HIGHWAY PROJECT MANAGEMENT
1.
Overview of the Highway Planning and Development Process:
Highway design is only one element in the overall highway development
process. Historically, detailed design occurs in the middle of the process,
linking the preceding phases of planning and project development with the
subsequent phases of right of way acquisition, construction, and maintenance.
While these are distinct activities, there is considerable overlap in terms
of coordination among the various disciplines that work together, including
designers, throughout the process.
THE STAGES OF
HIGHWAY DEVELOPMENT
Although the names may vary by State, the five basic stages in the
highway development process are: planning, project development (preliminary
design), final design, right-of-way, and construction. After construction is
completed, ongoing operation and maintenance activities continue throughout
the life of the facility.
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1.
Introduction
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1.1
Project Background
1.2
Core Network
1.3
Geography
1.4
Climatic Condition
1.5
The Sub-Project Road
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2.
Alignment
|
2.1
General
2.2
Sailent Features
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3.
Land Requirement
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3.1
General
3.2
Proposed ROW
3.3
Additional Land
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4.
Geometric Design Standards
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4.1
General
4.2
Terrain
4.3
Design Speed
4.4
Right of Way (ROW)
4.5
Roadway Width
4.6
Carriageway Width
4.7
Earthen Shoulders
4.8
Roadway width at cross-drainage structures
4.9
Sight Distance
4.10
Radius of Horizontal Curve
4.11
Camber & Super elevation
4.12
Vertical Alignment
4.13
Vertical Curves
4.14
Cross Section Element and Side slope
4.15
Extra Widening of Pavement
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5.
Topographic Survey
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5.1
General
5.2
Traversing
5.3
Levelling
5.4
Cross Section & Detailing
5.5
Data Processing
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6.
Soil and Materials Survey
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6.1
General
6.2
Soil sample collection and Testing
6.3
Analysis of Test Results
6.4
Coarse and Fine Aggregates
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7.
Traffic Survey
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7.1
General
7.2
Traffic Data and Analysis
7.3
Traffic Growth Rate and forecast
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8.
Pavement Design
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8.1
General
8.2
Pavement Design Approach
8.2.1
Design Life
8.2.2
Design Traffic
8.2.3
Determination of ESAL applications
8.2.4
Subgrade CBR
8.3
Pavement composition
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9.
Hydrological Survey
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9.1
General
9.2
Rainfall Data
9.3
Catchment Area
9.4
Time of Concentration
9.5
Existing Cross Drainage Structures
9.6
Justification for retaining/widening and replacement of
culverts
9.7
Hydraulic calculation for Culvert
|
10.
Design of Cross Drainage
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10.1
General
10.2
Hydrological Design
10.3
Design Feature
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11.
Protective Works & Drainage
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11.1
General
11.2
Road side drain
11.3
Protective Works
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12.
Specification
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13.
Environmental Issues
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14.
Analysis of Rates
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15.
Cost Estimate
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16.
Construction Programme
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17.
Environmental Code of Practice (ECoP)
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18.
Road Safety
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19.
Road Furniture including Citizen Information Signboards
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Various Study
Required:
20.
Geometric Design Standards
20.1
General
The
geometric design standards for this project conform to MORTH / PMGSY (ADB)
guidelines and the guidelines as stated in IRC-SP
20:2002. Recommended design standards vis-à-vis the standards followed for
this road are described below.
21.
Topographic Survey
21.1
General
Topographic
survey true to ground realties have been done using precision instruments like
Total Stations and Auto Levels, and bringing out data in digital form (x, y, z
format) for developing digital terrain model (DTM).
The
topographic survey was carried out by the Surveyors / Supervisors under the
guidance of DRE.
The
in-house standards, work procedures and quality plan prepared with reference to
IRC: SP 19-2001, IRC: SP 20, IRC: SP 13 (in respect of surveys for rivers /
streams) and current international practices have been followed during the
above survey.
21.2
Traversing
Traverse
will be done by Total Station having angular measurement accuracy of ± 1 sec.
Control
pillars were established at suitable intervals along the project corridor and
their coordinates were established by Total Station. The starting coordinate
was assumed and accordingly the coordinates of the other Reference/ Temporary
Benchmark (TBM) were established. All the Control points have been established
on concrete pillars.
21.3
Levelling
All
leveling for establishing Benchmark are to be carried out as per method adopted
by Survey of India. All leveling are to be carried out with Auto Level having
accuracy ± 2.5 mm/
km. The Consultant started the work by assuming arbitrary level, as no GTS
benchmark was available in the nearby location of the road.
21.4
Cross Section & Detailing
Cross
section taken at 50 m interval and at closer interval in curved portion of the
existing road. The following features of the road were recorded:
v Existing
road details
v Existing
toe point of Road
v Canal
/ River & Banks
v Natural
Surface Points
v Edge
of Water Body / Pond
v Edge
of ditch / Borrow pit
v Electricity
and Telephone poles
v Edge
of Building & Fence line
v Religious
Structure & Graves
v Temporary
House or Hut
v Edge
of Wall
v Bore
Well
v Concrete
Wall
v Level
Crossing / Railway Tracks
v Trees
v Cross
roads and other major crossings
21.5
Data Processing
All
data from topographic survey recorded by total station were downloaded and
final alignment, plan, profile is prepared and presented in AutoCAD Format.
22.
Soil and Materials Survey
22.1
General
The
soil and material investigations have been done following the guidelines of
IRC: SP 20 - 2002 and IRC: SP 72 - 2007 and other relevant IS codes. The
potential sources of borrow areas for soil and quarry sites have been
identified.
22.2
Soil sample collection and Testing
Soil
samples have been collected along and around the road alignment at three (3)
locations per km, from the adjoining borrow areas, as well as one sample is
collected from the existing road. Soil Classification tests like grain size
analysis and Atterberg’s limit were conducted for all the samples collected.
Standard Proctor test and the corresponding 4 day soaked CBR test were
conducted either for a minimum of one test per km for soil samples of same
group or more tests due to variation of soil type. The following tests were
conducted as detailed below:
v Grain
size analysis as per IS : 272 (Part 4) – 1985
v Atterberg’s
limit as per IS : 2720 (Part 5) – 1985
v Standard
Proctor density test as per IS : 2720 (Part 7) – 1980
v 4
day soaked CBR test as per IS : 2720 (Part 16) – 1985
22.3
Analysis of Test Results
The
laboratory soaked CBR value ranges from 4.2% to 4.4%.
22.4
Coarse and Fine Aggregates
Information
regarding the source of aggregate and sand was gathered. The stone aggregate
shall be procured from Nalhati. The source and the lead distance from the
quarry to project site was finalized in discussion with the PIU. The aggregates
and sand shall be used for bituminous work, Concrete works, other pavement
works.
23.
Traffic Survey
23.1
General
In
the present scenario of new connectivity road, 3 day, 24 hr. traffic volume
count has been conducted. The Classified Volume count survey has been carried
out in accordance with the requirements of the TOR and relevant codes (IRC: SP:
19-2001, IRC: SP: 20, IRC: SP: 72-2007).The surveys have been carried out by
trained enumerators manually under the monitoring of Engineering Supervisor.
23.2
Traffic Data and Analysis
All
field data sheet collected from site has been dispatched from site to project
design office for data entering and analysis. The traffic count done has been
classified into different vehicle category as given below:
v Motorized
vehicle comprising of light commercial vehicle, medium commercial vehicle,
heavy commercial vehicle, Car, Jeep, two wheelers etc.
v Non-motorized
vehicles comprising of cycle, rickshaw, cycle van, Animal drawn vehicle etc.
The
numbers of laden and un-laden commercial vehicles have also been recorded
during the traffic counts. Traffic volume count for this project road has been
done during lean season. However, as per local information, the traffic will be
double during the peak harvesting season.
Average
daily traffic (ADT) has been found for each vehicle type. Computation of
Average Annual Daily traffic (AADT) is given below:
AADT
=
T
= Average number of vehicles plying during lean season
nT=
Enhanced traffic during peak season, over and above lean season traffic T
t
= Duration of Harvesting season
23.3
Traffic Growth Rate and forecast
In
the absence of any specific information to the designer, an average annual
growth rate of 6% over the design life has been adopted. .
24.
Pavement Design
24.1
General
Considering
the subgrade strength , projected traffic and the design life, the pavement
design for low volume PMGSY roads have been carried out as per guidelines of
IRC : SP : 72 – 2007.
24.2
Pavement Design Approach
24.2.1
Design Life
A
design life of 10 years is considered for the purpose of pavement design of
flexible and granular pavements.
24.2.2
Design Traffic
The
average annual daily traffic (AADT) computed in the opening year is 2038 as
described in Chapter 7. The total commercial vehicle per day (CVPD) works out
to 23.
24.2.3
Determination of ESAL applications
Only
commercial vehicles with a gross laden weight of 3 tonnes or more are
considered. The design traffic is considered in terms of cumulative number of
standard axles to be carried during the design life of the road. The numbers of
commercial vehicles of different axle loads are converted to number of standard
axle repetitions by a multiplier called the Vehicle Damage Factor (VDF).An
indicative VDF value has been considered as the traffic volume of rural road
does not warrant axle load survey.
For
calculating the VDF, the following categories of vehicles have been considered
as suggested in paragraph 3.4.4 of IRC: SP: 72 – 2007.
v Laden
Heavy/Medium Commercial vehicles
v Un-laden
/partially loaded heavy/medium commercial vehicles
v Over
loaded heavy/medium commercial vehicles
Indicative
VDF values considered 10% of laden MCV and 10% laden HCV as overloaded &
given below:
Vehicle type
|
Laden
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Un-laden /Partially laden
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HCV
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2.86
|
0.31
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MCV
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0.34
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0.02
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Lane
distribution factor (L) for Single lane road = 1.0
Cumulative
ESAL application = To x 4811 x L, where To = ESAL application per day
The
Cumulative ESAL application for the project road works out to 74,907 and falls
in traffic category T3 as per paragraph 3.5 of IRC: SP: 72 – 2007.
24.2.4
Subgrade CBR
The
average subgrade CBR 4.2, range of 3-4 has been considered.
24.3
Pavement composition
The
designed pavement thickness and composition have calculated by referring Figure
4 (Pavement design catalog) of IRC : SP : 72 – 2007.The pavement layers
provided are given below:
Top
Layer
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Premix
Carpet with Type B Seal Coat
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26
mm
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Base
Layer
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WBM
Grading III & WBM Grading II
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150
mm
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Sub
– Base Layer
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Granular
Sub-base Grading II
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175
mm
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Total
thickness
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325
mm
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25.
Hydrological Survey
25.1
General
Hydrological
survey is necessary for design of adequate and safe Cross Drainage Structures
so that the rain water can pass as per natural slope. Hydrological survey of
the proposed road is based on the following observations:
v Rainfall
Data
v Catchments
Area
v Time
of Concentration
v Existing
Cross Drainage Structures
25.2
Rainfall Data
Rainfall
Data as applicable for the project road has been collected having an average
annual rainfall of more than 1500 mm with maximum rainfall occurring in the
months of July and August.
25.3
Catchment Area
The
Catchments area has been calculated by gathering local information as it could
not be calculated from topographical sheets due to their unavailability.
25.4
Time of Concentration
Time
of concentration (tc) is calculated from the formula of (0.87 x L3/H)0.385,
where L is distance from the critical point to the structure site in km and H
is the difference in elevation between the critical point and the structure
site in meters.
DIFFERENT DATA REQUIRED FOR ROAD WORK
Sl no
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Description of DATA
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Source
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Geography
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Site Plan / Internet
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Climatic Condition
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Internet
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Alignment
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Survey Data
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Geometric Design Standards
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Codal Provision
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Design Speed
Right of Way (ROW)
Roadway Width
Carriageway Width
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As per Client’s requirement / MORTH
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Earthen Shoulders
Roadway width at cross-drainage
structures
Sight Distance
Radius of Horizontal Curve
Camber & Super
elevation
Vertical Alignment
Vertical Curve
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MORTH
or other standerd
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Cross Section Element and
Side slope
v Existing road details
v Existing toe point of Road
v Canal / River & Banks
v Natural Surface Points
v Edge of Water Body / Pond
v Edge of ditch / Borrow pit
v Electricity and Telephone poles
v Edge of Building & Fence line
v Religious Structure & Graves
v Temporary House or Hut
v Edge of Wall
v Bore Well
v Concrete Wall
v Level Crossing / Railway Tracks
v Trees
Cross roads and other major crossin
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Survey data
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Soil and Materials
v Grain size analysis as per IS : 272 (Part 4)
– 1985
v Atterberg’s limit as per IS : 2720 (Part 5) –
1985
v Standard Proctor density test as per IS :
2720 (Part 7) – 1980
4 day soaked CBR test as per IS : 2720 (Part 1
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Lab Testing
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Coarse and Fine Aggregates
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Lab Testing
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Traffic Data and Analysis
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Traffic Survey
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Design Traffic
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Traffic
Survey
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Rainfall Data
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Internet
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2.
Difference between Flexible and Rigid Pavement
Flexible pavement
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Rigid pavements
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Deformation in the sub grade is
transferred to upper layers
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Deformation in the sub grade is
transferred to subsequence
Layers |
Have low flexural strength
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Have high flexural Strength
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Load transferred to gain to gain contract
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No such phenomenon of grain to
grain load transferred
exist |
Have low completion test but high
repairing cost
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Have low repairing cost but high
completion cost
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Damaged by oil and chemicals
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No damage by oil or Greece
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Design Based on load distribution
factor
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Design based on Flexural strength
or slab action
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Construction Steps for Cement
Concrete Pavement / Road
Concrete pavements are rigid pavements having very high flexure strength as compared to flexible pavements. Concrete pavements can be constructed using two different methods:
1.
Alternate Bay method
2.
Continuous bay method
·
In alternate bay method, concrete
pavement slab are laid on whole width of pavement in alternate bays.
·
In continuous bay method,
concrete pavement slabs are laid continuously only on one bay and another bay
is open for the traffic.
Generally
the second method of continuous bay, is preferred over alternate bay method
because, traffic movement is allowed while it is restricted in the first. Also,
the alternate empty spaces invites the rainwater collection and create
in-convenience to the construction work.
Various
steps for the construction of concrete pavements:
1.
Preparation of
Sub-grade and Sub-base
2.
Placing of forms
3.
Batching of
material and Mixing
4.
Transporting and
Placing of Concrete
5.
Compaction and
Finishing
6.
Floating and
Straight Edging
7.
Belting, Booming
and Edging
8.
Curing of Cement
concrete
3.
List of some common test:
Sl No
|
Type Of Test
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Requirement as per Code
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Code reference
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|
A.
Coarse Aggregate
|
||||
1
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Sieve Analysis
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IS:383 / IS 2386-Part I
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2
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Specific Gravity
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IS:383 / IS 2386-Part III
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3
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Flakiness Index
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Maximum 30%
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IS:383 / IS 2386-Part I
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4
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Crushing Strength
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Road - 30% (Max) Other -45%
(Max)
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IS:383 / IS 2386-Part IV
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5
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Impact Value
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Road - 30% (Max) Other -45%
(Max)
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IS:383 / IS 2386-Part IV
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6
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Moisture Content
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1% - 2%
|
|
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7
|
Abrasion Value
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Road - 30% (Max) Other -50%
(Max)
|
IS:383 / IS 2386-Part IV
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8
|
Soundness
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Maximum 12% & 18%
|
IS:383 / IS 2386-Part V
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9
|
Water absorption
|
1% - 2%
|
IS:383 / IS 2386-Part III
|
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10
|
Alkali Aggregate Reactivity test
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|
IS:383 / IS 2386-Part VII
|
|
11
|
Deleterious Material Content
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Maximum 5%
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IS:383 / IS 2386-Part II
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12
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Alkali Silica Reactivity Potential of
Aggregate
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|
ASTM C 289
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Sl No
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Type Of Test
|
Requirement as per Code
|
Code reference
|
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B. Soil
|
|
|
|
|
1
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Liquid Limit & Plasticity Index
|
below 50% & 25%
|
IS: 2720 - PART 5
|
|
2
|
Maximum Dry Density
|
|
IS: 2720 - PART 8
|
|
3
|
Field Dry Density
|
|
IS: 2720 - PART 28 & 29
|
|
4
|
Swelling Index
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Below 50%
|
IS: 2720 - PART 40
|
|
5
|
Moisture Content
|
|
IS: 2720 - PART 2
|
|
C. Bitumen
|
|
|
||
1
|
|
ASTM D5
[ASTM, 2001] / 1201 - 1220 :1978
|
||
2
|
|
ASTM
D1310 / 1201 - 1220 :1978
|
||
3
|
|
ASTM D
2042 / 1201 - 1220 :1978
|
||
4
|
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ASTM
D113 / 1201 - 1220 :1978
|
||
5
|
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ASTM
D2171/ 1201 - 1220 :1978
|
||
D. Cement
|
|
|
||
1
|
Compressive Strength
|
|
IS: 8112 - 2013
|
|
2
|
Normal Consistency
|
|
IS: 8112 - 2013
|
|
3
|
Setting time
|
|
IS: 8112 - 2013
|
|
4
|
Finesse
|
|
IS: 8112 - 2013
|
|
5
|
Soundness
|
|
IS: 8112 - 2013
|
26.
DETERMINATION OF AGGREGATE
IMPACT VALUE
AIM:
(i) To determine
the impact value of the road aggregates;
(ii) To assess
their suitability in road construction on the basis of impact value
APPARATUS:
The apparatus as
per IS: 2386 (Part IV) – 1963 consists of:
(i) A testing
machine weighing 45 to 60 kg and having a metal base with a painted lower
surface of not less than 30 cm in diameter. It is supported on level and plane
concrete floor of minimum 45 cm thickness. The machine should also have
provisions for fixing its base.
(ii) A
cylindrical steel cup of internal diameter 102 mm, depth 50 mm and minimum
thickness 6.3 mm.
(iii) A metal
hammer or tup weighing 13.5 to 14.0 kg the lower end being cylindrical in
shape, 50 mm long, 100.0 mm in diameter, with a 2 mm chamfer at the lower edge
and case hardened. The hammer should slide freely between vertical guides and
be concentric with the cup. Free fall of hammer should be within 380±5 mm.
(iv) A
cylindrical metal measure having internal diameter 75 mm and depth 50 mm for
measuring aggregates.
(v) Tamping rod
10 mm in diameter and 230 mm long, rounded at one end.
(vi) A balance of
capacity not less than 500g, readable and accurate upto 0.1 g.
THEORY:
The property of a
material to resist impact is known as toughness. Due to movement of vehicles on
the road the aggregates are subjected to impact resulting in their breaking
down into smaller pieces. The aggregates should therefore have sufficient
toughness to resist their disintegration due to impact. This characteristic is
measured by impact value test. The aggregate impact value is a measure of
resistance to sudden impact or shock, which may differ from its resistance to
gradually applied compressive load.
PROCEDURE:
The test sample
consists of aggregates sized 10.0 mm 12.5 mm. Aggregates may be dried by
heating at 100-110° C for a period of 4 hours and cooled.
(i) Sieve the
material through 12.5 mm and 10.0mm IS sieves. The aggregates passing through
12.5mm sieve and retained on 10.0mm sieve comprises the test material.
(ii) Pour the
aggregates to fill about just 1/3 rd depth of measuring cylinder.
(iii) Compact the
material by giving 25 gentle blows with the rounded end of the tamping rod.
(iv) Add two more
layers in similar manner, so that cylinder is full.
(v) Strike off
the surplus aggregates.
(vi) Determine
the net weight of the aggregates to the nearest gram(W).
(vii) Bring the
impact machine to rest without wedging or packing up on the level plate, block
or floor, so that it is rigid and the hammer guide columns are vertical.
(viii) Fix the
cup firmly in position on the base of machine and place whole of the test sample
in it and compact by giving 25 gentle strokes with tamping rod.
(ix) Raise the
hammer until its lower face is 380 mm above the surface of aggregate sample in
the cup and allow it to fall freely on the aggregate sample. Give 15 such blows
at an interval of not less than one second between successive falls.
(x) Remove the
crushed aggregate from the cup and sieve it through 2.36 mm IS sieves until no
further significant amount passes in one minute. Weigh the fraction passing the
sieve to an accuracy of 1 gm. Also, weigh the fraction retained in the sieve.
Compute the
aggregate impact value. The mean of two observations, rounded to nearest whole
number is reported as the Aggregate Impact Value.
OBSERVATIONS
Sample 1
|
Sample 2
|
|
Total weight of dry sample ( W1 gm)
|
||
Weight of portion passing 2.36 mm sieve (W2 gm)
|
||
Aggregate Impact Value (percent) = W2 / W1 X
100
|
Mean =
RESULT:
Aggregate Impact Value =
RECOMMENDED VALUES
Classification of aggregates using Aggregate Impact Value is as given
below:
Aggregate Impact Value
|
Classification
|
<20%
|
Exceptionally Strong
|
10 – 20%
|
Strong
|
20-30%
|
Satisfactory for road surfacing
|
>35%
|
Weak for road surfacing
|
27.
Determine the Maximum Dry
Density and the Optimum Moisture Content of Soil
This test is done to determine the
maximum dry density and the optimum moisture content of soil using heavy
compaction as per IS: 2720 (Part 8) – 1983.The apparatus used is
i) Cylindrical
metal mould – it should be either of 100mm dia. and 1000cc volume or 150mm dia.
and 2250cc volume and should conform to IS: 10074 – 1982.
ii) Balances – one of 10kg capacity, sensitive to 1g and the other of 200g capacity, sensitive to 0.01g
ii) Balances – one of 10kg capacity, sensitive to 1g and the other of 200g capacity, sensitive to 0.01g
iii) Oven – thermostatically controlled with an interior of non corroding material to maintain temperature between 105 and 110oC
iv) Steel straightedge – 30cm long
v) IS Sieves of sizes – 4.75mm, 19mm and 37.5mm
PREPARATION
OF SAMPLE
A
representative portion of air-dried soil material, large enough to provide
about 6kg of material passing through a 19mm IS Sieve (for soils not
susceptible to crushing during compaction) or about 15kg of material passing
through a 19mm IS Sieve (for soils susceptible to crushing during compaction),
should be taken. This portion should be sieved through a 19mm IS Sieve and the
coarse fraction rejected after its proportion of the total sample has been
recorded. Aggregations of particles should be broken down so that if the sample
was sieved through a 4.75mm IS Sieve, only separated individual particles would
be retained.
Procedure To Determine The Maximum Dry Density And The Optimum Moisture Content Of Soil
A) Soil not susceptible to crushing during compaction –
i) A 5kg sample of air-dried soil passing through the 19mm IS Sieve should be taken. The sample should be mixed thoroughly with a suitable amount of water depending on the soil type (for sandy and gravelly soil – 3 to 5% and for cohesive soil – 12 to 16% below the plastic limit). The soil sample should be stored in a sealed container for a minimum period of 16hrs.
ii)
The mould of 1000cc capacity with base plate attached, should be weighed to the
nearest 1g (W1 ). The mould should be placed on a
solid base, such as a concrete floor or plinth and the moist soil should be
compacted into the mould, with the extension attached, in five layers of
approximately equal mass, each layer being given 25 blows from the 4.9kg rammer
dropped from a height of 450mm above the soil. The blows should be distributed
uniformly over the surface of each layer. The amount of soil used should be
sufficient to fill the mould, leaving not more than about 6mm to be struck off
when the extension is removed. The extension should be removed and the
compacted soil should be levelled off carefully to the top of the mould by
means of the straight edge. The mould and soil should then be weighed to the
nearest gram (W2).
iii) The compacted soil specimen
should be removed from the mould and placed onto the mixing tray. The water
content (w) of a representative sample of the specimen should be determined.
iv)
The remaining soil specimen should be broken up, rubbed through 19mm IS Sieve
and then mixed with the remaining original sample. Suitable increments of water
should be added successively and mixed into the sample, and the above
operations i.e. ii) to iv) should be repeated for each increment of water
added. The total number of determinations made should be at least five and the
moisture contents should be such that the optimum moisture content at which the
maximum dry density occurs,
lies within that range.
lies within that range.
B)
Soil susceptible to crushing during compaction –
Five or more 2.5kg samples of air-dried soil passing through the 19mm IS Sieve, should be taken. The samples should each be mixed thoroughly with different amounts of water and stored in a sealed container as mentioned in Part A)
Five or more 2.5kg samples of air-dried soil passing through the 19mm IS Sieve, should be taken. The samples should each be mixed thoroughly with different amounts of water and stored in a sealed container as mentioned in Part A)
C)
Compaction in large size mould –
For compacting soil containing coarse material upto 37.5mm size, the 2250cc mould should be used. A sample weighing about 30kg and passing through the 37.5mm IS Sieve is used for the test. Soil is compacted in five layers, each layer being given 55 blows of the 4.9kg rammer. The rest of the procedure is same as above.
REPORTING OF RESULTS
Bulk density Y(gamma) in g/cc of each compacted specimen should be
calculated from the equation,
For compacting soil containing coarse material upto 37.5mm size, the 2250cc mould should be used. A sample weighing about 30kg and passing through the 37.5mm IS Sieve is used for the test. Soil is compacted in five layers, each layer being given 55 blows of the 4.9kg rammer. The rest of the procedure is same as above.
REPORTING OF RESULTS
Bulk density Y(gamma) in g/cc of each compacted specimen should be
calculated from the equation,
Y(gamma) = (W2-W1)/ V
where, V = volume in cc of the mould.
The dry density
Yd in g/cc
Yd = 100Y/(100+w)
The dry densities, Yd obtained in a
series of determinations should be plotted against the corresponding moisture
contents,w. A smooth curve should be drawn through the resulting points and the
position of the maximum on the curve should be determined. The dry density in
g/cc corresponding to the maximum point on the moisture content/dry density
curve should be reported as the maximum dry density to the nearest 0.01. The
percentage moisture content corresponding to the maximum dry density on the moisture
content/dry density curve should be reported as the optimum moisture content
and quoted to the nearest 0.2 for values below 5 percent, to the nearest 0.5
for values from 5 to 10 percent and to the nearest whole number for values
exceeding 10 percent
Penetration
Test on Bitumen
The
penetration test is one of the oldest and most commonly used tests on asphalt
cements or residues from distillation of asphalt cutbacks or emulsions. The
standardized procedure for this test can be found in ASTM D5 [ASTM, 2001]. It
is an empirical test that measures the consistency (hardness) of an asphalt at
a specified test condition.
Procedure of Penetration
Test on Bitumen:
In the
standard test condition, a standard needle of a total load of 100 g is applied
to the surface of an asphalt or Liquid bitumen sample at a temperature of 25 °C
for 5 seconds. The amount of penetration of the needle at the end of 5 seconds
is measured in units of 0.1 mm (or penetration unit). A softer asphalt
will have a higher penetration, while a harder asphalt will have a
lower penetration. Other test conditions that have been used include
- 0 °C, 200 g, 60
sec., and
- 46 °C, 50 g, 5 sec.
The
penetration test can be used to designate grades of asphalt cement, and to
measure changes in hardness due to age hardening or changes in temperature.
The
flash point test determines the temperature to which an asphalt can be safely
heated in the presence of an open flame. The test is performed by heating an
asphalt sample in an open cup at a specified rate and determining the
temperature at which a small flame passing over the surface of the cup will
cause the vapors from the asphalt sample temporarily to ignite or flash. The
commonly used flash point test methods include
- The Cleveland Open
Cup (ASTM D92)
- Tag Open Cup (ASTM
D1310).
The
Cleveland Open-Cup method
is used on asphalt cements or asphalts with relatively higher flash points,
while the Tag Open-Cup method is used on cutback asphalts or asphalts with
flash points of less than 79 °C. Minimum flash point requirements are included
in the specifications for asphalt cements for safety reasons. Flash
point tests can also be used to detect contaminating materials such as
gasoline or kerosine in an asphalt cement. Contamination of an asphalt cement
by such materials can be indicated by a substantial drop in flash point.
When
the flash point test is used to detect contaminating materials, the
Pensky-Martens Closed Tester method (ASTM D93), which tends to give more indicative
results, is normally used. In recent years, the flash point test results have
been related to the hardening potential of asphalt. An asphalt with a high
flash point is more likely to have a lower hardening potential in the field.
Initial and Final Setting Time Of Cement
To do so we need Vicat apparatus conforming to
IS: 5513 – 1976, Balance, whose permissible variation at a load of 1000g should
be +1.0g, Gauging trowel conforming to IS: 10086 – 1982.
Procedure
to determine initial and final setting time of cement
i) Prepare a cement paste by gauging the cement with 0.85 times the water required to give a paste of standard consistency.
ii) Start a stop-watch, the moment water is added to the cement.
iii) Fill the Vicat mould completely with the cement paste gauged as above, the mould resting on a non-porous plate and smooth off the surface of the paste making it level with the top of the mould. The cement block thus prepared in the mould is the test block.
A) INITIAL
SETTING TIME
Place the test block under the rod bearing the needle. Lower the needle gently in order to make contact with the surface of the cement paste and release quickly, allowing it to penetrate the test block. Repeat the procedure till the needle fails to pierce the test block to a point 5.0 ± 0.5mm measured from the bottom of the mould.The time period elapsing between the time, water is added to the cement and the time, the needle fails to pierce the test block by 5.0 ± 0.5mm measured from the bottom of the mould, is the initial setting time.
B) FINAL
SETTING TIME
Replace the above needle by the one with an annular attachment. The cement should be considered as finally set when, upon applying the needle gently to the surface of the test block, the needle makes an impression therein, while the attachment fails to do so. The period elapsing between the time, water is added to the cement and the time, the needle makes an impression on the surface of the test block, while the attachment fails to do so, is the final setting time.
4.
CAUSES OF DETERIOTION OF ROAD PAVEMENT:
Traffic:
Traffic
is the most important factor influencing pavement performance. The performance
of pavements is mostly influenced by the loading magnitude, configuration and
the number of load repetitions by heavy vehicles. The damage caused per pass to
a pavement by an axle is defined relative to the damage per pass of a standard
axle load, which is defined as a 80 kN single axle load (E80). Thus a pavement
is designed to withstand a certain number of standard axle load repetitions
(E80’s) that will result in a certain terminal condition of deterioration.
MOISTURE
(WATER):
Moisture
can significantly weaken the support strength of natural gravel materials,
especially the subgrade. Moisture can enter the pavement structure through
cracks and holes in the surface, laterally through the subgrade, and from the
underlying water table through capillary action. The result of moisture ingress
is the lubrication of particles, loss of particle interlock and subsequent
particle displacement resulting in pavement failure.
SUBGRADE:
The
subgrade is the underlying soil that supports the applied wheel loads. If the
subgrade is too weak to support the wheel loads, the pavement will flex
excessively which ultimately causes the pavement to fail. If natural variations
in the composition of the subgrade are not adequately addressed by the pavement
design, significant differences in pavement performance will be experienced.
CONSTRUCTION
QUALITY
Failure
to obtain proper compaction, improper moisture conditions during construction,
quality of materials, and accurate layer thickness (after compaction) all
directly affect the performance of a pavement. These conditions stress the need
for skilled staff, and the importance of good inspection and quality control
procedures during construction. Ø
MAINTENANCE:
Pavement performance depends on what, when,
and how maintenance is performed. No matter how well the pavement is built, it
will deteriorate over time based upon the mentioned factors. The timing of
maintenance is very important, if a pavement is permitted to deteriorate to a
very poor condition, as illustrated by point B in Error! Reference source not
found., then the added life compared with point A, is typically about 2 to 3
years. This added life would present about 10 percent of the total life. The cost
however of repairing the road at point B is minimum four times the cost if the
road had been repaired at point A. The postponement of maintenance hold further
implications, in that for the cost of repairing one badly deteriorated road
(Point B), four roads at point A would have to be deferred, which would mean
that in a few years the rehabilitation cost could be 16 times as much. Thus,
postponing maintenance because of budget constraints, will result in a
significant financial penalty within a few years.
Maintaining
and Repairing Bituminous Road:
The
maintenance and repair of roads and airfields are particularly important
because of increased mobility in modern warfare. Damage caused by the weight of
heavy loads, the abrasive action of military traffic, and combat conditions
must be repaired as quickly as possible. The repairs are often made under
adverse conditions, such as shortages of manpower, material, equipment, and
time and the possibility of an attack. Continuous maintenance cannot be
overemphasized; small repairs made immediately are much cheaper than major
repairs made at a later date.
PRINCIPLES
For effective results, the cause of a failure
must be corrected. If surface repairs are made without correcting a defective
subgrade or base, the damage will reappear and repairs can be more extensive.
Also, a minor maintenance job that is postponed can develop into a major repair
job involving the subgrade, the base, and the wearing surface. Repairing the
surface without correcting the base is justifiable only as a temporary measure
to meet immediate needs under combat or other urgent conditions. Ensure that the maintenance and repair of a
surface conform as closely as possible to the original specifications for strength,
appearance, texture, and design. Ignoring the original specifications can mean
recurring maintenance on areas that are below standard, and differences in wear
and traffic impact may result from spot strengthening.
The
priority for maintenance and repair depends on tactical requirements, traffic
volume, and hazards that can result from failure of the paved area. For
example, roads used to support tactical operations should have priority over
less essential facilities. A single pothole in a heavily used road that is in
excellent condition otherwise should have priority over a less used road that
is in poor condition.
MATERIALS.
Use any stable material for temporary repairs
in combat areas or in areas where suitable material is unavailable and the area
must be patched to keep traffic moving. Use good-quality soils and masonry or
concrete rubble for this purpose. Ensure that patches are thoroughly compacted
and constantly maintained. Permanently patch the area as soon as possible.
Blade
the shoulders to facilitate rainwater drainage from the surface, and fill in
ruts and washouts. Grade the shoulder material flush against the FM 5-436
Maintaining
and Repairing Bituminous Wearing Surfaces pavement edges to restrict water
seepage to the subgrade and to prevent the pavement edge from breaking under
traffic. Replace material that is displaced from the shoulders with new
material as required.
Successful
repair with bituminous materials is more likely in warm, dry weather. When
breaks occur during cold weather, repair them on a temporary, expedient basis
to prevent progressive failures until the weather conditions allow more
permanent repairs. Eliminate frost and moisture from the area with surface
heaters or blowtorches.
5.
Quality Control Measures During Construction of Road.
All materials to be used, all methods
adopted and all works
performed shall be strictly
in accordance with the requirements of Specifications.
The Contractor
shall carry out quality control tests on the
materials and work.
For cement, mild steel, and similar other materials where essential tests are to be carried out at
the manufacturer's
plants or at laboratories other than the site laboratory.
For testing of cement concrete
at site during construction,
arrangements for supply of samples, sampling, testing and supply of test results shall be made. The method of sampling
and
testing of materials shall be as required
by the
"Handbook of Quality
Control for Construction of Roads and Runways"
(IRC:
SP:
11), and these MOST Specifications.
Similarly,
the supply of aggregates for construction of
road pavement
shall be from quarries approved by
the
Engineer.
Cement
concrete
pavement:
The defective areas
having surface irregularity
exceeding 3 mm but not greater
than 6 mm may be rectified by bump
cutting or scrabbling
or grinding using approved equipment.
Dry lean concrete sub-base:
Sampling and testing of cubes: Samples
of dry lean concrete for making cubes shall be taken from the uncompacted material
from different locations
In-situ density:
The dry density of the laid material shall be determined from three density holes at marked locations
Thickness: The average
thickness of the subbase layer as
computed by the level data of sub-base and subgrade or lower sub-base shall
be as per the thickness specified in the contract drawings. The thickness at any single location shall not be 10 mm less than the specified thickness.
Pavement concrete
Sampling
and testing of beam and cube specimens:
At least two beam and two cube specimens, one each for 7 day and 28 day strength testing shall be cast for ever 150 cu.m (or part thereof)
of concrete
placed during construction.
On each day's work, not less than three pairs of beams and cubes shall be made for each type of mix from the concrete delivered to the paving plant.
In-situ density: The density of the compacted concrete shall be such that the total air voids are not more than 3 per cent. The air
voids shall be derived from
the difference between the theoretical maximum dry density of the concrete calculated from the specific gravities of the constituents of the concrete mix. Thickness
shall be controlled by taking levels as
indicated Thickness of the slab at any point
shall be within a tolerance of -5 mm to + 25 mm of the specified thickness as per Drawing. Thick ness deficiency more than 5 mm
may be accepted.
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