Introduction to construction management
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Transcript of Introduction to construction management
Introduction to Construction Management
Presentation By: Aditi K. Shah
Content
▪ Importance of machineries in construction
▪ Classification of Construction Equipment
▪ Plants & Equipment used in construction
▪ Factors affecting selection of construction equipment
▪ Financial aspects related to construction equipments
▪ Discounted present worth analysis
▪ Depreciation
▪ Cost of owning and operating construction equipment
▪ Economic life of construction equipment
▪ Equipment replacement policy
The importance of machineries for construction
▪ Work can be completed fast.
▪ Cost of project is reduced.
▪ Less number of laborers required.
▪ Excavation work can be carried out rapidly by using Power shovel, Dragline etc.
▪ Output is higher
▪ Transportation of construction materials can be done easily by using Trucks, Wagons, Dumpers etc.
▪ Heavy loads can be lifted with the help of Tower crane, Elevator etc.
The importance of machineries for construction (contd.)
▪ Better quality in construction is obtained by using construction equipments.
▪ E.g.: canal lining, concrete spreading, compaction & finishing are carried out by lining machine.
▪ Finishing & rolling of bituminous roads is not possible without Rollers.
Power Shovel
Dragline
Dumper
Tower
Crane
Lining Machi
ne
Concrete
Mixer
Bulldozer
Scrapper
Aircompres
sor
BeltConvey
or
Classification of Construction Equipment(according to work cycle)
1. Intermittent Type: a. Bulldozers
b. Scrappers
c. Power Shovels
d. Concrete Mixers
e. Dragline
2. Continuous Flow Type: a. Air Compressors
b. Belt Conveyors
3. Mixed Type: a. Motor Graders
Classification of Construction Equipment(according to nature of Automation)
1. Manually Operated Equipment
2. Semi-Automatic Equipment
3. Fully Automatic Equipment
Classification of ConstructionEquipment(according to Standardization of machine)
1. Standard Equipment
2. Special Equipment
Difference B/w Standard and Special Equipments
Standard Equipment▪ Commonly used in all projects
▪ Manufactured commonly & easily available from dealer
▪ Initial investment is low
▪ Resale price is high
▪ Delivery is easy & fast
▪ Repairs and spare parts are easily found
▪ Disposal is easy
▪ Unit cost of production is less
▪ Rent is low and reasonable
▪ E.g. Canal Trimmer
Special Equipment▪ Used only in special cases
▪ Manufactured as per requirements, special order has to be placed
▪ Initial investment is high
▪ Resale price is low
▪ Delivery is difficult & delayed
▪ Repairs and spare parts are difficult to find
▪ Disposal is difficult
▪ Unit cost of production is high
▪ Rent is high and unreasonable
▪ E.g. Belt Conveyor
Plants & Equipments used in Construction
▪ Equipment for Excavation
▪ Earthmoving equipment
▪ Hauling equipment
▪ Hoisting equipment
▪ Conveying equipment
▪ Pile driving equipment
▪ Drilling equipment
▪ Equipment for production of aggregate
▪ Plant for grouting and guniting
▪ Machineries for bituminous road
▪ Machineries for concrete works
▪ Dredging equipment
Equipment for
Excavation
Earthmoving
Equipment
Hauling Equipm
ent
HoistingEquipment
Conveying Equipment
PumpingEquipment
Compactingequipment
Pile DrivingEquipment
Drilling Equipment
Equipment for production of
Aggregate
Grouting
Guniting
Machinery for Bituminous Road
Dredging Equipment
Factors affecting the selection of Construction Equipment
1. Use of standard equipments
2. Size of equipment
3. Uniformity of type
4. Country of origin
5. Initial cost of equipment
6. Availability of spare parts
7. Unit cost of production
8. Operating facility
9. Suitability for future
Financial aspects related to construction equipments
▪ How to arrange finance
▪ Whether to buy or hire
Sources of equipment
Long term
BuyDown payment
On loans mobilized
Payment in installments
Lease
Time lease
Leasing with
option to buy
later
Short term
Direct purchase
Advantages▪ Equipment is always
economically operated
▪ It receives better care & maintenance
▪ It can be available and used at any time
Disadvantages▪ If equipment becomes obsolete, it
is useless
▪ Large sums involved remain blocked
▪ Tendency to perform work as per available equipment
▪ Disposal is difficult
▪ Equipment may be used beyond its economic life
▪ Equipment may remain in idle condition for some time
Hiring (advantages)
▪ Little care is required for maintenance and storage
▪ Desired equipment is available in working order at short notice
▪ Investment costs can be diverted to other better purposes
▪ No fear of obsolescence of equipment, full advantage is taken by contractor of the improved technical aspects of equipment
▪ If found useful, equipment can be bought later
Examples- Purchase/ Hire
▪ The original cost of bulldozer power shovel is Rs. 4 lacs & its salvage value is 8% of the original cost. The bulldozer is use for 1200 hours/year and its life is 4 years. The hiring charges for the bulldozer incl. maintenance & repairs is Rs. 20000/month. Suggest whether the bulldozer should be purchased or hired.
Solution: (on the board)
Discounted Present Worth Analysis
▪ It involves calculating the present value of all amounts involved in all the alternatives to determine the present worth of the proposed alternatives.
▪ Decision problems may be of two types:
a. Revenue dominated cash flow diagram b. Cost dominated cash flow diagram
What is Inflow and Outflow:
(a) Revenue Profit dominated cash flow diagram:
▪ In this type of cash flow diagram, the revenue, profit, salvage value, etc. (inflows) will be assigned a (+ve) sign while costs (outflows) will be assigned.
▪ Finally, the alternative having the maximum present worth amount should be selected as the best alternative.
(b) Cost dominated cash flow diagram:
▪ In this type of diagram, the cost(outflows) will be assigned with (+ve) sign and revenue, profit, salvage value(all inflows) etc. will be assigned with (-ve) sign.
▪ Finally, the alternative having the minimum present worth amount should be selected as the best alternative.
Depreciation
▪ It is the gradual loss in the value of the property due to its use, life, wear, tear and decay.
▪ It is dependent on its original condition, quality of maintenance & mode of use.
▪ Usually a % of depreciation per annum is allowed, which gradually increases with time
▪ Present value of property = Initial cost - Total amount of depreciation
Types of depreciation
a) Physical depreciation
1. wear and tear from operation
2. action of time and other elements
b) Functional depreciation
1. inadequacy or suppression
2. obsolescence
Methods of Calculating Depreciation:
1. Straight Line method
2. Constant Percentage method
3. Sinking Fund method
4. Sum of Digits method
5. Service Output method
Straight Line methodAssumption: Property loses its value by the same amount every year.
Therefore, Annual Depreciation= Annual Decrease in property value
where, D= Annual Depreciation
C= Original Cost
Depreciation of property after m years: S= Scrap Value
n , m= life in years
Therefore, Book value after m years:
Constant Percentage method▪ Assumption: Property will lose its value by a constant
percentage of its value at the beginning of every year.
Where, p= % rate of annual Depreciation
S= Scrap value
C= Original cost
n= life in years
▪ If any age of property is m years, the value of property after m years:
Sinking Fund method▪ Assumption: depreciation of the property = the annual
sinking fund + interest on the sinking fund for that year
▪ If I is the rate of interest, the annual sinking fund installment(p) to accumulate 1 Rs in m years:
▪ If I is the rate of interest, and 1 Rs is deposited every year, total sinking fund accumulated at the end of n years:
▪ Rate of depreciation in n years:
Factors affecting Cost of Owning & operating Equipment:
▪ Cost of the equipment to the owner
▪ Demand of the equipment at the end of its useful life
▪ Number of hours it is used per year
▪ Number of years it is used
▪ Severity of conditions under which it is used
▪ State of maintenance and repairs
Costs to be considered for owning and operating equipment:▪ Depreciation Cost
▪ Investment Cost (Average investment= )
▪ Maintenance and repair Cost
▪ Operation Cost (Repair charges, Depreciation on tyres and tubes, Labour Charges, Fuel Charges, Operators and maintenance crew charges, Miscellaneous Supplies)
▪ Down time Cost
▪ Obsolescence Cost
▪ Replacement Costs
NumericalFor construction Equipment following information is available.
Initial cost of acquisition = Rs 6500000
Cost of tyre sets = Rs 350000, replaced after every 4500 hours
Cost of lubricants, minor
Repairs and maintenance = Rs 1100/hour
Estimated life = 13500 hours of operation
Estimated salvage value = 15% of initial cost
Estimated usage of equipment= 1500 hours/year
If MARR is 20% per year, Estimate minimum hourly rental charges for equipment
Economic life of Construction Equipments:
Equipment should be replaced under following circumstances:
1. Depreciation
2. Downtime
3. Inadequacy
4. Normal Deterioration
Equipment Replacement Policy:
A firm has to face three type of decisions:
1. The replacement of equipment as it wears out
2. The equipment required for expansion
3. The replacement of old technology by new
Equipment is replaced before its estimated life to:
▪ Reduce production cost
▪ Reduce fatigue
▪ Raise quality
▪ Increase output
▪ Secure greater convenience, safety and reliability
What not to consider while selecting an equipment:
For Equipment in Use
▪ Original Cost
▪ Money already spent on repairs and maintenance
▪ Unrealistic book value
For New Equipment
▪ Any savings not clearly assessable
▪ Overhead charges
Thank you