Estimation of Civil Engineering Projects
The Main Methods Used in Estimating Civil Engineering Project
Do you find yourself in a pickle while working on project estimation? Well, we are here to help you sort it out. And you may as well learn a few tricks to execute projects cost-effectively. Let’s get cracking!
Estimation is a scientific way of calculating an engineering project's approximate cost before it is completed. In other terms, a construction cost estimate is the project's expected cost based on the plans and specifications.
Estimating needs a complete understanding of building techniques as well as material and labor costs, in addition to abilities, experience, and foresight.
Plans and specifications are used to determine cost estimates. The actual cost of the proposed work should not deviate by more than 5 to 10% from the rough cost estimate, assuming no uncommon or unexpected conditions develop.
What is the purpose of estimation?
- It helps estimate the project’s cost to determine its economic feasibility and ensure monetary resources if the project has been approved.
- Estimation of required construction materials, such as cement, aggregate, and reinforcement.
- It is responsible for preparing work tenders and monitoring the contractor's performance.
- The contractor's work plan and payment schedule.
- Resources are assigned to different project activities based on detailed estimates of work quantities. The durations are part of the project's overall planning and schedule.
Image source: Civil concept
What is a complete estimate?
- A detailed estimate is referred to as a "complete estimate." It's a calculation of the overall costs of all work-related things in addition to the main contract.
- The building access road, deed execution, title examination, and surveying are all included in the cost of the land.
- The cost of legal fees.
- The total cost of the primary contract, including supplies, labor, and monitoring.
- Engineering comprises estimating the plan design, paying a sanctioned cost, and monitoring.
- 5% of the overall work value as a contingency.
- Water and electricity permit fees both during and after construction.
- The expense of transportation.
What are the different types of estimation?
Basically, there are two main types of estimates;
- Approximate estimate
- Detailed estimate
|Approximate Estimate||Detailed Estimate|
Different types of estimate
It's also known as a budget or an initial estimate. In the early stages of a project, this form of estimate is created. To provide the owner (client) with a comprehensive understanding of the project's cost and obtain clearance from the appropriate sanctioning bodies (e.g., banks to get a loan). Documentation such as project drawing plans, data about the site, including water and electricity supplies, and a comprehensive, unambiguous report are required to complete the estimation. Typically, an approximate estimate is produced based on previous experience.
Plinth area method:
Multiplying the values of length, width, and plinth area rate yields a plinth area estimate. The outside plinth area of the building at floor level is referred to here as the plinth area. Simply said, it is the portion of a building's roof that is covered. Estimated plinth area = plinth area X plinth area rate
Cubic content method:
The volume of the structure is multiplied by the unit cubic rate calculated from a previous estimate to arrive at this estimate. This form of estimation is slightly more accurate than the other approaches and is best suited to multi-story buildings.
Estimated cubic content = building volume X unit cubic rate
Service unit method:
Every structure has a function. A hospital, for example, is built to hold a certain number of beds. As a result, each bed is considered a service unit of the hospital.
It is possible to calculate the cost of construction per service unit whenever a structure is built.
Estimated service unit = No. of service unit X Cost per service unit
Typical bay method:
This method is suitable and is commonly used in the case of structures with several bays.
The cost of a typical bay is calculated and multiplied by the number of bays in the structure. A bay is a distance between two supports measured from center to center.
Approximate cost = No. of bays X cost per bay
Approximate quantity method:
The structure for this method is separated into two parts:
- The foundation, which includes the plinth
To calculate the running meter rate for foundation, calculate the approximate quantities of items such as excavation foundation, masonry up to plinth level, and DPC per running meter, then multiply by the rates of these items to get the price or rate per running meter.
A detailed estimate for the revised quantities and work items rates is initially indicated in the estimate prepared and submitted for technical sanction.
During the actual execution of the work, some changes or additional work may be required for the project's development.
These variations are attributable to material derivation or structural design differences. An abstract sheet should be prepared separately. This is referred to as a supplementary estimate.
Revised and supplementary estimate:
Construction work is ongoing, and if it is found that the original project's volume has increased, at that time, supplemental work will be sanctioned.
In such instances, a revised and supplementary estimate is prepared. The additional estimated amount is added to the updated estimate, which is shown separately.
Repair and maintenance estimate:
After the work is completed, it is required to maintain the structure in good condition. An estimate is generated for this purpose, which is known as a repair and maintenance estimate.
For building, this estimate is prepared for whitewashing, coloring, painting of doors and windows.
Other project estimation methods include:
1. Individual or independent wall method
2. Centerline method
3. Using the working drawings as a guide, measure the length, breadth, and height or depth (plan, elevation, and section).
4. Pay special attention to the positions of wall junctions, corners, and wall meetings.
5. Any of the ways mentioned above to estimate earthwork in foundations, foundation concrete, foundation and plinth brickwork, and superstructure brickwork for symmetrical footings.
How 3D Modeling Helps in Reducing Cost of the Project?
Bridge being designed in SelfCAD software
Let’s now look into the technology and software that can cut down your project expenses. Nowadays, most engineers and architects use 3D modeling software for planning, designing, and project evaluation. 3D modeling is much helpful in product design. The structure and appearance of the projects in the software come even without having to do any 2D drawing on paper.
Before, 3D modeling software was only being used by professionals as they were complex and difficult to use. But with the development of easy-to-use programs like SelfCAD, anyone, regardless of their experience in 3D modeling, can use the software and even come up with professional designs of your projects without having to spend months or years in learning.
3D modeling together with 3D printing helps reduce the cost of the projects too. After the project prototype has been created, errors can easily be identified and corrected while still in the development process. This saves time and materials that would have been wasted if the issues had been detected when development was already late.
3D modeling and 3D printing are also helpful when showing the clients the structure of the projects as they can view them in 3D. 3D modeling software also makes it easier to generate realistic 3D renders of the project that can be used for marketing too
There are many 3D modeling software available on the market. Still, if you are a beginner who is just starting in 3D modeling or a professional who wants to create complex and professional designs with ease, then SelfCAD is for you.
What sets SelfCAD apart is the presence of the interactive tutorials feature that makes it easier for one to learn 3D modeling. With the interactive tutorials, you won’t have to struggle to figure out where each tool is located as you are guided all through. And you don’t have to watch video tutorials or read articles. The interactive tutorials will help you learn.
To sum it all up, you’ve learned the purpose, different types and methods of project estimation, and most importantly, the cost-cutting 3D modeling software in the field of civil engineering. Kindly reach out to us if you need further clarifications. We’ll get back to you in a minute.
Enjoy powerful modeling, rendering, and 3D printing tools without the steep learning curve.
Need to learn 3D modeling? Get started with interactive tutorials.