SOURCES OF ESTIMATING INFORMATION FOR CIVIL ENGINEERING PROJECTS

For matters relevant to estimating and costs, the best source of information is your historical data. These figures allow for the pricing of the project to match how the company actually performs its construction.

This information takes into account the talent and training of the craft personnel and the management abilities of the field staff personnel. In addition, it integrates the construction companies’ practices and methodologies.

This is why a careful, accurate accounting system combined with accuracy in field reports is so important. If all of the information relating to the job is tracked and analyzed, it will be available for future reference.

Computerized cost accounting systems are very helpful in gathering this information and making it readily available for future reference. See Construction Accounting and Financial Management by Steven J. Peterson for more information on managing construction accounting systems.

There are several “guides to construction cost” manuals available; however, a word of extreme caution is offered regarding the use of these manuals. They are only guides; the figures should rarely be used to prepare an actual estimate.

The manuals may be used as a guide in checking current prices and should enable the estimator to follow a more uniform system and save valuable time. The actual pricing in the manuals is most appropriately used in helping architects check approximate current prices and facilitate their preliminary estimate.

In addition to these printed guides, many of these companies provide electronic databases that can be utilized by estimating software packages. However, the same caution needs to be observed as with the printed version.

These databases represent an average of the methodologies of a few contractors. There is no simple way to convert this generalized information to match the specifics of the construction companies’ methodologies.

QUANTITY ESTIMATING CIVIL ENGINEERING PROJECTS BASIC INFORMATION AND TUTORIALS

In Canada, parts of Europe, and on most road construction projects in the United States, the estimated quantities of materials required on the project are determined by a professional quantity surveyor or engineer and provided to the interested bidders on the project.

This is often referred to as a unit price bid. In this method of bidding, the contractors are all bidding based on the same quantities, and the estimator spends time developing the unit prices. For example, the bid may be $47.32 per cubic yard (cy) of concrete.

Because all of the contractors are bidding on the same quantities, they will work on keeping the cost of purchasing and installing the materials as low as possible.

As the project is built, the actual number of units required is checked against the original number of units on which the estimates were made. For example, the original quantity survey called for 715 linear feet (lf) of concrete curbing.

If 722 lf were actually installed, then the contractor would be paid for the additional 7 lf. If 706 lf were used, then the owner would pay only for the 706 lf installed and not the 715 lf in the original quantity survey.

This type of adjustment is quite common. When errors do occur and there is a large difference between the original quantity survey and the actual number of units, an adjustment to the unit price is made. Small adjustments are usually made at the same unit rate as the contractor bid.

Large errors may require that the unit price be renegotiated. If the contractor is aware of potential discrepancies between the estimated quantities and those that will be required, the contractor may price his or her bid to take advantage of this situation.

With a belief that the estimated quantities are low, the contractor may reduce his or her unit price to be the low bidder. If the assumption is true, the contractor has the potential to make the same profit by distributing the project overhead over a greater number of units.

THE JOB OF ESTIMATOR ON CIVIL ENGINEERING PROJECTS

Most estimators begin their career doing quantity takeoff; as they develop experience and judgment, they develop into estimators. A list of the abilities most important to the success of an estimator follows, but it should be more than simply read through.

Any weaknesses affect the estimator’s ability to produce complete and accurate estimates. If individuals lack any of these abilities, they must (1) be able to admit it and (2) begin to acquire the abilities they lack. Those with construction experience, who are subsequently trained as estimators, are often most successful in this field.

To be able to do quantity takeoffs, the estimator must

1. Be able to read and quantify plans.

2. Have knowledge of mathematics and a keen understanding of geometry. Most measurements and computations are made in linear feet, square feet, square yards, cubic feet, and cubic yards. The quantities are usually multiplied by a unit price to calculate material costs.

3. Have the patience and ability to do careful, thorough work.

4. Be computer literate and use computer takeoff programs such as On-Screen Takeoff or Paydirt.

To be an estimator, an individual needs to go a step further. He or she must

1. Be able, from looking at the drawings, to visualize the project through its various phases of construction. In addition, an estimator must be able to foresee problems, such as the placement of equipment or material storage, then develop a solution and determine its estimated cost.

2. Have enough construction experience to possess a good knowledge of job conditions, including methods of handling materials on the job, the most economical methods of construction, and labor productivity. With this experience, the estimator will be able to visualize the construction of the project and thus get the most accurate estimate on paper.

3. Have sufficient knowledge of labor operations and productivity to thus convert them into costs on a project. The estimator must understand how much work can be accomplished under given conditions by given crafts. Experience in construction and a study of projects that have been completed are required to develop this ability.

4. Be able to keep a database of information on costs of all kinds, including those of labor, material, project overhead, and equipment, as well as knowledge of the availability of all the required items.

5. Be computer literate and know how to manipulate and build various databases and use spreadsheet programs and other estimating software.

6. Be able to meet bid deadlines and still remain calm. Even in the rush of last-minute phone calls and the competitive feeling that seems to electrify the atmosphere just before the bids are due, estimators must “keep their cool.”

7. Have good writing and presentation skills. With more bids being awarded to the best bid, rather than the lowest bid, being able to communicate what your company has to offer, what is included in the bid, and selling your services is very important. It is also important to communicate to the project superintendent what is included in the bid, how the estimator planned to construct the project, and any potential pitfalls.

People cannot be taught experience and judgment, but they can be taught an acceptable method of preparing an estimate, items to include in the estimate, calculations required, and how to make them. They can also be warned against possible errors and alerted to certain problems and dangers, but the practical experience and use of good judgment required cannot be taught and must be obtained over time.

How closely the estimated cost will agree with the actual cost depends, to a large extent, on the estimators’ skill and judgment. Their skill enables them to use accurate estimating methods, while their judgment enables them to visualize the construction of the project throughout the stages of construction.

ESTIMATING CONCRETE WORKS FOR CIVIL ENGINEERING PROJECTS

Concrete is estimated by the cubic yard (cy) or by the cubic foot (cf) and then converted into cubic yards. Concrete quantities are measured in cubic yards as it is the pricing unit of the ready-mix companies, and most tables and charts available relate to the cubic yard.

Roof and floor slabs, slabs on grade, pavements, and sidewalks are most commonly measured and taken off in length, width, and thickness and converted to cubic feet and cubic yards (27 cf # 1 cy). Often, irregularly shaped projects are broken down into smaller areas for more accurate and convenient manipulation.

When estimating footings, columns, beams, and girders, their volume is determined by taking the linear footage of each item times its cross-sectional area. The cubic footage of the various items may then be tabulated and converted to cubic yards.

When estimating footings for buildings with irregular shapes and jogs, the estimator must be careful to include the corners only once. It is a good practice for the estimator to highlight on the plans which portions of the footings have been figured.

When taking measurements, keep in mind that the footings extend out from the foundation wall; therefore, the footing length is greater than the wall length.

In estimating quantities, the estimator makes no deductions for holes smaller than 2 sf or for the space that reinforcing bars or other miscellaneous accessories take up. Waste ranges from 5 percent for footings, columns, and beams to 8 percent for slabs.

The procedure that should be used to estimate the concrete on a project is as follows:

1. Review the specifications to determine the requirements for each area in which concrete is used separately (such as footings, floor slabs, and walkways) and list the following:

(a) Type of concrete

(b) Strength of concrete

(c) Color of concrete

(d) Any special curing or testing

2. Review the drawings to be certain that all concrete items shown on the drawings are covered in the specifications. If not, a call will have to be made to the architect-engineer so that an addendum can be issued.

3. List each of the concrete items required on the project.

4. Determine the quantities required from the working drawings. Footing sizes are checked on the wall sections and foundation plans. Watch for different size footings under different walls.

Concrete slab information will most commonly be found on wall sections, floor plans, and structural details. Exterior walks and driveways will most likely be identified on the plot (site) plan and in sections and details.

ESTIMATING MARGIN MARK UP ON CIVIL ENGINEERING PROJECTS BASIC AND TUTORIALS

Margin comprises three components: indirect costs, company-wide costs, and profit.

Determining Indirect, or Distributable, Costs
The techniques used to calculate indirect costs (often called indirects) resemble those used to calculate direct costs .

Parametric Technique. The indirects calculated by this technique may be expressed in many ways, for example, as a percentage of the direct cost of a project, as a percentage of the labor cost, or as a function of the distance to the site and the volume of the construction materials that must be moved there. For a warehouse, for instance, the cost of indirects is often taken to be either one-third the labor cost or 15% of the total cost.

Unit-Price Technique. To determine indirects by the unit-price technique, the estimator proceeds as follows: The various project activities not associated with a specific physical item are determined. Examples of such activities are project management, payroll, cleanup, waste disposal, and provision of temporary structures.

These activities are quantified in various ways: monthly rate, linear feet, cubic yards, and the like. For each of the activities, the estimator multiplies the unit price by the unit quantity to obtain activity cost. The total cost of indirects is the sum of the products.

Crew Development Technique. To determine the cost of the indirects by this technique, the estimator proceeds as follows: The various project activities not associated\ with a specific physical item are determined. Next, the estimator identifies the specific personnel needed (project manager, project engineer, payroll clerks) to perform these activities and determines their starting and ending dates and salaries.

Then, the estimator computes total personnel costs. After that, the estimator identifies the specific facilities and services needed, the length of time they are required, and the cost of each and calculates the total cost of these facilities and services. The total cost of indirects is the sum of all the preceding costs.

Determining Company-Wide Costs and Profit
Company-wide costs and profit, sometimes called gross margin, are usually lumped together for calculation purposes. Gross margin is generally a function of market conditions. Specifically, it depends on locale, state of the industry and economy, and type of discipline involved, such as mechanical, electrical, or structural.

To calculate gross margin, the estimator normally consults standard handbooks that give gross margin as a percent of project cost for various geographic areas and industries. The estimator also obtains from periodicals the market price for specific work.

Then, the information obtained from the various sources is combined. As an example, consider the case of a general contractor preparing a bid for a project in a geographic region where the company has not had recent experience.


At the time that the estimate is prepared, the contractor knows the direct and indirect costs but not the gross margin. To estimate this item, the estimator selects from handbooks published annually the gross margin, percent of total cost, for projects of the type to be constructed and for the region in which the building site is located.

Then, the estimator computes the dollar amount of the gross margin by multiplying the selected percentage by the previously calculated project cost and adds the product to that cost to obtain the total price for the project.

To validate this result, the estimator examines reports of recent bids for similar projects and compares appropriate bids with the price obtained from the use of handbooks. Then, the estimator adjusts the gross margin accordingly.

ROLE OF CIVIL ENGINEERING PROJECT COST ESTIMATOR

Most estimators begin their career doing quantity takeoff; as they develop experience and judgment, they develop into estimators. A list of the abilities most important to the success of an estimator follows, but it should be more than simply read through. Any weaknesses affect the estimator’s ability to produce complete and accurate estimates.

If individuals lack any of these abilities, they must (1) be able to admit it and (2) begin to acquire the abilities they lack. Those with construction experience, who are subsequently trained as estimators, are often most successful in this field.

To be able to do quantity takeoffs, the estimator must

1. Be able to read and quantify plans.

2. Have knowledge of mathematics and a keen understanding of geometry.Most measurements and computations are made in linear feet, square feet, square yards, cubic feet, and cubic yards. The quantities are usually multiplied by a unit price to calculate material costs.

3. Have the patience and ability to do careful, thorough work.

4. Be computer literate and use computer takeoff programs such as On-Screen Takeoff or Paydirt.


To be an estimator, an individual needs to go a step further. He or she must

1. Be able, from looking at the drawings, to visualize the project through its various phases of construction. In addition, an estimator must be able to foresee problems, such as the placement of equipment or material storage, then develop a solution and determine its estimated cost.

2. Have enough construction experience to possess a good knowledge of job conditions, including methods of handling materials on the job, the most economical methods of construction, and labor productivity. With this experience, the estimator will be able to visualize the construction of the project and thus get the most accurate estimate on paper.

3. Have sufficient knowledge of labor operations and productivity to thus convert them into costs on a project. The estimator must understand how much work can be accomplished under given conditions by given crafts. Experience in construction and a study of projects that have been completed are required to develop this ability.

4. Be able to keep a database of information on costs of all kinds, including those of labor, material, project
overhead, and equipment, as well as knowledge of the
availability of all the required items.

5. Be computer literate and know how to manipulate and build various databases and use spreadsheet programs and other estimating software.

6. Be able to meet bid deadlines and still remain calm. Even in the rush of last-minute phone calls and the competitive feeling that seems to electrify the atmosphere just before the bids are due, estimators must “keep their cool.”

7. Have good writing and presentation skills. With more bids being awarded to the best bid, rather than the lowest bid, being able to communicate what your company has to offer, what is included in the bid, and selling your services is very important.

It is also important to communicate to the project superintendent what is included in the bid, how the estimator planned to construct the project, and any potential pitfalls.

People cannot be taught experience and judgment, but they can be taught an acceptable method of preparing an estimate, items to include in the estimate, calculations required, and how to make them. They can also be warned against possible errors and alerted to certain problems and dangers, but the practical experience and use of good judgment required cannot be taught and must be obtained over time.

How closely the estimated cost will agree with the actual cost depends, to a large extent, on the estimators’ skill and judgment. Their skill enables them to use accurate estimating methods, while their judgment enables them to visualize the construction of the project throughout the stages of construction.

COMPOSITION OF CIVIL ENGINEERING PROJECT PRICE BASICS AND TUTORIALS

CIVIL ENGINEERING PROJECT COST COMPOSITION
What Is The Composition Of Civil Engineering Project Cost?


The total price of a construction project is the sum of direct costs, contingency costs, and margin. Direct costs are the labor, material, and equipment costs of project construction.

For example, the direct cost of a foundation of a building includes the following:

Costs of formwork, reinforcing steel, and concrete
Cost of labor to build and later strip the formwork, and place and finish the concrete
Cost of equipment associated with foundation activities, such as a concrete mixer

Contingency costs are those that should be added to the costs initially calculated to take into account events, such as rain or snow, that are likely to occur during the course of the project and affect overall project cost.

Although the effects and probability of occurrence of each contingency event cannot be accurately predicted, the total effect of all contingencies on project cost can be estimated with acceptable accuracy.

Margin (sometimes called markup) has three components: indirect, or distributable, costs; company-wide, or general and administrative, costs; and profit.

Indirect costs are project-specific costs that are not associated with a specific physical item. They include such items as the cost of project management, payroll preparation, receiving, accounts payable, waste disposal, and building permits.

Company-wide costs include the following:

(1) Costs that are incurred during the course of a project but are not project related; for example, costs of some portions of company salaries and rentals.

(2) Costs that are incurred before or after a project; for example, cost of proposal preparation and cost of outside auditing.

Profit is the amount of money that remains from the funds collected from the client after all costs have been paid.

COST ESTIMATING ON BUILDING PROJECTS TECHNIQUE AND TUTORIALS

COST ESTIMATING ON BUILDING PROJECTS BASIC TECHNIQUE
How To Do Cost Estimates On Building Projects?


During the late 1950s the technique of elemental cost planning on buildings was established. This technique enabled the client to obtain a more reliable pre-tender estimate and gave the design team a template in order to control the cost during the design development stages.

The technique was embraced by the Hertfordshire County Council and used successfully on the CLASP modular school building projects in the 1960s.

The technique is now well established in the building sector and has been further developed by the Building Cost Information Service of the RICS (BCIS) to include a national database of elemental cost analyses, which can be accessed using online computer techniques.

Such information can be used to aid the pre-contract estimating process in the building sector as well as helping to ensure VFM by aiding the designer to ensure the most appropriate distribution of costs within the project.

Cost management is the total process, which ensures that the contract sum is within the client’s approved budget or cost limit. It is the process of helping the design team design to a cost rather than the QS costing a design.

The basis of the design cost control using the cost-planning technique is the analysis of existing projects into functional elements in order to provide a means of comparison between projects planned with data from existing projects. A building element is defined as part of a building performing a function regardless of its specification.

Elemental analysis allows the comparison of the costs of the same element to be compared between two or more buildings.

As the cost element under consideration is performing the same function, an objective assessment can be made as to why there may be differences in costs between the same elements in different buildings. There are four main reasons why differences in costs occur:

1. Differences in time (inflation)
2. Quantitative differences
3. Qualitative differences
4. Differences in location.

On a major project it is necessary to consider individual buildings or parts of buildings. A major shopping centre may be split into common basement, finished malls, unfinished shells, hotel and car parking. The parts of the whole may be physically linked and difficult to separate, but separation will ease estimating and control.

The costs of the identifiable parts can then be compared against other schemes. For example, a composite rate per square metre is meaningless when you mix the cost of finished atrium malls with unfinished shells.

It is not only important to separate out parts of the building that serve different functions but it is equally important to separate for phasing. Many major projects have to be built around existing structures, which increase the cost because of temporary works as well as inflation.

The client’s and project’s status with regard to VAT will also need to be established. In the UK VAT is currently payable on building work other than constructing new dwellings and certain buildings used solely on both residential and non-business charitable purposes and also on all consultants and professional fees. The current VAT rate is 17.5%.

It is customary to exclude this amount from estimates and tenders, a practice that is well understood in the construction industry. However, this must be pointed out to any client who otherwise may think that the estimate is their total liability (Ferry and Brandon, 1999).

COST ESTIMATING ON CIVIL ENGINEERING PROJECTS BASIC AND TUTORIALS

COST ESTIMATING ON CIVIL ENGINEERING PROJECTS BASIC INFORMATION
How To Make Cost Estimates For Civil Engineering Projects?


In carrying out cost management there should be a clearly defined route from feasibility stage through to the placement of a contract. There should be break points, or gateways, when the client can take the decision whether to proceed or not.  This is in line with the recommendations by the Office of Government Commerce in their Gateway Review Process.

One of the benefits of cost management in the pre-contract stage, especially in multicontract projects, is that it helps the project team to better establish the appropriate project contract strategy. That is, which work should be placed in which contract and possibly the form of contract which should be adopted for particular contracts.

Cost management can also help identify possible programme restraints both in contract preparation and execution. The preparation of the first estimate would be based on a variety of techniques, for example, historic data or approximate quantities.

Major projects often have substantial elements that are unique and for which there is no relevant historic data. In these cases it is necessary to analyse the project in as many individual work sections as can be identified, if possible to prepare indicative quantities and consider the resources necessary to carry out the work.

During this indicative stage it is wise to contact potential contractors and manufacturers especially with
regard to order-of-cost estimates for specialist sections.

Other matters that have an effect on cost and need to be addressed at this time include location of project and access thereto, especially with regard to heavy and large loads, availability of labour and the possible need for residential hostels or other accommodation for workmen, off-site construction, temporary works. It will also be necessary to consider allowances for design development, allowances for consultants’ fees and client’s costs, land-acquisition costs and general contingencies.

When the client has accepted the first estimate and instructs that the project proceed to the next stage, then this becomes the first cost plan against which further design developments and changes are monitored.

During the process of design development the main duties of the quantity surveyor as part of the cost management team are as follows: to check and report the cost of design solutions as they are established or refined by the engineers;  to prepare comparative estimates of various design solutions or alternatives and advise the engineer accordingly;  as changes are introduced into the project, to estimate the cost effect of the change and to report;  to prepare a pre-tender estimate based on a bill of quantities (BofQ) or priced activities;  to prepare a financial appraisal.


The monthly issue of the updated cost plan is the vehicle whereby the cost management team is made aware of the current estimated cost of the project. In its simplest form a pre-contract cost plan will set out in tabular form each and every work section, the approved estimate for that section, the estimate for the previous and the current month for the section and a note of the changes that have taken place in the month. The total of all the sections provides the estimated cost of the project.

There should be a continuous dialogue between the designers and the quantity surveyor (QS); ideally both should work together in the same office during the critical stages of design development. Normally, there are so many changes within a month during design development that these are better listed as an appendix to the cost plan.

One national client insists that a separate appendix to the cost plans lists all potential changes and these have to be approved by his project manager before changes can be included in the cost plan. In this way the cost plan represents committed cost only (Shrimpton, 1988).

The extent of detail in the preparation and updating of cost plans is such that it is best handled on a database for transfer to a spreadsheet.

The accepted estimate in the form of priced activities or BofQs becomes the basis for the first post-contract cost plan. This then acts as the client’s design datum for cost management and reporting in the construction stage.

PROJECT ESTIMATOR ROLE IN CIVIL ENGINEERING PROJECT GUIDE AND TUTORIALS

PROJECT ESTIMATOR ROLE IN CIVIL ENGINEERING PROJECT
What Is The Role Of Project Estimator In Civil Engineering Project?


The estimator for the project will be involved with putting together conceptual budgets, design development budgets, and progress construction document estimates, and preparing the project budgets including subcontractor trade costs, general conditions costs, contingencies, fees, insurances, and analysis of the subcontractors bids.

The estimator must have a full understanding of all aspects of the construction process, the delineation of the work among the subcontractor trades and jurisdictions, cost of construction materials, cost of construction personnel, and appropriate mark ups in order to put together meaningful estimates and budgets for the project.

During the preconstruction phase, the estimator will play a key role in working with the project team to define the project scope, design intent, architectural finishes, engineering systems, specialty items, long lead items, appropriate inflation, and contingency factors to develop a meaningful estimate for the project.

If the estimate is too high or too low, it can significantly affect the feasibility and scope of the project and cause a creditability problem for the CM/GC. The estimator must have a sixth sense and a magic scale to weigh and assess matters to come up with a meaningful estimate for the project, even when there is little documentation from the design team on which to base it.

Estimates during the preconstruction phase of the project are often done on an order of magnitude basis or by cost per square foot, cost per Btu of cooling or heating, and cost per kilowatt of electrical load. Often, allowances may be made where sufficient definition of the exact scope of certain items, such as the lobby, plaza, roof garden, and signage is not available.

In these cases, a target allowance is helpful for the entire project team to manage the design and engineering of the area or system. The estimator will usually work out of the home office during this phase of the project.

During the bid and award process, the estimator will be involved with developing the list of perspective bidders, screening and finalizing the list of bidders, developing bid packages, receiving bids, analyzing and leveling bids, recommending award of subcontracts, and reviewing the bid for completeness, qualification and exclusions, and unit prices.

This is a very important and critical task; if the subcontractor is not scoped out properly and is awarded without a complete project purchase, the amount of change orders and claims thereafter can be significant and have a negative impact on the project. The estimator will usually work out of the on-site project office for all phases of the project.

During the construction phase, the estimator will be involved with pricing change orders for bulletins, sketches, field information memos (FIMs), requests for information (RFIs), and reviewing subcontractor’s claims for extra work as it relates to their contracts.

All allowances that may have been included in a subcontract need to be accounted for and reconciled as the final scope of work and project is defined.

During the project close-out phase, the estimator will be finalizing all subcontractor final contract amounts, including all base contract amounts, approved change orders, adjustment of allowances, back charges, etc. to determine the final contract price for each subcontractor.

You want to be a project estimator? Give us your thoughts and leave a comment. :)

LABOR COST ESTIMATING IN CIVIL ENGINEERING CONSTRUCTION PROJECT TUTORIALS

LABOR COST ESTIMATES TUTORIALS ON CIVIL ENGINEERING PROJECTS
How To Make Labor Costing Estimates For Civil Engineering Projects?


Cost of Labor
For a detailed estimate, it is imperative that the cost of labor resources be determined with precision. This is accomplished through a three-part process from data in the construction bidding documents that identify the nature of work and the physical quantity of work.

The first step in the process involves identifying the craft that will be assigned the work and determining the hourly cost for that labor resource. This is termed the labor rate.

The second part of the process involves estimation of the expected rate of work accomplishment by the chosen labor resource. This is termed the labor productivity.

The third step involves combining this information by dividing the labor rate by the labor productivity to determine the labor resource cost per physical unit of work. The labor cost can be determined by multiplying the quantity of work by the unit labor resource cost.

Labor Rate — The labor rate is the total hourly expense or cost to the contractor for providing the particular craft or labor resource for the project. This labor rate includes direct costs and indirect costs.

Direct labor costs include all payments made directly to the craftsworkers. The following is a brief listing of direct labor cost components:

1. Wage rate
2. Overtime premium
3. Travel time allowance
4. Subsistence allowance
5. Show-up time allowance
6. Other work or performance premiums

The sum of these direct labor costs is sometimes referred to as the effective wage rate. Indirect labor costs include those costs incurred as a result of use of labor resources but which are not paid directly to the craftsworker. The components of indirect labor cost include the following:


1. Vacation fund contributions
2. Pension fund contributions
3. Group insurance premiums
4. Health and welfare contributions
5. Apprenticeship and training programs
6. Workers’ compensation premiums
7. Unemployment insurance premiums
8. Social security contribution
9. Other voluntary contribution or payroll tax

It is the summation of direct and indirect labor costs that is termed the labor rate — the total hourly cost of providing a particular craft labor resource. Where a collective bargaining agreement is in force, most of these items can be readily determined on an hourly basis.

Others are readily available from insurance companies or from local, state, and federal statutes. Several of the direct cost components must be estimated based on past records to determine the appropriate allowance to be included.

These more difficult items include overtime, show-up time, and performance premiums. A percentage allowance is usually used to estimate the expected cost impact of such items.

Labor Productivity — Of all the cost elements that contribute to the total project construction cost, labor productivity ranks at the top for variability. Because labor costs represent a significant proportion of the total cost of construction, it is vital that good estimates of productivity be made relative to the productivity
that will be experienced on the project.

Productivity assessment is a complex process and not yet fully understood for the construction industry.
The following example illustrates the calculation of a unit price from productivity data.


Example 11
To form 100 square feet of wall requires 6 hours of carpenter time and 5 hours of common laborer time. This assumption is based on standards calculated as averages from historical data. The wage rate with burdens for carpenters is $60.00/h. The wage rate with burdens for common laborers is $22.00/h.

Solution. The unit cost may be calculated as follows:
This labor cost is adjusted for the following conditions:
Carpenter — 6 h at $60.00/h = $360.00
Laborer — 5 h at $22.00/h = $110.00
Total labor cost for 100 ft2 = $470.00
Weather adjustment 1.05
Job complexity 1.04
Crew experience 0.95
Management 1.00
Labor cost per ft2 = $470.00 100 ft2 = $4.70 ft2
Adjusted unit cost = 4 70 ¥ 1 05 ¥ 1 04 ¥ 0 95 ¥ 1 00 =  $4 88/ ft2

CONCEPTUAL ESTIMATING IN CIVIL ENGINEERING PROJECTS TUTORIALS

CONCEPTUAL ESTIMATES IN CIVIL ENGINEERING PROJECT COST ESTIMATES SAMPLE
What Is Conceptual Estimates In Civil Engineering Construction Projects?


Conceptual Estimates
At the outset of the project, when the scope and definition are in the early stages of development, little information is available, yet there is often a need for some assessment of the potential cost. The owner needs to have a rough or approximate value for the project’s cost for purposes of determining the economic desirability of proceeding with design and construction.

Special quick techniques are usually employed, utilizing minimal available information at this point to prepare a conceptual estimate. Little effort is expended to prepare this type of estimate, which often utilizes only a single project parameter, such as square feet of floor area, span length of a bridge, or barrels per day of output.

Using available, historical cost information and applying like parameters, a quick and simple estimate can be prepared. These types of estimates are valuable in determining the order of magnitude of the cost for very rough comparisons and analysis but are not appropriate for critical decision making and commitment.

Many situations exist that do not warrant or allow expenditure of the time and effort required to produce a detailed estimate. Feasibility studies involve elimination of many alternatives prior to any detailed design work. Obviously, if detailed design were pursued prior to estimating, the cost of the feasibility study would be enormous.

Time constraints may also limit the level of detail that can be employed. If an answer is required in a few minutes or a few hours, then the method must be a conceptual one, even if detailed design information is available.

Conceptual estimates have value, but they have many limitations as well. Care must be exercised to choose the appropriate method for conceptual estimating based on the available information. The estimator must be aware of the limitations of his estimate and communicate these limitations so that the estimate is not misused. Conceptual estimating relies heavily on past cost data, which is adjusted to reflect current trends and actual project economic conditions.

The accuracy of an estimate is a function of time spent in its preparation, the quantity of design data utilized in the evaluation, and the accuracy of the information used. In general, more effort and more money produce a better estimate, one in which the estimator has more confidence regarding the accuracy of his or her prediction.

To achieve significant improvement in accuracy requires a larger-than-proportional increase in effort. Each of the three conceptual levels of estimating has several methods that are utilized, depending on the project type and the availability of time and information.