indian Roads Congress

Specia~P~bh~~t3On 24

:UEL~1~~ESON
THE CHOICE AND
PLANNING OF
APPROPRIATE
TECHNOLOGY
IN ROAD
CONSTRUCTION

NE DELH~ 1984
<<
 Indian Roads Congress
Special Publication 24

GUIDELINES ON
THE CHOICE AND
PLANNING OF
APPROPRIATE
TECHNOLOGY
IN ROAD
CONSTRUCTION

Published by
The Indian Roads Congress
Copies can be had by VP.P.
from the Secretary,
Indian Roads Congress,
Jarnnagar House,
Shahjahan Road,
New Delhi-hO 011

NEW DELHI 1984 Price As 23g. 32

(Pius packing &
postage)

<<
 First Published in June, 1984

(The Rights of Publication and Translation are reserved)

Published by Ninan Koshi, Secretary, indian Roads Congress, Jamnagar

House, Shahjahan Road, New Delhi. Printed at PRINTAID, New Delhi-20
<<
 FOREWORD

The resources for the development of roads continua to be

limited and far short of the demand because of the phenomenal
growth of traffic on our roads~ Highway Engineers are thus
pressei to evolve the most economical design and c rnstruciion
practices to match the specific technical requirements compatible
with the overall socio•economic needs, Though there have been
remarkable advancements in the use of equipment based technology
in the field of road construction, such technology may not be suit-
able for use in entirety in our country in view of the large surplus
manpower available with us. Hence, there is need for going
in for intermediate technology which perhaps is best suited to our
country.

The Highway Engineers have been quite conscious of this

requirement and keeping this in view, the “Guidelines on the
Choice and Planning of Appropriate Technology in Road Construc-
tion” have been evolved by the Indian Roads Congress through a
Special Committee. These guidelines were approved by the
Council in their 109th meeting held at Nagpur on the 8th January,
1984 for being issued as a Special Publication of the Indian Roads
Congress.

I hope that this publication will prove to be a very useful

guide to the Highway Engineers of our country. We wuuld, how-
ever, welcome feed back data from the field engineers in order to
know their difficulties, if any, so that the same could be given due
consideration.

New Delhi K K. SARIN

June, 1984 Director General (Road Development) &
Add!. Secretary to the Govt. of India

<<
 CONTENTS

Page
I. Introduction ... I
2.Scope ... 2
3. Site Planning .. 3
4. Considerations in the Choice ofthe Appropriate
Construction Method ... 6
4.1. General ... 6
4.2. Technical Feasibility ... 7
4.3. Economic Viability ... 8
4.4. Social Desirability ... 9
4.5. CompatibIlity In Working ... 10
4.6. Overall Philosophy In the Choice of
Appropriate Technology ... 10
5. GuIdelines on Planning and Organisatlon of’
Labour.Eased Methods ... 17
5.1. General ... 17
5.2. Labour ‘ ... 17
5.3. Site Clearance ... 19
5.4. Earthwork ...

5.5. Read Construction Aggregates ... 28

5.6. Compaction ... 33
5.7. Soil Stablllsatlon ... 33
5.8. BItuminous Works 35
6. Guidelineson Planning and Organisation of
Equipment-Intensive Methods 38
6.1. General ... 38
6.2. General Principles Governing the Seleglios
of Machinery ...

6.3. Equipment Suitable for Earthwork ,• 39

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 S
6.4. Output of Earthmoving Equipment 41
6.5. Other Road Construction Equipment 49
7. Cost Calculations 54
4
...

7.1. General 54.

7.2. Costing of Labour-based Methods 54
7.3. Costing of Equipment-intensive Methods 55
74. Comparison ofCost of Road Construction
Jobs by different Methods ... 57

LIST OP TABLES

No.
1. Listing ofTasks and Available Construction
Methods 4
2. Process of Choosing Optimum Construction
Method 7
3. Break—Even Wage Rates for Selected Tasks 13
4. Productivity Data for Manual Excavation Using
Hand Tools ... 14
5. Productivity Data for Manual Loadingor
Unloadiag j5
6. Productivity Data for Manual Spreading In
Earthworks 15
7 Productivity Data for Manual Haul and Unload
Operations 16
8. Productivity Data for Manual. Spreading of
Pavement Materials ... 16
9. Productivity Data for Manual Production of
Aggregates ... 17
to. Calculations for Number ofEffectIve Days for
Labour—An Example 19
11. Gang Balance Calculations for Earthwork by
fleadbasket ... 29
12. Gang Balance Calculations for Earthwork Using
Flat-bed Truck for Haulage 30
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No. Page
13. Characteristicsand Output of 81101
Three-wheeled Roller 34
14. Resource Calculations for 20 mm Thick Premix
Carpet Work Using Mini Hot Mix Plant 36
15. Sample Calculations for Earthwork with Front
End Loader and Dump Trucks 48
16. Sample Calculations for Working of Tractor.
Drawn Water Tanker on Earthwork Job St
17. Sample Calculations for PavIng 50 mm Thick
Bituminous Macadam ..: 53.
18. Norms for Calculating Usage Charges of
Machines ... 56
19. Usage Charges for some Earthmoving Equipment 58
a Cost ofEarthwork by Manual Methods 59
21. Cost ofEarthwork by Equipment—Intensive
Method ... 60

LIST OF FIGURES
1. Cost ofEarthwork Task In Borrow-to-Ill
(Based on World Bank Study) ... 11
2. Sequence of Borrow Excavation—Short Hauls
by Headbasket Method ... 23
3. Sequence of Borrow Excavation—Haulage by
CartsfVehicles ... 23
4. Balancing ofCut and Fill In Road Construction 25
5. Productivity of Bulldozer 43
6. ProductivIty of Towed Scraper 45
7. ProductIvity of Motorised Scraper 46
8. Productivity ofFront End Loader~Excavator 47

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 MEMBERS OP THE SPECiAL COMMITTEE ON MECIIAN1SED
ROAD CONSTRUCrION

1. Maj, Gen. J.M. Rai Director General Border Roads

(Convenor)
2. K. Arunachalam Deputy Secretary (Research), Indian Roads
(Member-Secretary) Congress
3. M.G. Dandavate The Associated Cement Cos. Ltd.
4. G.K. Deshpande Superintending Engineer, Maharashtra P.W.D.
5. S.K. Gupta Superintending Engineer (Mechanical) P.W.D.,
B&R, Haryana
6+ Jagman Singh Director (Technical), Continental Construction
Ltd. New Delhi
7. D.P. Jam Chief Engineer & Addl. Secy. (Retd.) Rajasthan
P.W.D.
8. MR. Malya 3, Panorama, 30, Pali Hill Road, Bombay
9, P.J. Mehta Secy. to the Govt. of Gujarat, B&C Deptt.,
Gujarat
10. R. Natarajan Chief Engineer (Elect.), C.P.W.D.
11. VII. Pandit Chief Engineer (Mechanical), Irrigation DeNt.,
Maharashtra
12. P.K. Ran Superintending Engineer, National Highway
Circle-I, Orissa
13. M.E. Madhusudan AddI. Industrial Adviser, Directorate General of
Technical Development
14. S.A. Salam Chief Engineer, Project Organisation, Jammu &
Kashmir
15. G. Viswanathan Chief Engineer (Mechanical), Ministry of Shipp-
ing & Transport (Roads Wing)
16. L.M. Verma Superintending Engineer (C), Directorate General
Border Roads
17. N. Sathyamurthy Director (P&M), Central Water Commission
is. M.N. Singh Manager (Project Management), Indian Road
Construction Corporation
19. N. Vasudevan Managing Director, Kerala State Construction
Corporation
20. K.K. Satin Director General (Road Development) & AddI.
Secretary to the Govt. of India -Ex- officio
<<
S

GUIDELINES ON THE CHOICE AND PLANNING OP

APPROPRIATE TECHNOLOGY IN ROAD
CONSTRUCflON

1. INTRODUCtION
1.1. The tbndamental principle of alignment, design and
construction of any road is to achieve the lent overall cost of
transportation having regard to the cost of initial construction of
the facility, its periodic maintenance and vehicle operation, while
ut the same tlme,satlsfying the social and environmental require-
ments. Once a road project has bees prepared on this’ principle,
the prime objective of the Site Engineer will be to complete the
construction to the stipulated requirements at the minimum cost,
and within the time schedule. Fulfilment of this objectIve will
involve several steps which will include, Inter elM, the choice of
the appropriate construction technology which Is economically
viable and technically suitable for the type ofwork and for which
the necessary Input resourcesare readily available or can be made
available In time. Once the construction method is chosen, what-
ever method it may he, the Site Engineer should arrange for the
needed resources in time and take all measures for their efficient
and economical working.
1.2. In the interest of better plaaning of works at site and
economical execution of highway projects, this publication provides
guidelines for the choice of appropriate construction methods
under different situations, and discusses the ways and means for
improving the efficiency and productivity ofthese methods. A large
number of worked out examples have bee. Included for assisting
the Site Engineers in this regard.
1.3. These guidelines were initially prepared by L Aruna-
chalsm, Deputy Secretary (Research), Indian Roads Congress.
These were considered and approved by the Special Committee
for Mechanised Road Construction in their meeting held at New
Delhi on the 2nd December, 1983. These were later approved by
the Executive Committee by circulatIon and then by the Council
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 4
2
in their meeting held at Nagpur on the 8th January, 1984 for being
issued as a Special ~ubllcatlonofthe Indian Roads Congress.

tecon 4
2.1. The choice of the appropriate construction method for
a work or task Is governed by several factors such as terrain,
climate, available resources, technical feasibility for the nature of
operations and relative economy. While for some operations, there
can be more than one method that could be feasible and the choice
will mostly be dictated by the svailsbility of the needed resources,
for some other technical requirements or the time factor will dic-
tate the adoption of only one type of method. For example,
compaction of aggregates for WBM can be done only by a power
roller even in cases where the aggregates are broken and hauled to
site of work by purely manual methods. Similarly, even though
the manual methods might be the most economical alternative for
earthworks within short leads, equipment-intensive methods might £

have to be resorted to in cases where time of completion Is the

crucial factor.
2.2. ThIs document gives guidelines for helping the Site
Engineer In choosing the appropriate methods for the various tasks
involved in toad construction under different situations and dis-
cusses the ways and means of improving the efficiency and•
productivity of these methods. It should be understood that these
guidelines are neither absolute nor static and would need changes
from time to time depending on the relative cost of materials,
equipment and services involved. It is, therefore, suggested that
road construction departments should colláct, compile and analyse
the productivity data along with the governing parameters at least
for major road constructionprojects so that the guidelines could
be up-dated in the years to come.
2.3. The construction methods are generally clsssSd into
three categories, namely:
(I) Labeur-latsadve metheds which depend inestb’ en nnskflisd lebeur
who may usenethin~mere than simple hand took.
(Ii) Intermediate methods which employ ~iak simple equipment us
ae.i-humaamouress for aldlnj the manual ope.atloas, such as peck
ef sekials, ttl cuts, email ivi~ macbless, a
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 3
(iii) Equipment intensive methods in which the operations are executed
by a single or series of machines and where no unskilled labour is
employed except in purely ancillary capacity.

ith Thus for any task, a broad spectrum of methods is available

with the labour-intensive and equipment-intensive methods falling
at either extreme and the intermediate methods falling in-between.
In actual practice, however, for certain ranges of site parameters,
it will be inevitable even for the labour-intensive methods to use
some simple equipment or devices. For example, haulage for a
distance of over 100 m for which pack animals, cart and the like
will necessarily have to be inducted though use of unskilled labour
will be predominant. Such cases almost merge with the inter-
mediate methods because of physical inevitability. From this
consideration, as also to avoid any confusion in the classification
of the different methods, both the labour-intensive and the inter-
mediate methods which are practiced extensively in the country
will be dealt with together in these guidelines under the broad
heading ‘Labour-based methods’.

3. SiTE PLANNING
Site planning forms the forerunner to the starting of any
construction operation. It is at this stage that the site engineer
decides on the appropriate construction method for the various
tasks to be accomplished, plans the needed resources and takes
measures for improving the productivity at task/activity level for
economical working. All this involves a step by step procedure
which will include the following

ti) Listing out all the required tasks along with the quantities split
according to critical site parameters (e. g. hardness of soil to be
excavated, haulage distance, eic.) and the possible construction
methods, A typical list is shown in Table I for illustration,
(ii) Selecting the most appropriate method of working for each task
from angles of technical feasibility, economic viability and social
desirability. This will require a good understanding and relevant
information relating to the specification requirements and the
capabilities of the different methods in achieving these, the produc-
tivity and cost of operation with these, the advantage and disadvan-
tage of adopting a method peculiar to a particular site, etc. This
exercise will involve the listing out of all the possible methods, and
choosing the most approriate one through a process of rational and

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5. Production of Hammer, mobile crushing Crushing plant with integral
stone aggregate plant with manual loading screens and conveyor, loaded
by wheeled loader

6. Loading, hauling Haul over Animal cart, tractor-trailer, Loader~dump truck

unloading 1 km flat-bed truck with manual
aggregate loading/unloading

7. Rolling Embankmentj Power roller Power roller

base/surfacing

8. Bitumen carpet Dense-graded Hot-mix plant, paver-finisher

Open-graded Tar boiler, mechanical mixer, Hot-mix plant, paver-finisher
hand laid

<< tJ~
 6
systematic elimination. This aspect is dealt with in more detail in
para 4.
(iii) Calculations for the quantity of resource inputs for each task based
on productivity norms for the chosen method and the laid-down
time schedule.
(iv) Preparation of a draft work plan showing the calendar of activities
along with the required resources, This plan is examined in light of
the resources which are readily available or which can he made
available. If the resources are sufficient or more than sufficient for
the target production, the work plan can he finalised accordingly.
If otherwise, the Site Engineer should explore the feasibility of
improving the productivity through management measures, or by
extending the working season, or by introducing an additional shift.
If these are of no avail, he should inform his Senior Officers of the
position and demand more resources or extension of the time
schedule.
4. CONSIDERATIONS iN THE CHOICE OP THE

APPROPRIATE CONSTRUCTION METHOD

4.1. General
In broad terms, the choice of appropriate construction
method should be based on the following considerations
(i) Technical feasibility
(ii) Economipviability
(iii) Social desirability
(iv) Compatibility in working

This would show that the choice of the appropriate construc-

tion method should be based not on a single consideration or in
isolation but in the light of a combination of factors. Also, the
governing factors will not have Ihe same importance for each and
every task. A realistic approach in this regard would be to
identify in the first instance all the technically feasible methods for
each major task without regard to cost of construction and then
choose the most appropriate method through a framework of
rational and systematic elimination, For this purpose, it would be
useful to make a listing of the type shown in Table 1. The step by
step procedure for elimination of the inappropriate methods as
illustrated in Table 2 can then be followed for choosing the
optimum method.

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 7
TABLE 2. Psocess OP CHOOSING OPTIMUM C0N5TRUc ION Mnnoo

LOCAL/JOB CONDITIONS
1. Terrain 7. General type of soil
2. Rainfall and rainfall season 8. Average height of embankment’
depth of cutting
3. Harvest/local festival season
9. Condition of haul roads
4. Effective working days in the work-
ing season 10. Nearest base mechanical work-
shop
5. Labour available locally or to be
brought from outside II. Range of equipment available
6. Stone quarry’pavement material 12. Any other condition affecting
source choice of method

PROCEDURE
1. List all technically feasible methods (see Table I). Exclude methods obviously
unsuitable in light of local conditions.
2. Estimate task level productivities for each remaining method. Exclude
methods where productivity is too low.
3. Estimate resources needed for each reniaining method. Exclude methods
for which available resources are insufficient.
4. Estimate unit cost of each remaining methods, Exclude methcds with
unit costs 25 per cent higher than the cheapest.
5. Check for compatibility of the remaining methods with those considered
for the other related tasks of the project. Exclude incompatible methods,
6. Estimate task/project cost for each remaining method. Tabulate the
results and choose the most appropriate method taking all other tasks of
the proiect into account.

4.2. Technical Feasibility

Many of the tasks involved in road construction can be
executed either by labour or equipment-intensive methods. How-
ever, there are some others which can be accomplished by either
of these methods alone with no other alternative. This situa-
tion may arise because of the following factors
(i) Specification requirements—for example, high-type asphaltic concrete
which has to be mixed, laid and compacted to a specified quality
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8
and within a stringent temperature range will call for equipment
intensive methods. Another example is subgrade compaction and
compaction of pavement courses which can be effected to the
specified degree only with power rollers even where labour-intensive
methods are adopted for other tasks.
(ii) Physical constraints of energy of worker—production of aggregates by
manual breaking is possible, hut when the required sizes are small,
say less than 25 mm, and the rock is hard as is warranted for bit-
uminous surfacings, effort required will be too considerable for the
human energy to cope with, particularly when the aggregates are
required in large quantities. Employnrent of mechanical crushers
will be inevitable in such cases.
(iii) Size of work—at some works because of sheer size, such as high
embankments in long lengths for major highways, or mass produc-
tion of aggregates, or those which have to be completed within a
tight time schedule, there will be no alternative hut to adopt equip-
ment-intensive methods, The labour-intensive alternative would
entail the deployment of a very large labour force in a concentrated
way and even if such labour could be mobilised, it would be physi-
cally impossible to have a good control either over the productivity
or quality.
(iv) Restricted site conditions—large but concentrated works will not have
sufficient space for working of a large labour force, and for such
cases, labour methods may have to be ruled out. On the other hand
at certain restricted locations, machines cannot operate or
manoeuvre and labour methods will be the only alternative.

4.3. Economic Viability

4.3 1. Economic viability is an important factor in the choice
a mong technically feasible construction methods. The exercise
involves the comparison of costs by the various possible methods
and choosing the least cost alternative. The viability of any method
will depend on its productivity and the relative prices of labour
and equipment. One meihod of comparing the relative economy
of equipment-intensive method vis-a-ris a labour-intensive alter-
native for the same task is th rough the concept of break~even
wages for unskilled labour, This is done by calculating the cost of
the task by assuming different wage rates for labour and comparing
the same with that by the equipmeat-intensive alternative, Break-
even wage rate is that wage at which the cost of carrying out a task
hy labour is equal to the cost by equipment. A labour method
will be economical when the actual labour rate is Less than the
break-even wage rate.

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 9
4.3.2. The basic data required for cost comparison is the
productivity by the different methods for various tasks. The
detailed World Bank Study* conducted in the country during early
seventies had shown that labour productivity can vary in a large
range, depending on parameters such as method of payment (daily-
paid, taskwork or piecework), and the quality of supervision and
site organisation. For example, the productivity on an earthwork
job was 3-4 times when the incentive piecework payment method
was adopted compared to daily-pa ic$ wage method. This is not to
say that the piecework method will be cheaper by 3-4 times since the
pieceworker will be earning almost two times that of a daily-paid
labourer, Better site supervision will also involve some additional
cost.

4.3.3. The studies have also shown that besides the incentive
wage system, further improvement iii the productivity could be
achieved through improved tools, project organization and site
management. Examples in this regard are avoidance of double
handling, balancing of tools and labour gangs, and taking measures
for reducing human effort like pre-ripping and pre-wetting of hard
soil prior to excavation.

4.4. Social Desirability

Jn a developing country like India, provision of gainful
employment to a large number of people is an important matter
of social desirability which cannot be overlooked in road construc-
tion which is known to be capable of engaging large labour force.
For this reason, it is a corn mom practice in the economic analysis
of development projects in the country to shadow price the cost of
unskilled labour to the extent of 50 per cent. This feature, if
taken into account in the choice of the method, will show the

*Summary of the Study and its findings may be seen in the following two Papers
published by the Indian Roads Congress in November, 1976. The First Paper
also lists out the Reports and Technical Memoranda or the World Bank where
more details of the various aspects of the Study can be found.
(i) Sud, 1K., Harral, C.G. & Coukis, B.P., Scope for the Substitution of
Labour and Equipment in Civil Construction.
(ii) Green, P.A. & Brown Peter D., Some Aspects of the Use of Labour-
intensive Methods for Road Construction.
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10
labour methods in better colour for most of the road construction
tasks.

4.5. Compatibility in Working

The tasks involved in road construction can be accomplished
adopting a wide range of methods from the most labour-intensive
to the most equipment intensive, but the method chosen for one
task may dictate the use of similar technology for some or all
other tasks in the project. For example, loading of a large capa-
city dump truck should be by mechanical loaders, as resorting to
labour loading, even if less costly for this activity, will entail idle
time for the expensive dump truck and consequently result in an
overall uneconomic operation.

4,6. Overall Philosophy in the Choice of Appropriate

Technology
4.6.1. Paras 4.1. through 4.5. have broadly discussed the
factors that should be considered in the choice of the most appro-
priate method(s) for road construction projects. Of these,
economic viability among the technically feasible methods emerges as
the most important parameter. An objective exercise for evaluating
this parameter will require realistic productivity norms of the
various methods under different site conditions. Productivity
norms adopted by the different State PW.Ds in the country for
working out the schedule of rates vary considerably from place to
place and cannot therefore be generalised.

4.6.2. Factual productivity data qualified by site and

management parameters for road projects in the country are not
available except in the case of labour methods observed in the
World Bank Study. The picture of relative economy of the
various methods (both labour-intensive and equipment-intensive)
for the earthwork operation as emerging from the Study is shown
in Fig. 1. While the data for the labour methods were actually
measured, those for equipment-intensive methods where derived
from the ideal productivity norms given in manufacturers’ manuals.
The equipment costs were at 1976 prices and the wages for
unskilled labour were taken to be R.s 4.5 for daily-paid worker
and Rs 9 for pieceworker. Break-even wage rates (see pam 4.3.1.
for definition) for some selected tasks as emerging from the Study
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 I!

1,
0

0
I- 2

~AVL DISTANCE I1~I

Fig. 1. Cost of earthwork task in borrow-to-fill

(Based on World Bank Study)
Notes:
Line A corres onds to piecework payment with good supervision
while Line B is for daily paid work with poor supervision
2. Assumed unskilled Labour daily wage (Line B) Rs 4.5, daily piece-
work earnings (Line A) Rs 9
3. Details of the methods are as follows:
(1) D7 dozer for all activities
(2) Cat 621 motor scraper, D8 pusher, l2G grader
(3) Cat 769B (35-tonne) dump truck, 988 wheeled loader, excavation
by D8 dozer, speading by 12G grader
(4) Headbasket and labour
(5) Wheelbarrow and labour
(6) 35 lip tractor and 3-tonne tipping trailers, manual excavation,
loading and spreading
(7) Mule with panniers and labour
(8) Mule-cart and labour
(9) Camel-cart and labour
(10) Second-hand truck of 5-tonne capacity and labour
4. Total production cost includes overhead and supervision

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 12

are given in Table 3. Till more realistic indigenous data are

available, these can be consulted to get a broad idea on the
economically feasible methods.

4.6.3. Besides knowledge about the most economical

method, the Site Engineer will be interested iii working out the
needed resources for the various tasks For this purpose, the
productivity information relating to certain important tasks abstrac-
ted from the World Bank Study are given in Tables 4 through 9.

4.6.4. It may be noted that productivity of both labour and

equipment is strongly influenced by various conditions or para-
meters. For example, in the case of earth excavation by labour,
the productivity will depend on age, sex, traditional skill, health
and nutritional standards of labour; the terrain and climatic condi-
tions; the hardness of soil; the payment method; the type of
management and supervision, etc. Similarly, for working with
machines, the specific parameters affecting productivity are the
age and standard of maintenance of the equipment, the operator
efficiency and the job efficiency. In view of the interplay of several
parameters and the large variations in the productivity from site
o site, it will be convenient to express the productivity in the
form of two enveloping lines, the upper one (line A) tepresenting
the most favourable conditions (ie. high incentive wages, good
supervision, etc.) and the lower one (line B) denoting poor condi-
tions (i.e. daily wages, poor supervi~ion, etc.). in Tables 4 to 9
relating to labour-based methods, the input coefficients which are
liverse of productivity are given for both line A and line B condi-
ions. On similar considerations, productivity of equipment can
also be expressed in terms of lines A and B as discussed in para
o.4.

4.6.5. The selection of the most appropriate method for the

Wiferent road construction tasks is not just sufficient, and for
efficient and economical completion of a road project the Site
Engineer will have to look for improvements in planning and orga-
nization of the works. Guidelines in this regard are given in para 5
for labour based methods and in para 6 for equipment-intensive
methods.

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 13
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0
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~ 1:1:

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II)

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1111
U Sn 2)
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=CS ISIS
h~ N
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2. If,
N ‘O N
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o 0.
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a
,~ -~
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1: C- ~0
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V CS 0 C
z V ~ 5.5,
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~0 N C.,
at - 1..
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ri 2)2).!
~ I)
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CS.3~ CS~
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IC
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—— .! 5,
5,5, ~0
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0O 50.!.an c~ 0\ 00 ~a
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19
~1 ~ ~ 29 a ~~0
CSE
~ N,
CS ~ ~- .~.~
IC 0
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.0.0 a a a a N2, N, a—
CT IS CS IS ~i~— -oCS
8E .0 .1: .1: -~ Vu
•0
0 0
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‘0 ~ N,
N, 115,
0C., I~4)
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0 C CS
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= 113 CS
Sc
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<<
14
TABLE 4. P~oDucTIv1TyDATA FOR MANUAL ExcAvATION thING HAND TooLs

Input coefficient
Man-hour (WT) per cu.m.
Material
A B

1. Ordinary soil 0.3 0.8

2. Hard soil 0.9 2.3

3: Soft rock 1.3 3.3

Correction to input coefficient for loading height

Loading height (m) A B

—0.3 —0.04 —0.10

0.5 0.08 0.19
1,0 016 0.43
1.5 0.26 0.70
2.0 038 l.’Z

4A’ corresponds to piecework payment and good supervision while

Votes: 1.
‘B’ is for daily-paid method and poor supervision.
2. Ordinary soil and hard soil are taken to correspond to soil para-
meters 2 and 5 respectively of the World Bank Study.
3. All negative loading heights may be taken as —0.3 m.
4. Output in cu.m. pertains to in-situ volume prior to excavation.
5. ‘WT’ means working time which can be taken as S hrs/day and 5.5
hrsjday for conditions and B respectively.
.~

6. The correction coefficients for the appropriate loading heights are

to be added to the excavation input coefficient.

<<
 15
TABLE 5. PRoDUcTIvITY DATA FOR MANuAL LOADING OR UNLOADING

Loading or unloading Input coefficient

height (m) Man-hour (WT)/tonne

-03 0.20 0.52

0 0.22 0.58
0.5 0.26 0.69
1.0 0.3! 0.82
1.5 0.37 0.98
2.0 0.44 1.16

Notes: I. Loading or unloading means moving broken- up earth, aggregates

or loose materials into or out of a haulage vehicle by hand or with
hand tools.
2. For definition of A, B and WT, see notes under Table 4.

TABLE 6. PRoDUcTIvITY DATA FOR MANUAL SPREADING IN EARTHWORKS

Input coefficient
Haulage mode Man-hour (WT)/cu.m.

A B

1. Headbasket 0J7 0.33

2. Wheel-barrows/animals 0.25 0.50
3. Animal carts, tractors, trucks 0.33 0.67

Notes 1. Spreading means distribute deposited loose soil in a uniform layer

200-400 mm loose thickness, breaking up any large lumps and
removing organic matter.
2. Output in cu.m. is measured in-situ in the borrow area.

<<
 16
TABLE 7. FRoDucnvITy DATA FOR MANUAL HAUL AND UNLOAD OPERATIONS

Equations for input-coefficient

Man-hour (WT)Jcu.m.
Methods
A B

1. Headbasket 0.07 + 0.021 L 0.68 + 0.047 L

2. Wheel-barrow 0.25 + 0.0076 L 0.67 + 0.0186 H
3. Donkey 0.! -1- 0.009 L
4. Mules 0.1 + 0.004 L **

5. Ox cart 0.1 + 0.001 L

6. Tractor-trailer (35 HP tractor 0.014 + 0.00017 L 0.04 + 0.00033 L
& 3 tonne tipping trailor)

Notes : 1. ‘L’ is the equivalent haul distance. One-metre rise may be taken as
equivalent to 10 m additional haul distance.
2. ~ Input coefficient may be taken as twice that for condition ‘A’.
3. For definition of A, B and WT, see notes under Table 4.

TABLE 8. PRoDuCTIvITY DATA FOR MANUAL SPREADING OF

PAVEMENT MATERIALS

Material Layer thickness Input coefficient

(mm) Man-hour (WT)/tonne

. A B

1. Aggregates for 100 0.25 0.4

base or sub-base 60 0.45 0.7
2. Filler for WBM 8 2.5 4.0

Notes.’ I - For definition of A, B and WT, see notes under Table 4.

2. Spreading does not include associated loading and hauling from
stockpiles.

<<
 17
TABLE 9. PRoDucTiviTy DATA FoR MANUAL PRODUCTION OF AGGREGATES

Activity Input coefficient

Man-hour (WT)/tonne

A B

I. Production of 50 mm aggregate—
reduction factor 4 4 12
2. Production of 10 mm chippings—
red uction factor 10 ii 30

5, GUIDELiNES ON PLA.NN!NG ~NL) ORGANISAT1ON OF

LABOUR.BASEt) METHODS

5.1. General
A large number of resources will be required for executing a
road project. The Site Engineer should arrange for these in the
required quantities and in time so that the work could he
completed within the time schedule. The major resources for
labour based construction nieihods are
(1) Labour
(ii) Earth for earthwork
(iii) Aggregates and other pavement construction materials.

Besides these, tools and small equipment for the different opera-
lions and water will be required, and these are discussed alongwith
the above resources as relevant. Provision of cross-drainage
structures ac not dealt with in this publication.

5.2. Labour
5.2.1. The number of labourers required for a task is given
by
Volume of task
Number of labourers = Labour effective days x Productivity
Where productivity is measured in terms of output per day
per person.

<<
 5.2.2. The labour effective days are affected by a number of
factors such as
(1) Length of construction season
(ih Weekly or periodical rest days and other holidays
(iii) Absenteeism because of illness or local crop planting[harvesting
(iv) Time lost in recruiting labour at start of the season
(v) Time lost due to bad weather during the working season
tvi) Time lost due to labour unrest.

While items (1) to (iv) can be estimated to a reasonable degree of

accuracy based on local experience, some ad hoc allowance will
have to be provided for the other two items.

5.2.3. Ideally, a constant number of labour should work

together in perfect balance to maximise utilisation of resources.
This, however, is not generally possible in actual practice as there
will be build-up of labour at the start of a job and a run-down
towards the end. Taking all these into account, an example for
working out the effective labour days for a typical road project is
illustrated in Table 10. Once this is calculated, the average
number of labour to be employed in a task can be computed by
the formula given in para 5.2.1. In cases, where a work is required
to be speeded up or where additional work volumes not originally
anticipated crop up, the labour resources should be augmented in
the non-agricultural periods where labour can be mobilised with
greater ease.

5.2.4, In harvest and other periods specific to the area, a

heavy run-down of labour availability will be a general feature. On
works where equipment like trucks, etc. are used alongwith labour,
any idling of the equipment during such periods would add to the
cost of the project. One way to avoid this is to take away
available labour from the tasks being carried out by labour alone
and put them to work with the equipment for ensuring their full
utilisation. Alternatively, import of labour from outside by
paying higher wages could be considered. However, the measure
adopted should be based on the relative costs of paying higher
wages or of having the equipment standing idle.

<<
 19

TABLE 10. CALcuLA’rloNs FOR NUMBER OF EFI~cTIvEDAYS FOR

LABOUR - AN EXAMPLE

1. NUMBER OF DAYS ON WHICH WORK IS DONE

(a) Length of season ... 8 months
(b) Length of working week ... 6 days
(c) Number of working days in the season = 8 x 30 x ,,. 206 days
d) Number of official/local holidays during the season ... 10 days
(e) Likely loss of time in recruiting labour at start of
season ... 10 days
(f) Likely loss of time owing to bad weather ... 15 days
(g) Likely loss of time owing to labour disputes ,.. 5 days
(hI Total days on which work will be
done~=206—(I0+l0+15+5) ,.. l66days
2. LOSS OF TIME OWING TO LABOUR FLUCTUATION
(i) 50% Labour present during the first and last
weeks (assumed)
Reduction factor =
0.5x2x6 ,.. 0.036
(j) 25% Labour present during four weeks of
harvest (assumed I
O.75x4x6
Reduction factor = 166 ... 0.108
(k) 5% time lost due to labour turnover
Reduction factor ... 0.050
(1) Total reduction factor ... 0.194
(m) Loss of time = 166 x 0.194 ... 32 days

3. NUMBER OF EFFECTIVE DAYS = 166—32 ... 134 days

5.3. Site Clearance

~.3 I. Site clearance which forms the first stage of any
construction activity may consist of removing and disposin~/
storing/stacking of one or more of the following
(i) Trees, bushes and shrubs
(ii) Grass and other vegetation
(iii) St~/~Tps,
rubbish, loose stones, etc.
(iv) Top soil from embankment, cut and borrow areas (removed and
stored for re-application)
<<
 20
Site clearance should proceed well ahead of construction so
that the construclion lines can be set out and the precise nature of
the ground can be known for planning the earthwork operations. It
will be a good practice to carry out all major clearance work and
to set out alignments, etc. for a whole season’s work before const-
ruction begins.

5.3.2. The project drawings would generally show the

clearing limits. If not, the limits should extend over the area
which in one way or the other affect the construction activities. In
either case, the following guidelines may be helpful during the
operations
(i) All trees and stumps falling within the excavationlfill toe lines
should be cut to such depths that these do not fall within 0.5 m of
the subgrade level.
(ii) In all other cases, the vegetation which protects the ground soil
against erosion should not be cut out unless their removal is
warranted either for facilitating construction operations, or for haul
roads, or for improving the visibility, etc. In such cases, the flees
etc. should be removed only upto the ground level leaving the roots
to remain in place.
(iii) Removal of top’ soil should be to the depth containing organic
matter, and this may generally be to the depth of 50—150mm.

5.3.3. Labour methods are well suited for site clearance

work. Labour can distinguish between the trees and plants to be
removed and to he left in place, and the actual depth of organic
top soil to be cleared. They should be provided with good
quality axes, saws and grubbing mattocks, portable tree pulling
devices like winches, etc Animals or tractors can be used for
removing the felled trees to the stackyard.

5.4. Earthwork
5.4.1. GeneraL
(I) Earthwork constitutes a major component in the cost of
any road project, and on the overall basis, the cost of earthwork
may amount to 25—30 per cent of the project cost. For lower
category roads, this percentage will be even more. Cai~fulplanning
and efficient operation of the involved activities is therefore
necessary for economising road construction cost.
<<
 (2) Earthwork can be broken down into the activities of
ripping (if required), excavation, loading of excavated material
into the hau!nge mechanism, hauling, unloading, spreading and
compaction, although more than one of these activities can he
combined into a single operation All these operations can he
economically performed by labour-based methods which include
use of some simple equipment like tractor-trailer, flat-bed trucks,
etc.

5.4.2. Excavation
(1) Excavation in road construction may be for cutting the
natural ground for roadway or drain construction, or for winning
earth from borrow areas for embankments, or for founding highway
structures. In all cases if excavation can be combined with load-
ing, the combined operation becomes more efficient. However, in
hard materials like moorum soft rock, etc. excavation and loading
generally will have to be done separately in labour based methods.

(2) The hardness of the material excavated is an important

factor affecting productivity of excavation tasks, The Ministry cf
Transport Specification divides soil into two categories, namely,
ordinary soil and hard soil with the following description
(a) Ordinary Soil
This shalt comprise vegetable or organic soil, turf, sand, silt, loam,
clay, mud, peat, black cotton soil, soft shale or loose moorum, a
mixture of these and similar material which yields to the ordinary
application of pick and shovel, rake or other ordinary diggng
implement. Removal of gravel or any other nod ular material
having diameter in any one direction not exceeding 75 mm occurring
in such strata shall be deemed to be covered under this category.
(b) Hard Soil
This shall include:
(i) stiff heavy clay, hard shale, or compact moorum requiring
grafting tool or pick or both and shovel, closely applied;
(ii) gravel and cobble stone having maximum diameter in any one
direction between 75 and 300 mm;
(iii) soling of roads, paths, etc., and hard core;
(iv) macadam surfaces such as water bound, and bitumen/tar bound;
(v) lime concrete, stone masonry in lime mortar and brick-work in
lime/cement mortar below ground level;
(vi) soft conglomerate, where the stones may be detached from the
matrix with picks; and
<<
 22
(vii) generally any material which requires the close application of
picks, or scariflers to loosen and not affording resistance to
digging greater than the hardest of any soil mentioned in (1) to
(vi) above.
Available data show that bard soils require 2-3 times the
manpower inputs compared to that for softer soils. Effort required
for hard soils can be reduced and the productivity increased to the
extent of 50- 100 per cent by:
(i) Pre-ripping, and
(ii) Wetting
(3) Pre-ripping may be by tractor/animal drawn ploughs.
Ripping is started on a narrow strip which after the process is
excavated and the material removed to form working space with
vertical faces. The adjoining strip is then ripped and the excava-
tion is continued on the vertical faces which has the advantage
that the cut material falls away from the face aided by gravity.
Also, the vertical face reduces drying cut and hardening of soil in
hot climates.
(4) Wetting prior to excavation softens the material and
makes the excavation task easier. However, over-wetting of clay
soils should be guarded against as this may make the materials
slushy and un-workable. It will be advantageous to time the
earthwork operation when the soil is fairly moist so that not only
the excavation effort is less but also not much Water will be required
to be added for compaction. The best time for the purpose is
at the beginning of construction season, i.e. soon after the
monsoons when every opportunity should be taken to plan the
bulk of the earthwork,
(5) The higher the mateTial has to be lifted for loading, the
greater will be the amount of effort expended, see Table 4. A
low or negative loading height will make the operation much
easier. The excavation should be so organised that as far as
possible, all haulage containers can be loaded within small lifts,
if negative lifts are not possible. For this purpose, a strip of
width sufficient to pass the haulage vehicle is first cut. Excavation
is proceeded with on the vertical faces so that the haulage system
can be loaded without much lift. Fig. 2, illustrates the sequence
of short-haul earthwork by headbasket method while Fig. 3, shows
possible arrangements for medium hauls using carts/vehicles.
<<
 23
EXrSNT OF BOLLRO~ ~

l.~....> STAGE
~ FILL. AREA

STAGE 2
SECTION TMcLOUGLI I9ORROw PIT ~

I ~ I ..

FL I.!.

-___C_~~ ® II
PLAP4 OF BORROW__AREA

Fig. 2. Sequence of borrow excavation—short hauls

by he~dbasketmethod
4~_. EXTENT OF BORROW AREA
fr
‘~‘\ ‘~~!I
F~T~N1 STAGE

~MU1 STAGE Z

STAGE 3
E’~C.
SECTION TLIROI.IGH SORROW PIT

Fig. 3. Sequence of borrow excavation—haulage by carts/vehicles

<<
 24

5.4.3. Hauling
(1) A variety of labour based methods are possible for haul-
ing soil for earthwork. In general, the choice of the method and
the cost of hauling are governed by
(i) Haulage distance
(ii) Rise/fall from the source to place of deposition
(iii) Conditions of the haulage routes such as roughness,
firmness, uniformity, slope, etc.

(2) For embankment construction, the soil is generally

obtained either from roadway and drainage excavation or borrow
areas, or from both. At the stage of designing the grade line for
the road, it will be expected that the cut and fill quantities are
balanced to the maximum extent possible. Balancing is possible
both in the lateral and longitudinal directions as depicted in Fig. 4.
Lateral balancing involves a half-cut, half-fill cross section with
or without retaining wall, but this will not be feasible when the
ground slope is very steep in which case the road may have to
be in full cutting. Lateral balancing, where possible will not
involve much haulage, but in longitudinal balancing, the distance
may vary from case to case. When the haulage distance is more
than 150-200 m, it will be more economical to go in for roadside
borrow if available.

(3) Winning earth from roadside borrow areas which involves

short haulage distances is ideally suiled for manual methods. The
borrow pits should preferably be located on both sides of the
line of work. Guidance on the location of roadside borrowpits
can be had from IRC : 10 “Recommended Practice for Borrowpits
for Road Ernbankments Constructed by Manual Operation”.
Roadside borrowpits may, however, be not possible in the case
of high embankments involving large earthwork quantities and in
certain other cases, for example, sections falling on low lying areas.

(4) The volume occupied by soil in compacted fill will usually

differ from in-situ volume in borrow areas because of difference
in densities. The correction factor for converting in-situ volume
into compacted volume is given by

Earthwork correction factor = In-situ density of borrow .

Compacted density of fill
<<
 25

Fig. 4. Balancing of cut and fill in road construction

Where vehicles are used for haulage, the output will be a function
of loose volume carried by the vehicle and therefore a knowledge
of the loose density of bulking factor of the soil will be required.
Bulking factor is given by
In~situdensity in borrow
Bulking factor = .
Loose density in haulage
<<
 26

The loose dry density of most of the soils will be in the range of
1.4 and 1.5 tonnes/m3.
(5) Rise or lift from source to place of deposition involves
additional effort, and roughly 1 metre rise can be taken as equi-
valent to 10 m haulage distance, Similarly, a rough haul route
involves additional effort, but the extent varies from method to
method. The different methods, therefore, require different treat-
ment to the haulage routes. While men and pack animals can
negotiate rough routes with steeper gradients, wheel barrow,
animal cart and other similar devices are highly sensitive to these
parameters. This aspect is discussed in subsequent paragraphs
under respective method of hauling.

Head Baskets
(6) Head baskets are one of the most common form of man-
power haulage and are efficient for distances upto 50-60 m. It is
reasonably independent of the route condition. Unloading is a
simple operation and little spreading is needed after unloading.
Load carried varies between 15 and 40 kg and speeds from 50 to
70 rn/minute. Use should be made of spare baskets for excavators
to fill the basket by the time the hauler returns.

Wheel Barrows
(7) Wheel harrows can be used for haulage between 25 and
100 m, and can be highly economical if a smooth and firm haul
route can be made. The most common method is by building
a barrow way usually made of planks if a hard and smooth surface
cannot be formed on the ground. Barrow has a triangular
body with a single wheel fitted in the forward part. With improved
barrows fitted with pneumatic tyres, pay loads in the range of
70-120 kg are possible at speeds 50.80 rn/minute.
Pack Animals
(8) A variety of animals like donkeys, mules, ponies and
camels can be used for pack work. Haulage by pack animals
becomes relatively advantageous where steep gradients and poor
haul routes are encountered. The load usually of the order of
100.200 kg, is carried on panniers made of woven rope. Loading
is by hoe or shovel and emptying is by tipping. This method can

<<
be found workable for distance upto 300 m and rise upto about
10 m. Usually gangs of 10-12 animals are loaded, led and
unloaded 4-5 labourers.

Animal Carts
(9) Wooden-wheeled or pneumatic tyred carts pulled by
bullock or buffalo can be used for haul distance upto 100 m.
While large diameter solid-wheeled carts can negotiate uneven
or slushy tracks, pneumatic tyred carts can work only on firm
and even ground. The load carried per trip varies between 500
and 1000 kg. Haul speeds vary from 48-60 rn/mm depending on
haul route condition. Loading is by headbaskets while unloading
is by tipping the cart (after unyoking the animals) and using a hoe.

Tractor-trailer and Flat-bed Truck

(10) Manual and animal haulage methods usually are uneco-
nomical on hauls of over 500 m. The most common form of
equipment for longer hauls in combination with manual loading is
either the tractor-trailer combination or the fiat-bed truck.

(11) Tractors are easily available during slack times in the

farmwork cycle. They have the advantage of being a basic and
robust machine and are more likely to have a well developed
repair facility. Two or more trailers may be used depending on
haul length so that when one is being hauled, the other may be
loaded. The labour for a tractor may be divided into three groups,
two at the borrow area (one for excavation and the other for
loading) and the third at the fill site for unloading and spreading.
The suggested load capacity of trailers are

Tractor HP Trailer Capacity

35 HP 3 tonnes
45 I, 4
60 ,, 5
75 ,, 6

(12) Two-axle trailers are capable of carrying a greater load

than a single axle trailer of the same size and are easier to hitch
and unhitch, Single axle trailer is much easier to manoeuvre
and can transfer load to the back aide of the tractor thereby
<<
 2g

greatly increasing the traction which may be required for haul

on poor routes or steep ramps.

(13) The lower the loading height, the quicker the trailer
may be loaded. The lie of the land can be utilised to ensure a
downhill approach for the loaders, or loading benches can be
excavated. Separate team of unloaders should be provided at
the unloading point. If tipping trailers are used, unloaders will
not be needed but the cost of the equipment will be high. The
nature of the haul route has an important effect on the productivity
as rough or rutted route will cut the travel speed and up gradients
will reduce the pay load. Ideally the route should not have a
gradient steeper than 10 per cent and should be well maintained.

(14) For flat-bed trucks, the economical haulage distance

varies between I and 5 km. The haul route should be good and
the loading and unloading operations should be quick. The labour
gang may be divided into three groups, one at the borrow area
(for excavation when the truck is hauling and for assisting in
loading when the truck returns) the second moving with the truck
for loading and unloading, and the third at fill site for spreading.

5.4.4. Gang balance: Gang balance is the distribution

of activities within a task so that all the men in a gang can work
at much the same pace in planning, the resources, this aspect
must be considered in any task which consists of a number of
inter-related activities. If the excavation-load-haul-unload task
is considered, the excavators and loaders should be able to work
at an even pace without having to wait for a hauler, while the
hauler should not have to wait for the haulage container to be
filled. Calculations for gang balance for the earthwork task with
the beadbasket and flat-bed truck for haulage are given in Tables 11
and 12 respectively.

5.5. Road Construction Aggregates

5.5.1. General : Stone aggregates are required for the
construction of road pavement and structures. Low-grade aggre-
gates like moorum, gravel and kankar can also be used in sub-base
of main roads and in sub-base/base/surfacing of low-volume roads.
Generally, cost of loading, hauling and unloading will form a
<<
 29
TABLE 11. GANG BALANCE CALcULATIoNs FOR EARTHWORK BY
HEADRA5KET

I. SITE PARAMETERS
Task excavate, load into
headbaskecs, haul
and unload
Soil ordinary soil
Haul distance 20m
Rise of haul route im

Management good
Payment method piecework

Gang strength 20

2. CALCULATIOt4S

(i) Activity level inputs

(a) Excavate input (Table 4) 0.3 man-hrjcu.m.
(b) Correction for loading
height (assuming 1.5 m) 0.26 man-hr/cu.m.
(c) Equivalent haul length
= 20+IOxI 30m
(d) Haul/unload input (Table 7) 0.7 maa.hrfcu.m.

(ii) Output for perfectly balanced gang

(a) Total input = 0.3+0.26+0.7 = 1.26 man~hrcu.m.
(b) Gang output (20 men) 20/1.26 = 15.9 cu.rn/hr

(iii) Best feasible gaag proportion

(a) Rates of excavator/loader to hauler = (0.3+0.26) :0.7 = 1:1.25
(b) Optimum gang proportion = 9 excavators to 11 loaders

(iv) Actual output

(a) 9 excavators excavate 9/0.56 = l5,Scu.m hr
(b) 11 haulers haul Il/U.? 15.7 cu.mthr
(c) Actual output of gang 15.5 cu.m/hr

<<
 3()

TAIuE 2, GANG BALANCE CALCULATrONS FOR EAR1lIwoRK USING

FLAT-Bn Txuck FOR HAULAGE

I. SiTE CONDITIONS AND ASSU~lPTtONS

Task excavate, load into flat-bed truck,
haul, unload and spread
Soil
hard soil
Haul distance 3km
Loading height (),5m
In-situ density of soil 1.7 gm/cc
Management good
Payment method piecework
Truck capacity 5 t or 3 cu. m (in-situ volume)
Truck speed, loaded 15km/hr
Truck speed, empty 20 km/hr

For operational convenience, 8 men load the truck, and 8 men who travel
with the truck perform unloading
2. CALCULATIONS
(i) Truck cycle time
Hormonic mean truck speed
= 17.1 km/hr
+
2x3x60
Haul time (out and return) = = 21mm
Collapsing truck sides and
remaking = 1mm
Loading input (Table 5) = 0.26 man-hr(tonne
= 0.44 man-hr/cu. m.

Loading time with S men = x 60 = 9.9 mm

Unloading input (Table 5) = 0.20 man-kr/tonne

= 0.34 man-hr/cu. rn
= 3x0.34
Unloading time with S men 6077.

Total cycle time for truck 21+1+9.9+7.7 ==39.6minor

say 40 mm
(ii) Excavators
Excavate input (Table 4) = 0.9 man-hr/cu. m.
Time available for excavation = 40—9.9 = 30.1 mm

3x0.9x60
Number of excavators required = —~.~-~--—— = 5.4orsay6

<<
 31
fl~i)Spreaders
Spreading input (Table 6) 0.33 man-hr/cum.
Time available for spreading = 40—7.7—1 = 3.1.3 mm
3x0.33x60
Number of spreaders requtred =‘ -~--ç-—•-= 1.9 or say 2
Note: These spreaders and excavators caa also help in unloading so
that the number of loaders/unloaders travelling with the truck
can be reduced to 6.
‘iv) Output
3 x 60
Output per hour = = 4.5 cu.m.

Output per truck per day of

S hours effective working time 8x4.5 36 Cu. m.
~v) Conclusion
A gang of 22 men (6 excavators, 8 loaders, 6 unloaders and 2 sprea-
ders) working with a 5 tonne fiat-bed truck can turn out 36 cu.m. of
excavate-load-haul-unload-spread operation,
Note,’ If the haul distance is less or the speed of travel is more, the
productivity will be more and will warrant more excavators
and spreaders for balanced working.

sizeable portion of the aggregate cost at the work site. Arranging

for gravity loading from a higher level at quarry site, cutting down
the idle time of haulage vehicle by providing adequate number of
labourers for loading-unloading, maintaining the haul route in good
condition and unloading the material at the pre-plarined locations
at work site to avoid double handling are some of the measures
for improving productivity and reducing cost. Flat.bed trucks
are extensively used in the country for aggregate haulage through
animal carts are also employed for shorter hauls and where only
small quantities are required.

5.5.2. Stone quarries Generally, stone aggregates for

road works are supplied from well established running quarries.
Side by side, developmental work in identifying new quarry sources
is also going on, and it will be worthwhile considering opening up
of new quarries for greater economy particularly in the case of
major civil engineering works where the demands will be large and
continuous. The first step in the process will be to test samples
of rock from the prospective quarries for conformity with sped-

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 32

fication requirements If the material is suitable, the main factors

to be taken into account in choosing the best alternative would be
(i) Cost of removal of overburden and opening up the quarry.
(ii) Ease of excavation through blasting or other means.
(iii) Existance of suitable areas for installing the crushers, the cost thereof
and the distance of the quarry point to the crusher or vehicle
loading point,
(iv Cost of providing vehicle manoeuvring area in the quarry and of
access routes.
(v) Haul length, haul route condition and rise/fall of haul route.
(vi) The quantity of stones required to be extracted to assess the economy
of opening up the quarry, providing access roads, etc.

Generally, the initial cost of opening a quarry, constructing

haul roads, installation of crushing equipment, etc. will be consi-
derable and outweigh the operating cost unless the quantities to
be extracted are large, and the quarry could be put to use in
future for other works.

The productivity of road aggregates by hand breaking depends

to a great extent on the hardness of stone and the reduction factor.
NormaLly 200-250 mm sized rubble are collected after blasting and
used for hand breaking with a 0.5.0.9 kg hand hammer, The pro-
ductivity of breaking to 25-50 mm size aggregate used for Water
Bound Macadam (i.e. a reduction ratio of about 4) will be of the
order of 0.5 to 1.0 cu. m./man day. For higher reduction ratio,
the effort required will be higher, and the productivity will be
correspondingly less. The effort required for breaking into smaller
sizes goes up steeply, and it will be more economical to go in for
mechanical crushing for such cases.

5.5.3. Moorum and gravel quarries: As in the case of stone

quarries, the suitability of the available material will he the first
consideration in the choice of moorum/gravel quarries. Generally,
the installation cost for such quarries will only be nominal, and for
choice among the suitable alternatives, the most significant factor will
be the haulage cost. The factors affecting haulage productivity
and cost such as loading height and time, haul distance, condition
of the haul route, etc. equally apply to this case.
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 33

5,6. Compaction
5.6.1. For the embankments, compaction is generally
specified in terms of standard Proctor density 95 per cent for body
-

of embankment and 100 per cent for subgrade portion and

shoulders. The compaction is to be done in 250 mm thick loose
layers. This will be possible only with power rollers which is
capital intensive. Different types of soils require different types of
rollers, but the 8/10 tonne three-wheeled roller will be found to be
useful for most cases. Where a power roller is used for com-
paction, it should be ensured that the hauling and spreading
activities are balanced to provide adequate work to the roller so
that it does not remain idle. Light-weight (0.5 2 tonne) tractorf
—

animal drawn rollers are also available but these should not be
used unless the road is a minor one and there is no other alter-
native.

5.6.2. Compaction of sub-bases of moorum(gravel, etc. will

be on the same lines as of subgrade compaction. Water bound
macadam requires large compactive effort for getting the aggre-
gates properly interlocked and this is possible only with power
rollers.

5.6.3. Compaction of bituminous layers can be done con-

veniently with 8/10 tonne three wheeled roller. The roller wheels
have to be kept moist to prevent the mix from being picked up.
Bituminous Macadam and asphaltic concrete surfacing will require
3-wheeled roller for break down rolling and tandem roller for
finishing.

5.6.4. The normally observed productivities of 8/10 tonne

roller in compacting different materials are given in Table 13.

5.7. Soil Stabilisation

5.7.1. Adequate pulverisation of soil, and thorough and
uniform mixing of stabilizer constitute essential requirements to the
success of soil stabilisation works. From this angle, it would be
preferable to use mechanical equipment wherever possible.
5.72. Lime stabilisation which is commonly adopted in the
country is applicable for clayey soils where pulverization of the soil

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 34
TABLE 13. CnARACIERIsTIcs AND OUTPUT OF 8/101
IHREE-WHEELED ROLLER

CHARAcI’ERISTICS
Width compacted ... 1.78 m
Speed of rolling ... 50 mfmin
Applicability ... Suitable for (I) all soil types except soft
wet clay and uniformly graded sand,
(ii) all bituminous layers through pnue-
matic tyred is preferable for surface
dressing

Type of material Average output/day

1. Earthwork in embankment in 150mm thick

compacted layers 400 cu.m
2. Moorum/gravel sub-base in 150 mm thick
compacted layers 300 cu.m
3. Moorum/gravel sub-base in 100 mm thick
compacted layers 250 cu.m
4. WBM over-size metal sub-base in 100mm
thick layer (compact) 35 cu.m
5. WBM base in 75 mm thick layer (compact) 30 cu.m
6. Surface dressing, single coat 770 sq.m
7. Surface dressing, two-coat 550 sq.m
8. Premix carpet, 25 mm thick 600 sq.m
9. Premix carpet, 20 mm thick 740 sq.m
10. Liquid seal coat for premix carpet 1000 sq.m
11. Sand seal for premix carpet 2000 sq.m
12. Bituminous macadam, 50-75 mm thick 280 sq.m
13. Asphaltic concrete 25-40mm thick 370 sq.m

prior to mixing is an important requirement. For such soils,

mould-board ploughs, disc harrows and off-set harrows hitched to
agricultural tractor which is often used for agricultural opera-
tions can be used. The tractor should be of about 50 HP
for depth of processing upto 200 mm and 110 HP where the
depth goes upto 400 mm. Mould-board plough is used first for
loosening the soil. The disc harrow is then passed over the
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 35
ploughed soil to break down clods further. The soil is then
processed further with off-set harrow. After achieving the required
degree of pulverisation, the soil is levelled, moisture content
adjusted, and the stabilizer is spread over it manually. The off-set
harrow is then used for 4-6 passes for mixing. After levelling, the
layer is compacted with power roller. For heavy clays, pre-
treatment with lime may be adopted for aiding pulverisation

5.7.3. The purely manual method consists of cutting the soil

several time with hoe/spade for pulverising it, then forming a stack
and adjusting the moisture, spreading the stabilizer on the stack,
and turning over the material 4.6 times till it is unifornially mixed.
This method should be~adoptedonly where the needed equipment
is not avilable.

5.8. Bituminous Works

5.8.1. A variety of bituminous constructions from thin sur-
face dressing to dense asphaltic concrete are practiced in the
country. Surface dressing though apparently simpler to construct
require uniform spreading of bitumen and even spreading of
aggregates before rolling. The quick succession of the operations
is important to ensure that the aggregate get properly embedded in
the binder before the latter becomes hard, as otherwise the aggre-
gates will whip-off. All this can be possible and a good quality
surfacing constructed only if mechanical sprayers and chip
spreaders are used. In the absence of truck-mounted sprayers,
hand operated sprayers attached to a tar boiler may be used.

5.82. Open-graded premix carpet construction requires

uniform coating of aggregates, and preferably hot mix plant is used
for the purpose though laying may be done manually. Mini hot mix
plant of 6-8 tonne capacity will he found suitable. Where such
plant is not available, the aggregates can be heated in stacks with
fire through empty bitumen drums embedded in them, and mixing
done in a concrete mixer or improvised mixer. A sample calculation
for working out the resources for laying 20 mm thick premix carpet
with mini hot mix plant is given in Table 14.

5.8.3. Bituminous macadam and asphaltic concrete mixes

should invariably be prepared in hot mix plant and laid with

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 36

TABLE 14. Rssou~caCALcuLATIoN FOR 20 mm THIcK PREMtx

CARPET Woak usn’~oMrrn HOT Msx PLA~r

DATA
1. Output of mixing plant 6tonne/hr
2. Output/day (effective working time 6 hrs) 36 tonnes
3. Cycle time for each batch ...3min
4. Weight of each batch of mix (6000 x ...300kg
5. Haulage of mix by large wheel barrow pushed by two
persons
Speed loaded 50m/min
Speed empty 6Om/min
Unloading time 0.5 mm
6. Width of paving
7, Aggregate dumped within an average distance of 10 m
from plant. Loading the bin is by headbasket method
8. Bulk density of aggregate 1.Stonne/cu.m.
9. Binder content by weight of total mix 4.45%

10. Calculations are done for two cases:

~a) The plant at one location will cater for the work
for a distance of’ 600 m on either side
(b) The plant at one location will cater for the work
for a distance of 1000 m on either side. On com-
pletion of the work, the plant will be shifted to a
new location,

CALCULATLONS
A. Plant to cater for 600 m length on either side
1. Output of plantfday = 6 x 6 .~ 36 tonnes
2. Aggregate to be dumped at plant site
2x600x7x0.27 =226cu.rn
(@0.27 cu.m/10 sq.m) = 10
3. Bitumen to be brought to plant site
(i~14.6 kg/lO sq.m) 2x600x7x14.6 = 12.2 tonne
IOxl000
36(100—4.45) = 22.8 cu.m
4. Volume of aggregate used per day
= - 1.5
5. Area of spread of mix/day
(0.27 cu,m/lO sq.m) — x 10 = 850 sq.m
— 0.27
6. Length of road paved/day 850
— = l2Om

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 37

7. Labour for hauling mix:

Average lead = 300 m
Time for loaded trip = 300)50 = 6 mm
Time for empty return = 300/60 = 5 mm
Unloading/turning time = 0.5 mm
Time per cycle = 11.5 mm
As each batch will be at 3 minutes,
provide four teams of two persons
each for hauling
8. Labour for spreading mix
Spreading input coefficient = 0.5 man-hr/tonne
Number of persons required = 6 x 0,5 = 3
9. Labour for loading bin
Hauling/unloading input coefficient
= 0.28 man-hrjcu.m.
(10 m lead)
22.8
Quantity of aggregate to be loaded/hr = —~- = 3.8 cu.m.
Number of persons required for
hauling = 0.28 x 3.8 = 1.05 or say 1
Provide one extra for loading
baskets
10. Provide 2 persons for loading bitumen
into boiler
it. Total number of labour required =8+3+2+2= ISpersons
12. Output of roller (Table 13) 740 sq. m
13. Provide one roller for rolling
14. Number of working days required for 2 x 600
= 120 = 10 days
completing the job
B. Plant to cater for 1000 m on either side
1. The other resources required will be
the same as for case. A except that
number of teams hauling the mix will
have to be increased.
Average lead = 500 m
Time for loaded trip = 500/50 = 10 mm
Time for empty return = 500/60 8.3 mm
Unloading/turning time = 0.5 mm
Time per cycle = 18.8 mm or say 18 mm
Number of teams of haulers 18/3 = 6
= 12 persons
2. Number of working days required 2 >~ 1000
for completing the job = 17 days

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mechanical paver. The operation, therefore, has to be equipment-

intensive
for obtaining the best results.

6. GUiDELINES ON PLANNING AND ORGANISATION OF

EQUIPMENT-INTENSIVE METHODS

6.1. General
As discussed in para 4, the choice of the most appropriate
technology for road works has several ramifications, and is not to
be based on micro-level cost coniparsion alone. For example, for
the task of earthwork within a lead of 25 m, the labour intensive
headbasket method will be the most economical, but if the work is
of large magnitude to be completed within a stringent time
schedule, or the required labour force is not available, the job may
dictate the adoption of equipment-intensive methods particularly
where the needed equipment are readily available at site. The
choice will, therefore, have to be judicious taking all the related
parameters into account. In this Section, considerations in the
choice of the appropriate equipment for the major tasks involved
in road construction and guidelines on their efficient utilisation are
given irrespective of the fact whether the job may be done equally
well or not with labour based methods.

6.2. General Principles Governing the Selection of Machinery

6.2.1. It will generally be necessary to have a good
experience in the operation and upkeep of equipment for satis-
factory selection and handling. The records which have been kept
for operating and maintenance of the various types of equipment
and the actual output obtained under comparable conditions of
previous projects will greatly assist in this regard. The types and
sizes of equipment available to accomplish a job are in wide
variety and range, and for selecting the best suited one, it would
b~advantageous to consider the following factors
(i) The equipment already available in the project may be used even
though it may not be the ideal choice. The heavy ownership cost
involved in keeping the available equipment idle may offset the
increasd cost involved in its operation cost vis-a-vis the ideal
alternative.
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 39

(ii) The capabiliti~.sof each type of equipment and the conditions under
which they can work efficiently.
(iii) The likely output of each machine and how this is affected by the
site conditions,
(iv) Co-ordination of the different machines employed on a job and
matching of their sizes and types so that all the machines work to
full capacity.
(v) Organisation available/required for the efficient operation and
maintenance of the machines.
tvi) Easy mobility of the plant particularly for cases where it has to b.
shifted from place to place.
(vii) The type of work such as nature of soil, haulage distance, restricted
space for working, etc.
(viii) Indigenous availabiliy.

6.3. Equipment Suitable for Earthwork

6.3.1. Site clearance: The equipment suitable for prepara-
tion of site, clearing and grubbing including removal of trees,
stumps and bushes is the crawler tractor with dozer blade attach-
ment. Other attachments like rooter, stumper, tree stinger, etc.
facilitate removal of trees and stumps. The draw-bar horse power
(DHP) of the tractor should be 90-120 for light clearance and
160-200 per heavy clearance.

6.3.2. Earthwork
(1) For cutting earth and pushing the cut material to short
leads, a bulldozer of about 100 DHP is suitable. For major dozing
and removal of excavated rock, a larger sized dozer of 160-200
DHP would be necessary. The economic lead for dozer operation
is about 100 m for crawler dozer and 130 m for wheeled dozer.
While the crawler dozer is more appropriate for working on soft!
muddy soil or rough/rocky formations, the wheeled dozer has
higher travel speeds which is of advantage for longer hauls and in
easy shifting from site to site. If the material to be excavated in
too hard but not rock, it will be advantageous to rip it by the
hydraulic ripper attachment at the back of the tractor before
dozing is done.

(2) For leads ranging between 100—1000 m, a scraper would

be preferable. The scraper does the entire work of excavation,

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 40

loading hauling and spreading by itself without the help of any

other equipment except perhaps a pusher tractor. Scrapers can
be towed or motorised. For relatively short haul distances upto
about 300 m, the crawler tractor pulling self-loading scraper can
move earth economically. Scrapers commonly used for road
works have 10-13 cu.m. heaped capacity. The tractor pulling the
scraper should have 180—250 DHP. These can negotiate steeper
grades, require less haul road maintenance and can work under
more adverse conditions.
(3) For longer haul distances, the low speed of the crawler
tractor becomes a bottleneck, and it would be preferable to go in
for self-propelled motorised scraper. Normally, motorised
scraper requires a pusher while loading. A heavy duty tractor of
230—300 DHP would be suitable for the purpose. One pusher
can help load several scrapers, the number depending on the load-
ing time and the cycle time of the scraper.

4. Some of the aspects involved in scraper operation are

(I) The scraper can excavate the material in layers~ándrequire a
long loading distance.
(ii) The scrapers can work successfully only where the material is not
mixed with boulders or there are no rock outcrops. If the scrapers
are to be used with very hard material (not rock or boulders), it
will be necessary to have the area ripped by using ripper attachment
on the crawler tractor.
(iii~The productivity of a scraper heavily hinges on the condition of
haul roads. The haul roads should be firm, dust-free and should
not have steep gradients to be negotiated on the loaded portion of
the haul cycle.
(iv) Scrapers are generally used in groups at a location depending on
the haul distance. This is from the angle that the expenses of
operating the pusher tractor at the borrow area and the levelling
tractor/grader at the fill area are distributed Over a large volume of
earthwork and the equipment are not kept idle.
(5) For leads beyond 1000 m, shovel-dumper or frOnt end
loader dumper combination will be found suitable Front end
loaders are either tracked or wheeled type and are ecOnomical for
a range upto 30 m. This piece of equipment can be used for light
excavation, truck/dumper loading as also for loading hoppersor
bins of hot mix plants. Loaders of 0 5 to 2 cu m. capacity are
made indigenously.

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 41
(6) Motor grader is useful for spreading and grading of earth.
As the scraper blade can be adjusted to any angle in vertical
plane, the grader can be effectively used of trimming and main-
taining the side slope of embankments, Grader is also useful for
road surface maintenance, ditching, stripping, scarifying and finish-
ing operations. However, for spreading and levelling earth dumped
by rear or bottom dumpers, dozers would be required. Motor
graders of 110 HP are manufactured indigenously.

6.4. Output of Earthmoving Equipment

6.4.1. General
(1) Equipment operation essentially comprises a series of
cyclic operations or cycles. The probable output of an equipment
per hour can be computed by multiplying the average net output
per cycle by the number of cycles per hour. The cycle time for
a machine is composed of two components—fixed time and vari-
able time. The variable time is the time actually spent on travel-
hag and is a function of the distance travelled and the speed of
the unit. The speed of travel depends on several job factors such
as rolling resistance, grade resistance, altitude and power rating
of the equipment. The fixed time comprises the time spent in the
performance of all operations other than travelling, such as load-
ing, dumping, turning, gear shifting, accelerating, etc.

(2) In production operations, the labour and equipment do

not work all the 60 minutes in an hour, and a value of 45-50 min/
hr will be appropriate for day working and 40-45 mm/hr for night
operation. The cycle time will, therefore, need to be corrected for
taking this aspect into account. Besides this, the output is also
affected by job and management factors. The job factors which are
inherent in the job itself relate to site topography, available working
space, climatic conditions, geology of the area affecting method of
excavation, specification of the work, etc. Management factors
pertain to efficiency of the organisation and operating staff, appro-
priateness of the equipment for the job, job planning, supervision,
maintenance of plants and haul roads, etc. It is on the management
aspects that the Site Engineer should apply all his effort for impro-
ving the efficiency and productivity of the operations.

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42

(3) The output of earthmoving equipment is generally expres-

sed in terms of ‘bank measure’ which is a measure of the soil in-
situ. When the soil is excavated, its volume increases and it is in
this loose state that the machines have to move the earth. The
capacity ratings of machines, struck or heaped, relate to loose
excavated material. The loose volume can be converted into
bank measure by applying the s~ellfactor which is given by

Swell factor = ~ +100

%Swell

The swell factor may vary from 0.75 to 0.85 depending on the type
of the soil and its compactness in-situ.

6.4.2. Bulldozer: The loose volume excavated/dozed per

trip can be estimated by measuring the area of the load profile
in front of the blade and multiplying it by the blade length. The
output may be estimated from
(Loose volume/trip) x swell factor
Output (bank volume)jhr = x 60 x efficiency
. . . —
Cycle time in minutes

The efficiency factor in the equation has three components, namely,

operator efficiency (0.6—0.9), job efficiency (0.6—0.8) arid soil hard-
ness, Generally manufacturers of the equipment indicate the pro-
ductivity of the machines under ideal conditions. Taking the
efficiency factors into account, it will generally be seen that the
actual productivity will be between 30 per cent (line B for poorly
managed jobs) and 50 per cent (Line A for well managed jobs) of
the ideal productivity. The corresponding values (Lines B and A)
for dozers of 3 different capacities are plotted against haul distance
upto 100 m in Fig 5. Mean of the values could be adopted for
planning purposes while the attempt during actual working should
be to achieve productivities corresponding to Line A.

6.4.3. Scrapers—General
(1) Scrapers are rated according to volume capacity, struck
or heaped volume, and the load capability. Two scraper bowls
having the same struck capacity may have different heaped capa-

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 43

U
I”

z
z

I-

40 ~O
H*UI. DISTANCE — METRES

Fig. 5. Productivity of bulldozer

cities, depending upon the ratio of the base area of the bowl to its
height.

(2) A major share of cycle time for scrapers goes for travel-
ling. Proper maintenance of haul roads is therefore Of prime
importance for better productivity and reduced maintenance c~st,
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44
(3) In scraper loading, the rate of filling the bowl diminishes
rapidly with the quantity of already loaded material, and it will be
preferable to keep the loading time to less than one minute.

(4) The output can be determined from the following

equation
Optimum (loose) load x swell factor
Output (bank measured)fhr =
x 60 x efficiency
- . —
Total cycle time in minutes

In the cycle time, the fixed time includes the time of loading and
unloading (done at the first gear) turning, gear shifting, accelera-
lion and deacceleralion, all totalling to 4-5 minutes. Variables time
is a function of speed of the unit and haul distance. The speed
depends on the available drawbar pull vis-a-vis the required pull
~hich depends on roiling resistance and grade.

6,4.4. Towed scraper: As in the case of dozers, the actual

output will be 30-SO per cent of ideal output indicated by the
manufacturers depending on the job/operator efficiency and soil
condition. These values are plotted (lines A and B) for scrapers
of three struck capacities, viz. 9.2 cum., 11.5 cu.m. and 13.8 cu.m.
in Fig. 6. Average of these lines may be used for planning pur-
poses.

6.4.5. Motorised scraper

(I) Motorised scrapers are assisted by pusher tractor during
oading operation. The combined tractive effort of the scraper
tractor and the pusher tractor, after allowing for resistances (grade
nd rolling) should be adequate to load the scraper by the desired
~mount. Number of scrapers that can be served by one pusher
tractor can be estimated by the equation

Total cycle time of scraper

No. of scrapers per pusher total cycle time of pusher

a scraper loading time of 1 minute, the pusher cycle time will

be of the order of 2-3 minutes, depending upon the scraper volume
and job conditions.
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 45

z
4

C
0

~00 200
I.~*tJ1. O~ST~~CE
—

Fig. 6. Productivity of toned scraper

(2) Practical productivities of scrapers of 7, 12 and 12.8

cu,m. bowl (struck) capacity corresponding to 30 per cent (line B)
and 50 per cent (Line A) of the ideal productivities are plotted
against haul distance in Fig. 7. Average of the Lines A and B may
be used far planning purposes.
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 46

D~$T.~CI
— ME T~

Fig. 7. Productivity of motorised scraper

6.4.6. Shovel/front end loader—dump truck

(I) Shovel/front end loader—dumper combination can be
used for picking up blasted/excavated material and dumping in fill
areas, picking up materi~ilslike moorum/gravel/sand, etc. from the
~.ources and hauling to work site, or for digging earth from inclined
faces and hauling, or hauling earth over distances beyond the
economic leads of scrapers. Front end loaders by themselves
can also be used for feeding hoppers of hot mix plants with aggre-
gates.

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 47

(2) Productivity of front end loaders depends on the bucket

size and haul distance, and can be taken to be 50-80 per cent (Line
B and Line A) of the ideal output. The corresponding productivi-
ties for front end loaders of 0.8, 1.15 and 1.3 cu. m. capacity are
plotted in Fig. 8. The mean of lines A and B may be taken for
planning purposes.

0 S 0 40
HAUl. DIST4MCE — METRE

Fig, 8. Productivity offront end loader/excavator

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 48

(3) The excavator/loader and the hauling units should be

properly matched in size and number for optimum working. As a
rough guide, the size of hauling unit may be fixed to provide a
capacity of 4 to 6 times the capacity of the loader bucket. After
selecting two or three possible sizes, the number of haul units per
loader as also the unit cost of handling the job are calculated for
choosing the most economical alternative.

(4) Sample calculations for finding the matching number of

haulage units for a job of earth excavation from side-hill and dum-
ping over a distance of 3 km are given in Table 15.

TABLE 15. SAMPLE CALcuLATIoNS FOR EARThwoRK WITH FRONT END

LOADER AND DUMP TRUCKS

DATA
Ordinary earth is to be excavated from sloping face. Haul distance of loading
10 rn. Dump trucks 7-tonne capacity are available. Haulage for dumper is
3 km. Speed loaded 15 km/h. Speed empty 20 km/h, Swell factor 0.8.
m =

CALCULATLONS
i. Capacity of dumper 7 tome
= 4.7 cu.m. loose choose excavator/loader
=

bucket capacity of 1.15 cu.m. (1.5 cyd) which is about one fourth the —

capacity of the hauling unit.

2. Productivity of loader for average of lines A & B (Fig. 8) 67 cu.m (bank)
3. Bank volume carried by truck per trip 4.7 x 0.8 3.76 cu.m.
=

4. Productivity of truck:
Truck loading time ~ x 60 = 3.4 mm.

Travel time (loaded) = x 60 = 12 mm.

3
Travel time (return) = x 60 = 9 mm.
Truck fixed time (turning, dumping) 2 miii. =

Total cycle time 3.4 12 + 9 + 2 26.4 mm.

= -~- =

No. of cycles made by truck/hr 60/26.4 2.27

= =

Productivity of one truck 2.27 x 3,76 8.6 cu.m (bank)

= =

Number of trucks required for each loader 67/8.6 78 or 8 = =

5. The productivity of one excavator/loader and 8 dump trucks will be

67 cu.mJhour (bank measure).

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 49
6.5. Other Road Construction Equipment
6.5.1. Compaction plant
(I) Whether the job is labour-based or equipment intensive,
power rollers are required. For mechanisation of major highway
or airfield jobs, it will be advantageous to go in for heavier and
higher efficiency compaction plants in place of the traditional three-
wheeled static rollers, for achieving better compaction and higher
productivity.

(2) One such plant is the 8-10 tonne vibrathry roller which is
equivalent in conipactive effort to 20-25 tonne static rollers. The
principle is that the vibrations imparted by the roller drum causes
the particles of material to shift themselves into the tightest
arrangement. This type of roller is suitable for compacting granu-
lar soils, granular base and sub-base materials and in the break-
down rolling of bituminous mixes. Because of the higher
compacting efficiency, higher degree of compaction can be achie-
ved, or a deeper lift can be constructed with the same number of
passes.

(3) Another specialised compaction plant is the pneumatic

tyred roller which compacts by the principle of kneading action.
This type of roller generally has two axles with four to nine wheels
each. The wheels are arranged so that the rear ones run in the
spaces between the front ones, thus leaving no ruts. The chassis of
the vehicle is also a container for solid or liquid ballast. The
rollers which may be towed or self-propelled can be of different
weights. A 8-10 tonne capacity roller is ideally suited for com-
pacting surface dressings without crushing the aggregate. As
regards soil compaction, pneumatic tyred rollers will work on most
types of soils except heavy clays. A heavier 40-50 tonne roller is
appropriate for achieving higher densities corresponding to modi-
fled AASHO density as is required for airfields and also for proof
rolling.

(4) For compacting cohesive soils, sheepfoot roller is the

suitable equipment. It can be towed or self-propelled, and the
units range in weight from 2 to 20 tonnes with feet projecting from
175 to 225 mm. Compaction starts from lower layers and proceeds
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upwards and the roller is removed when the compaction is complete.

The maximum depth which the roller can compact is about 5 cm
more than the length of the feet.

(5) For optimum utilisation of the compaction plant, it is

essential that the capacities of the hauling and spreading plants
must be matched and be adequate so that none of the equipment
remains idle.

6.5 2. Waterin~for compaction

(1) For earth compaction and conip~cticnofsin,ilar materials
like moorum, the moicture content of the material before compac-
tion will have to be adjusted so as to bring it near about the
optimum moisture content. Water bound macadam construction
will require a lot of water during compaction for driving in the
filler material. This water will have to be arranged by pumping
from suitable locations and brought to site for sprinkling on the
soil/material to be compacted.

(2) Usually, two types of water tankers are used, truck

mounted and trailer mounted. The tankers may be of 4000-5000
litre capacity fitted with sprinkler arrangement. Where water is to
be used continuously, truck-mounted tankers which have higher
travel speeds may be convenient. Trailer mounted type has the
advantage that the tractor can be used in conjunction with 2 or 3
trailers so that the power unit does not remain idle during filling.
The tractor can also be put to some other use at times when water-
ing is not required.

(3) Productivity of water tankers can be calculated from the

unit capacity and cycle time. As in the case of other hauling
equipment, the cycle time comprises two components, fixed time
involved in filling, turning and spraying, and variable time which
depends on speed and haul distance.
(4) Table 16 illustrates the working of tractor-drawn water

tanker for earthwork job.

6.5.3. Air compressor

(1) Air compressors of 3-4.5 cu.m/min capacity operating a
single jack hammer will be very useful for exploratory work on
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 51
TARL! 16. SAMPLE CALcuLATIoNS FOR WORKING OF TRACToR-
DRAWN WArsi~TANKER O~EARTHWORK Jon

DATA
Capacity of water tanker = 4000 litres
Haul length for water = 2 km
Speed of tractor — loaded 5 km/hr and empty 8 km/hr
Quantity of earthwork 60 cu.m./day (bank volume)
=

Swell factor for soil 0.8

=

Moisture content of b rrow = 6%

Optimum moisture content = 15%
cALCULATIONS

1. Additional moisture to be added

(including 1% extra for evaporation losses) =15—6+1=10%
2. Quantity of soil catered for by one
4000 x 100
round of tanker = lOx
1000=40tonnes
or 25 cu.rn loose
3. Length of soil spread covered by one run of tanker for
2.5 m width and 250 mm loose thickness 25 40 m

4. Cycle time of tractor

Haul time loaded = 4x60=24mun.

Haul time empty <60=l5min.

Spraying time 40 = 0.8 miii.

(speed 3 kmfhr)
=

Time for hitchinglunhitchung

tanker, turning, etc. = 2 mm.

Total cycle time 24 + 15 + 0.8 .~- 2 = 41.8 miii.

2~_~
4000 = 5750 litres
5. Productivity of tractor/hr = 4!~
6. Volume of earth catered
for by one tractor tanker = ~ x 25 x 0.8 = 28.6 cu.m (bank)

7. Number of watering
units required 60~286
= say 2 nos.

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hill road construction. This unit can be transported by manual

labour or by animals from one site to another For subsequent
development worlç air compressors of 6-10 cu.m/min capacity
operating two jack hammers would be found suitable.

(2) The output of a compressor and the air consumption of

pneumatic tools are affected by altitude and humidity, while per-
formance is affected by the loss of pressure in the pipelines.
Adequate care should be taken to ensure that all the connections
are tight and there is no leakage in the system.

6.5.4. Stone crushing plant: For production of aggregate,

stone crushers of 400 mm x 225 mm and 400 mm x 280 mm
capable of producing 14—18 tonnes/hr are suitable. Granulators
of sizes 300 mm x 175 mm and 300 mm x 100 mm are capable of
yielding 5—8 tonnes/hr, and are suitable for producing smaller size
aggregates. For major construction jobs requiring large quantities
of aggregates, it will be advantageous to install 100—150 t/hr
capacity base crushers and 50—100 t/hr secondary crushers.

6.5.5. Hot mix plant: Hot-mix plants of 20—30 tonnefhr

or 30—45 tonne/hr capacity can be used for mechanised paving
works in conjunction with tipper trucks and paver-finisher.
Generally, such plants in one location can cater for 20—30 km of
road on either side, For optimum working of the system, the
following points need attention:
(i) All the materials needed for the plant must be available at site in
time, It will he preferable if aggregates required for atleast 15 days
are stock piled at site.
(ii) The number of tipper trucks must be matched with the plant output.
(iii) The work of cleaning the road surface and applying tack coat should
proceed sufficiently in advance so that the paving work need not
have to stop on this account.
(iv) Front end loaders of adequate capacity should be employed for
loading cold feed bins.

Sample calculations for paving 50 mm thick bituminous

macadam using 30—45 tonne capacity hot-mix plant are given in
Table 17.

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 TABLE 17. SAMPLE CALcULATIoNs FOR PAvING 50 mm TRIcK 53

BITUMINOUS MAcADAM

DATA
Length of road to be paved with = 40km
50mm BNI
Width of paving = 7m
Hot-mix plant output = 30 tomes/hr
Binder content of mix 35%
Compact density of layer 2.1 gm/cc
Capacity of tipper truck = 5 tonnes
Speed of truck—loaded 20 kmfhr, empty 30 ,kmfhr
Average haul distance for mix = 10 km
CALCULATIONS
I. lime for hot~mixplant to produce
5 tonnes of mix = -~—x60=l0min.

2. Cycle time for tipper truck

Loading time = 10mm.
Haul time loaded 10
= ~-x60=3Omin.

Haul time empty = ~—x60=20min.

Time for discharging into paver = 2 mm.
Time for turning =2 mm.
Total cycle time = 64 mm.

3. Productivity of tipper/hr = -~- x 60 = 4.7 tonnes

4. Number of tippers required = 30/4.7 = 6.4 or say 7

5. Providea paver-finisher of 50 tonnefhr capacity
6. Assuming effective working time of 7 hrs~day,
output/day = 7 x 30 210 tonnes

7. Area paved/day = O~)5 2 1 =~ 2000 sq.m. or 285 m length

8. Number of working days
40 x 1000
for plant = 285 140
9. Bitumen consumption/day 210 < 3.5
= 100 = 7.35 tonne
10. Aggregate consumptionjday = 210 — 7.35 = 202.65 tonne
= 135 cu.m (loose)

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6.56. Soil stabilisation : Single pass stabilizer capable of

cutting the soil to the desired depth, pulverising and mixing it with
the stabiliser and htying the mix to level and regularity in a single
pass can be used for soil stabilisation.

7. COST CALCULATIONS
7.1. General
7.1.1. Cost calculations in road construction projects are
necessary for the following purposes
(i) Cost comparison at the task level for the different technically
feasible construction methods for selecting the least cost method.
The costing is usually done in terms of unit costs, i.e. the cost per
unit of output, for example, cost per cu.m. of earthwork.
(ii) Cost comparison for the choice of pavement materials. For
example, prospecting of aggregates from a quarry may involve
higher initial installation cost but lower haulage cost compared to
another alternative. Similarly comparison may be required for the
use of permissible but poorer locally available pavement material
which has to be used in larger thickness vls-a-vis a better material
availab’e from longer distances.
(iii) Costing of the total job for the preparation of financial estimates
for processing and sanction by the appropriate authorities.
7.1.2. For all the purposes mentioned above, the starting
point will be the unit Cost. The unit cost of a task can be calculated
by multiplying the input coefficient for the resources performing
the task by the rate for the resource. The rate is the cost of the
resource per unit of time, e.g. per hour or per day, except in the
case of construction materials when it is the cost per cu.m. tonne,
etc. If two or more resources are involved in the task, the product
of input coefficient and rate should be calculated separately for
each item and the products added.

7.2. Costing ofLabour-based Methods

7.2.1. Tables 4 through 9 give the input coefficients for
different labour-based activities as derived from the World Bank
Study. The input coefficients are in terms of working time in
ours, and their reciprocals give the output per man-hour (working
time). The output per man-day can be calculated by knowing the
working hours in a day which may be 5.5—6 hours for daily-paid
wage system and 8 hours for the incentive piecework system.

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7.2.2. The cost of unit output of an activity can be computed

by multiplying the input coefficient and the rate per working hour.
The rate for daily paid labour which is on day basis it governed
by statutory minimum wages. The day wage can be converted
into working hourly wage by dividing the former by the effective
working hours in a day. For example, unit cost of excavation can
be calculated as follows
Input coefficient (ordy. soil,
daily paid labour, Table 4) = 0.8 man/hr (WT/cu.m)
Working hours In a day — 6 bra
Wage rate Rs6fday
Working hourly rate = 6/6 = Re 1
Cost of activity = 08 x I Rs G.8/cu.m.
Output per labourer .ô!r x 6 7.5 cu.rn,/day

7.2.3. For tasks involving mare than one resource, e.g.

labour, animal cart, etc., the unit cost for each resource is
calculated and added together for finding the total unit cost. An
example of excavation, loading, hauling and unloading earth using
animal cart is illustrated below:
Excavation input coefficient = 0.8 man-hrJcu.m.
Loading input coefficient = 8.98 man-hr/cu.m.
(height of loading 1.5 ni)
Excavation + Loading = 1.78 mafl.hr/cU,m.
Input coefficient for hauling and
unloading by animal cart
(assumed) = 0.75 cart hr(cu.m.
Labour rate = Rel[hr(WT)
Cart rate (including driver) = Rs 3/hr (Wi)
Unit cost of labour = L78 x 1 Its L7Ife.um.

Unit cost of cart = 0.75 x 3 Rs 225)cu.m.

Unit cost of task = 1.78 +2.2~=E.s4.0~/cu.m.

7.3. Costing of Equipment-intensive Methods

7.3.1. The cost of using capital equipment is usually divided
into four broad heads, namely
(i) Ownership charges relating to the cost of the equipment brought to
site spread over the expected working hours during its life till it is
sold out or scrapped.

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(ii) Repair charges,
(iii) Running charges which include wages of operators and cost of
P.O.L. etc.
(iv) Overhead charges.

The usually accepted norms for calculating the usage charges of

equipment are given in Table 18.
TABLE 18. Noasss von CALcULATING UsAGE CHARGES OF MAcHINES

I. OWNERSHIP CHARGES
(A) Total investment at site of work
(This includes cost of equipment, sales tax,
excise and other duties, transport expenses
consisting of freight, insurance, loading/un-
loading, erection and commissioning)
(B) Deduct salvage value @ 15% of A = 0.l5A
(C) Total investment to be depreciated = A-B = 0.85A
(D) Economic life of the machine (Working hours) = varies by type of
machine and
operating condi-
tions from 10,000
to 15,000 hrs
C
(E) Depreciation per hour
—5
0.85 A
For the case of 10,000 hrs
—

(F) Storage charges (1% of E) 0.0085 A

= i0,000_

(G) Total ownership charges = E+ F 0.8585 A

= 10,000

II. REPAIR CHARGES

(H) Repair charges per hour including maintenance C 1.275A
1.5 ~= ~
and replacement of tyres
1,1335 A
Ill. HIRE CHARGES 0 + H
=
To,ooo
Note The fixed hire charges per hour can be directly computed by divid-
ing 1.1335 times the investment cost by the useful life In hours.

IV. RUNNING CHARGES

(a) Diesel oil consumption
BHP x load factor (0.6) x 0.5
— 7 4 x 3.785 1&tresf hour
0.154 x BHP litres/hour (Approx.)

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(b) Lubricating oil consumption
= BHP ~< x 0,006 x x 3.785 litres/hour

Where C = 0.06 x BHP

= time for changing oil = 100 hrs
(c) Other lubricants, grease, cotton waste etc. are assumed to cost twice the
cost of lubricating oil in the case of heavy machinery and the same cost
in the case of others.
(d) Wages for operating staff—For staff on regular strength, the annual
wages is divided by the annual utilisation in hours in a year.
V. OVERHEAD CHARGES
Taken as 5% of the total charges per hour.
Notes : 1. Repair charges (H) taken as equal to 150 per cent of depreciation
reflects the average for both wheeled and tracked vehicles considered
together. This can also be calculated in one other way, namely, by
separating out the cost of replacement tyres and the repair charges
for other items.
2. The diesel oil consumption depends on the condition and age of the
engine, and the equation given in IV (a) is for average conditions.
The load factor for different machines also varies, and the value
0.6 represents average conditions. The oil consumption is for the
prime mover and does not include that for heating aggregates etc.
as in the case of hot mix plants.
3. Interest charges have not been added in the calculations. These
will, however, have to be included where a machine is given out to
contractors or for economic analysis.

7.3.2. The usage charges for some of the commonly used

earth moving equipment are worked out in Table 19. For other
equipment too, the charges can be computed on similar lines.

7.4. Comparison of Cost of Road Construction Jobs by

Different Methods
7.4.1. The following cases of earthwork have been taken to
illustrate cost comparison

(1) Short haul of 20 m

(a) Labour intensive method of headbasket
(b) Equipment intensive method using 90 HP dozer

(ii) Long haul of 3 km

(a) Manual excavation, loading, hauling by flat-bde
truck and manual unloading/spreading.

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TABLE 19. USAGE CHARGES FOR SOME EARmM0vINQ EQUIPMSNT

SI. Equipment Cost at Econo- Hire Fuel Running charges Rs/hr Usage
No. site mic life charges consump- charges
Rs lakiss ~X~0’
hrs Rs/hr tion col. 5 +
litrelhr Fuel 011+ other Opera- Total cot. 10+
i cost lubricants tor running overhead
wages cost @5%

1 2 3 4 5 6 7 8 9 10 11

1. Dozer,90HP 10.2 10 115 16 48 9 10 67 190

2. Front end loader—
1.15 cu.m (1.5 cyd)
bucket 9.0 10 112 10 30 8 10 48 168
3. Tipper~uck7-8tcapacity 2.5 10 28 6 18 6 8 32 63
4
Flat bed truck, 5 t 1 75 10 20 5 15 5 8 28 50
~
Notes: 1. Cost of diesel is taken as Rs 3/litró.
2 Operator wages per hour has been computed by dividing tbc total annual wages by 1200 which is taken as utilisa..
tion hours in a year.
3. Hire charges ownership charges + repair charges. See Table 18 for the norms.
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(b) 1.15 curn. bucket loader/excavator, tipper trucks
for hauling and spreading by 90 HP d~zcr.

The calculations for the labour and equipment methods are given
in Tables 20 and 21 below

TABLr 20. CosT os’ EAwrHwoiuc DV MANUAL ME-moos

A. SHORTHAUL(20m)
The same case as worked out in Table II is taken.
The productivity for a gang of 20 persons = 1.5.5vu.m/hr
= 124 cit.m(day

Usually a pieceworker earns about twice

12x20
that of a daily paid worker. Assuming = — Ri 2
the daily earnings as Ks i2Jday, cost per
cu,m (bank measure)

B. LONG HAUL (3 km)

The same case as worked out in Table 12 is taken.
The productivity of a gang of 22 men plus one 5-t
flat-bed truck was 36cu,m/day.

Wages for Labour 22 x 12 = Ri 264/day

Usage charges ~ortrugk Ks $0/hr

—for workipg~hrs. = Ks 400
8

Cost per cu.m. (bank measure) = 664)36 = Ri 18.4

Note: The cost Ilgures do not take into account incidental expenses such as
those on labour mobillsation, provision of health, travel and acconi.
modation facilities to labour, small tools and plant, etc. Also, It should
be understood that the unit wage rate assumed ii only for the purposes
of this example, and the actual prevailing/statutory wage rates should
be applied for actual cases.
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TABLE 21. COST OF EARTIIW0RIC OY EQUIPMENT — INTENSIVE Momon
A. SHORTHAVL(20m)
Job details : Excavation in ordinary soil by dozer
and hauling/spreading at an effective
haul distance of 30 m
Equipment : 90 BHP Dozer
Productivity : Taken as mean of lines A and B
(average conditions) in Fig. 5
Calculations : Productivity of dozer = 80 cu.m/hr (from Fig. 5)
Usage charges for
dozer = Ks l9Ojhr (from Table 19)
Cost per cu.m = 190/80 = Ri 2.4
B. LONG }IAUL(3km)
The same case as worked out in Table 15 is considered. The’ productivity
of 1.15 cu.m loader/excavator and S ripper trucks will be 67 cu,mlhr.
Usage charges for loader = Ks 168
Usage charges for 8 trucks = 8 x 63 = Rs 504
Cost of spreading (using = Ks 190
90 HP Dozer)
Total usage cost/hr = Ks 862
Cost per cu.m = 862/67 = Ks 12.9

The picture emerging is:

Cost/cu,m (bank measure) Rupees

Haul 20m Haul3km

(I) Labour method 2,0 18.4
(ii) Equipment method 2.4 12.9

This would show that while the labour methods will be generally
cheaper for shorter hauls, equipment methods would be more
economical for longer hauls.
7.4.2. As discussed in detail in the earleir sections, each
method has its own advantages and disadvantages, and the choice
has to be judicious taking all the factors into account. Whatever
be the method dhosen, the objective should be to look for measures
for improving the productivity through organisational and mana-
gerial measures. While motivation of a large labour force for
improved productivity will be a crucial factor for labour methods,
for equipment intensive methods it will be better training of
operators and prompt and better maintenance facilities for the
equipment.

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