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Summary
How to calculate the amount of dirt youll have to move and the cost of owning and operating the machines youll do it with. Detailed, step-by-step instructions on how to assign bid prices to each part of the job, including labor and equipment costs. Also, the best ways to set up an organized and logical estimating system, take off from contour maps, estimate quantities in irregular areas, and figure your overhead.
Estimating excavation is hard - don't let anyone tell you otherwise. First, you're dealing with material that's largely hidden from view. You don't know what's down there until you start digging. Second, you're dependent on costly machines that can break down at any time. Third, your production depends on the employees who operate the machines - employees whose performance can change from day to day - even hour to hour. But there are techniques you can use to minimize those risks - and maximize your chances of making a decent profit from any job you estimate.
That's the purpose of this manual. It shows you, in simple, easy-to-understand language, how to calculate the amount of dirt you'll have to move, the cost of owning and operating the machines you'll do it with, and finally, how to assign bid prices to each part of the job.
The heart of every earthwork estimate is calculating the cubic yards you'll have to move. This book covers quantity estimating in detail, then explains how to assign labor and equipment costs per yard:
How to set up and use an organized and logical
How to get the information you need estimating
system from contour maps
How to read plans and specs
When you have to undercut
Why a site visit is mandatory
Dealing with irregular regions and odd areas
How to assess accessibility and job difficulty
Factors for estimating swell and shrinkage
How soil characteristics can affect your estimate
Balancing the job: spoil and borrow
The best ways to evaluate subsurface conditions
Calculating machine owning & operating costs
Figuring your overhead
The two common methods of estimating earthwork
quantities
Of course, some of the quantity estimating methods are complex, but, using clear, detailed illustrations and examples, the author makes it easy to follow and duplicate his system. The book ends with a complete sample estimate, from the take-off to completing the bid sheet.
The Author:
Deryl Burch has worked over 25 years in the construction industry, starting out as a laborer learning on the jobsite and progressing until he was estimating jobs ranging from single-family homes to major highway and utility projects.
Besides being a partner and estimator in an engineering consulting company, he has prepared estimates and bid jobs for the firm of Howard, Needles, Tammen & Bergendorf, one of the largest construction consulting firms in the world; for the Missouri State Highway Department, for the City of Fayetteville, Arkansas, and for Marion County, Kansas. |
Table of Contents
1 Get Started Right, 5
Why calculate quantities? 6
Reading plans and specifications, 8
Accuracy is essential, 10
Record keeping, 14
2 The Site Visit, 17
Review the plans first, 17
Make the visit productive, 18
Site visit for a sample project, 24
3 Properties of Soils, 31
Soil testing, 31
Soil classifications, 31
Soil characteristics, 34
4 Area Take-off by Plan and Profile, 41
Cut and fill sections, 42
Understanding surveys, 43
End area calculations, 47
Calculating the volume, 54
5 Reading Contour Maps, 61
Planimetric and topographic maps, 61
Understanding contour lines, 62
Locating unmarked points, 66
Monuments and bench marks, 67
6 Area Take-off from a Topo Map, 71
Comparing the contour lines, 71
Estimating with a grid system, 72
Doing the take-off, 75
Calculating cut and fill areas, 80
Using worksheets in a take-off, 85
Shortcuts for calculating quantities, 91
The equal depth contour method, 99
7 Irregular Regions & Cold Areas, 103
Finding area using compensating lines, 104
Finding volume using total area and average depth, 109
Using compensating lines with a coordinate system, 110
Using the trapezoidal rule, 117
8 Using Shrink & Swell Factors, 127
Soil states and their units of measure, 127
Using shrink/swell factors in earthwork estimates, 128
Estimating the number of haul trips, 130
Using material weights to customize shrink/swell factors, 131
Using soil weights to calculate equipment load factors, 131
Pay yards, 133
9 Topsoil, Slopes & Ditches, 135
Dealing with topsoil, 135
Calculating net volumes for earthwork 139
Slopes and slope lines, 142
Estimating trenches, 147
10 Basements, Footings, 155
Grade Beams & Piers, 155
Estimating basement excavation quantities, 155
Finding volume - outside basement walls, 157
Calculating the total volume for basement excavation, 164
Sample basement estimate, 170
Estimating ramps, 175
Grade beams and piers, 178
11 All About Spoil and Borrow, 181
Underlying costs of spoil and borrow, 181
Spoil and borrow volume calculations, 183
Calculating the volume of a stockpile, 184
Finding the volume for a stockpile of unknown height, 186
Calculating volume for a stockpile of set area, 190
12 Balance Points, Centers of Mass & Haul Distances, 195
Balance points to an excavation estimator, 195
Balance points to an engineer, 196
Reducing haul distances, 197
Calculating -haul distances, 200
13 Earthmoving Equipment: Productivity Rates and
Owning & Operating Costs, 209
Machine power, 210
Machine speed, 214
Machine production, 218
Productivity calculations for a simple dirt job, 221
Owning and operating costs, 230
Calculating the overhead, 234
Adding the profit, 237
Bid price per cubic yard, 237
14 A Sample Take-off, 239
General specifications, 240
Doing the take-off, 242
15 Costs and Final Bid for the Sample Estimate, 335
The bid preparation process, 336
Overhead, 340
Machine selection, 340
Blank Worksheets, 434
Grid square area and volume, 435
Grid take-off - existing contour, 436
Grid take-off - proposed contour, 437
Grid square calculation sheet, 438
Cut and fill prism calculations, 439
Quantities take-off sheet, 440
Index, 441 |
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