CE 415 Construc.on Management

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CE 415 Construc.on

Management

SCHEDULE OF TOPICS

_Topic

1 The Construc.on Industry and Terminology

2 What is Construc.on Management? 3 Construc.on Procurement

(Bid Analyses and Construc.on Contracts) 4 Construc.on Project Organiza.on

5 Construc.on Planning and Scheduling 6 Construc.on Cost Es.ma.ons

7 Midterm Exam

8 Cost Equa.on and Examples 9 Cost Equa.on and Examples 10 Cost Equa.on and Examples 11 Project Budgets

12 Project Payments Analyses 13 Project Payments Analyses 14 Project Payments Analyses

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6. Construc.on Cost

Es.ma.on

6.1. Introduc:on

Cost es.ma.ng is an aQempt to forecast the actual cost of a project.

Cost es.mates play an important role for determina.on of the bid amount as well as development of the project budget. Inaccurate cost es.mates may lead to lost opportuni.es, lower than expected returns, and unsuccessful projects.

There are numerous es.ma.ng methods that could be used depending on the project type, delivery method, and details of the drawings available.

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6. Construc.on Cost

Es.ma.on

6.2. Type of Es:mates

There are several classiﬁca.ons about the cost es.mates depending on their accuracy level, or methods being used to determine the es.mated cost.

In general cost es.mates could be classiﬁed into two groups;

-‐  preliminary cost es.mates

-‐  detailed cost es.mates.

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6. Construc.on Cost

Es.ma.on

Preliminary cost es.mates also some.mes named as conceptual cost es.mates are usually prepared before drawings and speciﬁca.ons are available and detailed cost es.mates are prepared aZer construc.on drawings and speciﬁca.ons are available.

According to cost es.mate deﬁni.ons of Construc.on Cost Ins.tute (CII SD-‐6) preliminary cost es.mates are expected to have an accuracy range of ±10% to ±50% depending on the level of informa.on and es.ma.ng method being used. Detailed cost es.mates on the other hand, are expected to have an accuracy of ±1 to ±10% depending on the type of project.

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6. Construc.on Cost

Es.ma.on

Preliminary Cost Es:mates:

Preliminary cost es.mates are usually performed at the early stages of the projects with very limited informa.on since drawing and speciﬁca.ons are not available.

One of the main reasons for having preliminary es.mates is to decide about feasibility of a project.

If a project is determined as feasible based on the preliminary es.mate than detailed design, bidding, and construc.on stages could be ini.ated, therefore early es.mates play a crucial role on commi^ng resources for further development of a project.

Preliminary es.mates could also be used for evalua.on of diﬀerent project alterna.ves and also for development of an ini.al project budget.

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6. Construc.on Cost

Es.ma.on

Preliminary Cost Es:mates:

Numerous techniques could be used for preliminary cost es.ma.ng. In general data of past projects are used to develop preliminary cost es.mates.

A very simple method to determine a preliminary cost es.mate is to use average unit cost of similar projects such as 250 $/ m2_for

building construc.on, or 100 million $/km for metro construc.on.

Cost es.mates determined by average unit cost method are not expected to be accurate since these es.mates are very general, and are based on very limited project informa.on.

Modeling techniques such as regression analysis method could be used to improve accuracy of preliminary cost es.mates.

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6. Construc.on Cost

Es.ma.on

6.2. Type of Es:mates Detailed Es:mates:

Detailed es.ma.ng requires determina.on of the quan..es and all of the costs to complete the project

The costs to complete the project can be grouped into four categories;

-‐  material,

-‐  labor,

-‐  Equipment and machinery,

-‐  overhead costs.

A proﬁt is added to the total cost es.mate for determina.on of the bidding price.

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6. Construc.on Cost

Es.ma.on

Material costs include cost of all the bulk materials such as concrete, steel, lumber, cables, as well as cost of the mechanical and electrical items such as elevators, boilers and transformers.

Labor costs are the cost of the workers that will par.cipate in the project such as; carpenters, electricians, welders and helpers.

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6. Construc.on Cost

Es.ma.on

Equipment and machinery costs include expenses for the construc.on equipment and machinery such as cranes, trucks and excavators.

Overhead costs are the expenses that cannot be related to a speciﬁc construc.on ac.vity but rather general project expenses such as; oﬃce expenses, mobiliza.on and camp expenses, bond and insurance expenses

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6. Construc.on Cost

Es.ma.on

6.3. Detailed Es:mates Material Costs:

Once the approximate quan..es of material that will be used for the project are determined the contractor would request quota.ons (prices) from material suppliers and manufacturers for all materials required.

Although some.mes prices of manufacturers may be available as a list, it is more desirable to obtain wriQen quota.ons that include speciﬁca.ons of the material, transporta.on details, .me required for delivery, materials included in the price, taxes, guarantees and terms of payment.

When material costs quoted by diﬀerent manufacturers are being compared they must be brought to common basis; for example, delivered to site including all expenses.

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6. Construc.on Cost

Es.ma.on

6.3. Detailed Es:mates Labor Costs:

Labor costs are generally classiﬁed into two groups; direct labor costs, and indirect labor costs.

Direct labor contributes physical comple.on of a construc.on task for comple.on of a permanent facility. Examples for direct labor are; carpenter, electrician, concrete ﬁnisher, welder.

Indirect labor supports the comple.on of the project but cannot be iden.ﬁed as directly working for a speciﬁc task. Examples for indirect labor are; project manager, planning engineer, and .mekeeper.

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6. Construc.on Cost

Es.ma.on

6.3. Detailed Es:mates

Equipment And Machinery Costs:

Determina.on of the equipment and machinery that will be used for the project and dura.ons that the equipment and machinery will be used are needed for es.ma.on of equipment and machinery costs.

In order to es.mate equipment and machinery expenses accurately, early management decision must be made concerning the machinery sizes and types and also whether exis.ng machinery will be used or addi.onal machinery will be rented or purchased

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6. Construc.on Cost

Es.ma.on

6.3. Detailed Es:mates Overhead Costs:

Overhead costs are expenses that cannot be related to any speciﬁc item of work.

If the costs can be related to an item of work they should be included under the material, labor, or equipment costs.

The overhead costs are usually es.mated as a percentage of total project cost.

In calcula.on of unit prices of Ministry of Environment and Urban Planning the overhead expenses and proﬁt is taken as % 25 of the cost.

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6. Construc.on Cost

Es.ma.on

6.4. Quan:ty Takeoﬀ

The ﬁrst step of detailed es.ma.on is inves.ga.on of the bidding documents for prepara.on of quan.ty takeoﬀ.

A quan.ty takeoﬀ is a detailed calcula.on of quan..es for each work item that is going to be performed to complete the project.

Quan.ty takeoff is an important step of es.ma.ng and bidding and a complete set of bid documents including drawings, specifica.ons and condi.ons of contract are needed for prepara.on of quan.ty takeoff accurately.

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6. Construc.on Cost

Es.ma.on

6.4. Quan:ty Takeoﬀ

Quan.ty takeoﬀ process is mainly calcula.on of volumes, areas and coun.ng of elements, but it requires an organized approach to every drawing and construc.on item to ensure that not a single work item is missed.

To accomplish this eﬀec.vely the project must be divided into smaller work packages and each work package must be u.lized with the correct units.

During quan.ty takeoﬀ a common unit of measure should be used for each item included.

For example; for excava.on and backﬁll m3_{, for}

formwork m2_{, for concrete m}3_{, for structural}

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6. Construc.on Cost

Es.ma.on

6.5. Unit Prices and Analyses

Unit prices of Ministry of Environment and Urban Planning are used cost es.ma.on in construc.on projects.

According to the Ministry of Environment and Urban Planning, all construc.on has unit price.

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16.058/1A Pozu Detay Bilgileri Poz No :16.058/1A

Tanım :BASINÇ DAYANIM SINIFI C20/25 (BS 20) OLAN HAZIR BETON DÖKÜLMESİ (BETON NAKLİ DAHİL)

Uzun Tanım : SATIN ALINAN VE BETON POMPASIYLA BASILAN, BASINÇ DAYANIM SINIFI C20/25 (BS 20) OLAN HAZIR BETON DÖKÜLMESİ (BETON NAKLİ DAHİL)

Birim M3

Bulunduğu Kitap Çevre ve Şehircilik Bakanlığı

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6. Construc.on Cost

Es.ma.on

Unit Price Descrip.on:

Yıkanmış, elenmiş ve/veya kırılmış gronülometrik agrega ile projesinde öngörülen mukaveme. sağlayacak şekilde hazırlanmış ve basınç dayanımı C 20/25 olan hazır beton harcının sa{n alınması, trans mikserlere yüklenmesi, işyerine kadar nakli, döküm yerine beton pompası ile basılması, serilmesi, vibratör ile sıkış{rılması, gerek.ğinde sulanması, soğuktan, sıcaktan ve diğer dış tesirlerden korunması, gerekli ve yeter sayıda deney için numune alınması ve gerekli deneylerin yapılması, her türlü işçilik, malzeme ve zayia{, makine araç, gereç ve laboratuar giderleri, işyerindeki her türlü yatay ve düşey taşımalar, yükleme ve boşaltmalar betonun şan.yeye nakli ile müteahhit genel giderleri ve kârı dâhil, yerinde dökülmüş ve basınç dayanımı C 20/25 betonun 1 m³ﬁya{:

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6. Construc.on Cost

Es.ma.on

Unit Price Descrip.on:

ÖLÇÜ : Projedeki boyutlar üzerinden hesaplanır.

NOT :

1)Hazır betonlar “TSEK” belgeli üre.cilerden temin edilecek.r.

2)Hazır beton harcına giren çimento miktarı beton sınıﬂarına bağlı olarak deneylerle belirlenir.

3)Pompa kullanılmaması halinde, pompaj bedeli düşülür.

4)Çimento ﬁyat farkı hesabına esas olmak üzere birim ﬁyat listesinin sonundaki hazır beton, harçlarına ait çimento girdi tablosu esas alınacak{r.

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6. Construc.on Cost

Es.ma.on

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