources of construction materials – borrow areas for earth
materials and quarries for stones and broken stone.
• (viii) Climatic factors, hydrological information, water-table levels,
water sources and maximum flood levels in the case of streams and
rivers.
• (ix) Availability of labour, power and water supply along the route.

3. Preliminary Survey:
• The objectives of a preliminary survey are:
• (i) To compare the proposed routes chosen during
reconnaissance for a good alignment.
• (ii) To carry out accurate field work for detailed
surveys on the chosen alternative routes
• (iii) To estimate the quantities of the earth work and
other materials to facilitate the preparation of
detailed and abstract estimates of the project cost.
• (iv) To choose the best alignment from all angles.

Detailed Survey:
• The various kinds of detailed survey carried out
are:
Traverse Survey:
• Open traverse are run with the help of a theodolite and
tapes, the lengths of each of the lines and the deflection
angles wherever a change in direction is required are
measured accurately.
Levelling:
• Longitudinal section along the proposed route and cross-
sections at intervals of 30 m to 100 m along the route are
to be taken, depending upon the nature of terrain – plain
or rolling.
• Contouring is also done in the vicinity of the route by using
either tachometry or precise levelling. Bench-marks are
connected to GTS bench-marks.

4. Location Survey:
• 1- Transferring the alignment on to ground.
• 2- This is done by transit theodolite.
• 3- Major and minor control points are established on
the ground and centre pegs are driven, checking the
geometric design requirements.
• 4- Centre lines tacks are driven at suitable intervals,
say 50m interval in plane and rolling terrains and 20m
in hilly terrain.

5. Soil Survey:
• The nature and extent of the soils available in and
around the chosen route have to be ascertained. The
purpose of soil survey is to identify and classify soil for
use in the design and construction of the road.
• Information is gathered on the presence of unstable
strata or marshy areas,
subsoil water level,
and demarcation of
possible borrow areas
along the road in
accordance with IRC
recommendations.

6. Construction Survey:
• This consists of removing all under-growths such as
shrubbery, thickets, tree stumps and rubbish along the
route, setting out the centre-line and the right of way
by affixing pegs at appropriate intervals, cutting a
narrow V- shaped cut called ‘Lockspit’ in between the
pegs along the
route and making
the necessary
preparations for
implementation
of the project.

MADE BY:-
GROUP NO.- 4
AAYUSH AGRAWAL-19BCL0050
PRANAY SINGHAL-19BCL0052
MANASH KEDIA-19BCL0020
UTKARSH JAISWAL-19BCL0018
UDIT AGRAWAL-19BCL0091

ROAD NETWORKING AND SURVEYING

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Similar to ROAD NETWORKING AND SURVEYING

Similar to ROAD NETWORKING AND SURVEYING (20)

Recently uploaded

Recently uploaded (20)

ROAD NETWORKING AND SURVEYING