Unit 37: Advanced Civil Engineering

HND in Construction & Built Environment (Civil Engineering) BCAS DOHA QATAR
Unit 37: Advanced Civil Engineering Page 1
Scenario: - 01
LO1 Understand the methods and techniques used in tunneling activities
1.1 List out the construction methods for tunneling?
 Cutandcover
 Boring machines (TBM)
 Drill and blast
 Claykicking
 Shafts
 Sprayed concrete techniques
 Pipe jacking
 Underwater tunnels
 Temporary way
 Enlargement
 Open building pit
 Other construction methods
Cut and cover method: Cutandcover is a simple method of construction for shallow tunnels
where a trench is excavated and roofed over with an overhead support system strong enough to
carry the load of what is to be built above the tunnel
Boring machines (TBM): Tunnel boring machines (TBMs) and associated backup systems
are used to highly automate the entire tunnelling process, reducing tunnelling costs. In certain
predominantly urban applications.
Drill and blast method: Drilling and Blasting is the controlled use of explosives and other
methods such as gas pressure blasting pyrotechnics, to break rock for excavation. It is practiced
most often in mining, quarrying and civil engineering such as dam or road construction. The
result of rock blasting is often known as a rock cut
Clay-kicking method: Claykicking is a specialised method developed in the United Kingdom
of manually digging tunnels in strong claybased soil structures, claykicking was relatively silent
and hence did not harm soft clay based structures.
Shafts method: A temporary access shaft is sometimes necessary during the excavation of a
tunnel. They are usually circular and go straight down until they reach the level at which the
tunnel is going to be built. A shaft normally has concrete walls and is usually built to be
permanent. Once the access shafts are complete
Sprayed concrete techniques: The New Austrian Tunneling Method (NATM) was developed
in the 1960s, and is the best known of a Number of engineering solutions that use calculated
and empirical realtime measurements to provide optimised safe support to the tunnel lining
Pipe jacking or micro tunneling: In Pipe jacking hydraulic jacks are used to push specially
made pipes through the ground behind a TBM or shield, commonly used to create tunnels under

existing structures, such as roads or railways. Tunnels constructed by pipe jacking are normally
small diameter tunnels with a maximum size of around 3.2m.
Underwater tunnels: An undersea tunnel is a tunnel which is partly or wholly constructed under
a body of water.
Ref: https://en.wikipedia.org/wiki/Tunnel

LO2 Understand the methods and techniques used in Hydraulic structures
2.1 Outline the classification of hydraulic structures on the basis of function
o Flow control structures: They are used to regulate the flow and pass excess flow.
They might be gates, spillways, valves, or outlets.
o Flow measurement structures: They are used to measure discharge. They are weirs,
orifices, flumes etc.
o Division structures: they are used to divert the main course of water flow. They are
coffer dams, weirs, canal head works, intake works.
o Conveyance structures: they are used to guide the flow from one place to another.
They areopen channels, pressure conduit, pipes, canals and sewers.
o Collection structures: they are used to collect water for disposal. They are Drain inlets,
infiltration galleries, wells.
o Energy dissipation structures: they are used to prevent erosion and structural
damage. They are stilling basins, surge dams, check dams.
o River training and water stabilizing structures: they are used to maintain river
channel and water transportation. Levees, cutoffs, locks, piers, culverts
o Sediment and quality control structures: they are used to control or remove
sediments and other pollutants. They are racks, screens, traps, sedimentation tanks,
filters, sluiceways.
o Hydraulic machines: they are used to convert energy from one form to another. They
are turbines, pumps, ramps,
o Storage structures: they are used for the purpose of storage of water. These may be
dams or tanks etc.
o Shore protection structures: they are used to protect banks. Dikes, groins, jetties,
revetments
Ref: https://www.scribd.com/doc/50496668/typesofhydraulicstructures

2.2 Explain in detail the construction methods of following Hydraulic structures.
o Earth dam
o Aqueducts
o Sluice Gate
Earth Dam
o They are trapezoidal in shape
o Earth dams are constructed where the foundation or the underlying material or rocks are
weak to support the masonry dam or where the suitable competent rocks are at greater
depth.
o Earthen dams are relatively smaller in height and broad at the base.
o They are mainly built with clay, sand and gravel, hence they are also known as Earth fill
dam or Rock fill dam.
o Earth dam is made of earth (or soil) built up by compacting successive layers of earth, using
the most impervious materials to form a core and placing more permeable substances on the
upstream and downstream sides.
o A facing of crushed stone prevents erosion by wind or rain, and an ample spillway, usually
of concrete, protects against catastrophic washout should the water overtop the dam.
o Earth dam resists the forces exerted upon it mainly due to shear strength of the soil.
o Although the weight of the earth dam also helps in resisting the forces, the structural
behavior of an earth dam is entirely different from that of a gravity dam.
o The earth dams are usually built in wide valleys having flat slopes at flanks (abutments).
o The foundation requirements are less stringent than those of gravity dams, and hence they
can be built at the sites where the foundations are less strong.
o They can be built on all types of foundations. However, the height of the dam will depend
upon the strength of the foundation material.
Examples of earth fill dam: Rongunsky dam (Russia) and New Cornelia Dam (USA).

HND in Construction & Built Environment (Civil Engineering)
Unit 37: Advanced Civil Engineering
Step for construction
o Setting out the dam site
o Analyze plant, equipments
o Site clearing and preparation
o Settlement
o Spillway design
o Constructing the embankment
 Setting out the dam site
This should be completed immediately prior to the start of construction to avoid
unnecessary ground clearing and the loss of pegs and benchmarks.
site survey pegs become lost, the dam centre line must be re
and substantial reference pegs, installed at each end of the centre line, a good distance
from where construction will occur. If the original bench
another should be established on a permanent site within easy reference distance.
The toe peg offset distances from the centre line are calculated using the formula:
HND in Construction & Built Environment (Civil Engineering)
Unit 37: Advanced Civil Engineering
Setting out the dam site
equipments & techniques.
clearing and preparation
Constructing the embankment
unnecessary ground clearing and the loss of pegs and benchmarks.
site survey pegs become lost, the dam centre line must be reestablished with additional
from where construction will occur. If the original benchmark(s) is (are) not satisfactory
BCAS DOHA QATAR
Page 5
unnecessary ground clearing and the loss of pegs and benchmarks. Should the original
established with additional
mark(s) is (are) not satisfactory

 Analyze plant, equipments & techniques.
Consideration of what plant and equipment is available, the conditions of operation and
distances materials are to be moved, as well as size and type of dam to be built, are the
most important factors in determining the plant and equipment to be used.
The compaction of soil is essential to increase the shear strength of a material to
achieve high levels of embankment stability. A high degree of compaction will increase
soil density by packing together soil particles with the expulsion of air voids. Comparing
the shear strength with the moisture content for a given degree of compaction, it is found
that the greatest shear strength is generally attained at moisture contents lower than
saturation.
In dam construction, following correct compaction techniques is probably as important as
choosing the correct materials. Where laboratory analysis is not available the following
guidelines should be adhered to:
 The soil to be compacted must be damp but not too wet and it must be layered
along the full length of the embankment in depths appropriate to the equipment
used.
 Where soil moisture content is low, borrow pit irrigation always results in a more
uniform distribution of water in the soil to be compacted. It is also more economic
than adding water to the construction surface and often assists working of the
soil by the excavators.
 Always adopt compaction techniques that will reduce the gross depth of any
layer by at least 25 percent.
 Site clearing and preparation
o Base of the dam: All trees and roots, grass, grass roots and topsoil must be
removed. Once the trees have been removed (by hand usually) the dam scoop or
scraper can be used to remove about 100 mm of top soil which can then be left in a
position from which it can be later retrieved to dress the completed embankment or
other disturbed areas.
o Borrow areas: Borrow areas should have been demarcated according to usefulness
some time previous to the start of construction with, if possible, analysis of soil
samples being undertaken by a local soils’ laboratory. For smaller dams, a visual or
rough physical assessment may suffice.
 Settlement
As the dam settles, the crest should fall close to horizontal. It is important to check this
by survey every few months in the first years of operation to ensure over or uneven
settlement does not occur. If this does occur, remedial measures (filling by topsoil and
grass is usually sufficient) will be required to restore the crest to its design level.

 Spillway design
Natural spillways are generally best for all earth dams but often some degree of cut is
required to obtain the necessary design slopes. In all cases the movement of machinery
over the spillway area should be minimized to avoid over compacting the existing soil,
establishing track ways (which could lead to erosion later) and destroying any existing
grass cover. Where a cut is required it should be kept to a minimum and, unless
unavoidable, should not involve complete removal of the topsoil
 Constructing the embankment
The core/cutoff trench:
As this is the most important part of any embankment, great care is necessary in the
excavation, fill and use of material. Width and depth should have been determined at the
design stage. Width (2 m minimum) will often depend on the equipment used in the
excavation and also on the size of the dam.
Embankment:
Once the cutoff has been brought up to ground level, the embankment can be
constructed. If necessary, and usually because of time limitations, it may prove prudent
to construct the cutoff some time before the rest of the dam (i.e. during the previous dry
season ensuring the works are protected from erosion).
Ref: http://www.fao.org/docrep/012/i1531e/i1531e.pdf
Aqueducts
Aqueduct (bridge): Bridges for conveying water, called aqueducts or water bridges are
constructed to convey watercourses across gaps such as valleys or ravines. The term
aqueduct may also be used to refer to the entire watercourse, as well as the bridge.
Large navigable aqueducts are used as transport links for boats or ships. Aqueducts
must span a crossing at the same level as the watercourses on each end. The word is

derived from the Latin aqua and ducere. A modern version of an aqueduct is a pipeline
bridge.
Navigable aqueduct: bridge structures that carry navigable waterway canals over other
rivers, valleys, railways or roads. They are primarily distinguished by their size, carrying a
larger crosssection of water than most watersupply aqueducts. Although Roman aqueducts
were sometimes used for transport, aqueducts were not generally used until the 17th century
when the problems of summit level canals had been solved and modern canal systems were
developed. The 662metre long steel Briare aqueduct carrying the Canal lateral a la
Loire over the River Loire was built in 1896. It was ranked as the longest navigable aqueduct
in the world for more than a century, until the Magdeburg Water Bridge in Germany took the
title in the early 21st century.
Sluice Gate
A sluice gate is a water channel controlled at its head by a gate. A mill race, leet, flume,
penstock or lade is a sluice channeling water toward a water mill. The terms sluice,
sluice gate, knife gate, and slide gate are used interchangeably in the water and
wastewater control industry.
A sluice gate is traditionally a wood or metal barrier sliding in grooves that are set in the
sides of the waterway. Sluice gates commonly control water levels and flow rates in
rivers and canals. They are also used in wastewater treatment plants and to recover
minerals inmining operations, and in watermills.
Operation
"Sluice gate" refers to a movable gate allowing water to flow under it. When a sluice is
lowered, water may spill over the top, in which case the gate operates as a weir. Usually,
a mechanism drives the sluice up or down. This may be a simple, handoperated, chain
pulled/lowered, worm drive or rackandpinion drive, or it may be electrically or
hydraulically powered.
Types of sluice gates
 Flap sluice gate
A fully automatic type, controlled by the pressure head across it; operation is similar to
that of a check valve. It is a gate hinged at the top. When pressure is from one side, the
gate is kept closed; a pressure from the other side opens the sluice when a threshold
pressure is surpassed.
 Vertical rising sluice gate
A plate sliding in the vertical direction, which may be controlled by machinery.
 Radial sluice gate

A structure, where a small part of a cylindrical surface serves as the gate, supported by
radial constructions going through the cylinder's radius. On occasion, a counterweight is
provided.
 Rising sector sluice gate
Also a part of a cylindrical surface, which rests at the bottom of the channel and rises by
rotating around its centre.
 Needle sluice
A sluice formed by a number of thin needles held against a solid frame through water
pressure as in a needle dam.
Ref: https://en.wikipedia.org/wiki/Sluice

2.3 Appraise the construction of rigid dam to retain and control the river flow.
It is constructed with rigid material such as stone, masonry, concrete, steel, or timber.
Steel dams (steel plates supported on inclined struts) and timber dams (wooden planks
supported on a wooden framework) are constructed only for small heights (rarely).
Eg: Steel Dams, Timber Dams, Arch Dams, concrete dam
Main Features of Rigid Dam
o The gravity dams are generally straight in plan (i.e. axis is straight from one abutment to
the other)
o The gravity dams are approximately triangular in crosssection, with apex at the top.
o The gravity dams are generally more expensive than earth dams but are more durable.
o They are quite suitable for the gorges with very steep slopes.
o They require strong rock foundation. However, if the foundation consists of soil, the height of
the gravity dams is usually limited to 20 m .
Advantages of Rigid Dam
o Rigid dams are quite strong, stable and durable.
o Rigid dams are quite suitable across moderately wide valleys and gorges having steep
slopes where earth dams, if constructed, might slip.
o Rigid dams can be constructed to very great heights, provided good rock foundations
are available.
o Rigid dams are well adapted for use as an overflow spillway section.
o Rigid dams are specially suited to such areas where there is very heavy downpour.
o The Rigid dam does not fail suddenly. There is enough warning of the imminent failure
and the valuable property and human life can be saved to some extent.
o Rigid dam can be constructed during all types of climatic conditions.
o The sedimentation in the reservoir on the upstream of a gravity dam can be somewhat
reduced by operation of deepset sluices.
Disadvantages of Rigid Dam
o Rigid dams of great height can be constructed only on sound rock foundations. These
cannot be constructed on weak or permeable foundations on which earth dams can be
constructed. However
o The initial cost of a Rigid dam is usually more than that of an earth dam. At the sites
where good earth is available for construction and funds are limited, earth dams are
better
o Rigid dams usually take a longer time in construction than earth dams, especially when
mechanized plants for batching, mixing and transporting concrete are not available.
o Rigid dams require more skilled labour than that in earth dams.
o Subsequent raising is not possible in a Rigid dam.
o Rigid dams small heights can be constructed even when the foundation is weak.

LO3 Understand the methods and techniques used in Marine Work
3.1 Outline the shore protection structures
Structural Methods for Coastal Shore Protection
o Seawalls Seawalls are usually massive, vertical structures used to protect backshore areas
from heavy wave action, and in lower wave energy environments, to separate land from
water.
o Bulkheads These are vertical retaining walls to hold or prevent the soil from sliding
seaward.
o Revetments Revetments are a cover or facing of erosion resistant material placed directly
on an existing slope, embankment or dike to protect the area from waves and strong
currents.
o Dikes and Levees Dikes are typically earth structures (dams) that keep elevated water
levels from flooding interior lowlands.
o Breakwaters Breakwaters are generally shoreparallel structures that reduce the amount of
wave energy reaching the protected area.
o Groins Groins are the oldest and most common shoreconnected, beach stabilization
structure.
o Sills / Perched Beaches Construction of a low retaining sill to trap sand results in what is
known as a "perched beach," one that is elevated above its original level.
o Jetties and Piers Jetties are shorenormal stone structures commonly used for training
navigation channels and stabilizing inlets. Pier structures are sometimes referred to as
jetties.
NonStructural Methods for Coastal Shore Protection
o Vegetation Planting Vegetation is an effective and inexpensive way to stabilize dunes and
protect marshes.
o Groundwater Drainage Groundwater drainage, or bluff dewatering is a common practice
used to rapidly drain ground and surface waters away from a bluff in order to eliminate or
reduce bluff failures initiated by groundwater seepage.
o Beach Nourishment Beach nourishment is the introduction of material along a shoreline to
supplement the natural littoral drift.
o Sand Bypassing Sand bypassing is the hydraulic or mechanical movement of sand, from
an area of accretion to a downdraft area of erosion, across a barrier to natural sand
transport.
o Flood Proofing One of the most common flood proofing measures is the elevation of
homes.
o Zoning Zoning measures involve the implementation and enforcement of planning and
zoning bylaws to control development in flood and erosion hazard zones.
o Retreat In some cases, it may be less expensive to relocate endangered structures than to
invest in large scale shore protection.
o Do Nothing The no action, or do nothing approach is commonly used by engineers to help
evaluate different courses of action.
Ref: http://chl.erdc.usace.army.mil/chl.aspx?p=s&a=Articles;199

3.2 Explain in detail the use of Cofferdams foundation and its’ application available for
marine structures.
A cofferdam is a temporary structure designed to keep water and/or soil out of the excavation in
which a bridge pier or other structure is built. When construction must take place below the
water level, a cofferdam is built to give workers a dry work environment. Sheet piling is driven
around the work site, seal concrete is placed into the bottom to prevent water from seeping in
from underneath the sheet piling, and the water is pumped out. The word "cofferdam" comes
from "coffer" meaning box, in other words a dam in the shape of a box. This lesson covers
structural cofferdams as temporary installation, explaining in stepbystep detail proper and safe
methods and materials to be used. There are different types of cofferdam, some are used to
support excavation operation and some are enclosed type box placed in the water
o Cofferdams are temporary enclosures to keep out water and soil so as to permit dewatering
and construction of the permanent facility (structure) in the dry.
o A cofferdam involves the interaction of the structure, soil, and water. The loads imposed
include the hydrostatic forces of the water, as well as the dynamic forces due to currents
and waves.
o In construction of cofferdams maintaining close tolerances is difficult since cofferdams are
usually constructed offshore and sometimes under severe weather conditions. Under these
circumstances, significant deformations of cofferdam elements may happen during the
course of construction, and therefore it may be necessary to deviate from the design
dimensions in order to complete the project according to plan.
o The loads imposed on the cofferdam structure by construction equipment and operations
must be considered, both during installation of the cofferdam and during construction of the
structure itself.
o Removal of the cofferdam must be planned and executed with the same degree of care as
its installation, on a stagebystage basis. The effect of the removal on the permanent
structure must also be considered. For this reason, sheet piles extending below the
permanent structure are often cut off and left in place, since their removal may damage the
foundation soils adjacent to the structure.
o In cofferdam construction, safety is a paramount concern, since workers will be exposed to
the hazard of flooding and collapse.
o Safety requires that every cofferdam and every part thereof shall be of suitable design and
construction, of suitable and sound material and of sufficient strength and capacity for the
purpose for which it is used, proper construction, verification that the structure is being
constructed as planned, monitoring the behavior of the cofferdam and surrounding area,
provision of adequate access, light and ventilation, and attention to safe practices on the
part of all workers and supervisors, and shall be properly maintained.
Advantages of Cofferdam for marine structure
o Performing work over water has always been more difficult and costly than performing the
same work on land.
o When the work is performed below water the difficulties and cost difference can increase
geometrically with the depth at which the work is performed.
o The key to performing marine construction work efficiently is to minimize work over water,
and perform as much of the work as possible on land.
o Allow excavation and construction of structures in otherwise poor environment
o Provides safe environment to work

o Contractors typically have design responsibility
o Steel sheet piles are easily installed and removed
o Materials can typically be reused on other projects

3.3 Assess the most appropriate method of construction (Method Statement) of breakwater
for harbor construction.
Purposes of breakwaters
The main purpose of a breakwater area to obtain acceptable mooring and for ships.
expensive structures, cost increases water depth.
Breakwaters reduce the intensity of wave action in inshore waters and thereby
reduce coastal erosion or provide safe harborage. Breakwaters may also be small structures
designed to protect a gently sloping beach and placed one to three hundred feet offshore in
relatively shallow water.
An anchorage is only safe if ships anchored there are protected from the force of high winds
and powerful waves by some large underwater barrier which they can shelter behind.
Natural harbors are formed by such barriers as headlands or reefs. Artificial harbors can be
created with the help of breakwaters. Mobile harbors, such as the DDay Mulberry harbors,
were floated into position and acted as breakwaters. Some natural harbors, such as those
in Plymouth Sound, Portland Harbor and Cherbourg, have been enhanced or extended by
breakwaters made of rock.
Parameters for the construction of a breakwater
When a breakwater is to be built at a certain location, and the environmental impact of such
a structure has already been evaluated and deemed environmentally feasible, the following
parameters are required before construction can commence:
o a detailed hydrographic survey of the site;
o a geotechnical investigation of the sea bed;
o a wave height investigation or hindcasting;
o a material needs assessment; and
o the crosssectional design of the structure.
Hydrographic survey
The results from a hydrographic survey are normally plotted to produce a bathymetric
contour map, which is a plan of the depth of the sea bed arranged in such a manner as to
show lines of equal depth from the coastline. In a hydrographic survey, the actual
measurement of the water depth is the easy part. The main problem is not knowing how far
the survey boat is from the coastline when the depth is recorded.
Geotechnical investigation
A geotechnical investigation of the sea bed is required to determine the type of founding
material and its extent. The results of this investigation will have a direct bearing on the
type of crosssection of the breakwater. In addition, it is essential to determine what the
coastline consists of, for example:
o soft or hard rock (like coral reefs or granite);
o sand (as found on beaches);
o clay (as in some mangrove areas); and

o soft to very soft clay, silt or mud (as found along some river banks, mangroves and other
tidal areas).
Wave hindcasting
The height of wave incident on a breakwater generally determines the size and behavior
of the breakwater. It is hence of the utmost importance to obtain realistic values of the
waves expected in a particular area. Behavior of water waves is one of the most
intriguing of nature’s phenomena. Waves manifest themselves by curved undulations of
the surface of the water occurring at periodic intervals. They are generated by the action
of wind moving over a water body; the stronger the wind blows, the higher the waves
generated. They may vary in size from ripples on a pond to large ocean waves as high
as 10 meters.
Material needs assessment
Given that most breakwaters consist of either rock or concrete or a mixture of both, it is
evident that if these primary construction materials are not available in the required
volume in the vicinity of the project site, then either the materials have to be shipped in
from another source (by sea or by road) or the harbor design has to be changed to allow
for the removal of the breakwater (the site may have to be moved elsewhere).
Crosssectional design
A suitable crosssectional design for the breakwater has to be
produced taking into consideration all the previous data, for example:
o water depths (in deep water, solid vertical sides are preferred to save on material);
o type of foundation (if ground is soft and likely to settle, then a rubble breakwater is
recommended);
o height of waves (rubble breakwaters are more suitable than solid ones in the
presence of larger waves); and
o availability of materials (if no rock quarries are available in the vicinity of the project,
then rubble breakwaters cannot be economically justified).
Previous surveys and soil investigations, particularly within the breakwater alignment,
had shown that the bearing capacity of the soil was insufficient to support the weight and
to ensure the stability of the breakwaters. Therefore, in future breakwater locations large
quantities of soil had to be removed to a level of –15.00 m. and backfilled with suitable

sand. This had to be accomplished in the short time frame during the nonmonsoon
period. Additional soil investigation, which was executed as a result of the realignment of
the Northern Breakwater, resulted in a further increase in depth and length of the trench
to be backfilled by suitable sand from the offshore borrow area. The unsuitable materials
were dredged with hopper dredgers and dumped at sea in a designated area at water
depths of at least 20 m. Suitable sand was dredged in an offshore borrow area, located
approximately 6 km from the tip of the Northern Breakwater. In May the first two trailing
suction hopper dredgers Orwell and Volvox Hansa arrived at Ennore to start the
dredging activities. Bringing in two trailing suction hopper dredgers was necessary,
because of the available time frame and the limited water depths of the working
locations where dredging and infill were required.
Ref: http://www.fao.org/docrep/013/i1883e/i1883e07.pdf

LO4 Understand the methods and techniques used in highway construction
and railway works
4.1 Define the types of pavement with neat sketches.
Types of Pavements
o Flexible Pavements
o Rigid Pavements
o Semi Rigid Pavements
Flexible Pavements
Flexible pavement can be defined as the one consisting of a mixture of asphaltic or
bituminous material and aggregates placed on a bed of compacted granular material of
appropriate quality in layers over the subgrade. Water bound macadam roads and
stabilized soil roads with or without asphaltic toppings are examples of flexible
pavements.

Rigid Pavements
A rigid pavement is constructed from cement concrete or reinforced concrete slabs. Grouted
concrete roads are in the category of semirigid pavements. The design of rigid pavement is
based on providing a structural cement concrete slab of sufficient strength to resists the loads
from traffic. The rigid pavement has rigidity and high modulus of elasticity to distribute the load
over a relatively wide area of soil.
Semi Rigid Pavements
The pavements constructed using the waste materials, which are more strong the traditional
aggregates may be treated as SemiRigid Pavement. A lot of research work has been done in
this direction. But the work in terms of real construction is not visible.

4.3 Explain in detail the method of construction of flexible pavement for the four lanes
divided, premix water bound macadam road having 4 feet wide brick paved center median
and 10 feet wide brick paved shoulders in either sides of the carriage way which has to be
constructed on hard soil. Note: Draw the labeled and dimensioned free hand sketch of the
road pavement structure
Transportation is the movement of people or goods from one place to another. Transport
is important since it enables to trade between people , which in turn establishes
civilizations. The transport system comprises of highways or roadways, Railways, water
ways and air ways.
Cross sections of Road Structure
Sub Grade
The sub grade or soil sub grade is a layer of natural soil prepared to receive the layers
of pavement placed over it. The sub grade should be sufficient strength so that the loads
are received and dispersed to the earth mass. The sub grade should be well compacted
under controlled conditions of optimum moisture content and maximum dry density. The
sub grade supports the road structure and form the bed for the road.
Sub Base
Sub base or sub base course is a layer of granular material placed on sub grade,
generally natural gravel. Boulder stone or bricks also may be used.
Base Course
Base course is a layer immediately under the weaning course. It is an important
structural part of the road. It should be strong enough to bear the loads of the traffic. The
material in a base course must be of extremely high quality. It must be well compacted.
Wearing Course or Surface Course
Wearing course is the top most layer of a road which is direct contact with the traffic. The
purpose of the weaning course is to give a dense smooth riding surface. It resists the

pressure exerted by tyres and takes up wear and tear due to the traffic. It acts as a water
tight layer and prevents percolation of water
Width of Pavement
The width of pavement or carriage way depends on the width of traffic lane and number
of lanes. The carriage way intended for one line of traffic movement may be called as a
traffic lane. The lane width is determined on the basis of the width of vehicle and the
minimum side clearance provided for the safety. When the side clearance is increased
there is an increase in speed of the vehicles and hence in increase in the capacity of the
pavement. A width of 3.75 m is considered desirable for a road having single lane for
vehicles of maximum width 2.44 m. For pavement having two or more lanes, width of 3.5
m per lane is sufficient.
Shoulders
Shoulders are provided along the road edge to serve as an emergency lane for vehicles
to be taken out of the pavement. These also acts as service lanes for vehicles that have
broken dawn. The minimum shoulder width recommended by the IRC is 2.5 m. The
shoulders should have sufficient strength to support loaded even in wet weather. The
surface of the shoulder should be rougher than the traffic lanes so that the vehicles are
discouraged to use the shoulder as a regular traffic lane.
Formation Width
Formation width or Road way width is the sum of the widths of pavements including
separators if any and the shoulders formation width is the top width of the highway
embankment on the bottom width of highways cutting excluding the side drains.
Right of Way
Right of way is the area of land acquired and reserved along its alignment for
construction and development of a highway is known as right of way. A minimum land
width is prescribed for different categories of road. The below table gives the minimum
width of right of way for different categories of road.
Water Bound Macadam Roads
Water bond macadam roads consists one or more courses of coarse aggregate whose voids
are partially filled with finer material usually gravel. The whole mass is interlocked together with
angular fragments and rolling. Water is added to make the gravel a slurry. This slurry fills the
voids and keeps the aggregate in the inter locked position. The details of water bound macadam
road is shown in fig. below.

The structure of the water bond macadam road consists of the following.
( i) A foundation course of boulder stones placed on the compacted subgrade to thickness of
about 25 cm.
( ii) A gravel layer of thickness 6 mm to 12 mm is placed at the top.
Bitumen roads
Bitumen road is a road constructed by bitumen. Bitumen is black viscous mixture of
hydrocarbons obtained by distillation of petroleum. Previously Tar was also used in construction
of bituminous roads, as the tar was susceptible for high temperatures, bitumen replaced tar in
road construction. Bitumen roads are flexible pavements consists of sub grade, subbase
course, base course and a bituminous surface course.
Prime Coat : Prime coat is the first application of a low viscosity liquid bituminous material over
an existing porous pavement surface like the WBM base course. The main object of prime coat
is to plug the voids of the porous surface and to bond the loose mineral particles on the existing
surface, using a binder of low viscosity which can penetrate into the voids. The prime coated
surface is allowed to cure for at least 24 hours.
Tack Coat : Tack coat is the application of bituminous material over an existing pavement
surface which is relatively impervious like an existing bituminous surface or a WBM surface
which has already been treated by a prime coat.
Construction procedure of bituminous concrete
The bituminous concrete is the highest quality of construction of bituminous roads. The
bituminous mixes are properly designed to the specification. The mixture contains dense course
aggregate, fine aggregate and mineral filler coated with bituminous binder. The mix is prepared
in hotmix plant.
Construction Steps
i. Preparation of the existing base course layer : The base course is made true to camber and
grade. Pot holes and depressions are filled with premix chippings.
ii. Application of Tack coat : The heated bitumen is sprayed at 6.0 to 7.5 kg per 10m2 area, just
before spreading the premix.
iii. Preparation and placing the premix : The premix is prepared in hot mix plant with the desired
quality. The hot mixed material is collected from the mixer by the transporters, carried to the
location and is spread by a mechanical paver. The camber and the thickness of the layer are
accurately checked.
iv. Rolling : After placing the mix on the base course, it is rolled and thoroughly compacted by 8
to 10 tonnes wheeled roller at a speed not more than 5 km per hour. The wheels of the roller are
kept damp with water. The number of passes required depends on the thickness of the layer.
v. Finishing and opening to traffic : The surface is to be checked for camber and depressions if
any are rectified.
vi. Opening to traffic : The surface is to be opened to traffic after 24 hours of laying the finished
surface.
Sheet Asphalt

Sheet Asphalt is a dense sand – bitumen premix of compacted thickness of 25 mm used as a wearing
course. This is usually laid over cement concrete pavement to provide an excellent riding surface. The
construction procedure is as follows.
i. Preparation of surface : The surface is cleaned.
ii. Application of Tack coat : The bitumen binder is heated to the required temperature and sprayed on
the surface first before the spreading of sheet asphalt.
iii. Preparation of premix : Graded dry sand, filler and bitumen are mixed in the mixer and the
temperature is maintained between 135oC to 177oC
iv. Spreading the sheet Asphalt : The prepared mix of sheet asphalt is conveyed and it is immediately
placed on the road surface. Camber and grades are to be checked.
v. Rolling : The surface is to be rolled with a 10 tonne roller. The rolling should start from the sides and
proceed towards the crown. In case where super elevation is provided, the rolling should start form
inner edge and proceed towards the outer edge.
vi. Finishing and Opening to Traffic : The surface is to be checked for camber and if there are any
depressions they are to be rectified. The surface is to be opened to traffic after 24 hours of laying of
sheet asphalt.
Ref: http://bieap.gov.in/Pdf/CTPaperIIIYR2.pdf

Scenario: - 02
LO5 Be able to solve problems arising from complex civil engineering activities
5.1 Design an appropriate solution to mitigate the further damage to the dam.
What are the problems could be created from complex civil engineering activities and
propose appropriate solution for such problem.
appropriate solution
we can approach two different type solutions.
1. Contingency plan
2. Preventive plan
In this situation I approach preventive solution. My proposal is Wait for maximum damage to
dam and reconstruction or repair the dam.
o Because if allow seepage water, it will be problem for downstream village (this is a third
party), this is not easy to giving compensation.
o Other cause if we allow seepage water it will be solution but this just a temporally for this
damage , this issue must happen in next time also (when heavy rain fall down) ,so ones
again downstream villages will be taking problems. So that is not a good solution.
o So we can identify what will be a maximum damage. if it will be major damages,
reconstruction is better, if it is minor damages repair is better.
o For the reconstruction we must consider all the situation, what will be the maximum
water.
o Also at last think about 50 year future plan..
Road construction
On construction period heavy traffic
Solutions
o Giving information to the public to use for different ways.
o Same think broadcasting on TV or radio it is better.
o Before construction make a traffic diversion plan.
o The construction must be step by step depend on traffic.

Marine construction
In the sea break water, water level higher then break water structure.
Solutions
o Above the existing break water to lay more rock material upto 1m up from water
level.
o And make more beak waters one by one same distance between

5.2 Comment critically the resource plan for the above civil engineering activities as appropriate.
Importance of resource plan.
o The scope of the project i.e. time and cost – within what time do you want to complete your
construction and working within what budget?
o Objectives of the project – what kind of structure are you setting up and what will be the
necessary requirements needed to be put in place to ensure that the project meets its
intended objectives? Is it a hospital, road, school, mall or home?
o Milestones – what activity or stage of the project will signify substantial progress?
o A work schedule and breakdown structure – given the different tasks that make up the
construction process, it is important to clearly indicate when each of these tasks will be
carried out and the systematic sequence that the different tasks will follow.
o Progress tracking – with respect to the schedule, one should be able to track the progress of
the project based on actual output against planned output and determine whether the
project is on course or lagging.
There are certain tasks and activities within the construction process that cannot be easily
rushed for example certain procurement lead times, concrete curing times etc.
o A network schedule that does not include resource constraints assumes that an unlimited
quantity of resources is available to the project. Schedules developed without resource
constraints may not be feasible or realistic when actual resources are considered.

Unit 37: Advanced Civil Engineering

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Unit 37: Advanced Civil Engineering