CEE 6141

Construction Operations and

Productivity

By

Dr. Balimu Mwiya

 History of Machines:
Machines make things possible
Started when things had to be transported
• Animal transportation (carts)
• Steam powered machines
• Internal combustion engines
• Internal combustion engines
• Torque converter (separate engine & transmission)
• Base machine with multiple attachments
• Future???
Computer aided earth moving system (laser & global
positioning system)
Remove operator
Transform operator to a video gamer
 THREE PRINCIPLE
CONSIDERATIONS:-
– Technical efficiency
• Ability
• Requirement
• Correct specification
• timeframe
– Commercial and financial ability
• Cost
– Availability
• Supplier (location and numbers of supplier)
• within the timeframe
 Factors Selecting Equipment
1. The function to be carried out
2. Standard or special types of
equipment
3. Capacity of the equipment
4. Method of operation
5. Replacement of parts
6. Maintenance and repairs
7. Investment costs
8. Operating cost
FACTORS AFFECTING SELECTION OF
CONSTRUCTION EQUIPMENT
1. Use of equipment available with the
organization.
2. Suitability for job condition with special
reference to climatic and operating conditions.
3. Uniformity of type.
4. Size of equipment.
5. Use of standard equipment.
6. Country of origin.
7. Unit cost of production.
8. Availability of spare parts and selection of
manufacturers.
9. Suitability of local labour for operation.
 Classification of Construction
Equipment
1. Earth moving equipment.
2. Hauling equipment.
3. Conveying equipment.
4. Aggregate and concrete production
equipment.
5. Pile driving equipment.
6. Tunneling and rock drilling equipment.
7. Pumping and dewatering equipment.
 Types of Construction
Equipments
• Used to ground leveling and bulk
earthmoving. Divided into two :-

– Moving Machines-
• Bulldozers, loaders, scrapers,
graders and trenching machines
• The excavated material is removed,
transported and deposited
• For removal of large of earth
 Types of Construction
Equipment
Stationary machines
– Face shovels, backhoes, draglines and
grabs
– The excavator loosens the soil and loads
without changing position
– Loss of mobility compared to scrapers
and bucket loaders
– More force may be applied
 Types of Construction Equipment

Bulldozers Loaders Graders

Trenching machines Scrapers

Motor graders, Bulldozers,
Scrapers
 Types of Construction Equipment

Face shovel dragline

grab backhoe
 Equipment of Earthwork Plant
COMPONENTS OF APPLICABLE TYPES OF PLANT
WORK
Clearing and grubbing Bulldozer, rake- dozer
Excavation Shovels (power shove ,back hoe, dragline, clamshell), tractor –
shovel, bulldozer, ripper, breaker
Loading Shovels (power shovel, backhoe, dragline, clamshell), tractor-
shovel, bucket wheel excavator
Excavation and loading Shovels (power shovel, backhoe, dragline, clamshell), tractor-
shovel, bucket wheel excavator
Excavation and hauling Bulldozer, scrape-dozer ,scraper
Hauling Bulldozer , dump truck, belt conveyer
Spreading and grading Bulldozer, motor grader
Compaction Pneumatic-tired roller, tamping roller, vibrating roller, road roller,
vibrating compacter, rammer, tamper, bulldozer
Blasting Drilling (crawler, pneumatic,hydraulic), air compressor, lorry
 EARTHWORKS
PRICING OPERATIONS
The cost of earthwork operations depends
on:
– kind of soil or rock encountered
– methods used to excavate, haul, and place the
material in its final deposition.
• To compute the volume of earth or rock to
be moved is straight forward
• The earthwork quantities and average
movement distances can be determined
using the techniques such as Earthwork
Quantities and Mass Diagram
 EARTHWORKS
PRICING OPERATIONS
• Task is estimating the cost of actually
performing the work
• depends on both a careful study of the
project plans and a diligent site investigation
to identify the characteristics of the
subsurface soils and rock that will be
encountered.
• Proper equipment and estimated production
rates are determined by:
– selecting an appropriate type of machine and
– using machine performance data
 EARTHWORKS
Spread Production
• To accomplish a task, machines usually work
together and are supported by auxiliary machines.
• To accomplish a loading, hauling, and compacting
task would involve an excavator, several haul units,
and auxiliary machines to distribute the material on
the embankment, and achieve compaction.
• Such groups of equipment are referred to as an
equipment spread.

Spread is defined as
• A group of construction machines that work
together to accomplish a specific construction task
such as excavating, hauling, and compacting
material.
 EARTHWORKS
• An excavator and a fleet of trucks can be thought of as
a linked system
• If spreading and compaction of the hauled material is
required, a two-linked system is created.
• Because the systems are linked, the capabilities of the
individual components of the spread must be
compatible in terms of overall production
• The number of machines and specific types of machines
in a spread will vary with the proposed task.
• The production capacity of the total system is dictated
by the lesser of the production capacities of individual
systems.
• Our objective calculate the spread production rate
(linked-system production rate) and the cost per unit
of production.
 Two-linked spread

Haul, dump & return Spread & compact

Excavate & load
 Payload
• The payload capacity of construction
excavation and hauling equipment can be
expressed either volumetrically or
gravimetrically.
• Volumetric capacity can be stated as struck
or heaped volume
– The volume can be expressed in terms of loose
cubic yard/metres, bank cubic yard/metres, or
compacted cubic yard/metres.
• The payload capacity of excavation buckets
and hauling units is often stated by the
manufacturer in terms of the volume of
loose material, assuming that the material is
heaped in some specified angle or repose.
 Payload
• A gravimetric capacity represents the safe
operational weight that the axles or structural
frame of the machine is designed to handle.
• Overloading a truck or any other haul unit to
improve production and overloading by 20%
might increase the haulage rate 15%
• The cost per ton hauled should show a
corresponding decrease, since direct labour costs
will not change and fuel costs will increase only
slightly.
• But this is only temporary, for the advantage is
being bought at the cost of premature aging of
the truck and a corresponding increased
replacement capital expense.
 Machine Performance

• Cycle time and payload determine a

machine's production rate, and machine
travel speed directly affects cycle time.

• "Why does the machine only travel at

20 kph when its top speed is listed as
40 kph?“ Understand
– Required power
– Available power
– Usable power
HYDRAULIC EXCAVATORS
• The original and most common form of
hydraulically powered excavator is the
hydraulic excavator equipped with a hoe
front end. This machine is also called a
hydraulic hoe or hydraulic excavator-
backhoe.

• A backhoe (or simply hoe) is an

excavator designed primarily for
excavation below grade. As the name
implies, it digs by pulling the dipper
back toward the machine.
 HYDRAULIC EXCAVATORS
• The components of a hydraulic excavator are
illustrated in Figure. In this machine, the boom and
dipper arms are raised and lowered by hydraulic
cylinders. In addition, the dipper is pivoted at the
end of the dipper arm so that a wrist-like action is
provided.

• The backhoe is widely utilized for trenching work. In

addition to excavating the trench, it can perform
many other trenching functions, such as laying pipe
bedding, placing pipe, pulling trench shields, and
backfilling the trench. In trench excavation the best
measure of production is the length of trench
excavated per unit of time.
Typical Hydraulic Operated Backactor
Counter weight
 Production Estimating
No production tables have been prepared for
the hydraulic excavator. However, production
may be estimated by using Equation together
with Tables 1 and 2, which have been
prepared from manufacturers’ data.
Production Estimating
Production Estimating
 Production Estimating
EXAMPLE

Find the expected production in loose cubic

metres (LCM) per hour of a small
hydraulic excavator. Heaped bucket
capacity is 3⁄4 cu yd (0.57 m3). The
material is sand and gravel with a bucket
fill factor of 0.95. Job efficiency is 50
min/h. Average depth of cut is 14 ft (4.3
m). Maximum depth of cut is 20 ft (6.1
m) and average swing is 90.
 Production Estimating
• Cycle output = 250 cycles/60 min
(Table 1)
• Swing-depth factor = 1.00 (Table 2)
• Bucket volume = 0.75 LCY (0.57 LCM)
• Bucket fill factor = 0.95
• Job efficiency = 50/60 = 0.833
• Production = 250 × 1.00 × 0.57 × 0.95
× 0.833 = 113 LCM/h