Material Equipment

- 1 - Construction Materials & Equipment Management

Construction Equipments & Material Management

ASSIGNMENT

Your company has been awarded a contract of developing and constructing a new

International Airport 30 K.M. away from a city. You have been appointed as

Planning Engineer (Materials and Equipment). Project is to be implemented in

phases. In Phase I, one strip of landing of 100 m width is to be constructed in 100

days. The scope of work for this assignment is only as follows –

a) Cutting and Dozing of 100,000 cum of earth. Average height 0.75 m.

b) Transportation of 20,000 cum of surplus earth from site to dumping place 3

k.m. away fro site (including spreading.) Filling of 80,000 cum in landing

strip.

c) Bringing in 3000 cum of sand from 20 k.m (including spreading and

leveling at site)

d) Procurement of 1, 50,000 liters of Bitumen, Duration of work 30 days from

60th day of starting of work. Bitumen to be obtained from refinery at

Bongaigaon in Assam. Lead time upto site is 45 days. Storage facility

available at site 50,000 liters tank.

Estimate total cost of work and your plan of

i. Equipment Planning – Procurement & Deployment.

ii. Ordering and replenishing of Bitumen.

COURSE: GDPMCOURSE NO: NCP 23REG NO: 26-05-14-2624-271CODE STUDENT NAME: POTE SONALI ACOURSE TITLE: CONSTRUCTION CONTRACT AND CONTRACTINGASSIGNMENT NO: 02


SCOPE OF WORK:

Construction of 100m wide airstrip for landing in 100 days i.e. 30 km away from

city.

Data Given:

Volume of earth - 100,000 cum

Agv. Ht. - 075 m

Width of Airstrip - 100 m

Length of Airstrip - 1333.33 m

Assumption:

Assume 50% of normal soil is filling & 50% of normal soil is cutting as per

standard mass design.

Avg. Embankment – 666.67 m

Avg. cutting view - 666.67 m

1) EXCAVATION EQUIPMENTS:

INTRODUCTION

Excavator is a self-propelled crawler or wheel mounted machine, with an upper

structure, capable of a minimum of 360° rotation, which excavates, elevates,

swings and discharges material, by the action of a bucket fitted to the boom and

arm or telescopic boom, without moving the chassis or under-carriage, during

any part of the working cycle, of the machine.

Hydraulic excavator is a multipurpose earthmoving machine, which can perform

many duties, in the field, such as digging earth, mining, loading, quarrying,

etc., apart from other activities like well-digging, material handling. The excavator

Is the only "Earthmoving" machine, capable of, working in three dimensions?

and in all directions.


APPLICATIONS

Below Ground Level Applications: The hydraulic excavators, can be used

(primarily with backhoe attachment) for digging below ground levels.

Applications are:

Canal excavation

Channel making

Trench digging

Pipe laying

Burrow pit excavation

Land leveling

Below or Above Ground Level in Vertical Plane: These are accomplished by

Clamshell attachments. Applications are:

Well sinking

Dredging

Handling of loose materials

Above Ground Level Applications: These are mainly done by using a shovel

attachment, either bottom dumping, or forward dumping. Applications are:

Mining

Quarrying

Bulk earthmoving against face

Tunneling

Under Ground Applications: These are generally handled by shovel or backhoe

attachment or hydraulic hammers. Applications are:

Tunnel making

Excavation

Scaling

Special Applications: By using special attachments, a hydraulic excavator can be

used for other applications, such as:

Rock breaking, demolition

Wood handling (Forestry)

General construction - vibratory pile drivers, extractors, etc.


Scrap handling

Specialized Mounting Applications: Depending on work requirement, excavator

can be -mounted on barge and pontoon for swamp, river and marine excavation or

dredging operations; mounted on railcar for route maintenance activity of railway

tracks

HYDRAULIC EXCAVATOR

INTRODUCTION

Excavator is a self propelled crawler or wheel machine, with an upper structure,

capable of a minimum of 360 degrees rotation which excavates, elevates, swings

and discharges materials, by the action of a bucket fitted to the boom and arm or

Telescopic boom, without moving the chassis or under-carriage during any part of

The working cycle of the machine (IS: 12138-1987).

Excavators are primary earthmoving machines and equipments used to excavate

earth and related materials and to lift items frequently used in construction

operations. They are called by different names and put to different uses,

depending upon the implements and attachments required. Excavator comprises

of fair basic machines namely backhoe, shovel, dragline and clamshell. All

Four are manufactured in India, along with the necessary implement and

attachments. They are made of various sizes and capacities to suit the need for

light, medium or heavy duty applications where as backhoe and shovels may be

either hydraulic or mechanical, the draglines and clamshells are only of the

mechanical type. Hydraulic excavator is a multi-purpose earthmoving machine,

which can perform many duties in the field such as digging earth, mining, loading,

quarrying etc., apart from other activities like well-digging, material handling the

excavator is only "earthmoving" machine capable of working in three dimensions

and in all directions. Unrivalled versatility is the main reason, for hydraulic

excavator's domination, of today's world construction equipment scene. Thirty five

years ago, when the hydraulic excavator was first introduced in Europe, it was

considered as an agricultural loading tool, but today, it can perform functions

frames from pile-driving to hedge trimming, often, just as efficiently as purpose

built equipment.


APPLICATIONS OF HYDRAULIC EXCAVATORS:

As stated in the previous chapter, a hydraulic excavator is the most versatile

construction machine. The excavator is the only "earthmoving" machine, capable

of working in three dimensions and in all directions, It can lift, lower, push,

pull and side shift at, above, and below ground level and in a full circle, without

having to move its under-carriage. The wheel loader, by comparison, can work

only at ground level and above and at severally limited reach, the scraper and the

Bulldozers are restricted to the horizontal plane at ground level, and the tractor

mounted backhoe, even ignoring its severe size restrictions, is effective through

less than half a circle.

The following are applications for hydraulic excavator:

Below Ground Level Applications: The hydraulic excavators can be used

(primarily with backhoe attachment) for digging below ground levels.

Applications are:

Canal excavation,

Channel making.

Trench digging.

Pipe laying.

Borrow pit excavation.

Land leveling.

Below or Above Ground Level in Vertical Plane: (These are accomplished by

Clamshell attachments.) Applications are:

Well sinking

Dredging

Handling of loose materials.

Above Ground Level - Applications: These are mainly done by using a shovel

attachment, either bottom dumping or forward dumping. Applications are:

Mining

Quarrying

Bulk earthmoving against face

Tunneling


Under Ground Applications: These are generally handled by shovel or backhoe

attachment or hydraulic hammers. Applications are:

Tunnel making

Excavation

Scaling

Special Applications: By using special attachments, a hydraulic excavator can be

used for other applications such as:

Rock breaking, demolition.

Wood handling (Forestry)

General construction - vibratory pile drivers, extractors etc.

Scrap handling.

Specialized Mounting Applications: Depending on work requirement, excavator

can be - mounted on barge and pontoon for swamp, river and marine excavation

Or dredging operations. Mounted on railcar for route maintenance activity of

railway tracks.

Equipment Considered In This Project.

FRONT SHOVELS:-

Front shovels are used predominantly for hard digging above track level and for

loading haul units. Loading of shot rock would be a typical application. Shovels

are capable of developing high break out force with their buckets but the material

being excavated would be such that it will stand as vertical bank i.e. a wall of

material that stands perpendicular to the ground most shovels are crawler mounted

and have very slow travel speeds less than 3 mph. The parts of the shovel are

designed machine balance. Each element of the front end attachment is designed

for anticipated load. The front end attachment weight about one third as much as

the superstructure with its power parts and cab.

Size Rating of Front Shovels:

The size of a shovel is indicated by the size of the bucket represent in cubic yards.

There are the three diff bucket – rating standards, power crane and shovel

association (PCSA) Standard No. 3, society of Automotive Engineer (SAE)

Standard J-296 and the Committee on European Construction Equipment +

(CECE) method. All of these methods are based only on physical dimension of


the bucket & do not address the bucket loading motion of a specific machine for

bucket’s than 3 cg. Capacity, rating in ¼ cy intervals and 1/8 cy intervals for

buckets less than 3 cy in size.

Struck Capacity – The volume actually enclosed by the bucket with no allowance

for bucket teeth is the struck capacity.

Heaped Capacity: Both PCSA and SAE use a 1:1 angle of repose for evaluating

heaped capacity. CECE specifies a 2:1 angle of repose.

Fill Factors: The amount of material actually in a bucket compared to its volume

is a vital factor in determining shovel production. Materials that are easy to dig

and that can be described as flowing (sand, gravel, or loose earth) should easily fill

the bucket to capacity with a minimum of void space. At the other extreme are the

hard, rocky materials that will have lots of void spaces. If the material dug has a

significant amount of oversize chunks or is extremely sticky, the average bucket

load will be reduced. Rated heaped capacities represent a net section bucket

volume, therefore they must be corrected to average bucket payload based on the

characteristics of the material being handled. Manufacturers usually suggest

factors, commonly called “fill factors” for making such corrections. Fill factors

are percentage that, when multiplied by a rated – heaped capacity, adjust the

volume by accounting for how the specific material will load into the bucket. It is

best, when possible; to conduct field tests based on the weight of material per

bucket load to validate fill factors.

Basic Parts and Operation:

The basic parts of a front shovel include the mounting, cab, boom, stick, and

bucket. With a shovel in the correct position, near the face of the material to be

excavated, the bucket is lowered to the floor of the pit, with the teeth pointing into

the face. A crowding force is applied by hydraulic pressure to the stick cylinder at

the same time the bucket cylinder rotates the bucket through the face.

SHOVEL PRODUCTION

There are four elements in the production cycle of a shovel:

1. Load bucket 2. Swing with load 3. Dump load 4. Return swing


It should be noted that a shovel does not a travel during the digging and loading

cycle. Travel is limited to moving into or alone the face as the excavation

progresses. One study of shovel travel found that on the average it was necessary

to move after about 20 bucket loads. This movement into the excavation took an

average of 36 sec.

Typical cycle element times under average conditions, for 3 to 5 cy size

shovels are -

1. Loud bucket - 7 - 9 sec.

2. Swing with load - 4 – 6 sec.

3. Dump load - 3 – 4 sec.

4. Return Swing - 4 – 5 sec.

The actual production of a shovel is affected by numerous factors,

including the –

1. Class of material

2. Height of cut

3. Angle of swing

4. Operator skill

5. Condition of the shovel

6. Haul-unit exchange

7. Size of hauling unit

8. Handling of oversize material

9. Cleanup of loading area.


EARTH MOVING EQUIPMENT:

Introduction – Earth moving is the planned, progressive modification of the

natural earth surface to give it a profile material to a proposed engineering

structure or use the material processing. While this is a more macro view of Earth

moving and its importance to mankind, more specifically the them Earth moving

is related to construction (dams, roads etc.) land clearness make of canals, mining

& querying etc.

Machines deployed commons for Earth moving

a) Dozers

b) Scrapers

c) Graders

d) Tractors

Equipment Considered In This Project.

DOZERS:-

A dozer is a tractor –power unit that has a blade attached to the machine’s front. It

is designed to provide tractive power for drawbar work. A dozer has no set

volumetric capacity. The amount of material the dozer moves is dependent on the

quantity that will remain in front of the blade during the push. Crawler dozers

equipped with special clearing blades are excellent machines for land clearing.

Heavy ripping of rock is accomplished by crawler dozers equipped with rear-

mounted rippers because of the power and tractive force that they can develop.

Dozers are self-contained units equipped with a blade. They are designed to

provide tractive power for drawbar work. Dozers may be either track laying

crawler or wheel-type machines. Consistent with their purpose, as a unit for

drawbar work, they are low-cement-of-gravity machines. This is a prerequisite of

an effective machine. The larger the difference between the line-of-force

transmission from the machine and the line-of –resisting force, the less effective

the utilization of developed power. Dozers are used for dozing (pushing

materials), land clearing, ripping, assisting scrapers in loading, and towing other

pieces of construction equipment. They can be equipped with either a rear-


mounted winch or a ripper. For long moves between projects or within a project,

the track dozer should be transported. Moving them under their own power, even

at slow speeds, increases track wear and shortens the machine’s operational life.

PERFORMANCE CHARACTERISTICS OF DOZERS

Dozers are classified on the basis of running gear;

1. Crawler (track laying) type

2. Wheel type

Crawler dozers are actually track laying machines. They have a continuous track

of linked shoes that moves in the horizontal plane across fixed rollers. At the rear

of the machine, the track passes over a vertically mounted sprocket drive wheel.

As the sockets turns, it forces the track forward or back, imparting motion to the

dozer. In the front of the machine, the track passes over a vertically mounted idler

wheel that it’s connected to a recoil device having adjustable tension. The idler

wheel maintains the proper tension in the track and enables it to absorb heavy

shocks. The linked shoes are made of heat treated steel designed to resist wear and

abrasion. There are several companies that now offer tracks having rubber-covered

steel shoes. The usable force available to perform work is often limited by

traction. This limitation is dependent on two factors:

1. Coefficient of traction of the surface being traversed.

2. Weight carried by the drive wheels

An advantage of a wheel-type dozer as compared with a crawler dozer is the

higher speed possible with the former machine – in excess of 30 mph for some

effort. Also, because of the lower coefficient of traction between rubber tire and

some ground surfaces, the wheel dozer may slip its wheels before developing its

rated pulling effort.

Manufactures provide dozers with a variety of transmissions, but primarily the

options are

Direct drive.

Torque converter and power-shift transmission.

Some less-than-100-hp dozers are available with hydrostatic power trains. The

smaller, lesss-than-300-hp, diesel-powered machines are commonly available with


either direct- or power-shift-type transmissions. Larger dozers are always

equipped with powers-shift transmissions.

Crawler Dozers with Direct Drive

The term direct drive means the power is transmitted straight through the

transmission as if there was a single shaft. This is usually what happens when the

transmission is in its highest gear. In all other gears, mechanical elements match

speed and torque. Direct drive dozers are superior when the work involves

constant loading conditions. A job where full blade loads must be pushed long

distances would be an appropriate application of a direct drive machine. Some

manufacturer’s specifications list two sets of drawbar pulls rated and maximum

for direct drive dozers. The rated value it the drawbar pull that can be sustained for

continuous operation. The maximum drawbar pull is the when passing over a soft

spot in the ground that requires a temporary higher tractive effort. Thus, the rated

pull should be used for continuous operation. Available drawbar pull is subject to

the limitation imposed by the traction that can be developed between the tracts and

the ground.

Crawler Dozers with Torque Converter and Power-Shift Transmissions

Transmissions that can be shifted while transmitting full engine power are known

as power shift. These transmission are teamed with torque converters to absorb

drive train shock loads caused by changes in gear ratios. A power –shift

transmission provides an efficient flow of power from the engine to the tracks and

gives superior performance in applications involving variable load conditions.

illustrates the performance curves for a track-type dozer equipped with a power-

shift transmission.

Crawler Dozers with Hydrostatic Power trains

Confined oil under pressure is an effective means of power transmission. A

hydrostatic power train offers an infinitely variable speed range with constant

power to both tracks. This type of power train improves machine controllability


and increases operational efficiency. Hydrostatic power train transmissions are

available on some small – size dozers.

Wheel Dozer

Most wheel dozers are equipped with torque converter and power-shift

transmissions. illustrates the performance curves for a wheel dozer equipped with

a power-shift transmission. Wheel dozers exert comparatively high ground

pressure, 25 to 35 psi (172-241 kpa).

Pushing Material

General Information

A dozer is a tractor power unit that has a blade attached to the machine’s

front. The blade is used to push, shear, cut, and roll material ahead of the dozer.

Dozers are effective and versatile earthmoving machines.

Dozer is used as both support and as production machines on many

construction projects. They may be used for operations such as

1. Moving earth or rock for short haul (push) distances, up to 300 ft (91 m) in

the case of large dozers.

2. spreading earth or rock fills.

3. Bank-filling trenches.

4. Operating up pilot roads through mountains or rocky terrain.

5. clearing the floors of borrows and quarry pits.

6. Helping load tractor –pulled scrapers.

7. clearing land of timber, stumps, and root mat.

BLADES

A dozer blade consists of a moldboard with replaceable cutting edges and side

bits. Push arms and tilt cylinders or a C-frame connect the blade to the dozer.

Blades vary in size and design based on specific work applications. The hardened

steel cutting edges and side bits are bolted on because they receive most of the

abrasion and wear out rapidly. The bolted connection enables easy replacement.

The design of some machines enables end of the blade to be raised or lowered n


the vertical plane of the blade, tilt. The top of the blade can be pitched forward or

backward varying the angle of attack of the cutting edge, pitch. Blades mounted

on a C-frame can be turned from the direction of travel, angling. These features

are not applicable to all blades, but any two of these may be incorporated in a

single mount. Figure 6.6 illustrates tilt, pitch, and angling. Tilt. This movement is

within the vertical plane of the blade. Tilting enable concentration of dozer driving

power on a limited portion of the blade’s length.

Pitch. This is a pivotal movement about the point of connection between bottom

edge moves back, and this increases the angle of cutting edge attack.

Angling. Turning the blade so that it is not perpendicular to the direction of the

dozer’s travel is known as angling. Angling causes the pushed material to roll off

the trailing end of the blade. This procedure of rolling material off one end of the

blade is called side casting.

PROJECT EMPLOYMENT

Stripping

Dozers are excellent machines for stripping, which is the removal of a thin layer of

material. On most projects, this is a term used to describe the removal of topsoil.

As with all dozer earthmoving operations, stripping should be conducted in such a

manner that push distances are minimized. Dozers are economical such a manner

that push distances are minimized. Dozers are economical machines for moving

material only about 300 ft in the case of large machines. The economical push

distance decreases as dozer size decreases, but economical push distance also

depends on the material being handled. A material exhibiting cohesion (clay

content) is easier to push than a granular material (sand), which tends to run in

front of the blade. In situation where material must be moved a distance grater

than 300 ft. scrapers should be considered. Dozers can be very effective support

machines for long-haul stripping situations when used to create windrows of

stripped material that can be easily picked up by the scrapers.

Side hill Cuts

It is very difficult to develop the initial working table for excavations made on

steep ground. Usually, the excavated material from such a cut is pushed over the


side of the hill. The first passes are made perpendicular to the long direction of the

project. Starting on the uphill side, short passes are made to push the material

across the centerline and over the side. Pushing downhill takes advantage of

gravity. Because these perpendicular passes are short, the dozer usually is not able

to develop a full-blade load. Therefore, once a bench is establish, the dozer should

push in the long direction of the project, develop a full-blade load, and them use

turns to push material over the side.

Ditching

A dozer can be used to accomplish ditching, but this is practical only for very

rough ditch sections. Small shallow ditches are usually cut with a motor grader.

Large deep ditches are either cut with excavators or, if the cut is made before

water enters the ditch. Scrapers can be used. A dozer will follow the scrapers and

perform the final dressing of the slopes. If a dozer is used to cut rough ditches, the

machine pushes the material out of the cut by working perpendicular to the line of

the ditch.

Backfilling

A dozer can efficiently accomplish backfilling by drifting material sideways with

an angle blade. This enables forwards motion parallel to the excavation. If a

straight blade is used, the dozer will approach the excavation at a slight angle and

then, at the end of the pass, turn in toward the excavation. No part of the tracks

should hang over the edge of the excavation. Caution must be exercised in making

the initial pass completely across pipes and culverts. As a minimum, 12 in. of

material should cover the pipe of structure before accomplishing a crossing. The

diameter of the pipe, the pipe type, the distance between the sidewalls of the

excavation, and the number of lines of pipe larger excavation dictate the minimum

required cover. Larger diameter pipe, larger excavation widths, and multiple lines

of pipe are factors that all dictate more cover before crossing the structure.

Rocks or Frozen Ground

With proper attack techniques, a dozer can move rocks or frozen ground. In both

cases, the blade must be worked under the material to be moved. This can be

accomplished by tilting the corner of the blade. To maximize the driving force of

the blade, hook only the titled end under the rock or ground. It may be necessary


to use the blade as a pry bar to lift the rock. Once the blade is in contact beneath

the rock and the dozer is driving forward, the operator lifts the blade to pry up the

rock Weak formations of soft rocks, such as shale and sandstone, can be attacked

in a similar manner. Work under the outcrop and lift. Once a plane of weakness

slides, a track machine can often crush the material by running over it. Is should

be remembered that dozer work in rocky areas increase track wear.

Spreading

The spreading of material dumped by trucks or scrapers is a common dozer task.

Ordinarily, project specifications state a maximum loose lift thickness. Even when

lift thickness limits are not stated in the contract specifications, density

requirements and proposed compaction equipment will force the contractor to

control the height of each lift. Uniform spreading is accomplished with a dozer by

keeping the blade straight and at the desired height above the previously placed fill

surface. The dumped material is forced directly under the blade’s cutting edge.

Fairly uniform spreading can be achieved, even by semiskilled operators, if two

complete passes are made across the dump area; with the second pass made

perpendicular to the first. Today laser blade controls are available for this type of

work

Slot Dozing

Slot dozing is the technique whereby the blade end spillage from the first pass or

the sidewalls from previous cuts are used to hold material in front of the dozer

blade on subsequent passes. When employing this method to increase production,

align cuts parallel, leaving a narrow uncut section between slots. Then, remove the

uncut sections by normal dozing. The technique prevents spillage at each end of

the blade and usually increases production by about 20%. The production increase

is highly dependent on the slope of the push and the type of material being pushed.

Blade-to-Blade Dozing

Another technique used to increase bulldozer production is blade-to-blade dozing.

the technique is sometimes referred to as side-by-side dozing. As the names imply,

two machines maneuver so that their blades are right next to each other during the

pushing phase of the production cycle. This reduces the side spillage of each

machine by 50%. The extra time necessary to position the machines together


increases that phase of the cycle. Therefore, the technique is not effective on

pushes of less than 50 ft because of the excess maneuver time required. When

machines operate simultaneously, delay to one machine is in effect a double delay.

The combination of less spillage but increased maneuver time tends to make the

total increase in production for this technique somewhere between 15 and 25%.

DOZER PRODUCTION ESTIMATING

A dozer has no set volumetric capacity. There is no hopper or bowl to load;

instead the amount of material the dozer moves is dependent on the quantity that

will remain in front of the blade during the push. The factors that control dozer

production rated are

1. Blade type.

2. Type and condition of material.

3. Cycle time.

Blade Load

The load a blade will carry can be estimated by several methods;

1. Manufacturer’s blade rating.

2. Previous experience (similar material, equipment, and work conditions).

3. Field measurements.

Manufacture’s blade ratings Manufactures may provide a blade rating

Based on SAE practice J 1265

Vs = 0.8 WH2

Vu = Vs + ZH (W-Z) tan x0

Where

Vs = capacity of straight or angle blade, in lcy

Vu = capacity of universal blade, in lcy

W = blade width, in yards, exclusive of end bits

H = effective blade height, in yards

Z = wing length measured parallel to the blade width, in yards

X = wing angle


Previous experience Properly documented past experience is an excellent

estimating method. Documentation requires that the excavated area by cross-

sectioned to determine the total volume of material moved and that the number of

dozer cycles by recorded. Production studies can also be made based on the weight

of the material moved. In the case of dozers, the mechanics of weighting the

material are normally harder to accomplish than surveying the volume.

Production

The formula to calculate dozer production in loose cubic yards per a 60-min hour

is presented below:

Production (lcy per hour)

60 min x blade load

= _____________________________________________

Push time (min) + return time (min) + maneuver time (min)

Production Formulas

Equipment manufactures have developed production formulas for use in

estimating the amount of material bulldozers can push. Equation is a rule-of-

thumb formula proposed by International Harvester (IH). This formula equates the

horsepower for a power-shift crawler dozer to lcy production.

Production (Icy per 60-min hr) = net hp x 330

(D + 50)

where

net hp = net horsepower at the flywheel for a power-shift crawler dozer

D = one-way push distance, in feet


HOULING EQUIPMENTS

Trucks are hauling units that provide relatively low hauling costs because of their

high travel speeds. The weight capacity of a truck may limit the volume of the

load that a unit may haul. The productive capacity of a truck depends on the size

of its load and the number of trips it can make in an hour. The number of trips

completed per hour is a function of cycle time. Truck cycle time has four

components: (1) load time, (2) haul time, (3) dump time, and (4) return time. Tires

for trucks and all other haul units should be suitably matched to the job

requirements.

TRUCKS

In transporting excavated material, processed aggregates, and construction

materials, and for moving other pieces of construction equipment, trucks serve one

purpose; they are hauling units that, because of their high travel speeds. Provide

relatively low hauling costs. The use of trucks as the primary hauling unit provides

a high degree of flexibility, as the number in service can usually be increased or

decreased easily to permit modifications in the total hauling capacity of a fleet.

Most trucks may be operated over any haul road for which the surface is

sufficiently firm and smooth, and on which the grades are not excessively steep.

Some units are designated as off-highway trucks because their size and weight are

greater than the permitted on public highways. Off-highway trucks are used for

hauling materials in quarries and on large projects involving the movement of

substantial amounts of earth and rock. On such projects, the size and costs of these

large trucks is easily justified because of the increased production capability they

provide.

Truck can be classified by many factors, including

1. The method of dumping the load – rear-dump, bottom-dump, or side-dump.

2. The type of frame- rigid-frame or articulated.

3. The size and type of engine – gasoline, diesel, butane, or propane.


4. The kind of drive- two wheel, four-wheel, or six-wheel

5. The number if wheels and axles, and the arrangement of driving wheels.

6. The class of material hauled – earth, rock, coal, or ore.

7. The capacity – gravimetric (tons) or volumetric (cubic yards)

If trucks are to be purchased for general materials hauling, the purchaser should

select units adaptable to the multipurpose for which they will be used. However, if

trucks are to be used on a given project for a single purpose, they should be

selected specifically to fit the requirements of the project.

Types of Dump trucks

a) Rigid frame Rear Dump trucks

b) Articulated Rear Dump trucks

c) Tractor with Bottom Dump Tractor considered

d) Articulated Raw Dump Track

ARTICULATED REAR-DUMP TRUCKS

The articulated dump truck (ADT) is specifically designed to operate over rough

or soft ground, and in confined working locations where a rigid-frame truck would

have problems. An articulated joint and oscillating ring between the tractor and

dump body permit all wheels to maintain contact with the ground at the times. The

articulation, all-wheel drive, high clearance, and low-pressure redial tires combine

to produce a truck capable of moving through soft or sticky ground.When haul-

route grades are an operating factor, articulated trucks can typically climb steeper

grades than rigid-frame trucks. Articulated trucks can operate on grades up to

about 35%, whereas rigid-frame trucks can navigate only grades of 20% for short

distances, and for continues grades, 8 to 10% is more reasonable limit. The most

common ADTs are the 4 x 4 models, but there are larger 6 x 6 models. Articulated

dump trucks usually have high hydraulic dumping pressures, which mean they

hoist their beds faster. The bed also achieves a steeper dump angle. One model can

attain a 720 dump angle in 15 sec. The combination of these two attributes, hoist

speed and a steep angle, translates into quick discharge times To solve the problem


of unloading sticky materials; one manufacturer is equipping its truck bed with an

ejector.

Rear-dumps, be they rigid-frame or articulated, should be considered when

1. The material to be hauled is free flowing or has bulky components.

2. The hauling unit must dump into restricted locations or over the edge of a

bank or fill.

3. Maximum maneuverability in the loading or dumping area is required.

CAPACITIES OF TRUCKS AND HAULING EQUIPMENT

There are at least three methods of rating the capacities of trucks and wagons:

1. Gravimetric – the load that it will carry, expressed as a weight.

2. Struck volume – the volumetric amount it will carry, if the load was water

level in the body.

3. Heaped volume – the volumetric amount it will carry, if the load was

heaped on a 2:1 slope above the body.

The gravimetric rating is usually expressed in pounds or kilograms and the later

two ratings in cubic yards or cubic meters.

The struck capacity of a truck is the volume of material that it will haul

when it is filled level to the top of the body sides. The heaped capacity is the

volume of material that it will haul when the load is heaped above the sides.

EFFECTS OF TRUCK SIZE

The productive capacity of a truck depends on the size of its load and the number

of trips it can make in an hour. The number of trips completed per hour is a

function of cycle time. Truck cycle time has four components: (1) load time, (2)

haul time, (3) dump time, and (4) return time. Examining a match between truck

body size and excavator bucker size yields the size of the load and the load time.

The haul and return cycle times will depend on the weight of the vehicle, the

horsepower of the engine, the haul and return distance, and the condition of the

roads traversed. Dump time is a function of the type of equipment and conditions


in the dump area. When an excavator is used to load earth into trucks, the size of

the trucks may introduce several factors, which will affect the production rate and

the cost of handling earth.

1. Advantage of small compared with large trucks :

a. They are more flexible in maneuvering, which may be an advantage on

restricted work sites.

b. They typically can achieve higher haul and return speeds.

c. The loss in production is less when one truck in a fleet breaks down.

d. It is easier to balance the number of trucks with the output of the excavator,

which will reduce the time lost by the trucks or the excavator.

2. Disadvantage of small compared with large trucks :

a. A small truck is more difficult for the excavator to load owing to the small

target for depositing the bucket load.

b. More total spotting time is lost in positioning the trucks because of the

larger number required.

c. More drivers are required to haul a given output of material.

d. The greater number of trucks increases the danger of units bunching at the

pit, along the haul road, or at the dump.

3. Advantage of large compared with small trucks :

a. Fewer trucks are required, which may reduce the total investment in

hauling units and the cost of maintenance and repairs.

b. Fewer drivers are required.

c. The smaller number of trucks facilities synchronizing the equipment and

reduces the danger of bunching by the trucks. This is especially true for

long hauls.

d. There is a larger target for the excavator during loading.

e. The frequency of spotting trucks under the excavator is reduced.

f. There are fewer trucks to maintain and repair, and fewer parts to stock.

4. Disadvantage of large compared with small trucks :

a. The cost of truck time at loading is grater, especially with small excavators.


b. The heavier loads may cause more damage to the haul road. Thus

increasing the cost of mechanical maintenance to the trucks and requiring

more support equipment for maintenance of the haul road.

c. It is more difficult to balance the number of trucks with the output of the

excavator.

d. The largest size may not be permitted to haul on highway.

Balancing the capacities of hauling units with the excavator bucket size is

important. When loading with excavators such as hydraulic hoes or shovels,

dragline, or loaders, it is desirable to use haul units whose load body volume is

balanced with the bucket size of the excavator. If this is not done, operating

difficulties will develop and the combined cost of excavating and hauling material

will be higher than when balanced units are used. A practical rule-of-thumb

frequently used in selecting the size of trucks is to use trucks with a minimum

capacity of four to five times the capacity of the excavator bucket. The

dependability of this practice is discussed in the following analysis.

CALCULATING TRUCK PRODUCTION

The following is a format that can be used to calculate truck production.

Step 1. Number of Bucket Loads.

The first step in analyzing truck production is to determine the number of

excavator bucket loads it takes to load the truck.

Balanced number of bucker loads = Truck capacity (Icy) (10.1)

Bucket capacity (Icy)

Step 2. Load Time

The actual number of bucket loads placed on the truck should be an integer

number. It is possible to light load a bucket to match the bucket volume to the

truck volume, but that practice is usually inefficient as it results in wasted loading

time. If one less bucket load is placed on the truck, the loading time will be

reduced; but the truckload is also reduced. Sometimes job conditions will dictate

that a fewer number of bucket loads be placed on the truck, i.e., the load size is


adjusted if haul roads are in poor condition or if trucks must traverse steep grades.

The truckload in such cases will equal the bucket volume multiplied by the

number of bucket swings. For the case where the number of bucket loads is

rounded down to an integer lower than the balance number of swings or reduced

because of job conditions:

Load time = Number of bucket swings X bucket cycle time

Truckload (volumetric) = Number of bucket swings X volume of the bucket

If the division of truck body volume by the bucket volume is rounded to the next

higher integer and that higher number of bucket swings is used to load the truck,

excess material will spill off the truck. In such a case, the loading duration equals

the bucket cycle time multiplied by the number by bucket swings. But the volume

of the load on the truck equals the truck capacity, not the number of bucket swings

multiplied by the bucket volume.

Number of bucket loads rounded up to next higher integer above the balance

number of swings:

Load time = Number of bucket swings X bucket cycle time

Truckload (volumetric) = Volumetric capacity of the truck

Always check the load weight against the gravimetric capacity of the truck.

Truckload (gravimetric) = Volumetric (Icy) X unit weight (loose vol. Ib/lcy)

Truckload gravimetric < Rated gravimetric payload?

Step 3. Haul Time

Hauling should be at the highest safe sped and in the proper gear. To increase

efficiency, use one-way traffic patterns.

Haul time (min) = Haul distance (ft)

88 fpm/mph X Haul speed (mph)

Based on the gross weight of the truck with the load, and considering the rolling

and grade resistance from the loading area to the dump point, haul speeds can be

determined using the truck manufacturer’s performance chart.


Because the cost of the excavation equipment is usually greater than the cost of a

haul truck it is common practice to use a greater number of trucks than the

balance number derived from the ratio of the loader and truck cycle times. When

considering this decision the mechanical condition of the trucks should be

considered. Another consideration is the availability of standby trucks. These are

not necessarily idle units but could be trucks assigned to lower priority tasks from

which they can easily be diverted. After the job has started, the number of trucks

required may vary because of changes in haul-road conditions, reductions or

increases in the length of hauls, or changes in conditions at either the loading or

dumping areas. Management should always continue to monitor hauling

operations for changes in assumed conditions.

SUMMARY

The use of truck as the primary hauling unit provides a high degree of flexibility,

as the number in service can usually be increased or decreased easily to permit

modifications in the total hauling capacity. When estimating what a truck will

carry both the rated gravimetric load and the rated –heaped volume must be

examined. The heaped capacity is the volume of material that the truck will haul

when the load is heaped above the sides. The actual heaped capacity will vary with

the material that is being hauled. Critical learning objective include:

An understanding of the necessity to achieve balance between excavator

bucket volume and truck load volume.

An ability to use performance charts to calculate truck speed.

An understanding of the job site constraints that affect dump times.

An ability to calculate the number of trucks required to keep the excavating

equipment working at capacity.

These objective are the basis for the problems that follow.


COMPACTION OF GEOTECHNICAL MATERILS

With time, material will settle or compact itself naturally, but the object of

compaction is to achieve the required density quickly. The earliest recorded use of

compaction can be found in the Roman Empire records of their road construction

projects. The Romans realized that compaction would improve the engineering

properties of soils; therefore, they used large cylindrical stone rollers to achieve

mechanical densification of their road bases.

Obtaining a greater soil unit weight is not the direct objective of

compaction. The reason for compaction is improve soil properties to

1. Reduce or prevent settlements.

2. Increase strength

3. Improve bearing capacity

4. Control volume changes

5. Lower permeability.

Density, however, is the most commonly used parameter for specifying

construction operations because there is a direct correlation between these

properties and a soil’s density. Construction contract documents usually call for

achieving a specified density, even though one of the other soil properties is the

crucial objective. There may be other methods whereby the desired properties

could be attained, but by far the most widely used method of soil strengthening is

compaction of the soil at optimum moisture. The benefits of proper compaction

are enormous, far outweighing their costs. Typically, a uniform layer, or lift, of

soil from 4 to 12 in thick is compacted by means of several passes of mechanized

compaction equipment.

TYPES OF COMPACTING EQUIPMENT

Applying energy to a soil by one or more of these methods will cause compaction:

1. Impact – sharp blow


2. Pressure – static weight

3. Vibration – shaking

4. Kneading – manipulation or rearranging

The effectiveness of different compaction methods is dependent on the individual

soil type being manipulated. Appropriate compaction methods based on soil type

are identified in.

Manufacturers have developed distinct compactors that incorporate at least one of

the compaction methods and in some cases more than one into their performance

capabilities. Many types of compacting equipment are available, including:

1. Sheepsfoot roller

2. Tamping rollers

3. Smooth drum vibratory soil compactors.

4. Pad drum vibratory soil compactors

5. Pneumatic-tired rollers.

summarizes the principal method of compaction for the various types of

compactors. There are also static, smooth steel-wheel rollers. These generally

consist of two tandem drums, one in front and one behind. Steel three-wheel

rollers are another version of this type of compactor, but they are not very

common today. Vibratory rollers are more efficient than static steel-wheel rollers

for earthwork and have largely replaced them.

Principal method of compaction used by various compactors.

Compactor type Impact Pressure Vibration Kneading

Sheepsfoot X

Tamping foot X X

Vibrating smooth X X

Vibrating pad foot X X

Pneumatic X X

On some projects, it may be desirable to use more than one type of

equipment of attain the desired results and to achieve the greatest economy. The

ultimate goal is to construct a quality embankment in the shortest time at the least

cost, and that means the compaction equipment must be matched to the material.


Therefore, the job should always be closely examined and samples taken of the

excavation or borrow materials. The proper excavation and compaction equipment

cannot be selected until the soils are identified. It provides guidance for selecting

compaction equipment based on the type of material that must be compacted. As

seen in the table, if the required density is not achieved within four to eight

coverage’s, a different type of compactor should be considered. Appropriate

project compaction equipment based on material type

Material Lift

thickness

(in)

Number of

passes

Compactor type Comments

Gravel 8-12 3-5 Vib. padfoot Foot psi 150-200

Vib. smooth -

Pneumatic Tire psi 35-130

Sheepsfoot Foot psi 150-200

Sand 8-10 3-5 Vib. padfoot -

Vib. smooth -


Smooth static Tandem 10-15

ton

Silt 6-8 4-8 Vib. padfoot Foot psi 200-400

Tamping foot -



Clay 4-6 4-6 Vib. padfoot Foot psi 200-400

Tamping foot -


Rock fills are usually spread in 18 to 48 in lifts. Attention to spreading the

material in a uniform lift is vital o achieving density during the compaction

process. Consistent spreading helps to fill voids and orients the rocks so as to

provide the compaction equipment with an event surface. The largest possible

smooth-drum vibratory rollers are used for deep rock lifts.


Considered in this project.

Smooth Drum Vibratory soil compactor.

The smooth drum compactors, whether single – or dual-drum models, generate

three compactive forces: (1) pressure, (2) impact, and (3) vibration. These rollers

are most effective on granular materials, with particle sizes ranging from large

rocks to fine sand. They can be used on semi cohesive soils with up to about 10%

of the material having a PI of 5 or greater. Large steel-drum vibratory rollers can

be effective on rock lifts as thick as 3 ft.

ROLLER PRODUCTION ESTIMATING

The compaction equipment used on a project must have a production capability

matched to that of the excavation. hauling, and spreading equipment. Usually,

excavation or hauling capability with set the expected maximum production for

the job. The production formula for a compactor is

Compacted cubic yards per hour = 16.3 X W X S X L X efficiency

n

where

W = compacted width per roller pass in feet

S = average roller speed in miles per hour

L = compacted lift thickness in inches

N = number of roller passes required to achieve the required density

The computed production is in compacted cubic yards (ccy), so it will be

necessary to apply a shrinkage factor to convert the production to bank cubic yards

(bcy), which is how the excavation and hauling production is usually expressed.


PAVING EQUIPMENT

ASPHALT PAVERS

An asphalt paver consist of a tractor, either track or rubber-tired, and a screed. The

tractor power unit has a receiving hopper in the front and a system of slat

conveyors to move the mix through a tunnel under the power plant to the rear of

the tractor unit. At the rear of the tractor unit, the mix is deposited on the surface

to be paved and augers are used to spread the asphalt evenly across the front of the

trailing screed. Two tow arms, pin connected to the tractor unit, draw the screed

the tractor. The screed controls the asphalt placement width and depth, and imparts

the initial finish and compaction to the material. There is one manufacturer that

offers a paver having two sets of twin screws to move the mix through the tunnel

to the rear of the paver. The use of the screw conveyors is said to reduce mix

segregation. Pavers can receive mix directly into their front hoppers or can pick up

a windrow of material placed in front of the paver. The traditional method for

directly loading the hopper has the truck directly dump the asphalt concrete into

the paver hopper. Push rollers mounted on the front frame for the paver, and

extending beyond the hopper, push against the wheels of the truck, or a bar on the

paver pushes the pusher bar of the truck. The material is then transferred to the

hopper by raising the truck bed or by activating the live bottom. Loading the

hopper with individual truckloads often requires that the paver stops

intermittently. This can cause problems with construction a smooth pavement

since frequently the paver must wait between truckloads, and mating up to the

truck can bump the paver, causing the screed to release material.

Screed

The “floating” screed is free to pivot about its pin connections. This pin connected

tow arm arrangement allows the screed to be self-leveling and gives it the ability

to compensate for base surface irregularities. The paver’s ability to level out

irregularities is controlled by the tractor’s wheelbase length and by the length of

the screed towing arms. Greater lengths of these two components mean smooth


transitions across irregularities and therefore a smooth riding surface. Mat

thickness, which is controlled by the screed, can be maintained by using grade

sensors tracing grade by the use of sensors tracing a stringline. When all the forces

acting on the screed are constant, it will ride at a constant elevation above the

grade or follow the stringline. However, there are factors that can cause the sensor

regulated screed height to vary:

The screed angle of attack. The head of asphalt in front of the screed The paver speed.

The angle created by the plane of the surface upon which the asphalt is being

placed and the plane of the screed bottom is known as the” screed angle of attack”.

This angle is the principal mechanical factor affecting variation in mat thickness.

It regulates the amount of material passing under the screed in a given distance.

When either the screed or the tow points are vertically displaces, the angle of

attack is changed. The screed will immediately begin to move, restoring the

original angle, but this correction requires about three tow-arm lengths to be

accomplished. The asphalt material directly in front of and across the length of the

screed is referred to as the head of material.. Paver speed is inked to the rate at

which asphalt mix is delivered from the plant. To produce a smooth mat, forward

travel speed should be held constant. Changes in paver speed will affect the

screed’s angle of attack. Increasing the speed causes the screed to ride down,

whereas decreasing the speed has the opposite effect. Additionally, when the paver

is stopped, the screed tends to settle into the mat. Initial mix compaction is

achieved by vibration of the screed. Vibrators mounted on the screed are used to

impart compaction force to the mat. To prevent material from sticking to the

screen at the beginning of a paving operation it is necessary to heat the screed.

Built-in diesel or propane burner heaters are used to heat the bottom screed plates,

Required burner-heating time will vary with air temperature and the type of mix

being placed. About 10 min of heating is normal, but care must be exercised as

overheating can warp the screed.

Paver Production


Continuous paving operations depend upon balancing paver production with plant

production. The critical choke points in the operation, which must be analyzed and

managed, are the plant load-haul unit and the haul unit-feed paver links.

EQUIPMENT PLANNING:

INTRODUCTION

Planning is very important for selecting the right type of equipment. First the

Planner has to see what type of work he is doing and then he should know various

types of equipments that can be used for the work. He has to see the Various

models and makes of equipments that are available in the market. He should study

the capacity and cost of equipment. He also has to see what type equipment he

possesses. Based on that he can go for similar type, make and model of

equipments so that there will be standardization and minimum inventory cost. He

also has to look into the probable life of equipment and its depreciation. He should

go in for equipment which has minimal maintenance. Experience is one of the

most important pre-requisite for equipment planners.

HOW TO SELECT THE EQUIPMENT

Factors to be first considered in selecting suitable equipment are discussed below:

Scope of work to be carried out: Apart from the evaluation of the quantities of

various items of work and the timeframe within which the work is required to be

carried out, the specification for work will have a bearing on the selecting of

equipments.

PLANNING FOR EQUIPMENT:

Equipment planning shall include the following aspects:

i. Selection of equipment

ii. Number and sizes of units

iii. Matching capacities

iv. Schedule of procurement

v. Arrangement of skilled staff for operation and maintenance

vi. Establishment of service and repair facilities


vii. Maintenance of spare parts inventory

viii. Decision regarding number of shifts per operation

Thus a systematic approach in respect of planning for equipment is necessary,

incorporating all the factors detailed above. In addition an important factor to

be considered is the necessary inter-disciplinary acceptance of the planning for

equipment. In a majority of the cases project may be headed by a Civil

Engineer whereas the construction equipment management will demand close

liaison with mechanical and electrical engineers. It will be prudent to have

detailed consultations among the disciplines before the final choice of the

equipment.

Having taken a decision to go in for additional equipment, the following

factors are required to be evaluated:

Suitability for job commissions – The nature of site terrain will often affect the

cost of constructing the plant and its supporting facilities. The plant must be

accessible to transportation facilities to be used. There may be limitations in

respect of the quality and capacity of roads, waterways bridges etc, which may

limit the size of transport vehicles used.

Infrastructure – The availability and cost of infrastructure are important

considerations. The supply of electricity from public utilities is either not

available or not dependable. Diesel powered equipment will be required or

electricity may have to be generated at site. Water supply is equally critical,

when required in large quantities for washing raw materials or for cooling

purposes.

LAYOUT OF CONSTRUCTION PLANT

The layout should ensure minimum movement of material, equipment and

personnel as well as minimum processing time. Proper drainage should be

planned. The wind conditions should be evaluated and provided for.

Operations of items like tower cranes are highly prone to heavy winds.

Crushers should be oriented so that the dust is carried by the wind away from

the crusher. Supporting facilities such as generators, offices, stores etc. should


be located out of the path of the dust flow. Adequate space must be provided

for handling and storing raw materials as well as finished products. Covered

storage may be required to protect it from the weather. Depending on the size

of the project, paved areas may have to be provided for storing raw materials

such as aggregates. Wherever possible, separate service roads should be

provided for incoming materials and outgoing products. As most of the

service roads are not paved, provision must be made for adequate regular

maintenance.

SELECTION OF EQUIPMENT – GENERAL CONSIDERATIONS

The proper selection of equipment for any construction project involves

decision on a number of parameters for economic operation and maintenance

of the equipment. The following aspects need detailed consideration at the

selection stage:

1. SUITABILITY FOR THE JOB

The equipment selected should obviously match the dimensions of the job

and ground conditions. Climatic and other operating conditions are also

required to be borne in mind. A piece of equipment designed and

manufactured for operations in temperate climatic conditions will not

necessarily function satisfactorily under hot climatic conditions.

2. USE OF AVAILABLE EQUIPMENT

Use of available equipment, though not operating under optimum

conditions, may sometimes have to be resorted to taking into account the

limited utility of any new equipment, depreciated low value of the available

equipment etc. In short, the economics of the two alternatives will have to

be evaluated before the final choice.

3. SIZE OF THE EQUIPMENT

The choice is indicated as neither a minimum number of large – size

machines nor several units of medium / small capacity machines. Large

size units will require matching equipment of equally larger sizes. It also

suffers the disadvantage of total breakdown of operations in the event of

one large size unit’s failure to operate. On the other and, the main


advantage is that the larger units are generally more sturdy and are suitable

for tough working conditions. The size of the standby equipment will also

be a consideration in the choice of the size of the equipment.

4. VARIETY REDUCTION

It is desirable to have the minimum possible number of varieties of

equipment. Preferably, the prime movers should be of a common type to

facilitate interchange of prime movers between various machines, if

required. Variety reduction also results in more efficient maintenance

programmed.

5. STANDARDISATION

Standardized equipment manufactured in large number is generally readily

available and cost effective. Spare parts availability is also an advantage.

The resale value of the standardized equipment is always higher.

6. VERSATILITY

The selected unit should, if possible, be capable of performing more than

one function. In short, it should be of multi-purpose variety for use on

different types of projects.

7. UTILISATION

The size and numbers of the equipment shall be fixed to ensure full

utilization of the equipment on the projects. The economics of ownership

and operation of the equipment shall be of paramount consideration.

8. SELECTION OF MANUFACTURE

It is desirable to have the units supplied by reputed manufacturers and to

have minimum number of different sizes / makes of equipment.

9. SUITABILITY FOR LOCAL CONDITIONS

The equipment should be such that the necessary technical and operating

personnel could be easily obtained or trained with minimum efforts.

10. ADAPTABILITY

Adaptability for future use if machine is likely to wok only for a short time

on a particular project, and subsequent utilization on other projects should

be kept in view. Full utilization of the equipment should be aimed at


during the life of the machine, so that investment could be recovered with

profits during its useful life.

11. TECHNICAL CONSIDERATIONS

The efficient performance of any piece of equipment and its service life are

conditioned by the following factors –

i. Strength ii. Rigidity iii. Vibration stability iv. Resistance to wear v. Heat resistance vi. Reliability vii. Maintainability

CLASSIFICATION OF EQUIPMENT

Any typical construction equipment may be classified in a number of ways:

a) The type of job b) The nature of the working process c) The operating conditions d) The prime mover e) The type of transmission f) The output capacity g) The type of control gear

In terms of the type of job, equipment used for construction operations are

generally divided into the following classes:

i. Horizontal off-track vehicle

ii. Load lifting machines for erection work

iii. Machines for loading / unloading operations

iv. Continuous conveyance machines

v. Material handling machines

vi. Machines for excavation and preparatory works

vii. Drilling and pile driving equipment

viii. Machines for working on stone materials

ix. Materials for preparation, transportation and placement of

concrete and mortar

x. Machines for finishing work

xi. Machines for making reinforced concrete products


xii. Power tools

xiii. Supporting equipment

The following types of prime movers are used as sources of power for operating

the equipment.

a) Electric motor

b) Internal combustion engine

c) Pneumatic motor

d) Hydraulic motor

e) A combination of two or more sources for example, diesel – electric

driven.

Mobility Machines are classified as stationary and mobile. The mobile units can

further be subdivided as self – propelled, semi – trailer and trailer types. Based on

the running gear, machines may be classified as crawler, pneumatic type units, rail

mounted units and walking units.

SELECTION OF EQUIPMENTS:

Selection of Equipment needs careful thought to ensure efficient and effective

performance. Though the actual selection would depend on factors like type of the

work, its magnitude location etc. certain guidelines can be laid down. Basically

the various operations involved are as below:

a) Earth moving

i) Clearing and grubbing

ii) Stripping

iii) Earth work in cutting and embankment

iv) Spreading earth for bank work

v) Providing camber

vi) Watering


The following table shows the suitable equipment for the works mentioned above.

Sr. No.

Operation Suitable Plant Remarks

1 Cleaning/grubbing a) Light / scrub & grass

a) Tractor mounted dozer

bulldozing

b) Grader motor

Blade to be used in position. For light scrub

a) Clearing debris rubble a) Tractor mounted dozer b) Tractor with heavy duty winch

For large objects

2 Stripping Top soil a) Dozer, tractor mounted

b) Motorized – Scraper Tractor towed scraper

c) Grader, motor

300m to 3000m haul

60m to 3000m haul

Light stripping

3 Earthwork in cutting and embankment a) Light & Medium soils

a) Dozer, tractor mounted

b) Tractor towed scraper c) Motorized scraper d) Grader motor e) Excavator and dump

trucks f) Front end loader

g) Tipping bucket

For hauls 60m to 300m.

Hauls 300m to 3000m.

b) Heavy soil a) Dozer Tractor mounted

b) Scraper tractor towed with pusher tractor to help loading or preceded by tractor towed rooter or tractor mounted ripper.

c) Motorized scraper with pusher tractor or preceded by tractor towed rooter.

d) Grader motor preceded by tractor

Upto 90m haul

Haul 60m. to 300m.

Haul 300m to 3000m.


towed rooter. 4 Spreading earth for bank

work a) Scraper tractor towed b) Scraper motorizedc) Grader motor d) Tipping motor

e) Dozer, tractor mounted

60m, to 300m

300m to 3000m.

5 Providing camber a) Grader motor b) Dozer, tractor

mounted

c) Scraper tractor towed or motorized

6 Watering (Embankment or surfacing)

Truck or trailer mounted water tanker with water pump and sprinkler.

Sr. No.

Operation Suitable Plant Remarks

1 Compaction of bank work and sub grade soils

a) Sheepsfoot roller b) Smooth wheel an

roller c) Pneumatic tyre roller d) Vibratory roller e) Power rammer

Blade to be used in position. For light scrub

2 Granular base and sub base

a) Smooth wheeled roller b) Vibratory roller

3 Macadam base / sub base a) Steel wheeled roller 4 Mix-in-situ bituminous

base a) Steel wheeled rollerb) Vibratory Contractor

5 Plant mix base course or surface course

a) Three wheeled roller b) Tandem roller

OUTPUTS AND PERFORMANCE OF THE EQUIPMENT:

Manufacturers of the equipment give output of their products. This however is

based on ideal conditions which are difficult to obtain on working site. Naturally

the actual output of an equipment is different and may vary from site to site. One

of the important tasks of the planner is to assess the requirement of the plant and

equipment on a particular job.


For this he must know.

i. Total quantity of work to be done and

ii. The output of the equipment proposed to be used.

Factors affecting the performance of equipment.

Factors which affect the performance and hence the output of an equipment have

to be carefully considered.

Factors related to the job are required to be considered which include:

i. Swell and shrinkage of material handled

ii. Gradient of the haul road

iii. Rolling resistance of the haul road

iv. Climate and topography

v. Tractice efficiency

vi. Moisture content of materials handled

vii. Altitude

In addition to the above factors which more or less have to be accepted as the are

on a job there are factors which relate to the way the job is managed. These

factors include:

i. How well the operators are trained

ii. Layout on job site

iii. Proper matching of various allied equipments.

iv. Availability of the facilities for maintenance, repairs etc.

v. Management and worker relationship.

Estimating the requirement of the equipment:

Equipment on a roadwork (or on any work) has either to be purchased, obtained

on hire or transferred from some other project. In either of the cases a fairly

accurate estimate of the requirement of equipment has to be done so as to ensure

that expenditure on equipment is not wasted. This needs planning well in

advance.

Factors to be considered are:

i. What is the most desirable sequence of operations involved in the work?

ii. Which of the operations are to be performed by the machinery?


iii. In case some or all equipment is to be transferred from other projects how

the programme of both the projects to be arranged so that there is no undue

to and from movement of the equipment and at the same time the work is

completed in optimum time.

Data Required:

Basic data required for estimating the equipment are:

i. Quantities of items of work: Road Project is sub divided in operations like

(a) Earthwork, (b) Aggregate production, (c) transporting aggregate to

road, (d) metalling (e) compaction, (f) wearing surface – concrete /

bituminous surface etc. Quantities of items are worked out.

ii. Period of completion of the project.

Period of completion would depend on the duration required for the various

constituent items and the sequence in which they are proposed to be

executed. Normally a given road work has to be completed in a stipulated

period particularly when the work is to be completed on contract. In such

cases the duration of the constituent operations has to be adjusted taking

into consideration the activity interrelation and overall period of

completion. While fixing the activity durations due allowance must be

made for bad weather, monsoon, loss of time due to shifting equipment,

break down, repairs and maintenance of equipment etc.

iii. Normally no work is possible for 3 to 4 months in a year due to monsoon.

Further considering weekly holidays normally 25 days could be considered

to be available for working. Though a working day is considered to

comprise 8 hours, a part is spent in inevitable operations like shifting,

waiting etc. Thus in about 200 days available, working hours would be

about 1200-1500.

iv. From (i) to (iii) above a fair estimate of requirement of equipment can be

done. Over and above this a suitable provision. (to the extent of 10%) is

done as stand by to take care of break down or unforeseen circumstances.


MATERIAL MANAGEMENT:

INTRODUCTION:

The management of materials in project is different from that in an on-going

situation. Some of the differences are described below.

i. Most of the materials in project are bulky and heavy.

ii. The lead time for procurement of materials in most cases is usually

much more.

iii. The principle of E.O.Q. has very limited applicability in project

situations. Usually sequential arrival of material is desired.

iv. The demand of materials in project is by and large highly deterministic.

v. Sufficient care has to be taken in the selection of vendors, as the

performance of vendors has significant impact on the project

performance.

In addition many project managers, more so in developing countries (where

procurement of capital equipments is rather difficult), feel a sense of achievement

and progress, when they see the capital equipments physically at site, though these

are required much later for erection. Due to these the classical principal of

Materials Management are not very effective in the project situation. Accordingly

suitable approaches in various of materials management in project are desirable.

MATERIAL PLANNING

The demand of materials in a project situation is highly deterministic. The gross

requirement of various materials is worked out during the detailed project Report

stage. The period at which the demand is to be met is also deterministic and is

known from the project network. The element of uncertainty is incorporated from

the uncertainty in activity realization. The primary concern in material planning

for projects is that the cost of not meeting a demand is very high, as it may lead to

delay in project completion. Hence the RIGHT TIME is the key word in material

planning for projects. The capital equipments are to be planned in such a way that

these are available at the site just before the erection/installation of these. Since

different equipments are to be erected/installed at different periods, a sequential

arrival of capital equipments based on their respective installation period is


desired, instead of getting all the capital equipments at a time and storing them till

they are installed. This calls for detailed planning and co-ordination with various

agencies like, technical consultants, designers, suppliers, transport contractors etc.

The demand for construction is known as soon as the resource requirement for the

project is finalized. These materials are normally required before the construction

can start and are to be planned for availability prior to the construction phase of

the project. The consumables are used throughout the project duration and the total

requirements are known. However, the consumption rate at different period is

different but deterministic. In order to take into account the varying demand rate

in the planning of consumable materials it is desirable to draw the aggregate

demand pattern of the materials it is desirable to draw the aggregate demand

pattern of the materials may run into hundreds, the analysis of aggregate demand

pattern may be restricted to high consumption value materials only, i.e. the so

called “A” category items. The consumables are procured in several lots and not

in one lot; due to limited storage space at project sites, wastage or spoilage or

certain materials (like cement) when stored for a long period, and to save the

inventory carrying cost. The concept of economic order quantity can be used in

planning for consumables materials taking into account procurement cost,

inventory carrying cost, wastage and spoilage cost etc.

MATERIAL MANAGEMENT CONCEPTS & THEIR APPLICABILITY:

Lead Time:

One of the factors to be considered in procurement of material is lead time. As the

name implies, it is the period elapses between the point of time when the need for

material is contemplated and the point of time the material actually available on

the site of construction for use.

It comprises time required for:-

a) User’s intimation to the materials manage department regarding the time and quantity of material required.

b) Materials management to decide that the materials purchased. c) Selecting the source, fixing the price and ultimately placing the order. d) To deliver material e) Transportation and receiving the material including inspection and testing

of material if necessary.


If no lead time is necessary (a rather impractical proposition) it would be very easy

to purchase mate knowledge its need in construction. Even if procurement

through purchase involves a lead time which is certain, problem could be tackled

by planning sufficiently in advance that the need for a material is assessed well

ahead of actual use and the lead time is taken care of.

From the user’s point of view the problem arises due to following factors:

a) The lead time in purchase is uncertain and if it delayed it will result in

stoppage of work.

b) There may be unexpected shortage due to scarcity (or total non-

availability) of material or some unexpected difficulties in transportation.

c) The continuously rising prices and small quantities purchased frequently

may make the materials costlier.

SAFETY LEVEL:

Related to the EOQ in the desired protection against stock depletion referred to as

a safety level. The ideal situation is often thought of by the inventory manager as

always avoiding both zero balance and backorder position. The existence of

shortage suggests that some additional stock should be placed on the shelf to

protect against uncertainty of demand during the resupply time. Therefore action

must be taken to adjust for unexpected demands from customer or delays I

delivery from acquisition since shortage can be quite costly interim of unit

readiness. The safety level is an attempt to overcome this problem. However

100% protection is theoretically impossible.

EOQ – Economic Order Quantity:

The curve AMB indicates the graph of inventory carry costs for various

frequencies of ordering. Please note that low ordering frequency means large

order, which in turn means m inventory and hence inventory carrying costs. It also

means few orders and hence less ordering costs. OMG shows the graph of

ordering costs corresponding to various frequencies. If we add the two costs we

get a graph PQR, which indicates the total invent cost corresponding to various


frequencies Q is the least c and hence the intercept OS shows the most desirable

frequency of ordering for which the total inventory cost is minimum. The quantity

of order corresponding to the frequency is known as Economic order quantity

(EOQ)>.We can also plot the graph with quantity per order plotted along x-axis

and costs along y-axis (what will be the nature j the two graph in such a case) Both

the costs when totaled will get the total cost. The intercept on x axis corresponding

to the lowest point on the total cost will now give economic order quantity (EOQ).

This is also known as Economic Lot size.

ROL – Reorder letter (Replenishment)

In the EOQ model discussed we have made the assumption that the lead time for

procuring material is zero. Consequently, the recorder point for replenishment of

stock occurs when the level of inventory drops down to zero. In vie of

imtantaneous replenishment of stock the levels of inventory jumps to the original

level from zero level in real life situation one never encounter a zero lead time.

There is always a time lag from the date of placing an order for material and the

date on which materials are received. As a result the recorder level is always at a

level higher than zero. And if the firm places the order when the inventor reaches

the recorder point, the new goodwill arrives before the firm ---- out of goods. The

decision on how much stock to hold is generally referred to as the order point

problem that in how should the inventory be depleted before it is reordered.

The two factors that determine the appropriate order point are the procurement or

delivery time stock which is the inventory needed during the lead time G.C. The

difference between the order date & the receipt of the inventory order with safety

stock which is the minimum level of the inventory that is held as a protection

against shortages.

Recorder Point = Normal consumption during lead time + safety stock =

= Avg. daily usage rate & lead time in day.

Ordering Schedule – Logistic & plan of conveyance of bitumen.

Ordering Schedule – Procurement of Materials.


PROCUREMENT:

Procurement is of special significance in a project situation. The net effect of

delay in delivery and supply of inferior quality of material is delay in the

completion of the project. Economic procurement is also important as it is a

determinant for the viability of the project. Because of these considerations

vendor selection plays an important role. In addition contingency procurement

plans are also necessary to minimize the effect of undesirable performance by

vendors. The consumables are standard materials and are usually available from

many sources. Occasionally, there is a scarcity of some of these materials. The

gross demand as well as the demand profile of these materials for the entire project

duration are known, and it is desirable to enter into contracts with the suppliers

(preferably more than, one for each material) for the entire requirement with

staggered delivery. The construction machineries need to be procured before the

construction activity is in full swing. The performance characteristics of these

machineries are important considerations while procuring these materials. It may

be possible to penalize the supplier for poor performance of the construction

machineries, but the cost to the project in terms of delays is much more than the

penalty that a be realized. The suitability of the construction machineries for the

particular construction site should also be evaluated. Another important, factor in

the selection of construction machineries is the maintenance requirement, in many

construction sties extensive maintenance facilities may not be available, specially

due to the limited period for which these construction machineries are to be used.

Keeping in view the severity of the requirements of construction machineries, it

may be desirable to procure these from reputed manufacturers even at a slightly

higher price.

Apart from the discussion on the technical details and price the negotiation can

centre around the following issues;

a) Delivery Schedule: To match with the project network. b) Payment terms c) Liquidated Damages d) Quality specifications and procedure for checking quality. e) Inspection at different stages of manufacture at the supplier’s premises. f) Incorporation of design changes while the manufacturing is in progress. g) Performance guarantee etc.


STORAGE AND LOGISTIC SYSTEM FOR MATERIALS:

The availability of storage capacity is very limited at project site. Further most of

the available space is open and very little covered area is available. In these

circumstances proper storage of material becomes important to facilitate quick

identification and location of material and to minimize the damage and losses of

materials while in stores. The materials, which need to be stored, are the

consumables and the capital equipments prior to their erection. The construction

machineries are put to use as soon as these are received. The consumables are

received in lots at different periods and used over the entire period of the project.

As such the stores operation of these materials is similar to those in an on-going

operation. Accordingly these materials are stored in fixed locations. Either in

open on covered space, and issued against store issue slips. The capital

equipments are one off type and are to be stored till these are required for erection.

A random storage system is normally followed for capital equipments, for better

utilization of the available storage space. The storage space is divided into various

zones and these are marked. The capital equipments, on arrival, are stored in the

available storage space and the zone identification codes are recorded in the

relevant material cards for easy retrieval. A simple Kardex system needs to be

maintained for the purpose.

TRANSITION FROM SITUATION TO ON-GOING STRUCTURE:

The planning for the materials management function on completion of the

construction activity need to be carried out much before the completion of the

project for smooth transition from project to on-going operation. The tasks to be

performed are:

i. Identification of the materials including spares required for on-going

operation.

ii. Assessment of consumption rates

iii. Codification and classification of the materials

iv. Assessment of storage requirement, store-layout, planning etc.


.

CALCULATION FOR PER DAY WORK:-

FRONT SHOVEL

1) Consider we are using

BEML front shovel model No. PC 220-3

Operating weight Tones – 22

Bucket capacity Range cum – 1.26 cum

Time in seconds - 24 secs for 1 bucket

Therefore,

in 1 min = 2.5 buckets

in 1 hr = 60 min x 2.5 bucket

1 hr = 150 bucket will be filled

= 150 x 1.26 cum

1 hr = 189 cum of earth will be filled

Taking in consideration of head, maintenance & Breakdown period and induction

& induction upto 2 hr in 1 shift per day.

Total working hrs. = 6hr.

6 hr = 189 x 6 = 1134 cum

1 day = 1134 cum will be excavated

The in 1, 00,000 cum of earth will be excavation 88 days / 1 shovel.


TRUCK PRODUCTION

Number of Bucket loads

Balanced number of bucket loads = Truck capacity

Bucket Capacity

= 4 Cum = 3.27 = 3 bucket

1.26 Cum

Load time:-

Load time = Number of bucket swing x bucket cycle time.

Load time = 3 buckets x 24 sec.

= 72 sec

Haul Time:-

Hauling should be at the highest safe speed and in the proper gear, to increase

efficient use one way traffic pattern.

Haul time (min) = Haul distance (ft)

88 fpm / mph x Haul speed (mph)

3km = 3000 m = 9840 ft.

Haul speed mph = 25mph

= 9840

88 x 25 mp/h

Haul time = 4.47 min = 287 Sec.

Return time:-

Based on the empty vehicle wt & the rolling and grade resistance from the dump

point to the loading area return speed can be determined using the trucks

manufacturer performance chart.

Return Speed = 48.30 Mph

Return time (min) = Return distance (ft)

88 f pm/mph x Return speed (mph)

= 9840 = 2.32 min

88 x 48.3

= 152 Sec.


Dump time:-

Approximately 3.5 min = 230 sec.

Truck cycle time:

Truck cycle time = load time + Haul time + Dumpling + Return

Truck Cycle time = 1.20 + 4.47 + 3.5 + 2.32

= 11.50 min

Number of Truck Required. :-

Number of Trucks = Truck cycle time (min)

Loader cycle time (min)

= 11.50

1.12

= 10.27 trucks

= 10 trucks

Production

Production (1cum/hr) = Truck load (1cum) x 60 min

loader cycle time (min)

production (1cum/hr)= 4 Cum x 60 = 214.29 cum/hr 1.12

The production per day:-

1 hr = 6 hr = 214.29 x 6

6 hr = 1285.74 cum per day / truck

The 1, 00,000 cy of earth will be transported in 78 days.

To transport 20,000 cum of earth from site to dumping place it will take 15.5 day

= 16 days/per truck

1 day – 6 trips/truck = 1285.74

16 day - 96 trips

11 trucks x 1285.74 = 14143.14 cum will be transported by 11 trucks in 1 day.

= 1.5 day for 20.000 cum.


To bring in 3000 cum of sand from 20 km.

Truck Production

1) Number of bucket load = 3 bucket

2) Load time = 72 sec = 1.2 min

3) Hail time

20 km = 20,000 m = 65600 ft.

Haul speed mph. 40 mph

= 65600 = 18.63 min

88 x 40

4) Return time

Return Speed = 60 mph

Return time (min) = 65600 = 12.45 min

88 x 60

5) Dump time

Approximately = 4 min

6) Truck Cycle time

= 1.2 + 18.63 + 12.42 + 4

= 36.25 min

7) Number of truck required.

= 36.25 = 32.36 = 33 trucks

1.12

8) Production = 214.29 cum hr.

6 hr. = 1285.57 cum.

To transport 3000 cum of sand no. of day required.

= 2.5 day = 15 trips


DOZERS:

Consider we are using dozer of make Catter pillar D9 - tracks

Model No. : CAT (18 Acert (D9T)

3408 Haul (D9R

Gross power: - 346 kW (464 hp) D9T

Tractor 354 kw (475 hp D9R)

Fly wheel power: 306 KW (410hp) D9T

306 kw (410hp) D9R

280 kw (375hp) D9N

343 kw (460hp) D9L

Operation wt. : 48784 kg. (107550 lb)

Length: 8.1 m Width: 4 m blade Ht: 4m

Speed: 11.9 km/h forward 14.7 km/h increase

Blade capacities: 13.5 m3 (17.7 d3) 9 sv blade, 16.4 m3 (21.4 yd3) 9 u blade

Suppose dozer is used to push material 90 ft.

Production (1 as per 60 min-hr) = net hp x 330 (D + 50) = 375 x 330 (90 + 50)

= 883.93 cy/hr = 675.32 cum/hr

Per hour rate of dozers is 1260 per/hour

To complete 83000 (80000filling + 3000 sand) = 123 hrs. = 20 day.


ROLLER:-

1) Consider we are using “Maxmech” make smooth Drum Vibratory Roller Model

No. MDVA 925 Given

Dimension:-

Overall L = 4435 mm

Overall W = 1835 mm

Overall H = 3000 mm (top of canopy

Drum base = 3050 mm = 3.050, cub clearance = 400mm

Drum width = 1675 mm = 1675 mm, Drum Shell thk (machined) = 18 mm

Articulation angle = steering angle = 40, Oscillation angle = 10

Working speed = 0 – 6.5 Kmph = 4.0389 miles per how (mph)

Compacted lift thk = 8 inches, Mumbai of roller panes = 3 nos

Compacted cubic yards per hour = 16.3 x W x SxL x efficiency n

W = Compacted width per roller pas in feet

S = average roller speed in miles per hour

L = compacted lift thk. In inches

N = number of roller pass required to achieve the required. Density

= 16.3 x 1.675 x 4.039 x 066 x 50/60

20.21

= 15.44 cy/per hour cum/per hour

= 15.44 x 6 = 92.64 = 93 cum per day.

To compact 83000 cum of earth 5376 hrs = 892.47 day i.e. 893 days


Sr. No.

Per no. No. of Equip

Rate Amount

1. Front Shovel 88 days 2 2000/- per hour

10,56,000.00

2. Trucks 16 + 2.5 = 18.519 days

11 + 3344 nos

2500/- per day 47,500.00

3. Dozers 20 day(123 hrs)

3 nos 2000/- per hour

2,46,000.00

4. Roller 893 day(6hrs)

10 nos 7000/- per day 62,51,000.00

76,00,500.00

Total cost of equipment for this project Rs.76,00,500.00

To complete the work in 60 days we require following no of equipments:

Front shovel - 2 nos

Trucks - 44 nos

dozers - 3 nos

roller - 10 nos

PROCUREMENT OF MATERIAL BITUMEN:-

Duration of work 30 days from 60th day of starting of work i.e. 60th to 90th day.

Bitumen to be obtained from refinery at Bongaigwon in Assam. Lead time upto

site us 45 days storage facility available at site 59000 liter tank.

i.e. from starting of work reach on site.

i.e. 1st order on – 12th day – on 57th day.

i.e. 2nd order on 22nd day – on 67th day.

3rd orders – 32nd day – on 77th day.


CONCLUSION:

Materials management is very important for timely completion of the projects. A

delay in providing the materials for construction will naturally put the project

behind schedule from which it may never recover or the cost of bringing it back on

schedule may be very high. Such shortage disrupts the workflow and apart from

the lowering morale, need additional organizational efforts to generate the flow

again. Men and machines remain idle while they await the arrival of the materials.

These delays are not simply a matter of few weeks or days; they have a cascading

effect on the entire project performance. Because the construction is delayed, the

billing gets help u and affects the cash flow. Added to it, the additional overheads

that will be required to carry on the project to its final completion and the

liquidated damages that a contractor may have to pay for exceeding the time, limit

or the loss in productions and revenue for the owners. These are but direct and

visible effects of the delays. Internally, it may create friction among the various

departments or work units and generate widespread discontent among the

employees. This is caused by the feelings that while the other departments,

specifically the construction, are sweating it out to maintain the schedule; the

materials management dept. is taking things easy and creating avoidable pressures

on the schedule. Externally, it may cause embarrassment to the organization and

dissatisfaction among its customers. This loss of face may take a long time to

heal. Thus considerable management skill must go into ensuring the time

provision of variety of materials to be used in Construction.

Planning includes aspects like selection of equipments, number of size of units,

matching capacities, schedule of procurement, maintenance etc. The general

consideration for selection of equipment are suitability for the job, use of available

equipment, size of the equipment, variety reduction, standardization, versatility,

utilization, selection of manufacturer, suitability for local conditions, adaptability

and technical considerations. It would be obvious from the above details that the

planner / estimator should have a good understanding of the work site, methods /


techniques of work as well as the characteristics of the equipment, their output

factors affecting the output etc.

BIBLIOGRAPHY:

1) Peurifoy / Schexnayder, Construction Planning Equipments & Methods,

Tata McGraw Hill.

2) S.Seetharaman, Construction Engineering & Management, Umesh

Publications Delhi.

3) Dr. Mahesh Varma, Construction Equipment & Planning, Metropolitan

Books Co. Delhi.

Documents

Material Equipment