Grading and excavation civil drawings

[Nunleyinc]

We are a small family owned company. We have successfully been in business for 15 years however some how we gotten by using the help of a very generous friend with our bids. He has helped us by doing the math but I feel it is time to step it up and learn this myself so I can help with the estimating. The square footage of a pad or a drive way is easy. Linear foot of lines is easy to bid looking at plans but when it comes to excavation and understanding the math of cutting a hill down and placing a pad on top I am clueless. Are there online classes or a way for me to learn this fast and effective? I coule take full courses but feel that almost all of them are hard to understand or teach a bunch of stuff that is irrelevant to what I need to learn. Ay help would be greatfully appreciated. Thanks

 

[Ron]

I am conflicted by your post. I won't bother to get into the fact that this site is for engineers to discuss engineering.

You are obviously not an engineer so I will presume you are a contractor. I applaud your desire to learn more about what you are doing, but I'm amazed that you have been successful in the business for 15 years without knowing how or why you are doing site work.

I will also assume that your location does not require contractors to be licensed, since those issues you noted are commonly found on licensing exams.

You are asking for a shortcut to learning what most contractors spend 4 years in a construction or construction management degree program. Yes, there are courses you can take and books you can read to help you understand some things, but you really need to try to learn more than just some disjointed facts and computations.

As an example, if you learn about different soil types you will learn to match the proper equipment to the task at hand so that you can optimize time and equipment use and make more PROFIT! A simple example is compaction. If you know something about the soil you are compacting and you understand the moisture-density relationship (Proctor) curve for that soil, you can significantly reduce your compaction effort, pass tests the first time, and reduce your time on site....all leading to more profit.

There are numerous books on the subject...I am the co-author of one that is used by many universities and contractor licensing groups, however, it would not be appropriate for me to plug that here.

Good luck. You owe it to yourself and your clients to know as much as possible about what you do.

 

[Nunleyinc]

Well as condescending as your post was Ron i will reply. Last night i had an ipad and a 3 year old in my lap so i tried to be brief. My father runs our company. He does most the bidding. When he gets to Jobs of a certain size he has a close friend of ours in the trades help with bidding the project, yes we are licensed and yes we can do the work thanks again for your condescending words. I have little experience in bidding a project though. I have done take offs that encounter linear foot and Square Footage type projects like PG&E lines or Driveways. When it comes to Earth Moving is what i am trying to learn. As you are a "Engineer" than you understand that i am trying to learn how to read the civil drawings not write them. I just want to be able to see how much dirt is coming off a mountain where the pad is going to be going.

Your example on soil is what a soils report is for. It tells me what type of soil i will be going through. What i can expect while digging. I have formulas already in place to deal with that.

Dont plug your book to someone your talking down to. If you were more helpful and did not talk down to me i most likely would have looked into your book but now i feel that your arrogance deserves none of my business.

Also...this website designed for Engineers? i do Engineered work does that not count? I had a question about Earth work and Grading, does that not count?

 

[Ron]

Nunleyinc...my apologies if you considered my comments to be condescending. I certainly don't intend that. I specialize in failure investigations of structures and construction, so I see numerous examples of contractors who don't understand even the basics of what they do. I am trying to offer you the benefit of that experience.

Again, I am glad you are seeking additional knowledge in your area of practice. My point was that it isn't as simple as taking a few disjointed courses, though some can be helpful. Yes, a soils report tells you lots of info, but you have to be able to interpret that info to best use it. As for excavation calculations, there are several approaches that are valid depending on the reason for the excavation. Many community colleges have courses that will give you some of the basics.

I am by no means plugging my book. I have not given you the title and you don't know my name, so I doubt you could find it. My point was that there are such texts available so you might look at a few.

I am a licensed contractor and an engineer. I have been exposed to a lot in my career. I'm not being arrogant nor condescending....just trying to inform.

By the way...the 3-year old is more important the all of this or anything else for that matter. Have fun with him/her!!

 

[oldestguy]

I have been acquainted with many a contractor and feel that asking here will not directly answer your question. Of the many experienced contractors I have known, most have learned from the bottom up. In the family situation it generally seems that the old man has done the teaching. Just recently the president of a large company, after the old man died, told me how the old man would make him grease the rigs and do other menial tasks so that he would later know what was going on out there.

My suggestion is check with your mentor about this. It would seem that such a contact would be a most useful way to gradually get the hang of the bidding process you have now taken on.

Another firm hired a good tech from an engineering firm I was with (our loss), mainly due to his smarts, but not necessarily his experience. Now that tech is the best estimator he has. Consider offering a job to someone experienced out there that may make a change.

Lastly, no one here takes pleasure in giving negative opinions about how to do something. It's hard to "say it like it is" without some one not taking it as intended. I've been called names, of sorts. One was true however saying I must be old. That was right ---soon 85.

 

[beej67]

Oh come on guys, I did this as an engineering intern when I was 16. It's not like it's rocket science.

Take a set of plans.

Draw a grid on it. Note the width of the grid you drew. Square the length of one side to determine grid area. Kids algebra.

Average the existing elevation at the for corners of a grid box. Write this number down in red pen in the middle of the grid box. More kids algebra.

Average the proposed elevation at the four corners of the same grid box. Write this number down in blue pen. More kids algebra.

Subtract the elevations. This gives you the average elevation difference for the grid box. Multiply by the grid area and you get an approximate volume difference between the existing finished grade and the proposed finished grade, for that box. Make all cuts negative and fills positive (or visa versa, whatever, just be consistent).

Now do it again and again for each grid square and add them up. Denser grids give greater accuracy. Certain grid orientations may provoke more errors, but a tight enough grid always gives you an answer that's close enough to what you need. Determine that through experience.

That's how you do volume takeoff, the old fashioned elbow-grease way. Have fun. That's not all you'll need to know, though. You have to take into account topsoil depth, because you can't backfill with that. Or maybe you can, if you can stockpile it, but only in landscaped areas, and maybe only to certain depths, so plan all that out. You have to take into account shrinkage and swell factors for different soils, which act like multipliers to the calculated volumes, but perhaps only for the cuts and/or fills. You have to take into account depths of rock if you have to rip it or blast it. Fun times. You have to take into account whether certain material is suitable fill, according to your geotech. And then if you're doing a construction cost estimate, you have to take into account how you're doing the cutting and/or filling, what machinery you're using, whether you have any haul-off or import, etc. For all that mess, I'd recommend learning how to use the Means Manual, or better, compiling a detailed list of the quantities of all your previous jobs, and what those cost, and using that as your indexing method to determine future costs. Or even better, hire an engineer.

There are other ways to do this, by the way, such as if you had road sections or other starting info to go off of. And most everybody nowadays uses a TIN in a CAD model. Grids are just the easiest method to explain.

Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East -

http://www.campbellcivil.com

 

[brandonbw]

Is what beej67 said what the poster wants to know?

If you are having trouble reading a grading plan to get cut and fill estimates, I would suggest getting a full plot of a plan. Then draw contours from daylight to daylight in different colored pencils at 1' or less intervals over the entire map. That is a good basic thing to understand when starting out. I am surprised at how many can't do this. Once you are comfortable with that you can take a planimeter to get the cut and fill between the existing and proposed contours you just drew. There is an equation to use which I can't remember off the top of my head that you plug into a spreadsheet and that's another way to get the cut and fill numbers. Then you get to deal with shrinkage and bulkage.

We get the numbers on our plans basically for bonding purposes, and we want the contractor to verify our numbers on larger jobs.

I think this is faster drawing a 3D model and using Land to get the numbers. But you need to learn to do this by hand before you can understand what is going into the computer.

I actually thought Ron gave a good comment. We all have run into people doing things that are way outside of their scope, and it becomes annoying what can happen as the project progresses. There is no fast way to learn how to do some of this stuff, and that's what his tone sounded like to me.

B+W Engineering and Design
Los Angeles Civil Engineer and Structural Engineer

http://bwengr.com

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http://bwstructuralengineer.com

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http://bwcivilengineer.com

 

[chicopee]

Better, courses in surveying will cover cuts and fills, so, see which local college or university offer such program. Another route is if you know AutoCad and you are capable of doing 3D drawings, you can determine these quantities.

 

[Dozerman56]

Nunley: I'm with BeeJ. Anyone that passed 7th grade math can do an earthwork takeoff. It's a question of methodology and tolerance. I use Agtek now, but 30 years ago I used a mylar sheet with a 1" grid on it. Lay it over your grading plan, mark some reference points. Go to the center of each grid. Look at the proposed contour and the existing contour. Make adjustments for stripping depth and pavement or building section. Mark each grid as you go along, either C4', F6', whatever. Then do the math. Simple.

 

[LincolnPE]

Instead of the Grid method your site may lend itself better to creating Sections and computing volumes with the Average End Area method.

 

[SoftEarth]

Nunleyinc,

The Construction Estimating Institute offers a "home study" course (ideal if you have a 3-year-old in your lap) for civil plan reading at this link:

http://www.estimating.org/components.php?id=35&course=14.

This is not an endorsement ... I've never taken any of their courses and I don't personally know anyone that has, but the outfit has been around for years so I thought I would bring it to your attention.

Hope that helps.

Michael E. Cope
Authorized AGTEK Software Training

http://www.EarthworkSoftwareServices.com