Excavation & Grading Handbook Revised
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Chapter One

Understanding Road Survey Stakes

This manual is a practical guide to excavation and grading. It's written for anyone who has to plan, estimate or supervise excavation and compaction for building sites, highways, drainage channels or trenching. It also covers installation of water, sewer and drain pipe and the laying of asphalt concrete pavement.

The first edition of this manual was published in 1978. Since then the book has gone through five printings and has been adopted as the primary reference by many schools and in many apprentice training programs. This second edition reflects the changes we've seen in the excavation business since the mid-1970's. Equipment has changed, materials have changed and the best way of getting the job done has changed. I had to make changes in every chapter of the first edition to be sure this second edition describes good current practice for excavation and grading contractors. In many cases I'm indebted to readers of the first edition who made suggestions for improvements or recommended alternate procedures. This second edition also includes new chapters on using contour line drawings to control excavation, using laser levels, and trench compaction.

I'm going to start by assuming that you're new to excavation and grading. The first three chapters cover the basics: reading and following survey stakes, understanding excavation plans and how excavation contractors use contour line drawings. If you've been working in the excavation and grading business for a while, you'll probably be able to skip the first few chapters. But if you need information on plan reading and stake markings, it's here for your use.

Now, let's get started at the beginning, reading and following survey stakes.

Survey Stakes

Excavation for roads, buildings and pipelines begins with a survey of the area where the excavation will be done. A survey crew working for the engineering firm that's designing the project will set out stakes and hubs which identify points that are on the construction plans. When a precise distance or elevation is needed, a surveyor's tack on top of the hub establishes the point from which elevations and distances are measured.

Beside each hub there will be an information stake which explains in surveyor's code the grades at various distances from the hub or other reference stake or point. It's essential that you know how to read the markings on these information stakes and follow the instructions they provide.

Figure 1-1 shows the kind of markings you'll find on an information stake. Usually these are called cut or fill stakes, depending on the type of excavation required. The front, back and both sides of a cut stake are shown in Figure 1-1. Below the stake there's a cross section drawing of the existing grade and final road grades that are described on the stake. This drawing will help you understand the markings on the stake. Refer to the drawing as I explain the markings on the information stake in Figure 1-1.

Figure 1-1
Cut Stake Reading

Cut Stakes

Look first at the stake labeled front in the upper left of Figure 1-1. That's the front of the information stake. The RS at the top of the stake means that there's a reference stake to be established, and that reference stake is the point from which measurements and elevations are taken. Find the reference stake in the drawing. It's labeled RS and is just to the left of the hub at the right edge. Below the letters RS on the stake, you see the letter C and a dash followed by some numbers. Below that you see a diagonal line and some more numbers. These markings above and below the diagonal line identify the amount of cut and distance needed to establish the correct grade at the reference stake. The number above the line is the elevation and the number below the line is the distance. In this case, the reference stake shows a cut 1 foot and zero tenths of a foot below the level of the surveyor's hub, 5 feet and zero tenths of a foot from the hub.

Some surveyors may use RP instead of RS. RP means reference point. Treat it exactly the same as the RS.

Notice that distances and elevations are measured in feet and tenths (or hundredths) of a foot, not feet and inches. The small number above the small horizontal line shows decimals of a foot. That's a little different from what you're probably used to, but you'll appreciate the difference when adding and subtracting feet and decimals of a foot rather than feet, inches and fractions of an inch. I'll explain more about this measuring system, called engineer's measure, later in this chapter.

The two horizontal lines below the first set of measurements are very important. All measurements above the double horizontal line are taken from the hub beside the information stake. The double horizontal line means and then, indicating that all measurements and elevations from that point down on the stake are taken from the RS point and not the hub. Note this very carefully: if the double horizontal line were replaced with a single horizontal line, all measurements and elevations would be taken from the surveyor's hub rather than a reference stake established. The next information on this stake shows the elevation and location of the ditch cut. It's to be 10 feet lower than the RS point and 20 feet from it. The grade falls 10 feet over a horizontal distance of 20 feet, thus creating a 2:1 slope. You'll see this indicated on the drawing. For every foot of cut, the grade line moves horizontally 2 feet.

Notice that all measurements are made from the reference stake. The ditch is cut 10 feet below the reference stake and 20 feet from that stake. Also note that the 20 foot distance is measured horizontally, not diagonally, from the reference stake. Glance at the drawing to be sure you understand how the 20 foot distance to the ditch is measured.

The next reading is the hinge point (HP) grade and distance. Note the hinge point on Figure 1-1. It's cut 2 feet above the ditch cut. The HP information indicates the grade must come up 2 feet and move out 4 feet. By computing the amount the HP rises from the ditch and the distance it moves towards the center of the road, you can see that it's again a 2:1 slope. Reading down the information stake, the next grade and distance is the edge of pavement (EP) point. The grade will be 7.9 feet below the reference stake. Notice the cut at EP is 0.10-foot less than the HP. The reason for this is that the road grade rises 2% in the 5 feet from HP to EP. Multiplying 5 feet by 2% gives the amount the shoulder rises in that distance (5.00 x .02 = .10).

The next markings give the centerline cut. You can see that the cut is again less than the previous cut at EP. Subtracting the 29 feet at EP from the 49 feet to the centerline leaves 20 feet. So the centerline is 49 feet from RS and 20 feet from EP. The cut at the centerline is 0.40 foot higher than EP, giving a 2% slope from the centerline to EP. This is computed by multiplying the 20 feet by 2% (20.00 x .02 = .40).

Look at the back of the cut stake. It's marked 3 + 50, indicating that this station is 350 feet from station 0 + 00, the point from which the survey began. Below the station number is the distance from the surveyor's hub to the center of the road. This includes 5 feet to the RS and 49 feet from the RS to the centerline, a total of 54 feet.

Now note the first stake marked side. This side of the stake identifies the percentage of slope from the centerline to HP. The minus sign indicates that the centerline slopes down to the HP. If it were a plus sign instead, the centerline would be sloping up to the HP. The second stake marked side first gives the rate the cut slope falls from RS to the ditch. In this case, it is 2 feet out for every foot downward. The second group of numbers is the elevation of the hub above sea level.

Figure 1-2
Comparing Inches and
Decimals of a Foot

Comparison of inches and decimals of a foot- Notice that all measurements are in feet and tenths of a foot rather than feet and inches. Setting grades requires many additions and subtractions. Using decimals speeds the work and makes errors less likely. Figure 1-2 compares inches with decimals of a foot.

If you're uncomfortable reading distances in tenths and hundredths of a foot, think of one foot as being like a dollar bill. One dollar is the same value as 100 pennies; one foot is the same distance as 100 hundredths of a foot. One dollar is the same value as 10 dimes; a foot is the same distance as 10 tenths of a foot. Pennies are hundredths. Dimes are tenths or ten hundredths.

Fill Stakes

Figure 1-1 shows a cut stake where material must be excavated to reduce the existing grade to the finish grade. Figure 1-3 shows a typical fill situation where soil has to be deposited to build up the existing grade. Again, the illustration shows four sides of the stake and the road cross section. The RS means that the reference stake (to the right of the hub) is the starting point and the place from which all measurements and grades are measured. The cuts and fills given for the RS point will be measured from the hub. Here, the RS is located 1.8 feet above the hub and 3 feet from it. The grade setter will have to set the reference stake the indicated horizontal distance from the hub and draw a horizontal line on the stake at the elevation given on the surveyor's information stake. Or he may elect to place his own hub there.

Reading down the stake, the two horizontal lines mean and then, indicating that the grade setter must measure from the RS point for the next fill and distance given instead of measuring or shooting grades from the original hub. For the hinge point (HP), measure 10 feet from the RS hub or lath. At this point a fill of 5 feet must be made to obtain the required grade. The hinge point is the place where the fill slope stops and the road grade begins. It's sometimes called the catch point. Next, reading down the stake, is the EP. This is the edge of the pavement and has a F-5.12 fill 14.0 feet from RS.

Below the EP data is PG. This is the projected centerline grade. In most cases, the surveyors will mark it as the centerline and not PG. From the RS, measure 32 feet and fill 5.66 feet. This will put the PG or centerline 18 feet from the EP and 0.54 of a foot higher.

Figure 1-3
Fill Stake Reading

The stake marked back has a 25 and a little worm line standing for + 00. Some jobs might have an A, B, C line with one being at the centerline. Check the plans to learn what these lines mean. The 25 + 00 identifies this stake as being 2,500 feet down the line from the point where the measurements started. The point the surveyors start from is most likely marked 0 + 00, but may not be in all cases.

Next, reading down, notice a C and an L, one over the other. This means centerline. The number 35 below that means that the center of the road is 35 feet from that point. Look back to the stake marked front and notice that when the RS distance of 3 feet is added to the PG distance of 32 feet, the total is 35 feet, the same distance as marked on the back.

The stake labeled side is marked SE-3.00%. This is the percentage that the road bed slopes from the centerline to the hinge point. On the far right stake marked side. the first reading is 2:1 (two to one). This is the rate the fill slope will rise from RS to HP. Notice that the first stake has a 5 foot fill over a 10 foot distance. This is what the 2:1 indicates. The next item down the stake is EL 96.6. This is the elevation of the hub at the information stake. All cuts or fills were computed from that hub by the surveyors.

What I've described so far in this chapter is more or less standard procedure for indicating elevations and distances on road stakes. However, surveyors in some counties and cities follow slightly different procedures. Some surveyors provide more information on the stakes. The stakes in Figure 1-4 show what you might see on some county or city road stakes.

The top of the stake has a 2 with a circle around it. This indicates that the first cut starts 2 feet out. The next markings indicate that the cut is 4 feet at 10 feet from the stake. The slope will again be 2:1 because the first 2 feet are not cut and the cut over the next 8 feet is 4 feet. Look at Figure 1-4 again. Notice that there is no double and then line. This means that you must take all measurements and grade shots from the hub set by the surveyors rather than from an RS or RP point as on the previous stakes shown.

Reading down the stake at the left in Figure 1-4, we find a second group of numbers that shows the top of the shoulder cut. This was referred to as the HP, or hinge point, on previous stakes. Notice there's no EP distance or elevation on the stake. In this case, you must look at the plans for the distance from shoulder to edge of pavement, and the elevation.

Engineering companies follow different conventions when marking their stakes. But the plans should clarify what is intended and which points are actually indicated. If something isn't clear, don't guess. Call the engineering company that created the drawing and marked the stakes. They should be eager to help.

The second illustration in Figure 1-4 is the back of the stake. It shows the rate of fall of the cut slope (2:1) and the station number (8 + 00). The far right illustration is the side of the stake. It gives the elevation above sea level (EL 82.56). In some cases the hub elevation will not be on the stake at all. It may be replaced with the percentage of slope on the road or both may be omitted entirely. The back of the stake in Figure 1-4 will still have the station number but no centerline distance because all the front measurements are from the hub and not an RS or RP point.

Many stakes have very little information. They have just the details required to allow you to set the grades. These stakes always have the station number on the back, though the percentage of slope and hub elevation may be absent.

Miscellaneous Information Stakes

Curb stake- Note Figure 1-5. The stake at the left is what you'd expect the surveyor to set for cutting and setting curb grades. From the hub at the base of this information stake, move out 5 feet and down 1.50 feet to the top of the curb to set the curb forms.

In some cases, the surveyors will give the front lip grade or even the flow line grade. If not, you 'II have to determine the distance from the back of the curb to the lip. This information is available in the plans. When setting curb subgrade, determine the thickness of the curb plus any aggregate base, if it's called for under the curb. The thickness of one or both must be added to the cuts and subtracted from the fills to find the subgrade rather than the finished grade level.

Street stake- The center stake in Figure 1-5 is a stake you would expect to find in a subdivision for the first road cut. The front of the stake indicates the centerline of the street, and the cut or fill to the finished grade. In this case, there's a 2 foot cut to the finished grade (F.G.). The plans should show the road width, percentage of slope or crown, and the thickness of the road section. Remember to add the thickness of the road to this cut. The station number will be on the back of the street stake.

Ditch channel stake- The stake at the far right in Figure 1-5 is a grade stake for a ditch or small channel. The 3 in a circle is the distance from the hub where the first cut starts. The west toe grade indicates the first slope and the bottom of that slope. The east toe is the bottom of the slope on the opposite side of the ditch. Both toe cuts are the same, so the bottom is flat. The east top cut is where the cut will be started on the opposite side. Subtracting the 3 foot offset from the 23 feet distance to the east top cut gives the distance across the top of the ditch, 20 feet. Subtract the small toe distance from the larger. This gives the width of the ditch bottom, 4 feet.

To find the rate of slope from the top cut to the toe of the channel, subtract the distance given to the top cut from the distance given to the toe cut. The 3-foot offset must be subtracted from the west side distance of 11 feet. This will make the distance 8 feet from top cut to toe on each side. Dividing the cut of 8 feet into the 8 foot horizontal distance gives an answer of 1. This indicates that for every foot cut vertically, the slope moves out 1 foot horizontally. That's a 1:1 slope.

A stake with only a few markings will usually provide all the information you need to do the excavation. If something is still unclear, the plans should have the answer you're looking for.

In this chapter we've described grades by either a ratio of run to rise, or as a percent above the horizontal. Most grades in excavation work are expressed as a ratio of horizontal distance (run) to vertical distance (rise). Figure 1-6 illustrates the four most common slope rations, and should help you visualize most of the slopes you work with in excavation.

If you’re still confused about the work required after reading the surveyor’s stakes and checking the plans, ask the survey crew about it if they’re still on the job.  If they’ve left, call the engineer and have him clarify the problem or send the survey crew out for a field meeting. Be sure you know what’s required before beginning the work.

Figure 1-6
Slopes 1:1 to 4:1

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